Effects of milk replacer powder added to pasteurized whole milk over different durations on dairy calves fed ground starter diet with alfalfa hay

Adding milk replacer powder (MRP) to whole milk during the entire preweaning period can increase growth but raises concern because of low starter feed intake and slumps in average daily gain (ADG) at weaning and postweaning. In the current study, effects of adding MRP to pasteurized whole milk (PWM) during d 10-41 or d 10-59 of age were investigated in comparison with PWM. Calves [24 females and 21 males; 39.8 ± 1.85 kg body weight (BW)] were randomly allocated to 1 of 3 treatments: 1) conventional protocol, 5 L/d PWM from d 3-56, and 2.5 L/d from d 57-59 of age (CONV; TS intake = 31.9 kg), 2) short duration of adding MRP to PWM protocol, 5 L/d PWM from d 3-9, 5 L/d PWM + MRP (18% TS) from d 10-41, 5 L/d PWM from d 42-56, and 2.5 L/d PWM from d 57-59 (SD; TS intake = 42.3 kg), 3) long duration of adding MRP to PWM protocol, 5 L/d PWM from d 3-9, 5 L/d PWM + MRP from d 10-56, 2.5 L/d PWM + MRP form d 57-59 (LD; TS intake = 47.7 kg). The osmolality of PWM and PWM + MRP was 278 and 519 mOsm/L, respectively. Calves were weaned on d 60, and the study terminated on d 75. There was a treatment × time interaction for starter intake, where intake was greater for CONV than other treatments from d 14-41 and was greater in CONV than LD during d 42-48 and d 56-62 of age. Final BW was lower in CONV calves than LD calves. Weaning BW and overall hip height were lower in CONV calves than other treatments. The CONV calves had lower ADG at d 14-27 and 35-41 and SD calves had lower ADG at d 42-48 than other treatments. Calves fed CONV treatment had lower ruminal acetate and greater propionate than SD calves during preweaning. Calves fed LD treatment had lower total volatile fatty acids and tended to have greater ruminal pH than other treatments. Calves fed CONV had greater neutrophils and neutrophils/lymphocytes ratio and lower lymphocytes than other treatments. Glucose concentration was greater for LD versus other treatments at d 56, and lower for SD versus other treatments at d 70 of study. Insulin concentration and homeostatic model assessment of insulin resistance index were greater in LD compared with other treatments during preweaning but were not different postweaning. Serum BHB was greater in CONV than other treatments. Albumin was greater for CONV versus other treatments at d 56, however, it was greater in LD-fed calves at d 70 of study. Results indicate that feeding a PWM + MRP to the calves during the entire preweaning period resulted in lower starter feed intake around weaning, but overall starter intake was similar with a greater final BW and fewer health related issues throughout the study. Shifting a PWM + MRP to the conventional whole milk at d 40 of age decreased the ADG of calves.

Effects of complete substitution of dietary grain and protein sources with by-products on the production performance of mid-lactation dairy cows fed diets based on barley silage under heat-stress conditions

This study evaluated the effects of replacing cereal grains and soybean meal with by-products (BY) on production performance, nutrient digestibility, ruminal fermentation, nutrient recovery, and eating and chewing behavior of moderate-producing dairy cows under heat-stress conditions. Twelve multiparous Holstein cows (116.7 ± 12.01 d in milk; 42.7 ± 5.06 kg/d milk yield; 665 ± 77 kg body weight; mean ± SD) were used in a replicated 3 × 3 Latin square with 28-d periods (21 d for diet adaptation and 7 d for sampling and data collection). Cows were fed a total mixed ration containing a 39.2:60.8 ratio of forage to concentrate throughout the experiment. All diets were formulated to be isoenergetic and isonitrogenous, with different concentrates. Diets were (1) control diet based on cereal grains (CON: ground corn and ground barley, plus soybean meal); (2) sugar-rich BY diet (S-BY-CM: beet pulp, citrus pulp, and liquid molasses, plus canola meal); and (3) cereal grain BY diet (CG-BY: rice bran, corn germ meal, wheat bran, barley sprout, and broken corn). Our results showed that replacing grains with BY increased neutral detergent fiber intake and digestibility but decreased starch intake, human-edible energy, and human-edible protein. Milk yield and dry matter intake (DMI) decreased more in cows fed the CG-BY diet compared with the other 2 treatments. In contrast, no significant differences were observed between the CON and S-BY-CM diets in terms of milk yield and DMI. The S-BY-CM diet increased energy-corrected milk production compared with the CG-BY diet (36.2 vs. 34.3 kg/d), but CG-BY enhanced feed conversion efficiency compared with the other 2 treatments. Although the S-BY-CM diet prolonged the eating and sorting of small particles, neither of the dietary treatments affected chewing activity or ruminal pH 4 h after feeding. Furthermore, both diets containing BY contributed to an increase in milk fat content in comparison to the CON group. Additionally, the CG-BY and S-BY-CM diets demonstrated better performance than the CON diet in terms of human-edible feed conversion efficiency for protein and energy. The results indicated that S-BY-CM can completely replace barley and corn grain in the diet of mid-lactating dairy cows exposed to heat-stress conditions without any negative effect on production and ruminal pH. However, the inclusion of CG-BY did impair DMI, milk yield, and digestibility of nutrients and is not recommended during heat-stress conditions.

In vitro addition of epinephrine, norepinephrine, and carnitine alters palmitate oxidation and esterification in isolated ovine hepatocytes

Hepatocytes from 4 wethers were used to study the effects of carnitine and increasing concentrations of epinephrine and norepinephrine on palmitate oxidation and esterification. Liver cells were isolated from the wethers and incubated in Krebs-Ringer bicarbonate buffer with 1 mM [¹⁴C]-palmitate. Radiolabel incorporation was measured in CO₂, acid-soluble products, and esterified products, including triglyceride, diglyceride, and cholesterol esters. Carnitine increased production of CO₂ and acid-soluble products from palmitate by 41% and 216%, respectively, but had no effect on conversion of palmitate to esterified products. Epinephrine had a quadratic-increasing effect on palmitate oxidation to CO₂, but norepinephrine did not increase palmitate oxidation to CO₂. Neither epinephrine nor norepinephrine affected the production of acid-soluble products from palmitate. Increasing concentrations of norepinephrine and epinephrine linearly increased rates of triglyceride formation from palmitate. Increasing norepinephrine concentrations linearly increased diglyceride and cholesterol ester formation from palmitate in the presence of carnitine; epinephrine did not affect diglyceride or cholesterol ester formation. In general, catecholamine treatment had the greatest effect on the formation of esterified products from palmitate, and effects of norepinephrine were more pronounced than epinephrine. Conditions that result in catecholamine release might lead to fat accumulation in liver.

Milk triglycerides from dairy cows abomasally infused with increasing amounts of high-oleic sunflower fatty acids

The triglyceride composition of milk fat largely determines the manufacturing characteristics of products containing milk fat. Increasing oleic acid content of milk fat might be desirable for human nutrition and also for butter and whipping cream, among other product applications. The objective of this research was to determine the effects of increasing intestinally available oleic acid (provided via abomasal infusion) on the profile of milk triglycerides. A control and 4 increasing doses of free fatty acids from high oleic sunflower oil (HOSFA) were infused into the abomasum of 4 lactating dairy cows in a changeover experimental design with periods of 7 d. Treatments were (1) control (no fatty acids infused), (2) HOSFA (250 g/d), (3) HOSFA (500 g/d), (4) HOSFA (750 g/d), and (5) HOSFA (1,000 g/d). All treatments included meat solubles and Tween 80 as emulsifiers. Infusion of HOSFA increased oleic acid and decreased short- and medium-chain fatty acids in milk fat. Statistical analysis of results showed linear changes in most of the milk triglycerides analyzed. The most significant changes as the result of increasing HOSFA infusion were a decrease in triglycerides with saturated fatty acids (butyrin-caprylin-palmitin, butyrin-laurin-olein, butyrin-myristin-palmitin, butyrin-palmitin-palmitin, caproin-myristin-palmitin, butyrin-palmitin-stearin, caproin-palmitin-palmitin) and an increase in dioleyl triglycerides (with butyric, lauric, myristic and palmitic acids) and triolein. The synthesis of triglyceride is position-specific and does not follow a random distribution model.

Effects of prepartum supplementation of β-carotene on colostrum and calves

Little is known about transfer of dietary β-carotene into colostrum, its absorption by the calf, and its effects on retinol and α-tocopherol in the calf when the dam's dietary vitamin A is adequate. Our objective was to assess the effect of β-carotene supplementation during the close-up dry period on the colostrum and calf. The study was conducted on a large commercial dairy farm in Indiana during early summer of 2015. Ninety-four multiparous Holstein cows were blocked by calving data, parity, and previous production, and then randomly assigned to either control or β-carotene (BC) treatments. While locked in headgates each morning, each cow received a topdress of β-carotene (Rovimix, DSM Nutritional Products, 8 g/d; provided 800 mg β-carotene) or carrier from 21 d before expected calving until calving. Colostrum was collected within 2 h of parturition. Calf blood samples were obtained within 2 h of birth before receiving the dam's colostrum, at 24 h after birth, and at 7 d and 60 d of age. Blood serum was analyzed for β-carotene, retinol, α-tocopherol, and other metabolites and enzymes. Colostrum was analyzed for β-carotene, retinol, α-tocopherol, colorimetry profile, and milk components. Data were analyzed using mixed-effects models in SAS (SAS Institute Inc.). Calf serum β-carotene data were analyzed using the FREQ procedure. Colostrum β-carotene was higher for BC cows. Colostrum from BC cows had increased a* [measures red (positive) to green (negative)] and b* [measures yellow (positive) to blue (negative)] colorimeter values, indicating that β-carotene altered colostrum color toward red and yellow. Supplementation did not affect colostral or calf IgG concentrations. Colostrum color indices were correlated with IgG concentrations as well as concentrations of β-carotene, retinol, and α-tocopherol. Before receiving colostrum, the concentration of β-carotene in calf serum was below the detectable threshold of 0.05 μg/mL. At 24 h of age, the number of calves with detectable β-carotene concentrations increased, with more calves from BC cows (52.1%) having detectable concentrations than calves from cows in the control group (6.1%). No differences in concentrations of retinol or α-tocopherol were observed in calf serum. Supplementation of β-carotene to cows decreased activities of gamma-glutamyl transpeptidase and glutamate dehydrogenase in calf serum. In pregnant cows already receiving adequate vitamin A, supplementation of β-carotene increased concentration of β-carotene in colostrum, altered colostrum color, and increased serum β-carotene in calves at birth.

Prepartum dietary energy intake alters hepatic expression of genes related to peroxisome proliferator-activated receptor and inflammation in peripartal dairy cows

We determined the effect of prepartum plane of energy intake on liver function and metabolism pre- and postpartum by combining in vivo and in vitro data with mRNA expression data. A subset of multiparous prepartal Holsteins (n = 18) from a previously conducted experiment consumed 1 of 3 amounts of dietary energy intake, relative to their requirements. A diet formulated to allow consumption of ≥150% of net energy requirements during the far-off dry period and the close-up dry period was fed for ad libitum intake (150E) or in restricted amounts so that cows consumed 80% of requirements for energy (80E). A second diet was formulated to include wheat straw (26.1% of dry matter) to limit energy intake to 100% of NRC (2001) requirements for energy when fed ad libitum during the far-off period (100E). In the close-up period, 100E was fed the 150E diet for ad libitum intake. Expression of mRNA for genes related to fatty acid oxidation (PPARA, CPT1A, ACOX1) was greater for 100E cows than 150E cows on d 14 postpartum. These expression patterns were related to in vitro data for conversion of palmitate to CO₂, acid-soluble products, and esterified products by liver slices. Abundance of mRNA for PC displayed a sharp peak for all groups on d 1 postpartum, but serum glucose did not reflect this peak. The mRNA expression of SREBF1 was greater for 150E and 100E cows prepartum compared with 80E, and was positively related to rate of palmitate esterification postpartum. Expression of NR1H3 (LXRA) mRNA was greater for 100E cows on d 14 postpartum compared with 150E cows, which corresponded to expression of PPARA. An inflammatory response occurred in the liver around the time of parturition for 150E cows, as expression of IL1B was elevated both pre- and postpartum compared with 100E cows. The spike in IL1B expression for 150E cows on d 14 postpartum corresponded to the peak concentration of total lipids in liver tissue for all groups in this experiment. Overconsumption of energy prepartum was detrimental to the expression of important genes related to PPAR and liver function, especially postpartum. Furthermore, results provide evidence for inflammation related to accumulation of lipids in liver and overnutrition prepartum.

Rumen effects of monensin in dry cow diets varying in energy density

Controversy has existed as to whether monensin will provide equal or differential benefits in a higher-energy, lower-roughage close-up diet versus a higher-roughage, lower-energy diet. Our objective was to determine the rumen effects of a controlled-energy, high-fiber diet balanced to meet but not greatly exceed energy requirements during the dry period or a traditional 2-group approach of higher-energy close-up diet. The effects of added monensin in each diet type were determined. Multiparous Holstein cows (n = 17) were fitted surgically with ruminal cannulas. During the first 4 wk of the dry period, all cows were fed a controlled-energy, high-fiber diet (CE) as a total mixed ration for ad libitum intake. During the last 3 wk before calving, half of the cows were switched to a higher-energy, close-up diet until calving (CU), whereas the other half continued to receive the CE diet. Within each dietary group, half of the cows received monensin (MON) supplementation in the diet (24.2 g/t of total dry matter) and half did not (CON). After calving, all cows received the same lactation diet containing monensin (15.4 g/t of dietary dry matter). At 14 d prepartum, dry matter intake was not different across treatments. The weight of rumen contents was greater for cows fed CE. Rumen liquid dilution rate, solids passage rate, pH, total volatile fatty acid (VFA) concentrations, molar proportions of acetate and propionate, and papillae length did not differ among diets. Butyrate percentage tended to be greater for cows fed CE. Postpartum, dry matter intake, mass of rumen contents, solids passage rate, pH, total VFA concentration, molar percentages of propionate and butyrate, and papillae length did not differ among treatments. Liquid dilution rate (16.6, 10.7, 16.0, and 18.2%/h for CE + CON, CE + MON, CU + CON, and CU + MON, respectively) was affected by a diet × monensin interaction. Cows on the CE + CON diet had a greater ruminal proportion of acetate than did cows fed CU + CON, whereas cows fed monensin on either diet were intermediate (diet × monensin interaction). Addition of MON to the CU diet decreased the proportion of propionate (diet × monensin interaction). Cows fed CE had greater mass of rumen contents before parturtition but the high inclusion of wheat straw in the CE diet did not negatively affect rumen papillae length. Monensin inclusion differentially affected liquid passage rate and VFA concentrations.

Feeding corn germ instead of corn grain on the performance of Holstein dairy cows fed low-forage diet and human-edible feed conversion efficiency

Using corn germ (CG) instead of corn grain could maintain dairy cow performance and might increase the efficiency of human food production. The primary objective of this study was to evaluate the effects of replacing corn grain with CG on the performance, nutrient intake, and digestibility of dairy cows. It also aimed to investigate the effect of CG on the efficiency of human food production in high-producing Holstein dairy cows in early lactation. Nine multiparous Holstein cows with 65.6 ± 8.5 DIM, milk yield of 55.6 ± 4.5 kg/d, and body weight of 611.3 ± 43.3 kg (mean ± SD) were used in a 3 × 3 Latin square design with 21-d periods. Treatments were (1) control treatment (CT, diet contains corn grain), (2) alternative treatment (AT, diet where corn grain was replaced with CG), and (3) balanced treatment (BT, diet where corn grain was replaced with CG but with the same energy content as CT). Control and balanced diets were isoenergetic (6.61 MJ/kg of DM); however, AT had higher energy (6.77 MJ/kg of DM). Treatments had no effect on dry and organic matter intake. NDF intake, however, was higher in CG diets compared with CT (P = 0.0001). Total-tract digestibility of DM tended to be reduced (P = 0.08), and OM digestibility was reduced (P = 0.05) by the inclusion of CG in diets. Whole and energy-corrected milk production were greater in AT compared with CT and BT (P < 0.05). Milk yield was similar in cows fed CT and BT. Treatments had no effect on milk composition or feed efficiency. Diet CT, when compared with CG diets, had lower efficiency in terms of human-edible feed conversion efficiency (HeFCE) and net food production (P < 0.05). Diet BT had greater HeFCE and net production of human-edible CP than AT (P < 0.05). Plasma BHBA, non-esterified fatty acids, and glucose concentrations were not affected by treatments, but plasma cholesterol was higher in cows that consumed CG diets (P = 0.04). The results indicate that, in high-producing early lactation dairy cows fed high concentrate diets, net food protein production can be substantially improved without lowering milk production through the reduction of dietary starch from 30.2 to 24.8% by replacing corn grain with CG.

Identification of cow-level risk factors and associations of selected blood macro-minerals at parturition with dystocia and stillbirth in Holstein dairy cows

A deeper understanding of the risk factors for dystocia and stillbirth could help farmers make decisions about dairy cow management. The objectives of this study were to investigate cow-level risk factors associated with dystocia and stillbirth in a relatively large sample of dairy cows using multivariable linear regression models. The data consisted of 51,405 calving records of 14,546 Holstein cows from 3 dairy herds in Isfahan Province, Iran, collected between April 2011 and September 2017. To investigate the association between selected blood macro-minerals and the incidence of dystocia and stillbirth, blood samples were collected at the time of parturition from a random subset of these cows, which included 1311 animals. The incidence of dystocia and stillbirths averaged 14.7% and 4.3%, respectively. Results showed that calving year, calving season, dry period length, BCS, parity, calf sex, calf birth weight, twin status, and stillbirth were significantly associated with the incidence of dystocia. According to the Random Forest (RF) classifier, we found that dry period length, calf birth weight, and parity were the most important cow-level risk factors for the incidence of dystocia. Calving year, calving season, parity, twin status, dry period length, calf birth weight, calf sex, and dystocia were significantly associated with the incidence of stillbirths. The most important risk factors identified by the RF classifier for stillbirths were twin status, parity, dry period length, and calf birth weight. Also, interactions between the cow-level risk factors associated with dystocia and stillbirth were identified. The incidence of dystocia was associated with the interactions of twin status × calf birth weight and twin status × stillbirth. According to our analysis, the incidence of stillbirth is caused by interactions among several factors, such as twin status × length of dry period, twin status × calving season, and twin status × parity. The highest incidence of dystocia (21.3%) and stillbirths (5.4%) was observed in hypo-calcemic cows. In conclusion, twin status seems to be a determining factor for the incidence of stillbirths but not for dystocia. Finally, the results of this study may help the dairy industry make management decisions aimed at reducing dystocia and stillbirth rates.

Performance, structural growth, and digestibility by Holstein calves fed different amounts of milk through step-up/step-down or conventional methods

Early life milk intake can influence the survival and future productivity of replacement heifers. The present study determined the effects of different amounts of milk through step-up/step-down or conventional feeding methods on the performance of dairy calves. Thirty-nine Holstein calves (18 male and 21 female) were used in a completely randomized design. Calves were randomly allocated to 1 of 3 treatments: (1) conventional milk feeding (CONV; 4.5 L/d of milk from d 1 to 50 and 2 L/d of milk at d 51 and 52 of the study; total milk intake = 229 L); (2) low milk intake with step-up/step-down method (L-SUSD, 4 L/d of milk from d 1 to 10, 6 L/d from d 11 to 20, 8 L/d from d 21 to 30, 6 L/d from d 31 to 40, 4 L/d from d 41 to 50, and 2 L/d milk at d 51 and 52 of the study, total milk intake = 284 L); (3) high milk intake with step-up/step-down method (H-SUSD, 6 L/d of milk from d 1 to 10, 8 L/d from d 11 to 20, 10 L/d from d 21 to 30, 8 L/d from d 31 to 40, 6 L/d from d 41 to 50, 4 L/d milk at d 51, and 2 L/d milk at d 52 of the study, total milk intake = 386 L). All calves were weaned at d 52 and followed until d 70. Performance data (every week), skeletal growth (d 52 and 70), and ruminal fermentation parameters and digestibility (d 35, 55, and 70) were analyzed as repeated measurements with PROC MIXED of SAS version 9.3 (SAS Institute Inc.). A treatment × time interaction was observed for total dry matter intake (TDMI) as follows: TDMI differed among all treatments where H-SUSD > L-SUSD > CONV from d 11 to 38 of study, greater for H-SUSD versus other treatments from d 3 to 10 and d 39 to 70 of study. Starter feed intake and average daily gain (ADG) were greater in H-SUSD calves than in CONV calves, and L-SUSD treatment was intermediate for those traits. The H-SUSD calves tended to have greater body weight (BW) and lower feed efficiency than calves fed CONV or L-SUSD treatments. The treatments did not affect structural growth parameters, except for hip width, which tended to be greater in H-SUSD calves than CONV calves. Regardless of treatments, ADG, starter feed intake, BW, and body measurements increased as calves aged, whereas feed efficiency increased from d 1 to 52 of study and decreased from d 52 to 70 of study. The treatments had no effect on digestibility, rumen parameters, or fecal score. Overall, in calves that were weaned at 52 d and fed milk 3 times daily, the high milk intake (386 L) through the SUSD method did not increase diarrhea or decrease digestibility but increased starter feed intake and ADG.

Evaluating the effect of finely ground, dry-rolled, and crumbled corn grain on performance, feeding behavior, and starch digestion in Holstein dairy heifers

Corn processing methods including finely ground (FGC), dry rolled (DRC), and crumbled corn (CRC) were evaluated to determine their effects on average daily gain (ADG), structural growth, starch digestibility, feeding behavior, and blood metabolites of young dairy heifers. In this study, 36 Holstein heifers [91 ± 4 d of age, 105 ± 6.5 kg of body weight (BW); mean ± standard deviation] housed in 9 pens (4 heifers per pen) were fed diets (dry matter basis) containing 20% forage (wheat straw) and 80% corn-based concentrate for 60 d. Pens were randomly assigned to 1 of 3 dietary treatments based on the type of corn grain used for the diets: (1) ground corn (FGC; fine: 1.11 ± 0.52 mm); (2) dry-rolled corn (DRC; 2.30 ± 0.68 mm); and (3) crumbled corn (CRC; 2.54 ± 0.70 mm). Heifers had ad libitum access to diets and water throughout the experiment and the feed intake was measured daily. Animals were weighed at the beginning (91 d of age) and end (151 d of age) of the study. The ADG (kg of BW/d) was calculated at the end of experiment at an individual level. Feeding behavior was recorded based on direct observation by monitoring each heifer every 5 min during a 22-h period at 150 d of age. The CRC and DRC tended to increase feed intake compared with FGC, whereas heifers fed CRC tended to have a greater withers height compared with other treatments. Feed efficiency was not affected; however, ADG and final BW increased in heifers fed the CRC diet compared with other diets. Feeding CRC increased total-tract starch digestibility compared with FGC and DRC diets (97.8 vs. 93.1 and 89.5%, respectively). Compared with FGC diet, feeding DRC and CRC tended to increase rumination time. The molar proportion of propionate was greater, and the molar proportion of acetate and acetate-to-propionate ratio were lower in heifers fed CRC than in those fed DRC. The blood glucose and insulin-like growth factor concentrations increased in heifers fed CRC compared with feeding DRC; however, blood urea concentrations decreased by CRC feeding. In conclusion, thermal processing (CRC diet) improved total-tract starch digestibility, ADG, feed intake, and skeletal growth, but had no effect on feed efficiency during the experimental period. Our results indicated that the thermal processing of corn grain improved growth performance of weaned heifers; however, the performance of heifers over a 60-d period did not differ between mechanical processing methods (grinding and dry rolling).

Effects of prepartum supplementation of β-carotene in Holstein cows

Whether supplemental dietary β-carotene affects periparturient cows and vitamins A and E in cows when dietary vitamin A is adequate remains uncertain. Our objective was to assess the effect of β-carotene supplementation during the close-up dry period in a herd with adequate status of vitamins A and E but low in β-carotene. The study was conducted on a large commercial dairy farm in Indiana during early summer of 2015. Ninety-four multiparous Holstein cows were assigned to either control (CON; n = 47) or β-carotene (BC; n = 47) treatments. When locked in headgates each morning, each cow received a topdress of β-carotene (Rovimix, 8 g/d; provided 800 mg of β-carotene) or carrier from 21 d before expected calving until calving. Blood samples were collected at 21 ± 1 d (mean ± standard deviation) before expected calving (before treatments began), 7 ± 1 d before calving, immediately following parturition, and 7 ± 1 d postpartum. Blood serum was analyzed for vitamins A and E, β-carotene, cholesterol, and other metabolites and enzymes. Data were analyzed using the MIXED procedure in SAS (SAS Institute Inc.). Cows had low β-carotene concentrations (0.85 μg/mL) in blood serum before treatments began. Compared with CON cows, BC cows had higher overall mean concentrations of β-carotene (2.87 μg/mL vs. 0.73 μg/mL) and retinol (165 vs. 143 ng/mL). Cows fed BC had lower α-tocopherol in serum than cows fed CON (2.26 vs. 2.46 µg/mL). Cows fed BC had lower peak milk than cows fed CON (50.9 vs. 55.3), but total lactation milk yield did not differ significantly. No effects of BC were observed on days to conception (100 d) or times bred (2.4). Treatments did not affect incidences of ketosis, retained placenta, displaced abomasum, off feed, lameness, footrot, mastitis, or metritis. In conclusion, in pregnant cows already receiving adequate vitamin A but with low serum β-carotene concentration, supplementation of β-carotene increased concentrations of β-carotene and vitamin A in blood serum, but did not affect production, reproduction, or health.

Metabolic and blood acid-base responses to prepartum dietary cation-anion difference and calcium content in transition dairy cows

Dairy cows commonly undergo negative Ca balance accompanied by hypocalcemia after parturition. A negative dietary cation-anion difference (DCAD) strategy has been used prepartum to improve periparturient Ca homeostasis. Our objective was to determine the influence of a negative DCAD diet with different amounts of dietary Ca on the blood acid-base balance, blood gases, and metabolic adaptation to lactation. Multiparous Holstein cows (n = 81) were blocked into 1 of 3 dietary treatments from 252 d of gestation until parturition: (1) positive DCAD diet and low Ca (CON; containing +6.0 mEq/100 g DM, 0.4% DM Ca); (2) negative DCAD diet and low Ca (ND; -24.0 mEq/100 g DM, 0.4% DM Ca); or (3) negative DCAD diet plus high Ca supplementation (NDCA; -24.1 mEq/100 g DM, 2.0% DM Ca). There were 28, 27, and 26 cows for CON, ND, and NDCA, respectively. Whole blood was sampled at 0, 24, 48, and 96 h after calving for immediate determination of blood acid-base status and blood gases. Serum samples collected at -21, -14, -7, -4, -2, -1, at calving, 1, 2, 4, 7, 14, 21, and 28 d relative to parturition were analyzed for metabolic components. Results indicated that cows fed ND or NDCA had lower blood pH at calving but greater pH at 24 h after calving compared with CON. Blood bicarbonate, base excess, and total CO₂ (tCO₂) concentrations of cows in ND and NDCA groups were less than those of cows in CON at calving but became greater from 24 to 96 h postpartum. The NDCA cows had lower blood bicarbonate, base excess, and tCO₂ at 48 h and greater partial pressure of oxygen after calving compared with ND. Cows fed ND or NDCA diets had lower serum glucose concentrations than CON cows before calving but no differences were observed postpartum. Serum concentrations of total protein and albumin were greater prepartum for cows in ND and NDCA groups than for those in CON. Postpartum serum urea N and albumin concentrations tended to be higher for ND and NDCA cows. Cows fed ND or NDCA diets had elevated serum total cholesterol concentration prepartum. During the postpartum period, triglycerides and NEFA of cows fed ND or NDCA diets tended to be lower than those of CON. Cows fed the NDCA diet had greater postpartum total cholesterol in serum and lower NEFA concentration at calving than ND. In conclusion, feeding a prepartum negative DCAD diet altered blood acid-base balance and induced metabolic acidosis at calving, and improved protein and lipid metabolism. Supplementation of high Ca in the negative DCAD diet prepartum was more favorable to metabolic adaptation to lactation in dairy cows than the negative DCAD diet with low Ca.

Feeding rumen-protected lysine to dairy cows prepartum improves performance and health of their calves

Providing adequate concentrations of AA in the prepartum diet is pivotal for the cow's health and performance. However, less is known about the potential in utero effects of particular AA on early-life performance of calves. This experiment was conducted to determine the effects on dairy calves when their dams were fed rumen-protected lysine (RPL; AjiPro-L Generation 3, Ajinomoto Heartland Inc.; 0.54% dry matter of total mixed ration as top dress) from 26 ± 4.6 d (mean ± standard deviation) before calving until calving. Seventy-eight male (M) and female (F) Holstein calves were assigned to 2 treatments based on their dams' prepartum treatment, RPL supplementation (PRE-L) or without RPL (CON). At the time of birth (0.5-2 h after calving), before colostrum was fed, blood samples were collected. An initial body weight was obtained at 1 to 3 h after birth. Calves were fed 470 g of colostrum replacer (Land O'Lakes Bovine IgG Colostrum Replacer, Land O'Lakes, Inc.) diluted in 3.8 L of water. Calves were provided water ad libitum and fed milk replacer (Advance Excelerate, Milk Specialties Global Animal Nutrition; 28.5% crude protein, 15% fat) at 0600 h and 1700 h until 42 d of age. Calves were measured weekly, at weaning (d 42), and at the end of the experimental period (d 56). Plasma concentrations of AA were measured on d 0, 7, and 14 d using ultra-performance liquid chromatography-mass spectrometry (Waters) with a derivatization method (AccQ-Tag Derivatization). Final body weight was greater for M (87 ± 11 kg) than F (79 ± 7 kg). Calves in PRE-L tended to have greater dry matter (814 ± 3 g/d) and crude protein (234 ± 6 g/d) intakes than those in CON (793 ± 9 g/d and 228 ± 11 g/d, respectively). Calves in PRE-L had greater average daily gain (0.96 ± 0.04 kg/d) than calves in CON (0.85 ± 0.03 kg/d) during wk 6 to 8. Calves in PRE-L tended to be medicated fewer days than CON (4.7 ± 1.2 d vs. 6.2 ± 3.4 d, respectively). Calves in PRE-L-M and CON-F (2,916 ± 112 µM and 2,848 ± 112 µM, respectively) had greater total AA concentration in plasma than calves in PRE-L-F and CON-M (2,684 ± 112 µM and 2,582 ± 112 µM, respectively). Calves in PRE-L-F and CON-M (4.09 ± 0.11% and 4.16 ± 0.11%, respectively) had greater concentration of Lys as a percentage of total AA compared with calves in CON-F and PRE-L-M (3.91 ± 0.11% and 3.90 ± 0.11%, respectively). Calves in PRE-L tended to have greater percentage of phagocytic neutrophils (39.6 ± 1.59%) than calves in CON (35.9 ± 1.59%). In conclusion, increasing the metabolizable lysine provided to prepartum dairy cows had modest effect over offspring performance, with the major result being a greater average daily gain for calves in PRE-L during the preweaning phase (wk 6-8).

Effects of different planes of milk feeding and milk total solids concentration on growth, ruminal fermentation, health, and behavior of late weaned dairy calves during summer

Background

In recent years, there has been an increasing interest in using high quantities of milk or milk replacer (MR) in heat-stressed calves to alleviate the negative effects of high environmental temperatures on their performance. However, observations have indicated a decline in growth performance in the weaning and post-weaning period, which might be optimized with increasing total solids (TS) in milk and weaning age. This study aims to optimize the effects of higher quantities of milk on late weaned calves' performance by increasing TS concentration or delivery route in summer conditions.

Method

Forty-eight newborn Holstein calves were used in a 2 × 2 factorial arrangement with the factors of pre-weaning total plane of milk (PM) intake (low vs. high) and milk TS content (12% vs. 17%). The treatments were (1) low PM (LPM) intake with 12% TS (TS intake = 45.9 kg), (2) LPM intake with 17% TS (TS intake = 65.1 kg), (3) high PM (HPM) intake with 12% TS (TS intake = 63.7 kg); and (4) HPM intake with 17% TS (TS intake = 90.3 kg). Calves were weaned at d 83, and the study was terminated at d 103 of age. Performance data (every 10 day), skeletal growth (d 80 and 100), ruminal fermentation parameters (d 48 and 91), and behavioral measurements (d 69, 70, 93 and 94) were analyzed as repeated measurements with PROC MIXED of SAS 9.4 (SAS Institute Inc., Cary, NC).

Results

Calves receiving HPM consumed less PMR from d 44 to 83 of age, but they had higher ADG from d 24 to 53 of age compared to those fed LPM (PM × age, P < 0.001). In addition, calves receiving milk with 17% TS had lower PMR intake from d 14 to 83 of age, but greater ADG from d 34 to 53 compared to those receiving milk with 12% TS (TS × age, P < 0.001). Calves that received HPM had greater skeletal growth parameters compared to LPM-fed calves, with a similar effect evident for calves fed milk with 17% TS compared with those fed milk with 12% TS. Calves receiving milk with 17% TS had greater fecal scores and diarrhea occurrence than those fed milk with 12% TS in HPM, but not LPM.

Conclusions

Increasing PM and milk TS concentration improved growth in summer-exposed calves as demonstrated by increased pre-weaning ADG, pre- and post-weaning BW, and structural growth.

Effects of spray-dried bovine plasma protein in milk replacers fed at a high plane of nutrition on performance, intestinal permeability, and morbidity of Holstein calves

Spray-dried plasma protein (SDP) has been shown to improve growth and intestinal function in young calves when included in milk replacers (MR) fed at conventional rates. Use of an SDP and wheat protein blend to replace a portion of whey protein has been shown to perform similarly to using an all-whey protein control MR. However, a trend in the dairy industry is to feed calves for greater rates of growth during the preweaning period. The purpose of this study was to determine the effects of increasing amounts of SDP inclusion in MR on growth and health of calves fed at a high plane of nutrition. Young (<7 d) Holstein calves were offered starter and assigned to 1 of 5 MR treatments: an all-milk protein (whey) control MR (0SDP, n = 26) or MR containing 5% SDP (5SDP, n = 20), 7.5% SDP (7.5SDP, n = 14), 10% SDP (10SDP, n = 20), or 12% of an approximate 1:1 SDP plus wheat protein blend (PW, n = 17). All MR were formulated to contain 26% CP and 16% fat and were fed at a maximum rate of 1 kg of powder (as fed) from d 8 to 36. Amounts of MR powder were decreased by 25%/wk from d 37 to weaning at d 57. Thereafter, calves were provided only starter feed until the end of the study at d 63. On d 4, 15, 36, and 57, intestinal permeability was assessed via oral administration of lactulose and d-mannitol followed by analysis of lactulose and mannitol in blood at 60 min after administration. Increasing SDP led to a small linear decrease in MR consumed. There was a tendency for a positive linear relationship between increasing SDP and average daily gain of body weight, and SDP had mixed effects on body frame variables. Increasing SDP tended to increase fecal scores and increased the amount of fluid therapy given. Diet had no effect on intestinal permeability. Increasing SDP led to an increase in serum total cholesterol and serum urea N and tended to have a quadratic effect on serum glucose concentration on d 36. Calves fed PW tended to have increased withers height, increased intestinal permeability on d 36, and an increased likelihood of being medicated for any reason or being medicated for respiratory illness, but growth and health were not different from the control diet otherwise. Feeding PW led to an increase in serum total cholesterol and tended to lead to increased serum glucose concentration on d 36. Results of this study indicate that SDP can be included at up to 10% as fed in the MR of calves fed at a high plane of nutrition (1 kg/d of MR powder, as fed) with improvements in average daily gain. Additionally, a 1:1 SDP plus wheat protein blend can be used at 12% inclusion with no difference in most health and growth parameters.

Effects of in vivo phlorizin treatment and in vitro addition of carnitine, propionate, acetate, and 5-tetradecyloxy-2-furoic acid on palmitate metabolism in ovine hepatocytes

Modulatory effects of l-carnitine, acetate, propionate, and 5-tetradecyloxy-2-furoic acid (TOFA; an inhibitor of acetyl-CoA carboxylase) on oxidation and esterification of [1-¹⁴C]-palmitate were studied in hepatocytes isolated from phlorizin-treated and control wethers. Our hypotheses were that (1) palmitate oxidation would be greater in hepatocytes from sheep injected with phlorizin; (2) l-carnitine would increase palmitate oxidation more in hepatocytes from sheep injected with phlorizin; and (3) acetate and propionate would decrease oxidation in sheep hepatocytes partly through action of acetyl-CoA carboxylase. Palmitate metabolism did not differ between cells from control and those from phlorizin-treated wethers. Carnitine increased oxidation of palmitate to CO₂ and acid-soluble products (ASP; mainly ketone bodies) and decreased esterification of palmitate in isolated hepatocytes from both groups of wethers, but the increase in oxidation to ASP was greater in cells from phlorizin-treated wethers. Propionate increased palmitate oxidation to CO₂ in phlorizin-treated wethers. Propionate increased oxidation of palmitate to ASP in control wethers but decreased oxidation to ASP in phlorizin-treated wethers. Propionate increased esterification of palmitate to total esterified products and triglyceride, and the effect was larger in phlorizin-treated wethers. Acetate decreased palmitate esterification to total esterified products in control wethers, but the effect was blunted in phlorizin-treated wethers. Acetate did not affect palmitate oxidation. Addition of TOFA increased production of triglyceride from palmitate in the presence of propionate. The lack of interaction between TOFA and propionate indicates that propionate does not inhibit carnitine palmitoyltransferase I via cytosolic generation of methylmalonyl-CoA by acetyl-CoA carboxylase. In conclusion, although in vivo phlorizin treatment did not affect in vitro metabolism of palmitate by isolated ovine hepatocytes, phlorizin increased the stimulatory effect of carnitine on oxidation of palmitate to ASP and the inhibitory effect of propionate on oxidation of palmitate to ASP. Metabolism of acetate and propionate by acetyl-CoA carboxylase did not affect palmitate oxidation or esterification. Results provide additional insight into control of fatty acid metabolism in hepatocytes.

Concentrate allowance and corn grain processing influence milk production, body reserves, milk fatty acid profile, and blood metabolites of dairy cows in the early postpartum period

The study goal was to determine the effects of a fast (FAS) or slow (SLW) incremental rate of concentrate feeding and corn processing method during the early postpartum period on lactational performance, body reserves, blood metabolites, and milk fatty acid (FA) profile. Forty multiparous Holstein cows were used in a randomized block design with a 2 × 2 factorial arrangement of treatments. Treatment diets were either a FAS [1.0 kg of dry matter (DM)/d] or SLW (0.25 kg of DM/d) incremental rate of concentrate feeding (up to 12 kg of DM/d) with either dry ground corn (DGC) or steam-flaked corn (SFC) as the primary starch source in concentrate. Treatments were fed from 5 to 64 d postpartum. The basal diet consisted of forage, soybean meal, and 5 kg/d concentrate in the postpartum period. Throughout the experiment, dry matter intake (DMI) and milk yield were measured daily, and milk components, body condition score, and body weight were recorded at 16-d intervals, whereas blood metabolites and milk FA profile were measured at 16 and 32 d in milk. The incremental rate of concentrate feeding interacted with corn processing method to affect plasma concentration of glucose with greater glucose in SFC treatment compared with DGC in cows fed with the FAS strategy. Cows fed FAS and SFC had a greater total DMI than those fed SLW and DGC counterparts (22.8 versus 22.1 kg and 22.7 versus 22.1 kg, respectively), and also SFC increased yield of actual milk compared with the DGC counterpart (42.7 versus 41.6 kg). The milk fat and energy-corrected milk yields were not different among treatments whereas milk protein yield was greater when SFC was fed. Greater incremental rate of concentrate feeding tended to increase milk lactose yield during the first 64 d of lactation. The loss of body condition score increased when cows were fed SLW for the entire period and plasma nonesterified fatty acids and β-hydroxybutyrate concentrations increased with the SLW strategy. The proportions of total trans 18:1 and trans-11 18:1 FA in milk fat were higher in cows fed FAS. However, feeding SLW enhanced milk de novo and mixed FA proportions compared with FAS, whereas the proportions of milk FA were not affected by corn grain processing method. The incremental rate of concentrate feeding had significant effects on DMI, milk yield, and body reserve changes. Although feeding SFC instead of DGC had benefits on DMI and milk yield at 48 and 64 d postpartum, treatments did not interact to affect production responses when cows were fed with the SLW strategy.

Nutrient digestibility and endogenous protein losses in the foregut and small intestine of weaned dairy calves fed calf starters with conventional or enzyme-treated soybean meal

The aims of this experiment were (1) to compare the effects of a soybean meal with an enzymatic treatment (ESBM) to reduce the concentration of antinutritional factors versus a standard soybean meal (SBM) on foregut and small intestine digestion in weaned dairy calves and (2) to estimate the endogenous losses of crude protein (CP) in the small intestine. Our hypothesis was that a diet containing ESBM instead of SBM would improve ruminal and small intestine digestion and absorption of nutrients. A T-cannula was placed in the duodenum, and a second T-cannula was installed in the distal ileum of 12 Holstein calves at approximately 3 wk of age. Calves were weaned on d 42, and on d 50 they were assigned randomly to a quadruplicated 3 × 3 Latin square with 10-d periods. Digesta samples were collected on d 7 and 8 from the ileum and d 9 and 10 from the duodenum. The diets were fed for ad libitum intake and consisted of a calf starter (CS) of 20% CP with SBM as the main source of protein (CTRL), and an isonitrogenous CS with an ESBM instead of SBM (ENZT). A third diet with a low content of CP (10%) and no soy protein was fed to estimate endogenous N losses and digestibilities of test ingredients. Flows and digestibilities of nutrients were compared between CTRL and ENZT and their test ingredients (SBM vs. ESBM, respectively). Duodenal net flows of CP and total AA as well as ruminal microbial protein synthesis per kilogram of digested CP were greater, and flow of nonprotein N and CP true (corrected by endogenous and microbial flows) foregut digestibility were lower with ENZT than CTRL. The apparent small intestine digestibilities of CP and total AA were greater for ESBM than SBM, but there were no differences between the CTRL and ENZT diets. We observed no differences in digestibilities at the duodenum or ileum of starch or NDF, but true small intestine digestibilities of CP and all AA were greater with ENZT than CTRL. Total endogenous protein losses in the small intestine estimated from calves fed the low-CP with no soy protein diet were 37 ± 1.5 g of CP and 29 ± 1.4 g of AA/kg of DMI. These values may be considered the basal endogenous losses as they are similar to values obtained with the regression method, which estimates N losses when dietary N is null. Our results indicated that the inclusion of an ESBM improved the efficiency of ruminal microbial protein synthesis per digested kilogram of organic matter and CP, and increased CP and AA absorption in the small intestine despite a greater proportion of undigested dietary protein entering the duodenum.

Effects of physical preparation of diets and inclusion rate of modified wet distillers grains with solubles on production and rumen measurements of lactating dairy cows

Our objective was to determine if methods for preparing total mixed ration [TMR; horizontal paddle mixer with knives (PK) vs. vertical auger (VA) mixer] would alter the physical form of the TMR and affect utilization of diets with increasing amounts of modified wet distillers grains with solubles (MWDGS). Holstein cows (n = 24 with 12 ruminally cannulated; 144 d in milk ± 31 d at start) were used in a split-plot design with mixer type as the whole plot and MWDGS concentrations as subplots in a replicated 3 × 3 Latin square arrangement with 35-d periods. Inclusion rates of MWDGS were 10, 20, and 30% of dietary dry matter, primarily replacing corn, soybean meal, soyhulls, and whole cottonseed. Feed dry matter intake (DMI) was less for PK (23.8 kg/d) than for VA (25.7 kg/d), but was unaffected by MWDGS concentration. Milk production did not differ by concentration of MWDGS or by interaction of MWDGS × mixer. Milk fat percentage declined with increasing MWDGS but the interaction between mixer and MWDGS showed that decreases were larger with VA mixing. Cows fed the diet containing 30% MWDGS mixed with PK averaged 3.45% (1.24 kg/d) milk fat, whereas cows fed the same diet mixed with VA averaged 2.81% (1.10 kg/d) fat. Concentrations of trans-10,cis-12 C18:2 in milk fat likely explain the differences observed in milk fat yield; the concentration of trans-10,cis-12 C18:2 increased as MWDGS was increased and the MWDGS × mixer interaction showed that VA had greater concentrations. Greater mean particle size and increased variation in particle size with VA may partially explain differences in milk fat via increased sorting that allowed for an altered rumen environment and favored alternative biohydrogenation pathways. Feed conversion efficiency (FCE; energy-corrected milk/DMI) decreased linearly as MWDGS increased, but FCE tended to be maintained when higher MWDGS diets were mixed using PK rather than VA. Ruminal pH and ammonia concentration decreased linearly as MWDGS increased. The PK mixer resulted in greater FCE when higher amounts of MWDGS were fed, primarily because milk fat content and yield were not as depressed and DMI was lower at similar milk yields.

Effects of starter protein content and alkali processing of wheat straw on growth, ruminal fermentation, and behavior in Holstein calves

The present study was conducted to investigate the effects of crude protein (CP) content of starter feed and wheat straw (WS) processing on growth performance, digestibility, ruminal fermentation, and behavior of Holstein calves. Sixty calves (28 male and 32 female) were randomly assigned to 1 of 4 treatments in a randomized complete block design. Treatments in a 2 × 2 factorial arrangement were (1) lower-CP ground starter feed mixed with alkali-processed WS (LP-PWS), (2) lower-CP ground starter feed mixed with unprocessed WS (LP-WS), (3) higher-CP ground starter feed mixed with alkali-processed WS (HP-PWS), and (4) higher-CP ground starter feed mixed with unprocessed WS (HP-WS). Wheat straw was fed at 4.75% of dry matter (DM), and low-protein (LP) and high-protein (HP) starter feed contained 19.5 and 23.5% CP, respectively. The calves were weaned on d 60 and remained in the study until d 75. During the experiment, the calves received 4.2 kg of whole milk per day and had free access to fresh water and starter feed. The interaction between WS processing and protein content of starter tended to be significant for starter feed intake, average daily gain (ADG), and body weight (BW); calves fed HP-PWS tended to have greater ADG and final BW than other treatments. The results showed that feeding HP ground starter feed increased ADG and feed efficiency compared with LP groups during the preweaning and the overall periods. Moreover, weaning and final BW were higher in HP-fed calves than in LP-fed calves. Apparent digestibilities of acid detergent fiber (ADF), starch, and CP were greater in calves fed HP than in calves fed LP starter feed. The HP ground starter feed increased rumen propionate and ammonia concentrations. Wheat straw processing had no effect on intake and growth of calves but increased DM, ADF, and neutral detergent fiber digestibilities and decreased ruminal pH. Using processed wheat straw (PWS) mixed with starter feed tended to decrease rumination time and ruminal acetate concentration in calves. Final body barrel and withers height tended to be greater in calves fed PWS. Overall, the results indicated that HP content of ground starter feed (23.5%) could be recommended for Holstein calves. Furthermore, PWS inclusion in the ground starter diet increased fiber digestibility but had no effect on calf performance. Moreover, calves fed HP-PWS had greater ADG and final BW than other treatments.

Influence of starter crude protein content on growth and body composition of dairy calves in an enhanced early nutrition program

Our objectives were to determine the effect of starter crude protein (CP) content on body composition of male Holstein calves from birth to 10 wk of age in an enhanced early nutrition program, and to compare the enhanced program to a conventional milk replacer program. Calves (n = 45) were purchased on the day of birth and assigned to a randomized block design. Eight calves were harvested at baseline and remaining calves were divided among the following 3 dietary treatments: (1) low rate of milk replacer [LMR; 20.6% CP, 21.7% fat; 1.25% of body weight (BW) as dry matter (DM)] plus conventional starter (CCS; 21.5% CP, DM basis); n = 11 calves; (2) high rate of milk replacer (HMR; 29.1% CP, 17.3% fat; 1.5% of BW as DM for wk 1, 2% of BW as DM wk 2-5, 1% of BW as DM wk 6) plus conventional starter; n = 12 calves; and (3) enhanced milk replacer (HMR) plus high-CP starter (HCS; 26% CP, DM basis); n = 14 calves. A subset of calves (n = 8) was harvested on d 2 to provide baseline data. Calves began treatments on d 2 or 3 of age. Calves were weaned at d 42. Starter was available ad libitum. Calves from each treatment were harvested at 5 (n = 18) and 10 (n = 19) wk of age and divided into 4 fractions: carcass; viscera; blood; and head, hide, feet, and tail. Fractions were analyzed for energy, CP, lipid, and ash. Average weekly starter intake did not differ between enhanced treatments. Gain of BW was greater for calves fed HMR than for LMR, but was unaffected by starter CP. Carcass weights at 5 wk were greater for HMR but did not differ between starter CP content. At 10 wk, carcass weights were heavier for HMR and had a greater percentage of empty BW for HMR + CCS than for HMR + HCS. At 10 wk, the weights of reticulorumen and liver were greater for calves fed HMR + HCS than for those fed HMR + CCS. At 5 wk, empty BW gain for HMR contained more water and less fat and ash than in calves fed LMR. At 10 wk, empty BW gain for calves fed HMR + HCS contained a greater percentage of water and less fat than for calves fed HMR + CCS. Plasma β-hydroxybutyrate was greater after weaning for calves fed HMR + HCS than for those fed HMR + CCS. After weaning, calves fed HMR had greater plasma total protein concentration than those fed LMR, and total protein was greater for calves fed HMR + HCS than those fed HMR + CCS. Plasma urea N was greater for calves fed HMR treatments, and postweaning was greater for calves fed HMR + HCS. A high-CP starter had minimal effect on empty BW gain before weaning, but after weaning it tended to increase mass of reticulorumen and liver.

Effects of prepartum diets varying in dietary energy density and monensin on early-lactation performance in dairy cows

Our objectives were to evaluate the effects of prepartum monensin supplementation and dry-period nutritional strategy on the postpartum productive performance of cows fed monensin during lactation. A total of 102 Holstein cows were enrolled in the experiment (32 primiparous and 70 multiparous). The study was a completely randomized design, with randomization restricted to balance for parity, body condition score, and expected calving date. A 2 × 2 factorial arrangement of prepartum treatments was used; the variables of interest were prepartum feeding strategy [controlled-energy diet throughout the dry period (CE) vs. controlled-energy diet from dry-off to 22 d before expected parturition, followed by a moderate-energy close-up diet from d 21 before expected parturition through parturition (CU)] and prepartum monensin supplementation [0 g/t (control, CON) or 24.2 g/t (MON); Rumensin; Elanco Animal Health, Greenfield, IN]. Lactation diets before and after the dry period contained monensin at 15.4 g/t. During the close-up period, cows fed CU had greater DM and NE_L intakes than cows fed CE. Calf BW at birth tended to be greater for cows fed CU than for those fed CE but was not affected by MON supplementation. Diet did not affect calving difficulty score, but cows supplemented with MON had an increased calving difficulty score. We found a tendency for a MON × parity interaction for colostral IgG concentration, such that multiparous MON cows tended to have lower IgG concentration than CON cows, but colostral IgG concentration for primiparous MON and CON cows did not differ. Postpartum milk yield did not differ between diets but tended to be greater for cows supplemented with MON. Milk fat and lactose content were greater for cows fed CU than for those fed CE, and lactose content and yield were increased for cows supplemented with MON. Solids-corrected and fat-corrected milk yields were increased by MON supplementation, but were not affected by diet. Overall means for postpartum DMI did not differ by diet or MON supplementation. The CU diet decreased the concentration of nonesterified fatty acids during the close-up period but increased it postpartum. Neither diet nor monensin affected β-hydroxybutyrate or liver composition. Overall, postpartum productive performance differed little between prepartum dietary strategies, but cows fed MON had greater energy-corrected milk production. In herds fed monensin during lactation, monensin should also be fed during the dry period.

Soybean oil supplementation and starter protein content: Effects on growth performance, digestibility, ruminal fermentation, and urinary purine derivatives of Holstein dairy calves

This study investigated the effects of feeding dairy calves starter diets containing 19% or 22% crude protein (CP) content on a dry matter basis and either supplemented or not with soybean oil (SBO, 0 vs. 3%, dry matter basis) on growth performance, digestibility, urinary nitrogen, and purine derivatives (PD) excretion. A total of 48 female Holstein dairy calves (mean 39.8 kg of body weight) were randomly distributed to experimental diets in a 2 × 2 factorial arrangement of treatments. The 4 dietary treatments were (1) starter diet without SBO supplement and 19% CP (NSBO-19CP), (2) starter diet without SBO supplement and 22% CP (NSBO-22CP), (3) starter diet with 3% SBO and 19% CP (SBO-19CP), and (4) starter diet with 3% SBO and 22% CP (SBO-22CP). Milk feeding value was similarly based on a constant protocol across experimental treatments and calves had ad libitum access to water and starter diets throughout the study. All calves were weaned on d 63 of age and remained in the study until d 83 of age. Calves supplemented with SBO had lower starter feed intake and average daily gain (ADG) and lower feed efficiency (FE) but had a higher fecal score indicating a higher likelihood of diarrhea occurrence compared with unsupplemented calves. Wither heights, digestibilities of organic matter, CP, and neutral detergent fiber were decreased, and ruminal volatile fatty acids tended to be reduced, and the molar proportion of ruminal butyrate (preweaning) and acetate (postweaning) reduced by supplemental SBO. The urinary allantoin and total PD excretion were reduced; however, urinary nitrogen excretion was increased when calves were supplemented with SBO. The CP amount did not affect starter feed intake, FE, or diarrhea occurrence rate, whereas the 22CP diets increased neutral detergent fiber digestibility, improved ADG (tendency), and increased allantoin and urinary PD excretion compared with the 19CP diets. The starter feed intake, ADG, FE, diarrhea occurrence rate, nutrient digestibility, and ruminal fermentation were not affected by the interaction between starter SBO and CP level; however, hip height and total PD in calves that received the SBO-22CP diets were higher than those fed the SBO-19CP diets. In conclusion, based on our experimental conditions, supplemental SBO could not be recommended for dairy calves. Furthermore, our findings indicate that SBO has negative effects on performance more attributed to reducing starter intake, digestibility, and ruminal volatile fatty acid concentration rather than because of a limitation of starter metabolizable protein supply and intestinal amino acid availability. Therefore, our results indicate that feeding the higher starter CP content is not a viable strategy to compensate for the negative effects of SBO supplementation on the growth performance of dairy calves.

Effects of late-gestation heat stress independent of reduced feed intake on colostrum, metabolism at calving, and milk yield in early lactation of dairy cows

The objective of this study was to differentiate the effects of acute heat stress (HS) from those of decreased dry matter intake (DMI) during the prepartum period on metabolism, colostrum, and subsequent production of dairy cows. Holstein dairy cows (n = 30) with similar parity and body weight were randomly assigned to 1 of 3 treatments on 45 d before calving: (1) cooled (CL, n = 10) conditions with ad libitum feed intake, (2) HS conditions with ad libitum feed intake (n = 10), and (3) pair-fed cooled (CLPF, n = 10) with reduced DMI similar to the HS group while housed under cooled conditions. The reduction in the amount of feed offered to the CLPF cows was calculated daily as the percentage decrease from the average DMI of HS cows relative to the CL cows. For CLPF and CL cows, barns provided shade, sprinklers, and fans, whereas the HS cows were provided only with shade. Cows in all groups received individually the same total mixed ration. Cows were dried off 60 d before the expected calving. Cows in the HS group and, by design, the CLPF cows had reduced DMI (~20%) during the experiment. Heat stress decreased gestation length, first colostrum yield, and calf birth weight compared with CL and CLPF cows. Milk yield decreased 21% (5 kg) in the HS and 8% (2 kg) in CLPF cows, indicating that reduced feed intake during late gestation accounted for 60% of the total reduced milk yield. The CLPF cows exhibited an elevated NEFA concentration compared with the CL and HS cows. The HS cows had a greater mRNA abundance of HSP70 in the peripheral blood leukocytes at 21 d prepartum compared with the other groups. At calving, the mRNA abundance of HSP70 was greater in HS cows, followed by CLPF, compared with the CL cows. In conclusion, HS during the late gestation period caused metabolism and production differences, which were only partially attributed to reduced feed intake in dairy cows.

Short communication: A pilot study to describe duodenal and ileal flows of nutrients and to estimate small intestine endogenous protein losses in weaned calves

The aims of this pilot study were (1) to evaluate the effect of an ileal and duodenal cannulation surgery on body weight and dry matter intake, (2) to estimate endogenous losses of crude protein (CP) and AA in the small intestine, and (3) to describe duodenal and ileal flows of nutrients in weaned dairy calves. Three Holstein male calves were fitted at 7 wk of life with a T-cannula at the terminal ileum and another cannula at the proximal duodenum. On wk 14 of life, calves were randomly assigned to a single 3 × 3 Latin square with 10-d periods. The 3 diets were fed ad libitum and consisted of a control calf starter (CS) with conventional soybean meal (SBM) as the main source of protein (CTRL), an isonitrogenous (20% CP) CS with an enzyme-treated SBM as the main source of protein (ENZT), and a CS with low content of CP (10%) and no soy protein (LOCP). Flows and digestibilities of nutrients were compared between the soy-based high-protein diets (HICP) and LOCP, and between CTRL and ENZT. Final data were only available from 2 calves per diet (n = 2) because cannulas from 1 calf became inoperative after the first collection period. Duodenal flows of CP, total AA, nonprotein nitrogen, microbial N, and fatty acids, as well as apparent duodenal digestibility of starch, were greater for HICP than for LOCP, indicating a greater foregut microbial activity and digestion. The apparent ileal digestibility (AID) of organic matter, CP, and total AA were greater for HICP than for LOCP. Duodenal net flow of CP was greater for ENZT than for CTRL, but flow of AA was not different. On the other hand, duodenal flow of microbial N was greater, and flows of nonprotein N and starch were lower for the ENZT diet, suggesting a more efficient microbial activity in the rumen. Even though CTRL had a greater AID when compared with ENZT, the AID of CP and AA were greater for enzyme-treated SBM than for SBM. Endogenous losses in the small intestine per kilogram of duodenal dry matter flow were 47 ± 15 and 37 ± 12 g/d, and the true ileal digestibilities for the HICP diets were 86 ± 0.1 and 87 ± 0.1% for CP and AA, respectively. An optimal supply of CP and the inclusion of an enzyme-treated SBM improved the efficiency of microbial digestion and increased AA absorption. Although further research with greater biological replication is needed, our results indicate that there is potential to improve digestion and absorption of proteins through dietary strategies in young weaned calves.

Effects of feeding frequency and protein source in milk replacer for Holstein calves

Whey proteins are a primary component of milk replacers (MR) and are considered the gold standard for calves. Alternative protein sources may decrease MR cost if calf performance is similar. A blend of bovine plasma protein and modified wheat protein might be a good partial replacement for whey protein. Usually MR is fed twice daily, but feeding 3 times daily might increase efficiency of nutrient use, especially with MR containing alternate proteins. Therefore, our objective was to determine the effects of 2 MR, containing either entirely whey protein (CON) or a combination of whey protein, bovine plasma protein, and modified wheat protein (WBP), when fed in either 2 or 3 meals daily on calf growth and health. Female and male Holstein calves (n = 103) housed in individual hutches were studied for the first 63 d of life, with additional measurements obtained at wk 12 of life in group housing. The MR contained 25% CP, 17% fat, and a Lys:Met ratio of 3.1:1. Individual treatments arose from the 2 × 2 factorial arrangement of MR formulation and frequency of feeding. After colostrum, calves were fed MR (12.5% solids) at daily rates of dry matter dependent on age. Amounts were as follows: d 3 to 10 = 0.52 kg/d (2× = 0.259 kg, 3× = 0.173 kg per feeding); d 11 to 20 = 0.68 kg/d (2× = 0.341 kg, 3× = 0.227 kg per feeding); d 21 to 42 = 0.84 kg/d (2× = 0.42 kg, 3× = 0.28 kg per feeding); d 43 to 46, 47, 49, and 51 = 0.42 kg/d, with both 2× and 3× changed to 1 feeding daily and skip days (d 48 and 50) between where calves were not given MR; and d 52 = calves weaned. Starter was fed and intake was measured from d 1 until d 63. Intakes, health scores, attitude scores, and fecal scores were measured daily. Body weight (BW) and growth measurements were obtained weekly until wk 8 and again at wk 12. Blood samples were obtained at 0, 24, and 48 h and then on d 5, 14, 28, and 42 of age. Starter intake was greater for calves fed WBP versus CON during wk 7 to 9. Final BW and hip width at wk 12 were greater for calves fed WBP than for calves fed CON. Calves fed 2× had greater mean and final BW to wk 6 and greater feed efficiency (gain:feed ratio) than calves fed 3×. Blood variables supported the generally similar growth outcomes. Health outcomes did not differ between diets or feeding frequencies. Overall, calves fed WBP had increased starter intake and greater BW gains during wk 7 to 12 than calves fed CON, and calves fed 2× had increased growth and feed efficiency compared with those fed 3×.

Comparison of prepartum low-energy or high-energy diets with a 2-diet far-off and close-up strategy for multiparous and primiparous cows

Previous research demonstrated that nutrition during the far-off (early) dry period may be as important to transition success as nutrition during the close-up dry period. Our objectives were to determine if a low-energy, high-fiber diet fed throughout the dry period improved metabolic status and production of dairy cows compared with a higher-energy diet or a 2-diet system, and to compare responses of cows and heifers to those diets. Holstein cows (n = 25 with 10 primiparous per treatment) were assigned to each of 3 diets at 60 d before expected calving. Treatment LO [40.5% wheat straw; 5.6 MJ of net energy for lactation (NE_L)/kg of DM] was designed to meet but not exceed National Research Council recommendations for ad libitum intake from dry-off until calving. Treatment HI was a high-energy diet (6.7 MJ of NE_L/kg of DM) fed for ad libitum intake from dry-off until calving. For the LO+HI treatment, the LO diet was fed ad libitum from dry-off until 21 d before expected calving, followed by the HI diet until parturition. After parturition all cows were fed a lactation diet (7.0 MJ of NE_L/kg of DM) through 63 d postpartum. Dry matter intake and body weight were greater for HI cows prepartum, but not postpartum. When LO+HI cows were switched to the HI diet, their dry matter intake increased to match that of HI cows. Cows fed HI had greater gain of body condition before calving but lost more postpartum. Energy balance postpartum was higher for LO cows than for HI cows. Milk production, protein content, and protein yield did not differ among diets. Milk fat content and yield were highest for HI cows, lowest for LO, and intermediate for LO+HI cows. The HI cows had lower serum nonesterified fatty acids prepartum than either LO or LO+HI, but greater concentrations postpartum. Serum β-hydroxybutyrate did not differ prepartum, but was greater for HI than for LO or LO+HI postpartum. Serum glucose and insulin were lower for LO than HI and LO+HI prepartum; insulin was lower for LO and HI than for LO+HI postpartum. The LO cows had lower liver total lipid concentration postpartum than the HI cows and LO+HI cows. Primiparous cows generally responded to diets the same as multiparous cows. The LO+HI feeding strategy provided no benefit over the LO diet. Moreover, the high-energy diet, even when fed for only 19 d before calving in the LO+HI group, resulted in increased serum β-hydroxybutyrate and liver total lipid concentrations compared with LO.

Corn processing and crude protein content in calf starter: Effects on growth performance, ruminal fermentation, and blood metabolites

This study aimed to investigate the effects of feeding dairy calves starter diets containing corn grain processed by different methods (ground versus steam-flaked; GRC vs. SFC) and either 18% or 21% crude protein (CP) contents (dry matter basis) on growth performance, digestibility, ruminal fermentation, urinary purine derivatives, and blood metabolites of dairy calves. Holstein dairy calves (39.3 ± 1.9 kg of body weight, n = 12 calves per treatment, 6 males and 6 females) were randomly distributed to experimental diets in a 2 × 2 factorial arrangement of treatments. The 4 dietary treatments were (1) starter diet containing GRC and 18% dietary CP (GRC-18CP; geometric mean particle size, GMPS = 0.73 mm); (2) GRC and 21% dietary CP (GRC-21CP; GMPS = 0.71 mm); (3) SFC and 18% dietary CP (SFC-18CP; GMPS = 2.21 mm); and (4) SFC and 21% dietary CP (SFC-21CP; GMPS = 2.16 mm). Calves were weaned on d 63 and remained in the study until d 83 of age. The starter feed intake did not differ among treatments; however, average daily gain and feed efficiency (FE) were improved and final body weight was higher for SFC diets compared with GRC diets. The organic matter and nonfiber carbohydrate digestibilities were greater for calves fed the SFC diets than for those fed the GRC diets. The ruminal total volatile fatty acid concentrations and the molar proportions of propionate and butyrate were greater, and the molar proportion of acetate and NH₃-N concentrations were lower, for calves fed the SFC diets than for those fed the GRC diets. The excretion of allantoin and total purine derivatives, and subsequently microbial protein synthesis, were greater for calves fed the SFC diets than the GRC diets. The total urinary nitrogen excretion and its proportion of N intake were lower for calves fed the SFC diets than the GRC diets. The blood concentrations of insulin (pre- and postweaning), glucose (postweaning), and β-hydroxybutyrate (preweaning) were greater and blood urea nitrogen (preweaning) was lower for calves fed the SFC diets than the GRC diets. The protein content of the concentrate did not affect feed intake, growth performance, or ruminal fermentation of the calves. The neutral detergent fiber digestibility was greater for calves fed the 21% CP diets than the 18% CP diets. No interaction between main effects was observed regarding the starter intake, average daily gain, body weight, FE, ruminal fermentation, and nutrient digestibility of calves. The interaction between corn grain processing and starter protein content was significant for withers and hip heights with the greatest values found for SFC-21CP treatment. Our results show that steam flaking of corn improved the organic matter and nonfiber carbohydrate digestibilities, weight gain, FE, and ruminal microbial protein synthesis, and reduced urinary nitrogen excretion compared with grinding corn. Regardless of the marginal benefit derived from feeding the diet containing SFC and 21% CP in the height of calves, lower starter protein content (18% CP) may be used efficiently when calves are fed the SFC diets.

Technical note: Evaluation of 3 methods to determine mucin protein concentration in ileal digesta of young preweaning calves

The use of alternative sources of protein to substitute for milk proteins in milk replacers (MR) can increase the synthesis of endogenous proteins and therefore alter ileal or total-tract digestibility calculations. Mucin is the main component of gastrointestinal mucus and represents the greatest contribution to total endogenous protein. Mucin is difficult to isolate and has not been extensively studied in dairy calves. We explored 3 different procedures to analyze and estimate mucin protein (MUP) in ileal digesta of young dairy calves. Ileal digesta samples were collected from nine 30-d-old ileal-cannulated calves that were enrolled in a 3 × 3 replicated Latin square with 5-d periods. The 3 diets were a control whey protein-based MR (WPC), an isonitrogenous MR in which 50% of the protein was from enzyme-treated soybean meal (ESBM), and an N-free MR (NFREE). Mucin protein concentration and flow were analyzed by fractionation of the digesta and ethanol precipitation; this process served as the reference method. Alternative methods to estimate MUP consisted of using commercial enzymatic kits to analyze glucosamine (N-acetylglucosamine, GlcNAc) and galactosamine (N-acetylgalactosamine, GalNAc), 2 amino-sugars that are highly enriched in mucin. Before GlcNAc determination, samples were processed using 3 different procedures: sample clarification (GLCL), clarification plus hydrolysis (GLCH), and hydrolysis alone (GLHL). The MUP was estimated by regression of the GlcNAc and GalNAc values using previously validated equations. According with the bias and agreement analysis, none of the methods yielded MUP values similar to the reference method. However, GLHL showed a strong association with the reference method (ρ = 0.73). It allowed identifying the smaller MUP flows with NFREE compared with the other 2 diets and detecting the greater flow of ESBM than WPC, as observed with the reference method. Using the GlcNAc values from GLHL and the MUP measured with the reference method, we were able to establish a linear relationship between both methods (adjusted R2 = 0.75). We found that the GLHL method enabled detecting differences in MUP ileal flows between diets differing in protein level and source. Inferences about MUP secretions must be done cautiously because many dietary and physiological factors are involved. The adoption of practical techniques to determine MUP can help to increase our knowledge about gastrointestinal tract function and to improve the accuracy of MR digestibility calculations.

Graduate Student Literature Review: The past and future of soy protein in calf nutrition

Our objective with this review is to encourage more research about the use of soy protein in young calf diets by learning from the mistakes of the past and acknowledging the promising results found when modern techniques are applied to treat soybeans. Total or partial substitution of milk proteins with soy proteins can represent a substantial increase in the economic efficiency of calf diets as long as it does not affect calf performance. Unfortunately, the results found in the literature indicate that the inclusion of soy protein in diets of young calves usually diminishes growth and health outcomes. The interaction of the antinutritional factors and antigenic proteins in soybeans with the gastrointestinal tract triggers a physiological response with negative consequences for the digestive tract and immune system of the calf. In this article, we highlight the importance of a correct processing method of soybeans by reviewing some of the published research that has evaluated different soy-based ingredients in diets for young calves. Conventional methods such as heating, ethanol extraction, and protein isolation can produce favorable results provided that the final product contains minimum or null amounts of antigenic and antinutritional factors. More recently, further processing methods such as microbial treatment of soybean meal reduces those antinutritional and antigenic factors, and can also increase the quality of soy protein by reducing the peptide size and by triggering the release of bioactive compounds. Experiments in which soy protein modified by this method was fed have increased in the scientific literature during the last decade due to the favorable results obtained in calves as well as in monogastric animals.

Negative dietary cation-anion difference and amount of calcium in prepartum diets: Effects on milk production, blood calcium, and health

Acidogenic prepartum diets with negative dietary cation-anion difference (DCAD) induce compensated metabolic acidosis, which stimulates calcium (Ca) mobilization before calving and decreases clinical and subclinical hypocalcemia postpartum. This strategy is often combined with limiting dietary Ca concentrations, which historically has been used to mobilize Ca prepartum to prepare cows for lactation. Supplemental dietary Ca in combination with a negative DCAD formulation that does not reverse the effect of compensated metabolic acidosis may be beneficial. Our objective was to determine the effects of prepartum dietary strategies on dry matter intake (DMI), milk production, peripartal Ca status, and health during the transition period in multiparous Holstein cows (n = 81). Treatments during the last 28 d before calving were: (1) positive DCAD diet, +6 mEq/100 g of DM, target urine pH >7.5, low dietary Ca (0.40% DM; CON); (2) negative DCAD diet, -24 mEq/100 g of DM, target urine pH 5.5 to 6.0, low dietary Ca (0.40% DM; ND); or (3) negative DCAD diet, -24 mEq/100 g of DM, target urine pH 5.5 to 6.0, , high dietary Ca (2.0% DM; NDCA). Preplanned treatment contrasts were: (1) CON versus (ND and NDCA), and (2) ND versus NDCA. Individual DMI were recorded daily. Cows were milked 3 times daily, with individual DMI and milk yield summarized by week. Whole blood sampled at calving and 24 h, 48 h, and 4 d after calving was analyzed for ionized Ca concentration, and serum was analyzed for total Ca. Prepartum urine pH for cows fed ND or NDCA averaged 5.7, whereas cows fed CON remained >7.5. During the 3 wk before calving, cows fed CON had greater DMI than cows fed ND or NDCA, with NDCA greater than ND. Postpartum DMI (% of body weight) tended to be less for cows fed CON than for those fed ND or NDCA prepartum. Thresholds for subclinical hypocalcemia were ionized Ca <1.0 mM at 24 h, and total Ca ≤2.125 mM at 48 h after calving. On average, blood Ca for cows fed CON indicated subclinical hypocalcemia, whereas blood Ca for cows fed ND or NDCA was greater than subclinical hypocalcemia thresholds for both ionized Ca and total Ca. No milk production differences were detected. Cows fed CON had an elevated adverse health score (calculated by assigning numerical values to recorded health events) and tended to have an elevated somatic cell count during the fresh period compared with cows fed ND or NDCA. Overall, an acidogenic diet prepartum without or with high Ca improved postpartum Ca status and health. Supplementation of additional Ca to the acidogenic diet had little effect.

Ileal digestibility and endogenous protein losses of milk replacers based on whey proteins alone or with an enzyme-treated soybean meal in young dairy calves

Our objective was to measure and compare apparent ileal digestibility, standard ileal digestibility, and true ileal digestibility of crude protein (CP) and amino acids (AA) in milk replacers (MR) containing all milk proteins (WPC) or with 50% of the CP provided by an enzyme-treated soybean meal (ESBM). A T-cannula was placed in the ileum of 9 Holstein calves (8 males and 1 freemartin female) at approximately 15 d of age. After 2 wk postsurgery, calves were randomly assigned to a 3 × 3 replicated Latin square with 5-d periods. Calves were fed twice daily at a rate of 2% (dry matter) of body weight (1.25 kg/d on average), reconstituted to 15% solids, and adjusted weekly. No starter was offered to minimize rumen development. Digesta samples were collected continuously during 12 h on d 4 and 5 of each period. Basal endogenous losses of AA and CP were estimated by feeding an N-free MR to each calf during 1 period. Total endogenous losses (basal + specific; ENDtotal) were estimated by multivariate regression of the chi-squared distances between digesta and reference protein AA profiles. Ileal digesta pH with the ESBM diet was lower than that with the WPC diet. According to the piecewise nonlinear model of pH fluctuation, digesta pH during ESBM decreased more slowly after feeding and reached its nadir later than with the WPC diet. Diet did not affect average daily gain, but calves on the ESBM diet showed a bigger increment of withers height and lower mean fecal scores. The basal endogenous losses of AA and CP were 13.9 ± 1.1 and 22.4 ± 1.1 g/kg of dry matter intake, respectively. The estimated ENDtotal of AA and CP was higher with ESBM than with WPC. Accordingly, apparent ileal digestibility and standard ileal digestibility of most AA, CP, and total AA were lower or tended to be lower with ESBM. However, true ileal digestibility did not differ between diets for CP and all AA except Ala and Ile, which were greater with WPC, and Arg, which tended to be greater with ESBM. In agreement with the estimated differences in ENDtotal, we found that flows of digesta DNA and crude mucin were greater with ESBM. Substitution of 50% of the protein from whey with enzymatically treated soybean meal did not affect major nutrient digestibility or calf growth and even improved fecal consistency. Adjusting digestibilities of CP and AA in MR by endogenous protein losses is crucial when comparing bioavailability of alternative proteins and milk proteins.

Symposium review: Nutrition strategies for improved health, production, and fertility during the transition period

Dairy cow nutritional programs are a major determinant of the profitability of dairy farms. Despite this, the sustainability of the dairy enterprise is beyond just cow nutrition. For almost 50 yr, the NC-2042 project (Management Systems to Improve the Economic and Environmental Sustainability of Dairy Enterprises) has been addressing most of these components as individual research units and in integrated ways. This review has the objective to report the body of research developed by members of the group in connection with the existing literature on dietary formulation and feeding management during the dry period, peripartal period, and early postpartum (fresh) period. Peak disease incidence (shortly after parturition) corresponds with the time of greatest negative energy balance (NEB), the peak in blood concentrations of nonesterified fatty acids, and the greatest acceleration of milk yield. Decreased fertility in the face of increasing milk production may be attributable to greater severity of postpartal NEB resulting from inadequate transition management or increased rates of disease. The depth and duration of NEB is highly related to dry matter intake. Periparturient diseases can result from adverse ruminal conditions caused by excessive grain in the precalving or fresh cow diet, perhaps aggravated by overcrowding, heat stress, or other stressors. Others have also implicated inflammatory responses in alterations of metabolism, occurrence of health problems, and impaired reproduction. Providing controlled-energy and negative dietary cation-anion difference diets prepartum may improve dairy cow performance during the transition period. A major area of concern in the fresh cow period is a sudden increase in dietary energy density leading to subacute ruminal acidosis, which can decrease dry matter intake and digestibility of nutrients. Adequate physical form of the diet, derived from either forage neutral detergent fiber content or a mixing strategy of different ingredients in a total mixed ration, must be present to stimulate ruminal activity and chewing behavior. In conclusion, formulation and delivery of appropriate diets that limit total energy intake to requirements but also provide proper intakes of all other nutrients (including the most limiting amino acids Met and Lys) before calving can help lessen the extent of NEB after calving. Effects of such diets on indicators of metabolic health are generally positive, suggesting the potential to lessen effects of periparturient disease on fertility.

Technical note: Establishment of an ileal cannulation technique in preweaning calves and use of a piecewise regression approach to evaluate effects on growth and pH fluctuation of ileal digesta

Digestibilities of nutrients, especially protein, are crucial characteristics of milk replacers in a calf-rearing program. Endogenous synthesis of proteins and microbial fermentation in the large intestine alter apparent total-tract digestibility of AA. Therefore, collection of digesta samples at the end of the ileum is the only method to estimate true small intestinal digestibility of AA. The aim of this work was to evaluate the effectiveness of inserting a T-cannula into the distal ileum of preweaning calves for use in digestibility studies. A second objective was to evaluate the use of a "broken-line" statistical model to compare treatment effects on calf growth and digesta pH. A T-cannula was surgically installed in the terminal ileum of 2 calves approximately 5 cm anterior to the ileocecal junction at 15 d of age, and 2 paired noncannulated calves were used as controls. Cannulation did not affect mean body weight (BW), average daily gain, milk and water intakes, and body frame dimensions. However, final BW (89.2 vs. 94.6 kg) was lower and starter intake (0.06 vs. 0.21 kg/d) tended to be decreased in cannulated calves compared with control calves. No effects on health scores, rectal temperature, or the odds of incurring diarrhea or being medicated were observed. Flow of digesta (46.4 ± 0.04 g/h) increased linearly after feeding, whereas there was a quadratic effect of time on digesta pH, with the nadir at approximately 8.5 h postfeeding. The broken-line model successfully fitted daily fluctuations of pH and allowed us to detect differences in growth slopes between cannulated and control calves. Despite the expected negative effect on BW, we conclude that this technique permitted sampling of representative ileal digesta while allowing satisfactory growth and health of the calves.

Intake and growth in transported Holstein calves classified as diarrheic or healthy within the first 21 days after arrival in a retrospective observational study

Strategies that can improve health and maximize growth in the preweaning period should improve the subsequent production and longevity of replacement animals. Few data are available that quantify feed and water consumption, as well as growth, in healthy versus non-healthy calves—the objective of this study. A database of Holstein calves (<1 wk of age; n = 313) was developed to compare calves that developed diarrhea in the first 21 d after arrival from commercial farms to the research facility versus calves that remained healthy. Individual calf data from 4 experiments included daily intake of milk replacer, free water, electrolyte solution, and starter grain, as well as weekly body weight (BW) and frame measures for 21 d after arrival. Calves with a fecal score of >2 for ≥3 consecutive days over the first 21 d of each experiment were retrospectively classified as diarrheic (DIA; n = 96); the remainder were classified as healthy (HEA; n = 217). Other health issues were minimal. The likelihood of elevated fecal score occurrence and the cumulative number of days with an elevated score were greater for DIA calves than for HEA calves. The initial total protein concentration in blood did not differ between classifications. Cumulative milk replacer dry matter intake (DMI) and water consumed from milk replacer were significantly less for DIA calves than for HEA calves, because DIA calves were more likely to refuse milk replacer. Cumulative starter DMI was decreased for DIA versus HEA calves. As a result, cumulative total DMI was significantly less for DIA calves than for HEA calves. Cumulative free water intake did not differ between classifications. The DIA calves were more likely to receive electrolyte solution and have more days given electrolyte solution than HEA calves. As a result, total cumulative intake of electrolyte solution was greater in DIA calves than in HEA calves. Cumulative total water intake did not differ between classifications. Initial BW did not differ between classifications; however, a classification × time interaction for BW indicated that HEA calves were heavier than DIA calves and had greater ADG. Significant classification × time interactions for hip height and heart girth revealed that HEA calves had a larger frame size. Gain–feed ratios for both milk replacer intake and total DMI differed between classifications: DIA calves were less feed-efficient than HEA calves. In conclusion, diarrhea in young calves decreases DMI, BW gain, and feed efficiency relative to HEA calves within 21 d of arrival.

Effects of close-up dietary energy level and supplementing rumen-protected lysine on energy metabolites and milk production in transition cows

The objective of this study was to investigate the effects of dietary energy levels and rumen-protected lysine supplementation on serum free fatty acid levels, β-hydroxybutyrate levels, dry matter (DM) intake, and milk production and composition. Treatments were arranged in a 2 × 2 factorial design with 2 dietary energy levels [high net energy for lactation (NE_L) = 1.53 Mcal/kg of DM vs. low NE_L = 1.37 Mcal/kg of DM; HE vs. LE) fed either with rumen-protected lysine (bypass lysine; 40 g/cow per day) or without rumen-protected lysine (control). Sixty-eight third-lactation Holstein dairy cows entering their fourth lactation were randomly allocated to 4 treatments groups: HE with bypass lysine, HE without bypass lysine, LE with bypass lysine, and LE without bypass lysine. Groups were balanced based upon their expected calving date, previous milk yields, and body condition score. All cows were fed the same diet (NE_L = 1.34 Mcal/kg of DM) during the dry period prior to the trial. Rumen-protected lysine was top-dressed on a total mixed ration to deliver 9.68 g/d of metabolizable lysine to pre- and postpartum cows. After calving, all cows received the same TMR (1.69 Mcal/kg of DM). Blood samples were collected at -21, -14, -7, 0, 3, 7, 14, and 21 d relative to calving, and free fatty acids and β-hydroxybutyrate concentrations were measured. Amount of feed offered and orts were collected and measured for individual cows 4 d/wk. Milk samples were collected once per week following calving, and milk composition was analyzed. Feeding high NE_L to close-up cows decreased the concentrations of free fatty acid and β-hydroxybutyrate in prepartum cows but not in postpartum cows. Addition of rumen-protected lysine increased postpartum DM intake, and decreased serum free fatty acid and β-hydroxybutyrate concentrations. Neither energy nor rumen-protected lysine supplementation nor their interaction affected milk yield or fat or lactose yields. However, cows in the group receiving HE with bypass lysine tended to produce more milk compared with other groups and had a lower blood β-hydroxybutyrate concentration postpartum. These results indicate that feeding a high-energy diet together with rumen-protected lysine improved DM intake and lowered serum free fatty acid and β-hydroxybutyrate concentrations in transition cows.

A 100-Year Review: Calf nutrition and management

The first calf paper, published in the May 1919 issue of the Journal of Dairy Science (JDS), described factors affecting birth body weight of different breeds of calves. Other studies were done on nonmilk ingredients, growth charts were developed, and early weaning was followed to conserve milk fed to calves. Calf papers did not report use of statistics to control or record variation or to determine whether treatment means were different. Many experiments were more observational than comparative. Typically fewer than 5 calves, and sometimes 1 or 2 calves, were used per treatment. During the next 20 yr, calf studies increased and included colostrum feeding, milk and milk replacer feeding, minerals and vitamins, and fats and oils. Many concepts fundamental to current knowledge and understanding of digestion, rumen development, and milk replacer formulation were developed during this period. In addition, the concept of using antibiotic growth promoters in dairy calf diets was first evaluated and developed during the 1950s. During the 20-yr period of January 1957 through December 1976, a large number of universities in the United States and 1 in Canada contributed almost 150 papers on a variety of calf-related topics. These topics included genetics, physiology of the calf, review of calf immunity, antibiotic feeding, and milk replacer ingredients. This became the golden era of calf rumen development studies, which also engendered studies of calf starter rations and ingredients. A classic review of management, feeding, and housing studies summarized research related to calf feeding and management systems up to that point with an emphasis on maintaining calf growth and health while reducing labor and feed costs. It was also during this period that metric measurements replaced English units. In the 20-yr period from 1977 to 1996, more than 400 articles on calf nutrition and management were published in JDS. With the growing research interest in calves, a paper outlining standardized procedures for conducting and reporting data from calf experiments was first published. A very active area of calf nutrition research from the late 1970s to the mid 1980s was colostrum quality, feeding, and preservation; more than 60 such research articles were published in the journal during this time. Various nonmilk protein sources were evaluated. Extensive studies were done evaluating trace and major mineral requirements in calves along with some vitamin studies. Throughout the 1970s, 1980s, and 1990s, the primary objective of most calf research was how to wean healthy, adequately grown calves at an early age-generally less than 30 d of age. This program was reviewed in a 1979 publication. Research on calf starter ingredients, nutrient composition, and additives was minimal in the 1980s and 1990s given the importance of starter intake to the success of early weaning, but the role of water intake in starter intake and growth was established. Research on issues with calves continued to increase during the last 20-yr period as evidenced by publication of more than 580 articles in JDS as well as many more in other refereed journals. In addition to papers contributed by several universities in the United States and Canada, the number of papers authored by scientists at universities and institutes in other countries increased dramatically during this period. Factors influencing colostral antibody absorption, heat treatment of colostrum, and efficacy of colostrum supplements and replacers were reported. Most studies in this period related to nutrition. Studies were published supporting greater neonatal growth rates from feeding more milk replacer but with a higher crude protein content than traditional. Protein energy effects on growth and body composition were evaluated in concert with greater growth rates. Milk and nonmilk protein sources in milk replacers along with AA supplementation were evaluated. Limited studies were done with fat sources and fatty acid supplementation along with trace minerals and fat-soluble vitamins. Waste milk feeding and heat treatment became more prevalent. Studies established starter ingredient palatability and use of forage when fed with pelleted starters. With the advent of automatic milk and milk replacer feeders, factors influencing how and when to wean were established. Research programs established factors affecting calf behavior and welfare. Several databases were evaluated along with various published studies, and established calf growth during the first 2 mo was subsequently reflected in first- and later-lactation milk production of those calves. A new area of calf research that emerged from 1997 on was the effects of maternal environment and nutrition on calf health, growth, and future productivity. From a mechanistic standpoint, the field of epigenetics seems likely to explain many of these phenomena. Some possibilities for future calf nutrition and management were elaborated.

Transcriptional changes in mesenteric and subcutaneous adipose tissue from Holstein cows in response to plane of dietary energy

Background

Dairy cows can readily overconsume dietary energy during most of the prepartum period, often leading to higher prepartal concentrations of insulin and glucose and excessive body fat deposition. The end result of these physiologic changes is greater adipose tissue lipolysis post-partum coupled with excessive hepatic lipid accumulation and compromised health. Although transcriptional regulation of the adipose response to energy availability is well established in non-ruminants, such regulation in cow adipose tissue depots remains poorly characterized.

Results

Effects of ad-libitum access to high [HIGH; 1.62 Mcal/kg of dry matter (DM)] or adequate (CON; 1.35 Mcal/kg of DM) dietary energy for 8 wk on mesenteric (MAT) and subcutaneous (SAT) adipose tissue transcript profiles were assessed in non-pregnant non-lactating Holstein dairy cows using a 13,000-sequence annotated bovine oligonucleotide microarray. Statistical analysis revealed 409 and 310 differentially expressed genes (DEG) due to tissue and diet. Bioinformatics analysis was conducted using the Dynamic Impact Approach (DIA) with the KEGG pathway database. Compared with SAT, MAT had more active biological processes related to adipose tissue accumulation (adiponectin secretion) and signs of pro-inflammatory processes due to adipose tissue expansion and macrophage infiltration (generation of ceramides). Feeding the HIGH diet led to changes in mRNA expression of genes associated with cell hypertrophy (regucalcin), activation of adipogenesis (phospholipid phosphatase 1), insulin signaling activation (neuraminidase 1) and angiogenesis (semaphorin 4G, plexin B1). Further, inflammation due to HIGH was underscored by mRNA expression changes associated with oxidative stress response (coenzyme Q3, methyltransferase), ceramide synthesis (N-acylsphingosine amidohydrolase 1), and insulin signaling (interferon regulatory factor 1, phosphoinositide-3-kinase regulatory subunit 1, retinoic acid receptor alpha). Activation of ribosome in cows fed HIGH indicated the existence of greater adipocyte growth rate (M-phase phosphoprotein 10, NMD3 ribosome export adaptor).

Conclusions

The data indicate that long-term ad-libitum access to a higher-energy diet led to transcriptional changes in adipose tissue that stimulated hypertrophy and the activity of pathways associated with a slight but chronic inflammatory response. Further studies would be helpful in determining the extent to which mRNA results also occur at the protein level.

Evaluation of serum protein-based arrival formula and serum protein supplement (Gammulin) on growth, morbidity, and mortality of stressed (transport and cold) male dairy calves

Previous studies with calves and other species have provided evidence that blood serum-derived proteins and fructooligosaccharides (FOS) may benefit intestinal health. We assessed the effects of supplementing products containing serum proteins as a component of arrival fluid support or serum proteins plus FOS (in addition to additional solids, minerals, and vitamins) in an early life dietary supplement on performance, morbidity, and mortality of stressed (transport, cold) male calves. Male Holstein calves (n = 93) <1 wk old were stratified by arrival body weight (BW) and plasma protein concentration, and then randomly assigned to 1 of 4 treatment groups in a 2 × 2 factorial arrangement of one-time administration of fluid support [either control electrolyte solution (E) or the serum protein-containing arrival formula (AF)] and 14 d of either no supplementation (NG) or supplementation with Gammulin (G; APC Inc., Ankeny, IA), which contains serum proteins and FOS in addition to other solids, minerals, and vitamins. Upon arrival at the research facility, calves were orally administered either AF or E. At the next feeding, half of the calves from each fluid support treatment received either milk replacer (20% crude protein, 20% fat) or the same milk replacer supplemented with G (50 g/d during the first 14 d). Starter and water were freely available. Feed offered and refused was recorded daily. Calf health was assessed by daily assignment of fecal and respiratory scores. Stature measures and BW were determined weekly. Blood samples were obtained at d 0 (before treatments), 2, 7, 14, and 28. Calves were weaned at d 42 and remained in the experiment until d 56. After 2 wk of treatments, calves previously fed AF had greater body length (66.6 vs. 66.0 cm), intakes of dry matter (38.7 vs. 23.5 g/d) and crude protein (9.2 vs. 5.6 g/d) from starter, and cortisol concentration in blood (17.0 vs. 13.9 ng/mL) than calves fed E. Supplementation with G resulted in greater BW gain during the first 2 wk, increased intakes of dry matter and CP, and decreased respiratory scores. For the 8-wk experiment, G supplementation resulted in lower mean fecal score (1.6 vs. 1.8) and fewer antibiotic treatments per calf (1.5 vs. 2.5) than NG. Survival was greater in G than in NG calves (98 vs. 84%). Despite the marked reduction in morbidity and mortality, blood indicators of acute-phase response, urea N, and total protein were not affected by AF or G in transported cold-stressed male calves.

Changes in the intestinal bacterial community, short-chain fatty acid profile, and intestinal development of preweaned Holstein calves. 1. Effects of prebiotic supplementation depend on site and age

Digestive disorders are common during the first few weeks of life of newborn calves. Prebiotics are nondigestible but fermentable oligosaccharides that modulate growth and activity of beneficial microbial populations, which can result in enhanced gut health and function. Galactooligosaccharides (GOS) have demonstrated such prebiotic potential. In this study, the effect of GOS supplementation on intestinal bacterial community composition and fermentation profiles; intestinal health, development, and function; and growth was evaluated in dairy calves fed for high rates of growth. Eighty male Holstein calves were assigned either to a control treatment consisting of commercial milk replacer or to a GOS-rich (i.e., 3.4% of dry matter) milk replacer treatment. After 2 and 4wk, 8 calves per treatment were slaughtered at each age. Samples of intestinal digesta and tissue were collected for assessment of bacterial communities, short-chain fatty acid concentrations, in vitro measurement of nutrient transport and permeability, histomorphology, and gastrointestinal organ size. The remaining 48 calves continued to wk 8 to measure body growth, nutrient intake, and fecal and respiratory scores. Calves fed GOS displayed greater Lactobacillus and Bifidobacterium relative abundance and more developed intestinal epithelial structures, but also had greater fecal scores presumably related to greater colonic water secretion. Control calves showed slightly better growth and milk dry matter intake. Size of intestinal organs, intestinal nutrient transport, and epithelium paracellular resistance were not affected by treatment. Excessive GOS supplementation had both prebiotic and laxative effects, which led to slightly lower growth performance while promoting commensal bacteria population and greater intestinal epithelium growth.

Changes in the intestinal bacterial community, short-chain fatty acid profile, and intestinal development of preweaned Holstein calves. 2. Effects of gastrointestinal site and age

The objective of this work was to assess the effects of age and gastrointestinal location (rumen vs. colon) on bacterial community diversity and composition, as well as short-chain fatty acid profiles of preruminant male Holstein calves on an intensive milk replacer feeding program. Thirty-two calves were fed at 2% of their body weight (dry matter basis) from d 10 until harvest. Sixteen calves were euthanized at 2wk and another 16 at 4wk of age to collect digesta samples from the rumen and colon. The rumen and colon bacterial communities of preruminant calves showed a similar degree of diversity (i.e., Shannon index) whereas composition differed considerably. The colonic bacterial population was characterized by dominance of lactic acid bacteria such as Lactobacillus, Streptococcus, Enterococcus, and Bifidobacterium. In addition, colonic short-chain fatty acid and lactic acid concentrations were between 50 and 850% higher than in the rumen, indicating greater fermentative activity in the colon. On the other hand, in the rumen, no genus over-dominated and more variation was present among calves. Because of an active reticular groove and low starter grain intake during the first 1 to 3wk of life, ruminal fermentation may not contribute to significant metabolizable energy supply until after 4wk of life in intensively fed calves. Until then, calf hindgut fermentation, characterized by high abundance of lactic acid bacteria along with increased lactate and butyrate concentrations, could be beneficial for intestinal health and survival of the calf during the first weeks of life.

A comparison of the effect of soybeans roasted at different temperatures versus calcium salts of fatty acids on performance and milk fatty acid composition of mid-lactation Holstein cows

To evaluate the effect of soybeans roasted at different temperatures on milk yield and milk fatty acid composition, 8 (4 multiparous and 4 primiparous) mid-lactation Holstein cows (42.9±3 kg/d of milk) were assigned to a replicated 4×4 Latin square design. The control diet (CON) contained lignosulfonate-treated soybean meal (as a source of rumen-undegradable protein) and calcium salts of fatty acids (Ca-FA, as a source of energy). Diets 2, 3, and 4 contained ground soybeans roasted at 115, 130, or 145°C, respectively (as the source of protein and energy). Dry matter intake (DMI) tended to be greater for CON compared with the roasted soybean diets (24.6 vs. 23.3 kg/d). Apparent total-tract digestibilities of dry matter, organic matter, and crude protein were not different among the treatments. Actual and 3.5% fat-corrected milk yield were greater for CON than for the roasted soybean diets. Milk fat was higher for soybeans roasted at 130°C than for those roasted at either 115 or 145°C. No differences were observed between the CON and the roasted soybean diets, or among roasting temperatures, on feed efficiency and nitrogen concentrations in rumen, milk, and plasma. Milk from cows fed roasted soybeans had more long-chain fatty acids and fewer medium-chain fatty acids than milk from cows fed Ca-FA. Compared with milk from cows fed the CON diet, total milk fat contents of conjugated linoleic acid, cis-9,trans-11 conjugated linoleic acid, cis-C18:2, cis-C18:3, and C22:0 were higher for cows fed the roasted soybean diets. Polyunsaturated fatty acids and total unsaturated fatty acids were greater in milk from cows fed roasted soybean diets than in milk from cows fed CON. Concentrations of C16:0 and saturated fatty acids in milk fat were greater for CON than for the roasted soybean diets. Cows fed roasted soybean diets had lower atherogenic and thrombogenic indices than cows fed CON. Milk fatty acid composition did not differ among different roasting temperatures. In summary, results showed that cows fed CON had higher DMI and milk yield than cows fed roasted soybean diets. Among different roasting temperatures (115, 130, and 145°C), soybeans roasted at 115°C led to higher milk production and lower DMI. Cows fed roasted soybeans, regardless of the roasting temperature, had more unsaturated fatty acids in milk. Using roasted soybeans in dairy cow rations could, therefore, improve the health indices of milk for human nutrition.

Assessment of the effect of methionine supplementation and inclusion of hydrolyzed wheat protein in milk protein-based milk replacers on the performance of intensively fed Holstein calves

The objectives of this study were to compare 2 milk replacers containing only milk proteins with or without supplemental Met, and to compare a milk replacer containing hydrolyzed wheat protein at 4.5% of dry matter (DM) and supplemental Lys and Met against the 2 all-milk-protein formulas, by assessing their effect on the growth performance, efficiency, and plasma urea nitrogen of pre-weaning Holstein calves. Thus, 57 Holstein calves were allotted to the following 3 treatments: (1) a skim milk plus whey protein concentrate-based milk replacer (SMWP) containing about 2.6% Lys and 0.6% Met on a DM basis; (2) SMWP + M based on skim milk and whey proteins, containing about 2.6% Lys, and supplemental Met to reach 0.9% on a DM basis; and (3) a skim milk plus whey protein concentrate plus 4.5% of the DM as hydrolyzed wheat protein based milk replacer (HWP + LM) where the wheat protein replaced 50% of the whey protein concentrate, and also contained supplemental Lys and Met to match the profile of SMWP + M (i.e., Lys 2.6 and Met 0.9% on DM basis). No difference in any of the responses was observed by supplementing the milk protein based formula with Met or when hydrolyzed wheat protein was added to the formula. Results indicate that (1) a milk replacer based on skim milk protein and whey protein with a Lys concentration of ~2.6% does not benefit from Met supplementation, and (2) milk replacer containing 4.5% of the DM as hydrolyzed wheat protein and supplemented with Lys and Met can support the same growth performance as milk protein-based formulas.

Late-gestation heat stress abatement on performance and behavior of Holstein dairy cows

The objective of this study was to evaluate cooling to lessen the effects of heat stress during the last 3 wk of gestation on performance and behavior of multiparous Holstein cows. Twenty nonlactating cows were randomly assigned to treatments approximately 21 d before their expected calving date based on mature equivalent milk production and parity. Treatments were only imposed during the last 3 wk of gestation and included heat stress (HT; n=10) and cooling (CL; n=10), both under a similar photoperiod (14 h of light and 10 h of dark). Dry cows were housed in a sand-bedded stall with the stall areas for CL cows equipped with sprinklers and fans that were on from 0700 to 1900 h, whereas those for the HT cows were not. After parturition, all cows were housed in a barn with cooling devices. Rectal temperatures were measured daily at 1400 h and respiration rates were recorded by counting the flank movements for 1 min at 1500 h on odd days over the last 3 wk of gestation to calving. Daily dry matter intake was measured from -21 d relative to expected calving to 21 d after calving and milk production was recorded daily up to 180 d in milk. Behavioral changes of dry cows were studied continuously for 24 h at -10 d relative to expected calving. The average temperature-humidity index during the last 3 wk of gestation was 69.7 and was not significantly different between treatments. Heat-stressed cows exhibited greater rectal temperatures (39.5 vs. 39.2°C), greater respiration rates (70.4 vs. 63.3 breaths/min), and decreased dry matter intake (13.7 vs. 15.5 kg/d) compared with CL cows. Compared with HT cows, CL cows produced more milk during 180 d in milk (40.5 vs. 44.6 kg/d). Heat stress decreased ruminating (243.2 vs. 282.5 min/d) and chewing times (390.6 vs. 448.7 min/d) at -10 d before calving. The CL cows had shorter standing times than their HT counterparts (390.4 vs. 474.0 min/d). These results confirm that heat stress abatement in the late gestation period improves performance of dairy cows in subsequent lactation.

Effects of alfalfa hay and its physical form (chopped versus pelleted) on performance of Holstein calves

Inclusion of forage and its physical form in starter may affect rumen development, average daily gain (ADG), and dry matter intake (DMI) of dairy calves. To evaluate the effects of forage and its physical form (chopped vs. pelleted) on growth of calves under a high milk feeding regimen, 32 Holstein calves (38.8±1.1kg) were assigned at birth to 1 of 3 treatments in a completely randomized block design. Dietary treatments (% of dry matter) were (1) 100% semi-texturized starter (CON); (2) 90% semi-texturized starter + 10% chopped alfalfa hay (mean particle size=5.4mm) as a total mixed ration (TMR; CH); and (3) 90% semi-texturized starter + 10% pelleted alfalfa (mean=5.8mm) hay as a TMR (PH). Data were subjected to mixed model analysis with contrasts used to evaluate effect of forage inclusion. Calves were weaned at 76 d of age and the experiment finished 2 wk after weaning. Individual milk and solid feed consumption were recorded daily. Solid feed consumption and ADG increased as age increased (effect of week), but neither forage inclusion nor physical form of forage affected these variables pre- or postweaning. Plasma urea N was affected by treatments such that the CON group had a lower concentration than forage-fed groups. Forage inclusion, but not physical form, resulted in increased total protein in plasma. Although days with elevated rectal temperature, fecal score, and general appearance were not affected by dietary treatments, calves fed alfalfa hay during the first month of life had fewer days with respiratory issues, regardless of physical form of hay. We concluded that provision of forage does have some beneficial effects in calves fed large amounts of milk replacer, but pelleted alfalfa hay did not result in any improvement in calf performance or health.