Intraday and interday variations of milk fatty acids in dairy cows in early and late lactation

The composition of milk fatty acid (FA) was determined using Fourier-transform mid-infrared spectroscopy, which enables the rapid measurement of many samples. Milk FA is one indicator supporting the management of dairy cows and herds. This study aimed to determine an appropriate sampling method for milk FA in a practical farm condition based on intraday and interday variations in milk FA composition during early and late lactation stages. Milk samples were collected in the morning (07:00-08:00 h) and afternoon (16:30-17:30 h) for five consecutive days during early and late lactation. Within the day, de novo FA as the total FA basis was higher in the morning than in the afternoon, whereas preformed FA as the total FA basis was lower in the morning than in the afternoon. The weighted averages of milk FA composition according to milk yield collected in the morning and afternoon were significantly different between cows in early and late lactation; however, these were not significantly different among the consecutive five sampling days in each period. It was concluded that milk samples collected in the morning and afternoon for 1 day are suitable for milk FA determination. These results provide basic data for determining precise sampling methods for practical farms.

Relationships between dietary rumen-protected lysine and methionine with the lactational performance of dairy cows - A meta-analysis

OBJECTIVE

Our objective was to examine the relationships of supplemental rumen-protected lysine (RPL) or lysine + methionine (RPLM) on lactational performance, plasma amino acids (AA) concentration, and nitrogen use efficiency of lactating dairy cows by using a meta-analysis approach.

METHODS

A total of 56 articles comprising 77 experiments with either RPL or RPLM supplementation were selected and analyzed using a mixed model methodology by considering the treatments and other potential covariates as fixed effects and different experiments as random effects.

RESULTS

In early lactating cows, milk yield was linearly increased by RPL (β1 = 0.013; p<0.001) and RPLM (β1 = 0.014; p<0.028) but 3.5% fat-corrected milk (FCM) and energy-corrected milk (ECM) (kg/d) was increased by only RPL. RPL and RPLM did not affect dry matter intake (DMI) but positively increased (p<0.05) dairy efficiency (Milk yield/DMI and ECM/DMI). As a percentage, milk fat, protein, and lactose were unchanged by RPL or RPLM but the yield of all components was increased (p<0.05) by feeding RPL while only milk protein was increased by feeding RPLM. Plasma Lys concentration was linearly increased (p<0.05) with increasing supplemental RPL while plasma Met increased (p<0.05) by RPLM supplementation. The increase in plasma Lys had a strong linear relationship (R2 = 0.693 in the RPL dataset and R2 = 0.769 in the RPLM dataset) on milk protein synthesis (g/d) during early lactation. Nitrogen metabolism parameters were not affected by feeding RPL or RPLM, either top-dress or when supplemented to deficient diets. Lactation performance did not differ between AA-deficient or AA-adequate diets in response to RPL or RPLM supplementation.

CONCLUSION

RPL or RPLM showed a positive linear relationship on the lactational performance of dairy cows whereas greater improvement effects were observed during early lactation. Supplementing RPL or RPLM is recommended on deficient-AA diet but not on adequate-AA diet.

Quantitative Associations between Season, Month, and Temperature-Humidity Index with Milk Yield, Composition, Somatic Cell Counts, and Microbial Load: A Comprehensive Study across Ten Dairy Farms over an Annual Cycle

This current study addresses the knowledge gap regarding the influence of seasons, months, and THI on milk yield, composition, somatic cell counts (SCC), and total bacterial counts (TBC) of dairy farms in northeastern regions of Iran. For this purpose, ten dairy herds were randomly chosen, and daily milk production records were obtained. Milk samples were systematically collected from individual herds upon delivery to the dairy processing facility for subsequent analysis, including fat, protein, solids-not-fat (SNF), pH, SCC, and TBC. The effects of seasons, months, and THI on milk yield, composition, SCC, and TBC were assessed using an analysis of variance. To account for these effects, a mixed-effects model was utilized with a restricted maximum likelihood approach, treating month and THI as fixed factors. Our investigation revealed noteworthy correlations between key milk parameters and seasonal, monthly, and THI variations. Winter showed the highest milk yield, fat, protein, SNF, and pH (p < 0.01), whereas both SCC and TBC reached their lowest values in winter (p < 0.01). The highest values for milk yield, fat, and pH were recorded in January (p < 0.01), while the highest protein and SNF levels were observed in March (p < 0.01). December marked the lowest SCC and TBC values (p < 0.01). Across the THI spectrum, spanning from -3.6 to 37.7, distinct trends were evident. Quadratic regression models accounted for 34.59%, 21.33%, 4.78%, 20.22%, 1.34%, 15.42%, and 13.16% of the variance in milk yield, fat, protein, SNF, pH, SCC, and TBC, respectively. In conclusion, our findings underscore the significant impact of THI on milk production, composition, SCC, and TBC, offering valuable insights for dairy management strategies. In the face of persistent challenges posed by climate change, these results provide crucial guidance for enhancing production efficiency and upholding milk quality standards.

Calcium dynamics and associated temporal patterns of milk constituents in early-lactation multiparous Holsteins

At the onset of lactation, calcium (Ca) homeostasis is challenged. For the transitioning dairy cow, inadequate responses to this challenge may result in subclinical hypocalcemia at some point in the postpartum period. It has been proposed that dynamics of blood Ca and the timing of subclinical hypocalcemia allow cows to be classified into 4 Ca dynamic groups by assessing serum total Ca concentrations (tCa) at 1 and 4 days in milk (DIM). These differing dynamics are associated with different risks of adverse health events and suboptimal production. Our prospective cohort study aimed to characterize the temporal patterns of milk constituents in cows with differing Ca dynamics to investigate the potential of Fourier-transform infrared spectroscopic (FTIR) analysis of milk as a diagnostic tool for identifying cows with unfavorable Ca dynamics. We sampled the blood of 343 multiparous Holsteins on a single dairy in Cayuga County, New York, at 1 and 4 DIM and classified these cows into Ca dynamic groups using threshold concentrations of tCa (1 DIM: tCa <1.98 mmol/L; 4 DIM: tCa <2.22 mmol/L) derived from receiver operating characteristic curve analysis based on epidemiologically relevant health and production outcomes. We also collected proportional milk samples from each of these cows from 3 to 10 DIM for FTIR analysis of milk constituents. Through this analysis we estimated the milk constituent levels of anhydrous lactose (g/100 g of milk and g/milking), true protein (g/100 g of milk and g/milking), fat (g/100 g of milk and g/milking), milk urea nitrogen (mg/100 g of milk), fatty acid (FA) groups including de novo, mixed origin, and preformed FA measured in grams/100 g of milk, by relative percentage, and grams/milking, as well as energy-related metabolites including ketone bodies and milk-predicted blood nonesterified FA. Individual milk constituents were compared among groups at each time point and over the entire sample period using linear regression models. Overall, we found differences among the constituent profiles of Ca dynamic groups at approximately every time point and over the entire sample period. The 2 at-risk groups of cows did not differ from each other at more than one time point for any constituent, however prominent differences existed between the milk of normocalcemic cows and the milk of the other Ca dynamic groups with respect to FA. Over the entire sample period, lactose and protein yield (g/milking) were lower in the milk of at-risk cows than in the milk of the other Ca dynamic groups. In addition, milk yield per milking followed patterns consistent with previous Ca dynamic group research. Though our use of a single farm does limit the general applicability of these findings, our conclusions provide evidence that FTIR may be a useful method for discriminating between cows with different Ca dynamics at time points that may be relevant in the optimization of management or development of clinical intervention strategies.

Patterns of Fourier-transform infrared estimated milk constituents in early lactation Holstein cows on a single New York State dairy

Cows undergo immense physiological stress to produce milk during early lactation. Monitoring early lactation milk through Fourier-transform infrared (FTIR) spectroscopy might offer an understanding of which cows transition successfully. Daily patterns of milk constituents in early lactation have yet to be reported continuously, and the study objective was to initially describe these patterns for cows of varying parity groups from 3 through 10 d postpartum, piloted on a single dairy. We enrolled 1,024 Holstein cows from a commercial dairy farm in Cayuga County, New York, in an observational study, with a total of 306 parity 1 cows, 274 parity 2 cows, and 444 parity ≥3 cows. Cows were sampled once daily, Monday through Friday, via proportional milk samplers, and milk was stored at 4°C until analysis using FTIR. Estimated constituents included anhydrous lactose, true protein, and fat (g/100 g of milk); relative % (rel%) of total fatty acids (FA) and concentration (g/100 g of milk) of de novo, mixed, and preformed FA; individual fatty acids C16:0, C18:0, and C18:1 cis-9 (g/100 g of milk); milk urea nitrogen (MUN; mg/100 g of milk); and milk acetone (mACE), milk β-hydroxybutyrate (mBHB), and milk-predicted blood nonesterified fatty acids (mpbNEFA) (all expressed in mmol/L). Differences between parity groups were assessed using repeated-measures ANOVA. Milk yield per milking differed over time between 3 and 10 DIM and averaged 8.7, 13.3, and 13.3 kg for parity 1, 2, and ≥3 cows, respectively. Parity differences were found for % anhydrous lactose, % fat, and preformed FA (g/100 g of milk). Parity differed across DIM for % true protein, de novo FA (rel% and g/100 g of milk), mixed FA (rel% and g/100 g of milk), preformed FA rel%, C16:0, C18:0, C18:1 cis-9, MUN, mACE, mBHB, and mpbNEFA. Parity 1 cows had less true protein and greater fat percentages than parity 2 and ≥3 cows (% true protein: 3.52, 3.76, 3.81; % fat: 5.55, 4.69, 4.95, for parity 1, 2, ≥3, respectively). De novo and mixed FA rel% were reduced and preformed FA rel% were increased in primiparous compared with parity 2 and ≥3 cows. The increase in preformed FA rel% in primiparous cows agreed with milk markers of energy deficit, such that mpbNEFA, mBHB, and mACE were greatest in parity 1 cows followed by parity ≥3 cows, with parity 2 cows having the lowest concentrations. When measuring milk constituents with FTIR, these results suggest it is critical to account for parity for the majority of estimated milk constituents. We acknowledge the limitation that this study was conducted on a single farm; however, if FTIR technology is to be used as a method of identifying cows maladapted to lactation, understanding variations in early lactation milk constituents is a crucial first step in the practical adoption of this technology.

A multi-species direct-fed microbial supplement alters the milk lipidome of dairy cows

The study evaluated the effects of supplementing a multi-species direct-fed microbial (DFM) on the milk lipidome of lactating dairy cows. Twenty-four multiparous Holstein cows (41 ± 7 d in milk) were used in a randomized complete block design with experimental duration of 91 d. Cows were blocked based on energy-corrected milk yield from a 14-d pretreatment period, and were assigned randomly within each block to the following treatments: (1) control (CON): corn silage-based total mixed ration without DFM; or (2) BOV+: basal diet top-dressed with a DFM containing a mixture of Lactobacillus animalis (LA-51), Propionibacterium freudenreichii (PF-24), Bacillus subtilis (CH201), and Bacillus licheniformis (CH200) at 11.8 × 109 cfu/d. Milk samples were taken from morning and evening milkings on 2 consecutive days of each week of the pretreatment and treatment periods. Separate composites of pretreatment period and treatment period samples were prepared for individual cows and used for lipidome analysis. Lipidome analysis of the milk samples was performed using an ultra-high-performance liquid chromatograph linked to a quadrupole time-of-flight mass spectrometer in both positive and negative ionizations. The relative concentrations of 14 lipid species, including long-chain polyunsaturated fatty acids (LC-PUFA) such as FA 20:8 and FA 28:7 and triacylglycerides (TG) such as TG 40:3 and TG 54:2, were increased [false discovery rate (FDR) ≤0.05], whereas 13 lipid species, including saturated FA 24:0 and TG 40:0 were decreased (FDR ≤0.05) by supplemental BOV+. The relative concentration of de novo FA in milk was greater, whereas that of preformed FA was lower in dairy cows supplemented with BOV+. Results from this study demonstrate the potential of a DFM containing L. animalis, P. freudenreichii, Bacillus subtilis, and B. licheniformis to alter the milk lipidome in lactating dairy cows toward increased relative concentration of LC-PUFA, which might offer a healthier profile of FA to consumers with its associated health benefits.

Effects of Environmental Temperature and Humidity on Milk Composition, Microbial Load, and Somatic Cells in Milk of Holstein Dairy Cows in the Northeast Regions of Iran

The present study aims to examine the relationships between temperature and humidity and milk composition, microbial load, and somatic cells in the milk of Holstein dairy cows. For this purpose, the temperature−humidity index, ambient temperature, and relative humidity data were obtained from the nearest weather stations. Production data were obtained from four dairy farms in Golestan province, Iran, collected from 2016 to 2021. The traits investigated were protein, fat, solids-not-fat (SNF), microbial load, and somatic cell count (SCC) in milk. The effects of the environmental temperature, humidity, month, and season on the milk composition, microbial load, and somatic cells were analyzed through analysis of variance. The effects of environmental temperature, humidity, month, and season on the milk composition, microbial load, and somatic cell composition were analyzed using a mixed procedure with a restricted maximum likelihood model. Although our findings revealed that there were significant differences in fat, protein, SNF, and SCC among the different months of the year (p < 0.01), no significant difference was observed in the total microbial count in milk. Environmental temperature presented significant impacts on fat, protein, SNF, SCC, and total microbial count within various temperature ranges (p < 0.01). When the temperature increased from 6.2 °C to 31.3 °C, the milk protein, fat, SNF, and somatic cell count significantly decreased, by approximately 4.09%, 5.75%, 1.31%, and 16.8%, respectively; meanwhile, the microbial count in milk significantly increased, by approximately 13.7%. Humidity showed an influence on fat, protein, non-fat solids, somatic cells, and total microbial count within different temperature ranges (p < 0.01). When the humidity increased from 54% to 82%, the milk protein, fat, SNF, and SCC significantly increased, by approximately 3.61%, 4.84%, 1.06%, and 10.2%, respectively; meanwhile, the microbial count in milk significantly decreased, by approximately 16.3%. The results demonstrate that there is a negative correlation between different months of the year, temperature, and the humidity of the environment, in terms of milk components and SCC. Our findings demonstrate that the optimum performance, in terms of milk composition, occurred in the first quarter of the year. As temperature increases and humidity decreases, milk quality decreases. Therefore, the adverse effects of environmental conditions on agricultural profits are not negligible, and strategies to better deal with the negative environmental effects are needed in order to improve milk quality in dairy cows.

Relationships between Milk and Blood Biochemical Parameters and Metabolic Status in Dairy Cows during Lactation

This study aimed to determine blood and milk metabolic parameters and their correlations for the purpose of evaluating metabolic status in dairy cows. Blood and milk samples were collected from 100 Holstein dairy cows during morning milking. The cows were allocated to four groups according to the production period, including cows in early (n = 18), full (n = 26), mid (n = 25) and late (n = 31) lactation. The value of non-esterified fatty acids (NEFA), β-hydroxybutyrate (BHB), glucose, triglycerides (TG), total cholesterol (TChol), total protein (TP), albumin, globulin, urea, total bilirubin (TBil), aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), gamma-glutamyl transferase (GGT), and lactate dexydrogenase (LDH) in the blood were determined. The following milk parameters were measured: fat, protein, lactose, urea, AST, ALT, ALP, GGT, LDH and BHB. Blood serum NEFA, BHB, TBil, AST, ALT, ALP and LDH were higher in early lactation cows, whereas glucose, TP, globulin and urea levels were significantly lower in early lactation cows. Milk fat and lactose levels were lower in early lactation cows, whereas milk protein and the activities of AST, ALT, ALP and LDH in milk were highly greater in early lactation cows. Milk fat was positively correlated with glucose, TP and TG, and negatively correlated with BHB, NEFA, TBil, ALT, LDH and ALP levels in the blood. Enzyme activities in milk were positively correlated with those in blood and with blood NEFA, BHB and TBil levels, and negatively correlated with blood glucose, TChol and TG. A significant positive correlation existed between blood and milk BHB values. Many correlations showed the same slope during all lactation periods. In conclusion, similar changes in blood and milk metabolite concentration during lactation and milk to blood correlations confirm that milk has great potential in predicting of blood metabolites and metabolic status of cows.

Diurnal variation of milk fatty acids in early-lactation Holstein cows with and without hyperketonemia

Estimates of milk constituents by Fourier-transform mid-infrared (FTIR) analysis have been shown to be a useful tool in monitoring energy deficit in early-lactation dairy cows. Our objectives were to describe the diurnal variation in milk fatty acids (FAs) and estimate the association of hyperketonemia with concentrations and diurnal patterns of FTIR estimates of milk FA. Blood samples were collected via jugular catheters bihourly for 5 d from multiparous Holstein cows (n = 28) enrolled between 3 and 9 days in milk. Milk samples were collected thrice daily at 0600, 1400, and 2200 h for d 2, 3, and 4 of the study period. Cows were retrospectively classified as hyperketonemic (HYK; n = 13) or non-HYK (n = 15) based on blood beta-hydroxybutyrate (bBHB) concentrations analyzed during the study period. Cows were classified as HYK if bBHB was ≥ 1.2 mmol/l for ≥ 50% (22/44) of bihourly timepoints; cows were classified as non-HYK if bBHB was ≥ 1.2 mmol/l for < 50% of bihourly timepoints. The HYK cows had bBHB ≥ 1.2 mmol/l for 31.4 ± 6.8 timepoints while the non-HYK cows had bBHB ≥ 1.2 mmol/l for 8.0 ± 3.9 timepoints. We used generalized linear mixed models to analyze concentrations of milk FA over time and differences between HYK groups. The relative percentage of de novo, mixed, and preformed FAs all followed diurnal patterns, however only the yield of preformed FA diurnally cycled, reaching a nadir at 0600 h and peaking at 1400 h. The yield per milking of preformed FA was also greater in the HYK cows than in the non-HYK cows. Oleic acid in milk followed a similar diurnal pattern to the yield of preformed FA, likely driving the cyclical nature of preformed FA. Finally, stearic acid was greater in HYK cows. Our results suggest that FTIR estimates of milk FA offer the potential to provide insight on the energy status of early-lactation cows, and when interested in understanding the absolute concentrations and yields of milk FA, diurnal variation should be considered.

The Impact of Dietary Berberine Supplementation during the Transition Period on Blood Parameters, Antioxidant Indicators and Fatty Acids Profile in Colostrum and Milk of Dairy Goats

The objective of this study was to investigate the effect of berberine (BBR) supplementation on productivity, antioxidant markers, and the fatty acid (FA) profile in the colostrum and milk of goats. Twenty-four primiparous Saanen goats were supplemented with 0, 1, 2, and 4 g/d (per goat) of BBR in control (CON), BBR1, BBR2, and BBR4 groups (n = 6 per group), respectively, from 21 days before expected kidding to 21 days after parturition. Blood sampling was carried out at -21, -14, -7, 0, 7, 14, and 21 d relative to delivery. Colostrum was collected within the first and second milking (d 1 of lactation), and milk was harvested weekly after kidding. Both BBR2 and BBR4 increased dry matter intake (DMI) (p ≤ 0.05) and energy balance (EB) as well as colostrum and milk production. Both BBR2 and BBR4 decreased (p ≤ 0.05) plasma levels of cholesterol, haptoglobin, and ceruloplasmin, while elevating the plasma albumin and paraoxonase (p ≤ 0.05), which may indicate that BBR mitigates inflammation during the transition period. BBR reduced (p ≤ 0.05) malondialdehyde (MDA) and increased (p ≤ 0.05) total antioxidant capacity (TAC), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) in blood, colostrum, and milk. Concentrations of de novo fatty acid in colostrum and milk were increased (p ≤ 0.05) with both BBR2 and BBR4. Free fatty acid (FFA) concentration in colostrum and milk fat were lower (p ≤ 0.05) in BBR2 and BBR4 compared to CON. The concentration of saturated fatty acids (SFAs) in colostrum and milk fat increased (p ≤ 0.05) with BBR2 and BBR4, while unsaturated fatty acids (USFAs) decreased (p ≤ 0.05) in milk. In summary, supplementation with at least 2 g/d BBR may enhance the EB and antioxidant status of dairy goats.

Stability of milk fatty acid profile during simulated shipping for analysis by gas chromatography

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Milk fatty acid profile was very stable at all storage temperatures.

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Shipping on dry ice is not required for fatty acid analysis by gas-liquid chromatography.

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Importantly, this conclusion is specific for gas-liquid chromatography analysis and not other infrared spectrometry-based methods.

Milk fat trans-10 C18:1 can be used in diagnosing low milk fat production on dairy farms because it is a specific marker of biohydrogenation-induced milk fat depression. Individual fatty acids (FA), including the trans C18:1 isomer, can be determined only by gas-liquid chromatography. The analysis is currently available at a limited number of laboratories and often requires long-distance shipping. Expedited shipping with dry ice or ice packs is expensive. Therefore, the objective of this study was to determine the effect of heat treatment before shipping, shipping temperature, and shipping time on milk FA profile. Samples were collected from 3 farms on 2 occasions and stored in a polystyrene foam cooler with an ice pack, at room temperature, or at 37°C for 1, 2, 3, and 7 d. Heating the sample before shipping, shipping temperature, and shipping time had very little effect on any FA analyzed. Differences observed were of small magnitude and not of practical importance, demonstrating that milk FA profile is expected to be very stable during shipping. Based on this, we propose that freezing samples and shipping in a sealed bag by second-day shipment is appropriate and demonstrated that this had little effect on FA profile of 48 milk samples. Importantly, these methods are recommended only for gas-liquid chromatography analysis of FA profile. Freezing is not appropriate for shipping for analysis by mid-infrared spectrometry-based methods or methods quantifying compounds per unit of milk because it is difficult to homogenize samples after freezing or extended shipping that results in denaturization of proteins and breaking of fat globules.

Bias of Calf Sex on Milk Yield and Fat Yield in Holstein Crossbreed Cows

Simple Summary

Cattle comprise a species of a domestic animal that is primarily bred for milk production. The birth of a calf is the initiator for the lactation period and the sex of the calf can affect milk yield. Additionally, a calf from a new pregnancy can affect the lactation from the previous calving, since the mother gets pregnant and remains pregnant during most of the lactation, usually at lactation peak. Therefore, the aim of this paper was to further investigate the possibilities of sexually biased milk production of Holstein and Holstein crossbreed cows using data from the Republic of Serbia. We also wanted to test the Trivers–Willard (TW) hypothesis that natural selection favors unequal parental investment between daughters and sons under certain maternal conditions. At the same time, this hypothesis assumes that mothers in good health and condition invest more in sons, while mothers in a poor condition invest more in daughters. The obtained results deviate from the view of the TW hypothesis because it was found that milk and fat yields in the first two lactations were the highest in cows that had a female calf and were then pregnant with a second female calf while the lactation from the previous calving was still in progress. We were the first in the world to investigate the effect of the sex of calves at first and second calving on milk yield and fat yield in the first and second standard lactation, depending on milk production levels on farms.

Abstract

In order to examine the biased milk production depending on the sex of calves, data on calving and milk yield characteristics of 15,181 Holstein type cows in PK Belgrade, Serbia were analyzed. A total of 30,362 lactations that were realized in the period from 1985 to 2017 were analyzed. Data were prepared and analyzed using the SAS software package (SAS Institute Inc. Software License 9.3, 2012). The expression and variability of investigated traits were determined using the PROC MEANS procedure, while the effect of individual factors on milk yield traits was analyzed using the PROC GLM procedure. Obtained results deviate from the views of the Trivers–Willard (TW) hypothesis. The results indicate that mothers invest more in female offspring by producing a higher milk and fat yield in the first and second lactation compared to male offspring. This is especially emphasized under better environmental conditions. The highest milk yield (7788 kg) and fat yield (271 kg) in the second lactation were achieved in the combination with two consecutive female calves in the group of higher-than-average milk production farms, and lowest in the combination of two consecutive male calves (6783 kg for the MY and 243 kg for the FY), respectively.

The effect of concentrate supplement type on milk production, nutrient intake, and total-tract nutrient digestion in mid-lactation, spring-calving dairy cows grazing perennial ryegrass (Lolium perenne L.) pasture

The objective of this study was to evaluate the effect of concentrate supplement type on milk production, nutrient intake, and total-tract nutrient digestion in lactating dairy cows grazing mid-season perennial ryegrass (Lolium perenne L.; PRG) pasture. Twelve primiparous (mean ± standard deviation; 95 ± 30 d in milk and 470 ± 43 kg of body weight) and 68 multiparous (99 ± 24 d in milk and 527 ± 64 kg of body weight) lactating dairy cows were blocked based on pre-study milk yield and parity and randomly assigned to 1 of 4 dietary treatments. The 4 dietary treatments were a non-supplemented PRG control (PRG); PRG supplemented with 4.4 kg of dry matter (DM) per cow per day of citrus pulp and 0.067 kg of DM/cow per day of urea (PRG+C); PRG supplemented with 0.8 kg of DM/cow per day of heat-treated soybean meal (PRG+PP); and PRG supplemented with 3.1 kg of DM/cow per day of a combination of heat-treated soybean meal and citrus pulp (PRG+C+PP). The study consisted of a 2-wk adaptation period and a 10-wk period of data collection. Weekly measurements of milk yield, body weight, body condition score, and feeding and rumination time were made. Nutrient intake and total-tract digestibility were measured during wk 6 of the study. A large soil moisture deficit was experienced during the study that probably reduced herbage growth rate and likely altered the chemical composition of the PRG offered when compared with typical mid-season PRG. Total dry matter intake was increased in cows fed PRG+C compared with cows fed PRG and PRG+PP and was similar to cows fed PRG+C+PP (18.0, 15.9, 16.4, and 17.2 ± 0.41 kg of DM/d, respectively). The apparent total-tract neutral detergent fiber digestibility of cows fed the PRG+C diet was lower compared with the PRG and PRG+PP diets and was similar to the PRG+C+PP diet (0.67, 0.70, 0.70, and 0.69 ± 0.01 g/g, respectively). The energy-corrected milk (ECM) yield of cows fed PRG+C+PP was highest (23.7 kg/d), PRG+C was intermediate (22.2 kg/d), and PRG was lowest (20.8 kg/d). Cows fed PRG+PP produced more ECM (22.9 kg/d) compared with cows fed PRG and produced similar ECM compared with cows fed PRG+C and PRG+C+PP diets. The PRG+PP diet increased milk protein yield compared with the PRG diet, tended to increase milk protein yield compared with the PRG+C diet, and was similar to the PRG+C+PP diet. Milk fat concentration and the composition of milk fat were not influenced by treatment. The results demonstrated that, for cows consuming pasture-based diets, increasing metabolizable protein supply allowed higher milk yield as metabolizable protein was more limiting than metabolizable energy. However, due to the large soil moisture deficit experienced during this experiment, caution is recommended when extrapolating these results to cows consuming typical mid-season PRG herbage.

Effect of protein concentrate mixtures and dietary addition of exogenous phytase on major milk minerals and proteins, including casein phosphorylation

Variations in major milk minerals, proteins, and their posttranslational modifications are largely under genetic influence, whereas the effect of nongenetic factors is less studied. Through a controlled feeding experiment (incomplete balanced Latin square design), the effect of concentrate mixtures, based on fava beans, rapeseed meal, or soybean meal as main P and protein sources, on milk composition was examined under typical Danish management conditions. Concentrations of P, Ca, and Mg, together with proteomics for relative quantification of major milk proteins and their isoforms, were analyzed in milk samples from 24 cows sampled in 4 periods. Each cow was fed 1 of the 3 diets in each period with or without addition of exogenous phytase. Cows were blocked by lactation stage into early and mid-lactation (23.3 ± 6.7 and 176 ± 15 d in milk, respectively, at the beginning of the experiment, mean ± standard deviation). Significant effects of feed concentrate mixture were observed for milk protein concentration, milk urea nitrogen, citrate, and the percentage of mixed and preformed fatty acids as well as mineral composition, and their distributions within micellar or serum phases. Furthermore, relative contents of α_S1-casein (CN) 9P form and unglycosylated κ-CN and thereby phosphorylation degree of α_S1-CN (PD) and the glycosylation degree of κ-CN were found to be significantly affected by these diets. To our knowledge, we are the first to document that feed concentrate mixture can affect the relative concentrations of α_S1-CN phosphorylation isoforms in milk, and the results suggested an effect on α_S1-CN 9P and PD, but not on α_S1-CN 8P. Furthermore, although only significant for α_S1-CN 8P, we found a lower relative concentration of α_S1-CN 8P and higher α_S1-CN 9P (and thus higher PD) in milk from cows in mid compared with early lactation. Also, protein concentration and concentration of Mg in skim milk and serum as well as relative concentration of α-lactalbumin were found to be significantly affected by lactation stage. Addition of dietary exogenous phytase only had a minor effect on milk composition or functionality with significant effect detected for α-lactalbumin and micellar Mg concentration.

Annatto seeds as Antioxidants Source with Linseed Oil for Dairy Cows

Simple Summary

Currently, functional foods are gaining widespread attention. Polyunsaturated fatty acids (PUFA) and antioxidant compounds have beneficial effects on health. It is possible to increase the concentration of these compounds in the milk obtained from dairy cows by manipulating their diets, thereby improving milk quality and consequently the health of animals and humans who consume this milk. Annatto seed (Bixa orellana L.) is a source of antioxidants, whereas linseed oil is rich in omega 3 fatty acid. We evaluated the inclusion of annatto seeds and linseed oil in the diets of dairy cows and their effects on dry matter intake (DMI), nutrient digestibility, milk yield, milk composition and antioxidant capacity in milk and blood. There was no effect of treatment on nutrient digestibility and antioxidant capacity, but the addition of annatto seeds decreased DMI and milk production and linseed oil supplementation reduced milk fat content.

Abstract

This study aimed to evaluate the effects of annatto seeds, linseed oil and their combination on DMI, apparent total tract digestibility, antioxidant capacity and milk composition of dairy cows. Four lactating Holstein cows (120 ± 43 days in milk; 15.98 ± 2.02 kg of milk/day, mean ± SD) were allocated in a 4 × 4 Latin square with a 2 × 2 factorial arrangement (with or without annatto seeds at 15 g/kg of dry matter (DM); with or without linseed oil at 30 g/kg of DM) and provided four different diets: control (no annatto seeds or linseed oil); annatto seeds (15 g/kg of DM); linseed oil (30 g/kg of DM); and a combination of both annatto seeds and linseed oil. Annatto seeds reduced DM intake, and milk yield, protein and lactose, but increased content of fat, total solids and short chain fatty acid, with no effect on total antioxidant capacity of milk. Linseed oil supplementation decreased medium chain fatty acid proportion and n-6/n-3 ratio, conversely it increased long chain fatty acids and n-3 fatty acid content of milk, ether extract intake and total-tract digestibility. Thus, linseed oil supplementation in dairy cow diets improved the milk FA profile but decreased milk fat concentration, whereas annatto seeds did not influence antioxidant capacity and depressed feed intake and milk yield.

The relationship of excessive energy deficit with milk somatic cell score and clinical mastitis

Periparturient cows go through a period of immune suppression often marked by immune cell dysfunction. Further exacerbation of this dysfunction through early-lactation excessive energy deficit (EED) has been associated with increased susceptibility to infectious conditions such as mastitis. Our objective was to explore the association of milk somatic cell score (SCS) and clinical mastitis (CM) diagnosis in cows identified with EED, diagnosed using each of the following: blood and milk β-hydroxybutyrate (BHB), milk predicted blood nonesterified fatty acid (mpbNEFA) concentrations, or milk de novo fatty acid (FA) relative percentages (rel %). We analyzed data collected from 396 multiparous Holstein cows from 2 New York farms in a prospective cohort study. Coccygeal vessel blood samples and composite milk samples were collected twice weekly from 3 to 18 days in milk (DIM) for a total of 4 time points per cow (T1, T2, T3, T4). Blood was analyzed using a hand-held meter, and milk was analyzed using Fourier-transform mid-infrared spectrometry for milk BHB and mpbNEFA concentrations, milk de novo FA rel %, and somatic cell count. Excessive energy deficit was diagnosed as blood BHB ≥ 1.2 mmol/L, milk BHB ≥ 0.14 mmol/L, mpbNEFA ≥ 0.55 mmol/L, or de novo FA ≤ 22.7 rel %, depending on the model. Clinical mastitis cultures were collected from 4 to 60 DIM by on-farm personnel. Incidence of hyperketonemia as determined by blood BHB was 13.4%, and incidence of CM was 23.9%. Separate repeated-measures ANOVA models were developed for each EED diagnostic analyte for parity groups 2, 3, and ≥4 to assess differences in SCS; t-test analyses were similarly used to assess the association of each diagnostic analyte with CM at each time point. For all diagnostic analytes, apart from milk BHB, cows diagnosed with EED tended to have lower SCS than their non-EED counterparts. This was especially apparent at T1 for all parity groups, and at T2, T3, and T4 for blood BHB and mpbNEFA. For EED diagnosis via mpbNEFA, mean SCS were lower in parity ≥4, with a difference in mean SCS between EED and non-EED animals of 0.7 SCS units, equating to a somatic cell count in EED animals approaching half that of non-EED (EED = 67,000 cells/mL, non-EED = 107,000 cell/mL). No important relationships were observed between CM diagnosis and blood BHB, milk BHB, or mpbNEFA. For de novo FA rel %, reductions in this analyte were noted before CM diagnosis at all time points. Although the relationship between EED and CM is still unclear, our findings suggest that cows in EED, diagnosed using blood BHB or mpbNEFA during the first 18 DIM, have a tendency toward lower SCS compared with their non-EED counterparts.

Meta-analysis of the relationship between milk trans-10 C18:1, milk fatty acids <16 C, and milk fat production

The economic value of milk fat and its responsiveness to management strategies provides strong interest in maximizing milk fat production by minimizing occurrence of biohydrogenation-induced milk fat depression (BH-MFD) and maximizing de novo synthesized fatty acids (FA). Tools that allow a timely diagnosis of BH-MFD would improve nutritional management. Specific milk FA or FA categories correlate to milk fat concentration and are of interest for diagnosing the cause of changes in milk fat concentration. The objective of the current study was to characterize the relationship between milk fat concentration and trans-10 C18:1, a proxy for BH-MFD, and FA <16 carbons that originate solely from de novo lipogenesis using a meta-analysis approach that used data from the literature and unpublished Penn State experiments. Prior to the meta-analysis, the effect of FA methylation method on milk FA profile was tested to determine potential bias between papers. There was no difference between sodium methoxide, acid, and acid-base methylation methods on trans-10 C18:1 concentration, but acid methods resulted in loss of short-chain FA. The relationship between trans-10 C18:1 and milk fat percentage was investigated using a 2-component model, where one component described the fraction unresponsive to BH-MFD and the other described a responsive fraction that is exponentially related to trans-10 C18:1. The 2 fractions where characterized utilizing a Bayesian hierarchical model accounting for between-study variability. The model was defined by the function f(x, θ1, θ2, θ3) = θ1 + θ2exp(θ3), where the unresponsive θ1 fraction was 2.15 ± 0.09%, the responsive θ2 fraction was 1.55 ± 0.08%, and the exponential term θ3 was -0.503 ± 0.07 (posterior mean ± posterior standard deviation from the Bayesian hierarchical model). A Lin's concordance correlation coefficient of 0.67 suggested good agreement between observations and predictions from the Bayesian hierarchical model, computed only with the model's mean population parameters. There was a linear relationship between milk fat concentration and FA <16 C as a percentage of total FA (intercept = 2.68 ± 0.237 and slope = 0.043 ± 0.011; coefficient of determination = 0.31). The relationship between milk FA <16 C and milk fat concentration is weaker than what has been published, likely because multiple factors can reduce de novo FA without reducing milk fat and the broad range of diets present in the literature.

Feeding rumen-protected lysine prepartum increases energy-corrected milk and milk component yields in Holstein cows during early lactation

Feeding rumen-protected Lys (RPL) may be used to increase lactation performance in dairy cows; however, the effect of feeding RPL during the prepartum period and subsequent effect on postpartum performance is not well explored. Therefore, this experiment was conducted to determine the effects of feeding RPL (AjiPro-L Generation 3, Ajinomoto Heartland Inc., Chicago, IL) prepartum, postpartum, or both on performance, health, and blood metabolites. Seventy-five multiparous Holstein cows, blocked by parity, previous 305-d mature-equivalent milk production, expected calving date, and body condition score during the far-off dry period were assigned to 1 of 2 dietary treatments: total mixed ration with or without RPL in a randomized, complete block design. A 2 × 2 factorial arrangement of treatments was used. Prepartum (-28 d to calving), animals were fed a diet (forage, 68% of dietary DM) with RPL [PRE-L; 0.54% RPL of dietary dry matter intake (DMI)] or without RPL (control; PRE-C). After calving, half of the cows from each prepartum treatment group were assigned to a diet (forage, 55.5% of dietary DM) with RPL (PRE-L POST-L; PRE-C POST-L; 0.40% RPL of dietary DMI) or without RPL (PRE-C POST-C; PRE-L POST-C) until d 28 postpartum. Cows were milked twice a day and milk samples were taken on 7 ± 1.3, 14 ± 1.4, and 28 ± 1.1 d relative to calving (DRC). Milk yield and DMI were recorded daily. Blood samples were taken for plasma AA analysis on -7 ± 0.5, 0 ± 0.5, 7 ± 0.9, and 14 ± 0.9 DRC. Cows in PRE-L had greater body weight at -2 and -1 wk before calving compared with those in PRE-C, though body weight change from wk -4 to -1 was not different. Body weight (717 ± 6 kg) was greater and DMI (18.1 ± 0.7 kg) tended to be greater for cows in PRE-L POST-L and PRE-L POST-C compared with those that were in PRE-C POST-L and PRE-C POST-C (707 ± 6 and 16.8 ± 0.7 kg, respectively). Energy-corrected milk (48.8 ± 1.9 kg/d), milk fat (1.9 ± 0.1 kg/d), milk true protein (1.4 ± 0.1 kg/d), milk casein (0.6 ± 0.04 kg/d), and milk lactose yields (2.1 ± 0.1 kg/d) were greater for cows in PRE-L POST-L and PRE-L POST-C compared with those that were in PRE-C POST-L and PRE-C POST-C (44.2 ± 1.9, 1.7 ± 0.1, 1.3 ± 0.1, 0.5 ± 0.04, 1.9 ± 0.1 kg/d, respectively). Plasma concentrations of Lys prepartum (69.8 ± 1.8 µM) increased for cows in PRE-L compared with those in PRE-C (62.5 ± 1.3 µM). In conclusion, RPL consumed prepartum tended to increase postpartum DMI and increased energy-corrected milk and milk component yields. This indicates that prepartum supply of intestinally available Lys is pertinent to postpartum performance. However, postpartum supply of intestinally available Lys had no effect on cows' performance.

Evaluation of source of corn silage and trace minerals on lactational performance and total-tract nutrient digestibility in Holstein cows

We evaluated the effects of source of corn silage and trace minerals on lactational performance and total-tract digestibility (TTD) of nutrients in 16 Holstein cows averaging 82 (standard error = 3) days in milk in a replicated 4 × 4 Latin square design with a 2 × 2 factorial arrangement of treatments with 28-d periods. The diets consisted [dry matter (DM) basis] of 55% conventional (CON) or brown midrib-3 (BM3) corn silage, 2% chopped wheat straw, and 43% grain mix with either sulfate (STM) or hydroxy (HTM) sources of copper, manganese, and zinc trace minerals. The targeted supplemental concentrations of copper, zinc, and manganese were 194, 1,657, and 687 mg/d, respectively. The dietary treatments were CON-STM, CON-HTM, BM3-STM, and BM3-HTM. The dietary nutrient composition of the BM3 diets averaged 32.1% amylase neutral detergent fiber on an organic matter basis (aNDFom) and 6.9% undigested neutral detergent fiber at 240 h (uNDF240om; % of DM), and CON diets averaged 36.2% aNDFom and 8.6% uNDF240om (% of DM). The average supplemental concentrations of copper, zinc, and manganese for the STM diets were 10, 41, and 64 mg/kg, respectively, and the average supplemental concentrations of copper, zinc, and manganese for the HTM diets were 10, 40, and 62 mg/kg, respectively. The average total dietary concentrations of copper, zinc, and manganese for the STM diets were 17, 104, and 60 mg/kg, respectively, and the average total dietary concentrations of copper, zinc, and manganese for the HTM diets were 17, 91, and 66 mg/kg, respectively. Data were summarized by period and analyzed as a replicated Latin square design with fixed model effects for corn silage, trace minerals, corn silage × trace mineral interaction, period within replicated square, and replicated square using the MIXED procedure of SAS. Cow within replicated square was a random effect. Cows fed the BM3 diets had greater dry matter intake (DMI) and milk yield (28.1 and 47.0 kg/d) than cows fed the CON diets (27.5 and 44.7 kg/d). We found no significant interaction between corn silage and trace minerals for DMI and milk yield. Cows fed the HTM diets (28.1 kg/d) had a greater DMI than cows fed the STM diets (27.5 kg/d). Cows fed the BM3 diets had greater TTD of DM and OM (72.8 and 74.1% of DM) than cows fed the CON diets (71.1 and 72.3% of DM). Cows fed the HTM diets had a tendency for greater TTD of aNDFom than cows fed the STM diets (56.8 vs. 54.9% of DM). Cows fed the CON diets ruminated longer during the day than cows fed the BM3 diets (524 vs. 496 min/d). Corn silage with greater NDF digestibility and lower uNDF240om enhanced DMI, milk yield, and TTD of DM and OM, and hydroxy trace minerals improved DMI and tended to improve TTD of aNDFom. The source of corn silage and trace minerals should be taken into consideration when formulating diets for high-producing dairy cows.

Association of mid-infrared-predicted milk and blood constituents with early-lactation disease, removal, and production outcomes in Holstein cows

Partial least squares regression estimates of milk and blood constituents using Fourier-transform mid-infrared (FTIR) analysis have shown promise as a tool for monitoring early-lactation excessive energy deficit in dairy herds. Our objective was to analyze milk via FTIR to determine the association of early-lactation predicted milk β-hydroxybutyrate (BHB) concentrations, predicted blood nonesterified fatty acid (NEFA) concentrations, and predicted milk de novo fatty acid (FA) percentages relative to total FA concentrations, with the risk of disease or removal in early lactation (hyperketonemia, displaced abomasum, metritis, culling, or death) and average daily milk yield during the first 15 wk of lactation. We enrolled 517 multiparous Holstein cows from 2 dairy farms in New York. Composite milk samples were collected twice weekly from 3 to 18 DIM for a total of 4 timepoints (T1, T2, T3, T4) and analyzed using FTIR spectrometry for milk BHB and FA composition and predicted blood NEFA. Blood samples were collected for hyperketonemia determination (BHB ≥ 1.2 mmol/L) using a handheld meter, and farm-diagnosed occurrence of disease or removal during the first 30 DIM and average daily milk yield during the first 15 wk of lactation were collected from herd management software. The incidence of disease or removal between 3 and 18 DIM was 20.2%. Explanatory models for disease or removal were developed for each predicted constituent of interest at each timepoint using fixed-effect multivariable Poisson regression. Repeated measures ANOVA models were developed for each predicted constituent to assess differences in average daily milk yield. For all timepoints, increased risk of disease or removal was associated with higher predicted milk BHB [relative risk (RR)_T1 = 2.0; RR_T2 = 3.4; RR_T3 = 5.2; RR_T4 = 9.1], higher predicted blood NEFA (RR_T1 = 2.7; RR_T2 = 2.5; RR_T3 = 3.8; RR_T4 = 10.0), and lower predicted milk de novo FA relative percentages (RR_T1 = 2.9; RR_T2 = 3.3; RR_T3 = 5.8; RR_T4 = 7.2). Average daily milk yield was increased for cows above the cut point for predicted milk BHB (2.1 kg/d) and predicted blood NEFA (3.5 kg/d) and below the cut point for de novo FA relative percentages (2.3 kg/d). Our results suggest that FTIR-predicted milk BHB, blood NEFA, and milk de novo FA relative percentages are promising indicators of subsequent disease or removal in early lactation; their positive relationship with milk yield warrants further exploration.

Influence of Supplemental Feed Choice for Pasture-Based Cows on the Fatty Acid and Volatile Profile of Milk

The purpose of this study was to examine the impact of a variety of supplemental feeds on the composition and quality of milk in a pasture-based dairy system. Four pasture-supplemented feeding systems were compared: Group 1 supplementation with 16% crude protein parlour concentrate (CONC); Group 2 supplementation with palm kernel expeller plus parlour concentrate (PKE); Group 3 supplemented with soya hulls plus parlour concentrate (SOYA); Group 4 was supplemented with molassed beet pulp plus parlour concentrate (BEET). Supplemental feeding system was demonstrated to have a significant effect on the size of native casein micelles and the gelation properties of milks. While CONC feeding produced significantly higher casein micelle size, gel strength (Young’s Modulus) was significantly negatively correlated with casein micelle size. Supplemental feeding system had a significant effect on a number of fatty acids (FA) and indices derived therefrom, including total saturated and unsaturated fatty acids, de novo produced FA, omega 3, and omega 6 FA. The volatile profile of milks was also affected by supplemental feed choice, whereby multivariate analysis demonstrated that the CONC diet was distinctly different to that of the PALM, SOYA, and BEET milks. Multivariate analysis demonstrated that it is possible to distinguish milks from different pasture-supplemented feeding systems by their FA profile.

Effects of feeding synthetic zeolite A during the prepartum period on serum mineral concentration, oxidant status, and performance of multiparous Holstein cows

The objective of this study was to determine the effects of feeding synthetic zeolite A for 3 wk before expected calving on peripartal serum mineral concentrations, hypocalcemia, oxidant status, and performance. Holstein cows (n = 55) entering their second or greater lactations were assigned randomly to 1 of 2 dietary treatments starting 21 d before expected calving: control (CON: 40% corn silage, 33% wheat straw, and 27% concentrate; n = 29) or experimental [EXP: CON plus zeolite A (X-Zelit, Protekta Inc., Lucknow, ON, Canada/Vilofoss, Graasten, Denmark; n = 26) at an inclusion rate of 3.3% of dry matter, targeting 500 g/d as-fed]. Cows were fed the same postpartum diet and housed in individual tiestalls through 28 d in milk. Cows fed EXP had higher serum Ca concentrations as parturition approached and during the immediate postpartum period. Serum P concentrations were lower for the EXP-fed cows during the prepartum period and the first 2 d of lactation, whereas serum Mg concentrations were lower than those of the CON-fed cows only during the immediate periparturient period. Cows fed EXP had decreased prevalence of subclinical hypocalcemia (SCH) from d -1 through 3 relative to day of parturition, with the largest difference occurring within the first day postpartum. Prepartum dry matter intake tended to be decreased and rumination was decreased in cows fed EXP; however; postpartum dry matter intake, rumination, milk yield, milk component yield, and colostrum measurements did not differ between treatments. Cows fed EXP tended to have increased hazard of pregnancy by 150 d in milk when controlling for parity compared with CON-fed cows; potential reproductive benefits merit further study. This study demonstrated that zeolite A supplementation during the prepartum period results in markedly improved serum Ca concentrations around parturition and similar postpartum performance compared with controls and is effective at decreasing hypocalcemia in multiparous Holstein cows.

Management practices, physically effective fiber, and ether extract are related to bulk tank milk de novo fatty acid concentration on Holstein dairy farms

The objective of this study was to evaluate the relationship of management practices and dietary factors with de novo fatty acid concentration in bulk tank milk from commercial dairy farms milking Holstein cows. Farms were selected based on de novo fatty acid concentration during the 6 mo before the farm visit and were categorized as high de novo (HDN; 24.61 ± 0.75 g/100 g of fatty acids, mean ± standard deviation; n = 19) or low de novo (LDN; 23.10 ± 0.88 g/100 g of fatty acids; n = 20). Farms were visited once in February, March, or April 2015 and evaluated based on management and facility design known to affect cow behavior, physical and chemical characteristics of the diet, and ration formulation and forage analyses obtained from the farm's nutritionist. We observed no differences between HDN and LDN farms in farm size, time away from the pen for milking, days in milk, or body condition score. We detected no differences between HDN and LDN farms in milk fat or true protein yield; however, milk fat and protein content and de novo fatty acid yield per day were higher for HDN farms, as was gross income per unit of milk sold. High de novo farms tended to be more likely to deliver fresh feed twice versus once per day, have a freestall stocking density ≤110%, and provide ≥46 cm of feed bunk space per cow. We observed no detectable differences in forage quality or ration dry matter, crude protein, or starch content. However, ether extract was lower and physically effective neutral detergent fiber was higher for HDN farms. Feeding management, stocking density, dietary ether extract content, and the physical characteristics of the diet are related to de novo fatty acid, fat, and protein concentration in bulk tank milk from high-producing Holstein dairy farms.