Interrelationships among plasma metabolites, production, and ovarian follicular function in dairy cows

Associations of blood metabolites and production variables with ovarian function and parity, specifically, interval to first ovulation (IFO) and the incidence of ovarian cysts (OC) and multiple ovulation (MOV) at the first ovulation postpartum, were determined in lactating dairy cows. This retrospective study involved data on 169 Holstein cows from three studies on the same herd. Blood samples were taken weekly from week −1 to week 4, relative to calving, and transrectal ultrasonography was performed twice weekly from day 7 to day 60 postpartum. The overall IFO was 32.6 ± 1.9 d (mean ± SEM) and did not differ among lactations. Primiparous cows were at a greater risk of failing to ovulate before day 60 postpartum and cows in the third or greater lactation were at a higher risk for OC and MOV. Blood metabolites and production variables indicating a negative energy balance were associated with cows failing to ovulate before day 35 postpartum, but were not related with OC. Increased dry matter intake and milk yield, particularly in second lactation cows, were associated with a higher incidence of OC. While beta-hydroxybutyrate acid and insulin-like growth factor 1 were associated with MOV, the relationship was weak. Reducing negative energy balance is necessary to reduce IFO but may increase the incidence of MOV.

Effects of the supplemental chromium form on performance and metabolic profile in laying hens exposed to heat stress

This experiment was conducted to compare the effect of the supplemental chromium (Cr) form on performance, egg quality, and metabolic profile in laying hens exposed to heat stress (HS). Laying hens (n = 1800; 16-wk-old; Lohmann LSL-Lite) were kept in cages in temperature-controlled rooms at either 22 ± 2°C for 24 h/d (thermoneutral, TN) or 34 ± 2°C for 8 h/d, from 08:00 to 17:00 h, followed by 22°C for 16 h (HS) for 12 wks. Hens reared under both environmental conditions were fed 1 of 3 diets: a basal diet and the basal diet supplemented with either 1.600 mg of chromium-picolinate (CrPic, 12.43% Cr) or 0.788 mg of chromium-histidinate (CrHis, 25.22% Cr) per kg of diet, delivering 200 μg elemental Cr per kg diet. Data were analyzed by 2-way ANOVA. Exposure to HS caused decreases in feed intake (P < 0.0001), egg production (P < 0.0001), egg weight (P < 0.0001), eggshell weight (P < 0.0009), eggshell thickness (P < 0.0001), eggshell strength (P < 0.0001), and Haugh unit (P < 0.0001), deterioration in feed conversion ratio (P < 0.0001), increases in serum glucose and cholesterol concentrations (P < 0.0001 for both), decreases in serum and egg yolk Cr concentrations (P < 0.0001 for both), and decreases in serum Na (P < 0.002) and K (P < 0.01) concentrations. Both Cr sources were equally effective in alleviating performance variables under the HS condition. However, neither Cr sources alleviated deteriorations in egg quality parameters and serum electrolytes. Both Cr sources decreased serum glucose and cholesterol concentrations and increased serum and egg yolk Cr concentrations under the HS condition. In conclusion, HS adversely affected laying performance, egg quality, and metabolic profile. Both CrPic and CrHis partially alleviated the adverse effect of HS on these parameters. Inclusion of either Cr source could be a part of nutritional management strategies to overcome the adverse effects of HS performance and metabolic profile in laying hens.

Effects of the supplemental chromium form on performance and oxidative stress in broilers exposed to heat stress

This experiment was conducted to investigate effects of the organic complex form of supplemental chromium (Cr) on performance, oxidative stress markers, and serum profile in broilers exposed to heat stress (HS). A total of 1,200 10-day-old boilers (Ross-308) was divided into one of the 6 treatments (2 environmental temperatures x 3 diets with different Cr forms). The birds were kept in temperature-controlled rooms at either 22 ± 2°C 24 h/d (thermoneutral, TN group) or 34 ± 2°C for 8 h/d, 08:00 to 17:00 h, followed by 22°C for 16 h (HS group) and fed either a basal diet (C) or the basal diet supplemented with Cr (200 μg/kg) through 1.600 mg of CrPic (12.43% Cr) and 0.788 mg of CrHis (25.22% Cr). Feed intake and body weight were recorded weekly. After cervical dislocation, liver samples were harvested to analyze Cr concentration and glucose transporter-2,4 (GLUT-2,4) expression. The breast meat also was sampled for the concentration of Cr and expressions of nuclear factor erythroid 2-related factor 2 (Nrf2) and nuclear factor kappa B (NF-κB). Data were analyzed by 2-way ANOVA. Heat stress caused depressions in feed intake (12.1%) and weight gain (21.1%) as well as elevations in feed conversion (11.2%) and abdominal fat (32.8%). It was also associated with depletion of Cr reserves and increases in serum concentrations of glucose, cholesterol, creatine, and enzymes. Exposure to HS was accompanied by suppression of the expressions of Nrf2 and GLUT-2 in muscle and GLUT-4 in the liver and amplification of the expression of NF-κB in muscle. Both Cr sources partially alleviated detrimental effects of HS on performance and metabolic profile. The efficacy of Cr as CrHis was more notable than Cr as CrPic, which could be attributed to higher bioavailability. In conclusion, CrHis can be added into the diet of broilers during hot seasons to overcome deteriorations in performance and wellbeing related to oxidative stress.

Reliability of the i-STAT for the determination of blood electrolyte (K+, Na+, and CI-) concentrations in cattle

Background

Rapid determination of blood electrolyte concentrations can help determine electrolyte status and delivery of effective volume of electrolyte solutions in field conditions.

Objective

To evaluate reliability of the i‐STAT, a point‐of‐care (POC) device, in measuring blood K⁺, Na⁺, and CI⁻ concentrations in cattle.

Animals

Ninety‐eight cattle with various diseases.

Methods

In this prospective study, blood samples collected from the jugular vein were processed for determination of K⁺, Na⁺, and CI⁻ concentrations in blood and plasma using the i‐STAT and auto‐analyzer (Cobas C501), respectively. Blood and plasma electrolyte data were subjected to student t‐test for comparison, the concordance analysis for agreement, accuracy, and precision, the Passing‐Bablok regression and the Bland‐Altman plot for reliability, and receiver operating characteristics curves for sensitivity (Se) and specificity (Sp).

Results

Plasma concentrations of K⁺ (4.39 versus 4.2 mmol/L; P < .0001) and CI⁻ (100.30 versus 99.4 mmol/L; P < .04) were greater than their concentrations in blood. Plasma and blood Na⁺ concentrations were similar (136.95 versus 136.8 mmol/L). The i‐STAT results were highly correlated with the Cobas C501 results (r = 0.970, 0.922, and 0.866 for K⁺, Na⁺, and CI⁻, respectively). Regression equations fitting blood (Y) and plasma (X) concentration did not deviate from the identity line for K⁺ (Y = −0.10 + 0.98 × X), Na⁺ (Y = X), and CI⁻ (Y = 3.04 + 0.96 × X). The mean bias (blood concentration ‐ plasma concentration) was −0.20 for K⁺ (P = .03), −0.16 for Na⁺ (P = .12), and −0.87 for CI⁻ (P = .93). The i‐STAT had 76–100% Se and 87.7–100% Sp for assessing electrolyte statuses.

Conclusions and Clinical Importance

The i‐STAT yielded results that were in agreement with the auto‐analyzer, with negligible biases in measurement of plasma K⁺, Na⁺, and CI⁻ concentrations. The i‐STAT is a reliable POC device and can be used in field condition to assess electrolyte status in cattle.

Epigallocatechin-3-gallate exerts protective effects against heat stress through modulating stress-responsive transcription factors in poultry

1. The aim of the study was to describe the effect of Epigallocatechin-3-gallate (EGCG), a polyphenol derived from green tea, on activator protein-1 (AP-1) components (phospho-c-Jun and c-Fos), cyclooxygenase-2 (COX-2) and heat shock proteins (HSPs) in the liver of heat-stressed quails. 2. A total of 180 5-week-old female Japanese quails were reared either at 22°C for 24 h/d (thermoneutral, TN) or 34°C for 8 h/d (heat stress, HS) for 12 weeks. Birds in both environments were randomly given 1 of 3 diets: basal diet and basal diet with 200 or 400 mg of EGCG added per kilogram of diet. 3. The hepatic c-Jun, c-Fos, COX-2 and HSPs gene expression for quails reared under the HS environment was greater than those reared under the TN environment. Supplemental EGCG decreased hepatic expression of these proteins at a greater extent under HS than TN. 4. In conclusion, suppression of AP-1 COX-2 and HSPs may partly account for the inhibitory effect of EGCG in heat-stressed quail.

Evaluation of 4 point-of-care units for the determination of blood l-lactate concentration in cattle

BACKGROUND

Despite being used commonly in bovine medicine, information on reliability of point-of-care (POC) lactate meters is limited.

OBJECTIVE

To determine the validity of 4 commercially available POC lactate meters in cattle.

ANIMALS

Cattle with various diseases (n = 120).

METHODS

Blood samples collected from the jugular vein were processed immediately on POC lactate meters. Plasma l-lactate concentration was measured by the enzymatic-colorimetric method (ELISA). Data were subjected to Friedman's test for comparison, Passing-Bablok regression and Bland-Altman plot analyses for reliability, and receiver operating characteristics analysis for sensitivity (Se) and specificity (Sp).

RESULTS

The POC lactate meters were highly correlated with ELISA (r = 0.98-0.99) despite disagreements among units. When regressed on ELISA, blood l-lactate concentrations generated from Accutrend Plus and Lactate Pro were linear up to 16.6 and 15.7 mmol/L, respectively, whereas those generated from i-STAT and Lactate Scout were linear up to 19.5 and 19.7 mmol/L, respectively. All POC lactate meters had a Se of 100% with Sp of 95.7-98.6% at a plasma l-lactate cut-off concentration of 4 mmol/L. i-STAT had the best accuracy (99.0%) and precision (99.8%), the best linear fit (y = -0.13 + 1.04X) yielding the lowest bias (-6.6%) as well as the highest Se (100%) and Sp (98.6%).

CONCLUSIONS AND CLINICAL IMPORTANCE

Despite high correlation with the reference method, dilution is needed for Accutrend Plus/Lactate Pro and i-STAT/Lactate Scout if concentrations >15 and 20 mmol/L, respectively. i-STAT provided the most accurate and precise results.

Tomato powder in laying hen diets: effects on concentrations of yolk carotenoids and lipid peroxidation

1. The effects of tomato powder supplementation on performance, egg quality, serum and egg yolk carotenoids, vitamins and malondialdehyde (MDA) concentrations in were investigated in laying hens in mid-lay. 2. A total of 90 laying hens, 49 weeks old, were divided into 3 groups consisting of 6 replicate cages, 5 birds per cage. Birds were randomly fed on one of three diets: basal diet and basal diet added with 5 or 10 g tomato powder per kg diet. 3. As tomato powder concentration increased, there were linear increases in feed intake, egg production, egg weight and yolk colour and a linear decrease in feed conversion. Shell weight, shell thickness and Haugh unit remained unchanged in response to dietary treatments. 4. Concentrations of serum and egg yolk lycopene, β-carotene, lutein and vitamin A increased for both diets including tomato powder, whereas MDA decreased linearly with increasing supplemental tomato powder concentration. 5. Tomato powder supplementation increased egg production persistency and increased carotenoids and vitamin A contents in egg yolk, accompanied by reduced yolk lipid peroxidation.

Exclusion of dietary sodium bicarbonate from a wheat-based diet: effects on milk production and ruminal fermentation

Milk production, rumen fermentation, and whole-tract apparent nutrient digestibility in response to feeding 20% steam-rolled wheat with or without sodium bicarbonate were evaluated in 12 Holstein cows averaging 165±16 DIM. Cows were fed 1 of 2 isoenergetic and isonitrogenous diets containing either 0 or 0.75% sodium bicarbonate on a DM basis for 21 d in a crossover design. Rumen fluid samples were obtained 18 times during the last 2 d of each period, and fecal samples were collected on 12 occasions from d 18 to 21 of each period. Removal of sodium bicarbonate from the diet did not affect DMI (21.0 kg/d), yields of milk (30.8 kg/d), or milk components (1.16, 1.01, and 1.40 kg/d for fat, protein, and lactose, respectively). Whole-tract apparent digestibility of DM, CP, ADF, and NDF did not differ between the 2 treatments (75.3, 76.6, 67.2, and 63.6%, respectively). The mean rumen pH was 6.24 and was not affected by excluding sodium bicarbonate from the diet. Rumen NH3-N (12.31 mg/dL) and lactic acid (3.63 mM) concentrations were not different, whereas total volatile fatty acids concentration tended to increase when sodium bicarbonate was present in the diet (110 vs. 116 mM). However, average concentrations of the individual volatile fatty acids, as a proportion of total volatile fatty acids, were not affected by treatment. In conclusion, dairy cow diets can include up to 20% steam-rolled wheat without the need for added sodium bicarbonate as long as the diets are formulated to meet the fiber requirements of the cow.

Effects of dietary resveratrol supplementation on egg production and antioxidant status

Resveratrol, a polyphenol derived from red grapes, berries, and peanuts, exerts antiinflammatory, antioxidant, and immunomodulatory effects. The objective of this study was to investigate the effects of dietary resveratrol supplementation on performance and serum and egg yolk antioxidant status in quail (Coturnix coturnix japonica). A total of 150 five-week-old quails were allocated randomly to 1 of 3 dietary treatments: basal diet and basal diet supplemented with 200 or 400 mg of resveratrol/kg of diet. Each diet was offered to 10 cages of 5 birds in each from 4 to 16 wk of age. Serum and egg samples were collected at the beginning and end the experimental period to be evaluated for malondialdehyde (MDA), vitamin A, and vitamin E. Data were subjected to analysis of covariance using the MIXED procedure. There was no treatment effect on feed intake, egg production, or egg quality parameters related to shell, yolk, and albumen. There were no effects of resveratrol supplementation on serum and egg yolk vitamin A concentrations. The quails supplemented with resveratrol had a lower serum MDA concentration (0.56 vs. 0.88 mg/L, P<0.03) and a higher serum vitamin E concentration (5.72 vs. 3.56 mg/L, P<0.008) than those not supplemented with resveratrol. Moreover, there was a linear decrease in serum MDA concentration (P<0.02) and a linear increase in serum vitamin E concentration (P<0.01) as supplemental resveratrol level increased. The treatment groups had less egg yolk MDA concentration than the control group (0.21 vs. 0.15 microg/g, P<0.002). Egg yolk MDA concentration decreased linearly in response to increasing dietary resveratrol level (P<0.0003). In conclusion, inclusion of resveratrol up to 400 mg/kg into quail diets enhanced antioxidant status of birds and eggs. Further studies should investigate the carryover effects of dietary resveratrol supplementation on product quality with respect to shelf life, antioxidant stability, and its nutritive value for human consumption.

Role of dietary zinc in heat-stressed poultry: a review

High ambient temperatures compromise performance and productivity through reducing feed intake and decreasing nutrient utilization, growth rate, egg production, egg quality, and feed efficiency, which lead to economic losses in poultry. Environmental stress also leads to oxidative stress associated with a reduced antioxidant status in the bird in vivo, as reflected by increased oxidative damage and lowered plasma concentrations of antioxidant vitamins (e.g., vitamins E, A, and C) and minerals (e.g., Zn). Zinc has an important role in numerous biological processes in avian and mammalian species. For instance, Zn is an essential component of many enzymes, and it has both structural and catalytic functions in metalloenzymes. Furthermore, dietary Zn is required for normal immune function as well as proper skeletal development and maintenance. One of the most important functions of Zn is related to its antioxidant role and its participation in the antioxidant defense system. This work compiles past and present information about the role of Zn in heat-stressed poultry health.

Effects of increasing amounts of dietary wheat on performance and ruminal fermentation of Holstein cows

Twelve second-lactation Holstein cows were used in a replicated Latin square design to examine the effects of dietary wheat on lactation performance, ruminal fermentation, and whole-tract nutrient digestibility. Cows were randomly assigned to 1 of 3 diets containing 0, 10, and 20% steam-rolled wheat on a dry matter basis at the expense of steam-rolled barley. Cows were fed and milked twice daily. Six of the cows were ruminally cannulated, and rumen fluid samples were obtained from these cows 18 times during the last 2 d of each period. Treatment did not affect dry matter intake (20.9 kg/d) or yields of milk (36.1 kg/d) or milk components (1.25, 1.10, and 1.67 kg/d for fat, protein, and lactose, respectively). Fat percentage was not different among the treatments but protein content of the milk was reduced by the wheat treatments, and was lower when 10% wheat was included in the diet versus 20%. Cows fed wheat had lower ruminal pH (6.36 vs. 6.44) and greater NH(3)-N (11.49 vs. 8.10 mg/dL) and total volatile fatty acids (121 vs. 113 mM) concentrations than cows not fed wheat. The acetate:propionate ratio was lower for cows fed wheat than for those not fed wheat (3.21 vs. 3.36), but was not different between cows fed 10% versus 20% wheat. Wheat feeding did not alter whole-tract apparent digestibility of dry matter, crude protein, acid detergent fiber, and neutral detergent fiber. Results of this study show that up to 20% steam-rolled wheat can be included in the diet of dairy cows without compromising production or causing subacute ruminal acidosis if adequate fiber is provided and the diets are properly formulated and mixed.

Sunflower oil supplementation alters meat quality but not performance of growing partridges (Alectoris chukar)

This study was conducted to evaluate the effects of sunflower oil supplementation (0%, 3%, 6% and 9%) to partridge chicks (Alectoris chukar) on growth performance, nutrient digestibility and carcass characteristics. Feed consumption and live weight gain were responsive to dietary sunflower oil inclusion during the starter period, but not during the grower period. Increasing sunflower oil level linearly increased crude protein and fat digestibilities. Except for abdominal fat, weights of inedible parts and edible organs remained unchanged by the diets. The treatments linearly decreased weight and efficiency of carcass and weights of wings and breast and did not alter weights of thighs and neck. Breast meat saturated fatty acids decreased linearly by 17.9% and unsaturated fatty acids increased linearly by 10.6%, as sunflower oil level increased in the diets. Monounsaturated fatty acids decreased linearly by 27.3%, whereas polyunsaturated fatty acids increased linearly by 51%. Overall, n-3 (0.78% vs. 0.59%) and n-6 (42.6% vs. 29.8%) were greater in breast meat in treatment groups than in control group. In conclusion, sunflower addition into diets has minimal effects on performance of growing partridges, but significantly alters meat fatty acid composition.

The role of exogenous insulin in the complex of hepatic lipidosis and ketosis associated with insulin resistance phenomenon in postpartum dairy cattle

As a result of a marked decline in dry matter intake (DMI) prior to parturition and a slow rate of increase in DMI relative to milk production after parturition, dairy cattle experience a negative energy balance. Changes in nutritional and metabolic status during the periparturient period predispose dairy cattle to develop hepatic lipidosis and ketosis. The metabolic profile during early lactation includes low concentrations of serum insulin, plasma glucose, and liver glycogen and high concentrations of serum glucagon, adrenaline, growth hormone, plasma beta-hydroxybutyrate and non-esterified fatty acids, and liver triglyceride. Moreover, during late gestation and early lactation, flow of nutrients to fetus and mammary tissues are accorded a high degree of metabolic priority. This priority coincides with lowered responsiveness and sensitivity of extrahepatic tissues to insulin, which presumably plays a key role in development of hepatic lipidosis and ketosis. Hepatic lipidosis and ketosis compromise production, immune function, and fertility. Cows with hepatic lipidosis and ketosis have low tissue responsiveness to insulin owing to ketoacidosis. Insulin has numerous roles in metabolism of carbohydrates, lipids and proteins. Insulin is an anabolic hormone and acts to preserve nutrients as well as being a potent feed intake regulator. In addition to the major replacement therapy to alleviate severity of negative energy balance, administration of insulin with concomitant delivery of dextrose increases efficiency of treatment for hepatic lipidosis and ketosis. However, data on use of insulin to prevent these lipid-related metabolic disorders are limited and it should be investigated.

Dry matter intake and energy balance in the transition period

It is easy, based on theoretic considerations, to make the argument that maximizing DMI is important to minimize postpartum complications and losses in milk production that may be associated with them. However, research over the past several years provides ample evidence that successful "passage" through the periparturient period is more complicated than simply maximizing feed intake. Anecdotal evidence from veterinarians and nutrition consultants also confirm that feeding low-NDF diets to achieve high prepartum feed intakes during the prefresh transition period does not necessarily solve fresh-cow problems. Perhaps more important than maximizing feed intake is to minimize the likelihood of cows experiencing large drops in feed intake immediately before parturition. Retrospective analysis of existing data sets indicates that this hypothesis has merit; research must be conducted to vigorously test it. Until then, it seems reasonable to try to achieve high DMI, if it can be sustained through parturition. If it cannot, perhaps a more conservative approach is to limit voluntary intake by increasing dietary fiber, because data suggests that cows fed in such a manner experience less dramatic decreases in feed intake as parturition approaches. We examined the importance of parity, body condition score, and various diet components that may influence DMI during the final 3 weeks before parturition, but they only explained 18% of the variation in intake among cows. Clearly, there are many other factors that affect intake that need to be identified. Aspects of farm management that may influence animal stress need to be investigated, particularly during the prefresh transition period when cows are inherently prone to reductions in feed intake.

Factors affecting dry matter intake prepartum in relationship to etiology of peripartum lipid-related metabolic disorders: A review

Transition from gestation to lactation is a tremendous challenge for dairy cattle and requires metabolic and hormonal adjustments. The periparturient period, particularly the last week of gestation, is characterized by a dramatic decline (20 to 40%) in dry matter intake (DMI) prior to parturition and a slow rate of increase in DMI after parturition. As a result of negative energy balance during the periparturient period, excessive fat mobilization in adipose tissue and inability of disposing fatty acids (F A) via β-oxidation and exporting triglyceride (TG) as very low density lipoproteins (VLDL) in the liver cause hepatic lipidosis. Controlling hepatic lipidosis, therefore, depends on either limiting non-esterified fatty acids (NEFA) uptake by the liver or increasing oxidation of FA and export of TG by the liver, or both. Results of studies regarding lipid metabolism in the liver to minimize lipidosis are controversial. Thus, until factor(s) limiting hepatic VLDL-TG export are identified, limiting fat mobilization from adipose tissue will play a key role in prevention of hepatic lipidosis and ketosis. Depression in DMI prior to parturition shifts metabolism from anabolism to catabolism. Animal factors such as parity and body condition score and dietary factors such as density of organic nutrients influence DMI. Particularly, increasing energy density of the transition cow diet, without causing acidosis, by supplemental nonstructural carbohydrate (NFC) increases DMI and serum insulin concentration, which suppress lipolysis in adipose tissue and favors anabolic status. In summary, level of DMI and magnitude of DMI depression prior to parturition are linked to the etiology of postpartum lipid-related metabolic disorders. Thus, easing transition from gestation to lactation by offering high dietary NFC in consideration with other factors allows cows to produce more milk, become healthier, and be rebred sooner during postpartum. Key words: Periparturient dairy cattle, dry matter intake, hepatic lipidosis, ketosis

The Effects of Supplementation of Humate and Probiotic on Egg Production and Quality Parameters During the Late Laying Period in Hens

This study was designed to investigate whether inclusions of humate and probiotic into diets of hens during the late laying period increases egg production and improves egg quality. Hisex Brown layers (n = 300), 54 wk of age, were fed a control diet, 0.1% humate, 0.2% humate, 0.1% probiotic, or 0.2% probiotic for 75 d. Active ingredients of humate and probiotic were polymeric polyhydroxy acids (humic, fulvic, ulmic, and humatomelanic acids) and bacterial cultures (Lactobacillus, Bifidobacterium, Streptococcus, and Enterococcus spp.), respectively. Egg production and feed intake were measured daily, and egg weight was measured biweekly. Also, a sample of 12 eggs from each group was collected randomly to determine egg quality every 25 d. The data were analyzed as repeated measures with time as subplot. There were no effects of dietary treatments on feed intake and egg weight. Egg production for hens supplemented with humate and probiotic was not different but was greater than for control hens. Egg production increased linearly and mortality and feed conversion efficiency (weight of feed/weight of eggs) decreased linearly with increasing levels of supplemental humate and probiotic. There were no effects of treatments on egg quality. In conclusion, supplementation of humate and probiotic during the late laying period increased egg production, reduced mortality, and improved feed conversion efficiency but did not improve egg quality.

Models for predicting dry matter intake of Holsteins during the prefresh transition period

The objectives of this study were to develop and validate a model for predicting dry matter intake (DMI) of Holsteins during the prefresh transition period. The original database (ODB) for model development was established by compiling parity, body condition score (BCS), and DMI data during the final 3 wk of gestation from 366 Holsteins fed 24 different diets that were used in eight experiments conducted at three universities. For model validation, a validation database (VDB) was established by compiling data from 333 prefresh transition Holsteins fed 25 different diets that were used in eight experiments conducted at five universities. Dry matter intake during the prefresh transition period was fitted to an exponential function: DMI(t) = a + pe(kt), where DMI(t) = DMI as a percentage of body weight (BW) at time t, a = asymptotic intercept at time--infinity, p = change in intake (kg) from the asymptotic intercept until parturition, k = rate constant influencing the shape of the curve, and t = day relative to parturition expressed as days pregnant--280. The model developed from the ODB predicted DMI of heifers in the VDB with satisfactory accuracy and precision. However, this was not true for cows, probably due to differences in BCS of cows and diets fed to cows from the two data sets. When a subset of cows was selected from each data set that had similar BCS (> 4.0) and were fed similar diets, accuracy and precision of the model predicting DMI was improved. Finally, both databases were combined to develop final models for predicting DMI of heifers and cows. Proposed models for predicting mean daily DMI of heifers and cows during the prefresh transition period were DMI(t) = 1.713-0.688e(0.344t) (R2 = 0.96) and DMI(t) = 1.979-0.756e(0.154t) (R2 = 0.97), respectively. Adjustment factors for animal and dietary factors were generated to demonstrate the plausibility of adaptive fitting of the prediction. The regression coefficients of prediction models (a, p, and k) were affected by BCS and dietary organic macronutrient concentrations.

Animal and dietary factors affecting feed intake during the prefresh transition period in Holsteins

Parity, body condition score (BCS), and dry matter intake (DMI) data of 699 Holsteins fed 49 different diets during the final 3 wk of gestation (prefresh transition period) were compiled from 16 experiments conducted at eight universities. The objectives of this study were to determine the effects of animal and dietary factors on DMI and to elucidate interactions between animal and dietary factors and among dietary factors on DMI during the prefresh transition period. Animal factors examined were parity and BCS, whereas dietary factors examined were rumen undegradable protein (RUP), rumen degradable protein (RDP), neutral detergent fiber (NDF), and ether extract (EE). DMI decreased 32% during the final 3 wk of gestation, and 89% of that decline occurred during the final week of gestation. Day of gestation, animal factors, and dietary factors accounted for 56.1, 19.7, and 24.2% of explained variation in DMI, respectively, and R2 of this linear multivariable model was 0.18. Cows had higher DMI than heifers. DMI decreased linearly as BCS, RUP, and NDF increased, decreased quadratically as EE increased, and increased quadratically as RDP increased. Moreover, the magnitude of DMI depression as animals approached parturition was affected by characteristics of animals and dietary nutrient composition. There were significant parity x EE, BCS x NDF, RUP x NDF, RDP x NDF, NDF x EE, and RUP x EE interactions on DMI. In conclusion, parity, BCS, and concentrations of organic macronutrients in diets affected DMI during the prefresh transition period, and the magnitude of DMI depression as animals approached parturition.

Effects of slow-release insulin on production, liver triglyceride, and metabolic profiles of Holsteins in early lactation

The objective of this experiment was to determine whether there is a dose of slow-release insulin (SRI) that decreases concentrations of plasma nonesterified fatty acids (NEFA) and liver triglyceride (TG) without decreasing plasma glucose concentration, dry matter intake (DMI), and milk yield. Forty-three Holsteins weighting 765 +/- 70 kg with body condition score of 3.29 +/- 0.25 (mean +/- SD) were fed for ad libitum consumption of the same diet from 2 wk before parturition through 6 d postpartum. Cows were blocked according to actual calving date and parity and then assigned randomly to intramuscular injection of a single dose of 0, 0.14, 0.29, or 0.43 IU of SRI per kilogram of body weight (BW) on d 3 postpartum. On the day of injection, cows were fed hourly to minimize fluctuations in blood hormones and metabolites due to feed intake pattern. Blood samples were collected via jugular catheter every hour from 0 to 24 h and every 6 h from 24 to 48 h postinjection. Pre- and postinjection period liver samples were taken on d 2 and 5 postpartum. One cow injected with 0.29 and two cows injected with 0.43 IU of SRI per kilogram of BW could not complete the trial due to severe hypoglycemia (< 20 mg/dl). Both DMI and milk yield during d 3 to 5 postpartum tended to increase quadratically by increasing dose of SRI. Concentrations of serum insulin and glucagon increased linearly, concentration of plasma glucose decreased linearly, and concentrations of plasma NEFA and beta-hydroxybutyrate decreased quadratically from 0 to 24 h postinjection by increasing dose of SRI. Serum insulin concentrations remained higher in cows injected with SRI (CISRI) than in cows injected with sterile water (CISW; 0 IU of SRI/kg of BW), the quadratic effect of SRI on plasma NEFA concentration continued, and the linear effect of SRI on plasma glucose concentration diminished from 24 to 48 h postinjection. Concentration of hepatic TG for CISRI tended to be lower than for CISW, and increasing dose of SRI quadratically decreased hepatic accumulation of TG. Increasing dose of SRI tended to increase concentration of hepatic glycogen (GLY) quadratically and decreased the ratio of TG to GLY quadratically. In conclusion, a low dose of SRI (0.14 IU/kg of BW) could be considered for prophylactic use against hepatic lipidosis and ketosis.

Effect of chromium supplementation on production and metabolic parameters in periparturient dairy cows

The effect of supplemental chromium as chromium-methionine (Cr-Met) on production and metabolic parameters was investigated in 48 cows from 28 d before expected calving date through 28 d of lactation. Average body weight (BW) was 730 +/- 61 kg before treatment. Treatments were supplementation of 0, 0.03, 0.06, and 0.12 mg of Cr as Cr-Met/kg of BW(0.75). Dry matter intake increased linearly and quadratically during the prepartum and postpartum periods, respectively, and body condition score loss decreased linearly during the postpartum period with increasing Cr-Met. Increasing Cr-Met supplementation caused quadratic increases in milk, fat, and lactose yields. Treatments did not affect concentrations of blood metabolites and liver triglyceride. Serum insulin concentration and molar ratio of insulin to glucose for cows receiving Cr-Met were lower than for cows not receiving Cr-Met, but they increased quadratically with increasing Cr-Met. Glucose tolerance tests (GTT) were conducted on d 10 prepartum and d 28 postpartum. Chromium-methionine supplementation attenuated insulin sensitivity prepartum and enhanced glucose tolerance postpartum, but not prepartum. Basal insulin concentrations for cows receiving Cr-Met were higher than for cows not receiving Cr-Met during the prepartum GTT. During the postpartum GTT, peak glucose concentration and clearance rate decreased and half-life (t(1/2)) and time to reach basal concentration (T) were prolonged quadratically by increasing Cr-Met. Additionally, peak insulin concentration, area under the curve, and molar ratio of insulin to glucose were higher for cows not receiving Cr-Met than for cows receiving Cr-Met and t(1/2) and T were shortened quadratically by increasing Cr-Met.