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

Effects of feeding rumen-protected lysine during the postpartum period on performance and amino acids profile in dairy cows: A meta-analysis

Lysine is one of the limiting AA in the diets of dairy cows and is typically fed as rumen-protected Lys (RPL). We hypothesized that supplementation of RPL during the postpartum period would improve the productive performance in dairy cows. Objectives were to use meta-analytic methods to explore the effects of feeding RPL on performance and blood AA profile in lactating dairy cows. An additional objective was to identify an optimal concentration (%) of Lys in metabolizable protein (LYSMP) and determine if responses to LYSMP were associated with the concentration (%) of Met in metabolizable protein (METMP). The literature was systematically reviewed and 13 experiments, comprising 40 treatment means and 594 lactating cows, were included in the meta-analysis. All experiments had a non-supplemental control (CON; n = 17 treatment means), or a supplemental group (RPL; n = 23 treatment means). Cows supplemented with RPL were supplied additionally with a mean (±standard deviation) 19.3 ± 10.3 g/d metabolizable Lys (5.1 to 40.6 g/d). Meta-analytical statistics were used to estimate the weighted mean difference in STATA. Mixed models were fitted to the data to investigate the linear and quadratic effects of LYSMP, METMP, and interactions between LYSMP and METMP. All models included the random effect of experiment and weighting by the inverse of the standard errors of the means squared. Cows that began receiving RPL in early lactation (≤90 d in milk) or for an extended duration (≥70 d in milk) produced 1.51 kg/d more milk compared with CON cows. Increasing digestible LYSMP from 6.5 to 8.5% linearly increased yields of milk, fat-corrected milk (FCM), energy-corrected milk (ECM), and milk fat by 1.8, 2.5, 2.4, and 0.10 kg/d, respectively, and tended to increase milk protein yield and body weight gain by 0.07 and 0.09 kg/d, respectively, without a concurrent increase in dry matter intake (DMI). Interactions between linear effect of LYSMP and METMP were observed for FCM/DMI or ECM/DMI. In a diet with low METMP (e.g., 1.82% of MP), a digestible supply of 7.40% LYSMP would result in 1.46 and 1.47 kg/kg FCM/DMI or ECM/DMI, respectively; however, with high digestible METMP (e.g., 2.91% of MP), supplying 7.40% of digestible LYSMP would result in 1.68 and 1.62 kg/kg FCM/DMI or ECM/DMI, respectively. Increasing digestible LYSMP from 6.5 to 8.5% linearly increased blood concentrations of Lys by 16.6 µM, whereas blood concentrations of Met and Ala decreased by 4.6 and 6.0 µM, respectively. Nevertheless, an interaction was also observed between LYSMP and METMP for blood concentrations of total EAA because as METMP increased, the positive response to LYSMP on total EAA was also increased, suggesting a competitive mobilization of AA and their utilization in various body tissues. Only 4 out of the 13 experiments in this meta-analysis involved primiparous cows, thus, there was insufficient data to understand the role of supplemental RPL in primiparous cows. Collectively, feeding RPL improved productive performance and the increments were maximized up to 9.25% of LYSMP in multiparous dairy cows.

INVITED REVIEW: Nutritional and management factors that influence colostrum production and composition in dairy cows

Colostrum is a rich source of nutritional and non-nutritional components and is recognized as essential to transfer passive immunity to newborn calves. Because of the individual and seasonal variability in colostrum yield and composition, maintaining an adequate supply of high-quality colostrum year-round remains a challenge for commercial dairy producers. In this narrative review, we described the individual, seasonal, and herd-level variability of colostrum production and summarized the association between individual animal factors such as parity, sex of the calf, calf birth weight, as well as indicators of the cow's metabolic status and the yield and composition of colostrum. Further, we reviewed the current knowledge on the influence of prepartum nutrition and management strategies on colostrum production. Research on the metabolizable energy and protein supplied in the prepartum diet as well as into the inclusion and source of vitamins, minerals, and feed additives suggests prepartum nutrition influences the yield, quality, and composition of colostrum. Furthermore, the prepartum environment and dry period length remain influential factors in the production of colostrum. However, additional research is needed to understand the mechanisms by which prepartum nutrition and management affects colostrum production. Lastly, time to colostrum harvest and oxytocin administration as well as the current knowledge on the effect of heat-treatment and colostrum storage strategies on colostral components were discussed. To conclude, we identify critical gaps in knowledge for future focus of investigation in colostrum research.

The effect of maternal supply of rumen-protected protein to Holstein Friesian cows during the dry period on the transfer of passive immunity and colostral microbial composition

The objective of this study was to analyze if maternal supply of rumen-protected protein during the dry period can affect the IgG concentration and microbial composition of colostrum and the IgG absorption and fecal microbial composition in the calf. Seventy-four multiparous Holstein Friesian (HF) dairy cows were stratified per parity and randomly assigned to one of 2 different dry period diets, a diet with a low crude protein (CP) level (LP) and a diet with a high CP level (HP) by addition of rumen-undegraded protein (RUP; formaldehyde-treated soybean meal, Mervobest, Nuscience, Drongen, Belgium). Colostrum was collected within 1 h after calving and IgG concentration was quantified by radial immunodiffusion analysis. Forty-nine calves (23 female and 26 male) were enrolled in the trial with a 2 × 2 factorial design, with prenatal and postnatal treatment as the 2 independent variables. This led to 4 experimental groups: LPLP, LPHP, HPLP, and HPHP, in which the first 2 letters refer to the prenatal treatment (diet of the dam) and the last 2 refer to the postnatal treatment (diet of the colostrum-producing cow). Calves received 3× 2 L of colostrum within 2, 6, and 24 h after birth. Meconium and feces were collected solely from female calves (n = 18) by digital palpation of the rectum, immediately after birth and before colostrum administration and at d 3 of age. Microbial DNA was extracted from meconium (n = 9), feces (n = 15), and colostrum (n = 49). Amplicon sequencing of the bacterial V3-V4 region of the 16S rRNA gene was performed for characterization of the bacterial communities. Colostrum IgG concentration was higher in cows that were supplemented with RUP, especially in cows entering their second lactation (LSM ± SEM 61.3 ± 2.3 vs. 55.2 ± 2.8 g of IgG/L). Calves born out of LP cows that received colostrum from HP cows (LPHP) had a lower serum IgG level compared with HPHP and LPLP calves (LSM ± SEM 14.2 ± 1.3 vs. 18.8 ± 1.2 and 20.9 ± 1.3 g of IgG/L in HPHP and LPLP, respectively). The most abundant phyla in colostrum were Proteobacteria (48.2%), Firmicutes (24.8%), Bacteroidetes (9.5%), and Actinobacteria (5.0%). The most abundant phyla in calf meconium and feces were Firmicutes (42.5 and 47.5%), Proteobacteria (21.7% and 33.7%), Bacteroidetes (16.8% and 15.7%), and Actinobacteria (2.9% and 3.1%). There was no difference in the overall microbial communities between colostrum from HP and LP cows. However, 2 genera (both members of the family Lachnospiraceae) were more abundant in colostrum from HP cows compared with LP cows. The microbial composition of meconium, feces and colostrum differed from each other. Fecal samples were more similar to each other and are characterized by a lower intersample diversity compared with colostrum and meconium samples. To conclude, increasing the CP level by addition of RUP in the dry period diet affected the colostrum IgG concentration and the transfer of passive immunity, but did not change the overall microbial composition of colostrum nor of meconium and feces in the calf.

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.

Association of dry matter intake, milk yield, and days to first ovulation with cytological endometritis in Holstein cows

Dry matter intake (DMI, kg/d) is closely related to the magnitude of negative energy and protein balance during the transition period, and the metabolic adaptations to support lactation in dairy cows. Thus, DMI might affect the development of cytological endometritis in the early postpartum period. Difficulty to adapt to these metabolic changes is related to impaired immune function and increased occurrence of reproductive disorders. We aimed to examine the association of pre- and postpartum DMI, body weight (BW), body condition score, milk yield and milk composition, and days to first ovulation with cytological endometritis at 15 (CYT15) and 30 DIM (CYT30). A second objective was to understand the association of vaginal discharge with CYT15 and CYT30 and performance. We conducted a pooled statistical analysis of 5 studies, including data from 280 multiparous Holstein cows. Based on the cutoffs for the percentage of uterine polymorphonuclear cells (PMN), determined by taking the median value of the data set for 15 and 30 DIM, cows were categorized as follows: LOW15 (PMN % at 15 DIM ≤24%; n = 125), HIGH15 (PMN % at 15 DIM >24%; n = 125), LOW30 (PMN % at 30DIM ≤7%; n = 141); and HIGH30 (PMN % at 30DIM >7%; n = 139). Cows in HIGH15 consumed an average of 1.97 ± 0.5 kg/d less DM than cows in LOW15 during prepartum, and 3.01 ± 0.5 kg/d less DM during postpartum. Dry matter intake (as a percentage of BW) was higher for cows in LOW15 during pre- and postpartum than for cows in HIGH15. Moreover, cows in HIGH15 tended to have lower milk yield than cows in LOW15 from the third until the fifth week postpartum. Although DMI was not associated with CYT30, DMI (as a percentage of BW) was lower for cows in LOW30 pre- and postpartum than for cows in HIGH30. There was no association between CYT30 and milk yield. Cows in LOW15 had greater days to first ovulation than cows in HIGH15, while cows in LOW30 also had greater days to first ovulation than cows in HIGH30. Simple regression analyses demonstrated linear associations of increased DMI, particularly postpartum, with decreased uterine PMN percentage and lower vaginal discharge score. Additionally, increased units of vaginal discharge score and increased percentage units of uterine PMN were linearly associated with decreased milk yield. Corroborating with the notion of the ovarian function being associated with uterine inflammatory status, cows in HIGH15 and HIGH30 ovulated on average 3 d before than cows in LOW15 and LOW30, respectively. Cytological endometritis at 15 DIM was associated with lower DMI from 4 wk before calving until 4 wk postpartum and was associated with lower milk yield. The association of vaginal discharge with cytological endometritis was variable and dependent on the day of evaluation.

Feeding rumen-protected lysine prepartum alters placental metabolism at a transcriptional level

Rumen-protected Lys (RPL) fed to Holstein cows prepartum resulted in a greater intake and improved health of their calves during the first 6 wk of life. However, whether increased supply of Lys in late gestation can influence placental tissue and, if so, which pathways are affected remain to be investigated. Therefore, we hypothesize that feeding RPL during late gestation could modulate placental metabolism, allowing for improved passage of nutrients to the fetus and thus influencing the offspring development. Therefore, we aimed to determine the effects of feeding RPL (AjiPro-L Generation 3, Ajinomoto Health and Nutrition North America) prepartum (0.54% DM of TMR) on mRNA gene expression profiles of placental samples of Holstein cows. Seventy multiparous Holstein cows were randomly assigned to 1 of 2 dietary treatments, consisting of TMR top-dressed with RPL (PRE-L) or without (control, CON), fed from 27 ± 5 d prepartum until calving. After natural delivery (6.87 ± 3.32 h), placentas were rinsed with physiological saline (0.9% sodium chloride solution) to clean any dirtiness from the environment and weighed. Then, 3 placentomes were collected, one from each placental region (cranial, central, and caudal), combined and flash-frozen in liquid nitrogen to evaluate the expression of transcripts and proteins related to protein metabolism and inflammation. Placental weights did not differ from cows in PRE-L (15.5 ± 4.03 kg) and cows in CON (14.5 ± 4.03 kg). Feeding RPL prepartum downregulated the expression of NOS3 (nitric oxide synthase 3), involved in vasodilation processes, and SOD1, which encodes the enzyme superoxide dismutase, involved in oxidative stress processes. Additionally, feeding RPL prepartum upregulated the expression of transcripts involved in energy metabolism (SLC2A3, glucose transporter 3; and PCK1, phosphoenolpyruvate carboxykinase 1), placental metabolism and cell proliferation (FGF2, fibroblast growth factor 2; FGF2R, fibroblast growth factor 2 receptor; and PGF, placental growth factor), Met metabolism (MAT2A, methionine adenosyltransferase 2-α), and tended to upregulate IGF2R (insulin-like growth factor 2 receptor). Placental FGF2 and LRP1 (low-density lipoprotein receptor-related protein 1) protein abundance were greater for cows that received RPL prepartum than cows in CON. In conclusion, feeding RPL to prepartum dairy cows altered uteroplacental expression of genes and proteins involved in cell proliferation, and in metabolism and transport of glucose. Such changes are illustrated by increased expression of SLC2A3 and PCK1 and increased protein abundance of FGF2 and LRP1 in uteroplacental tissue of cows consuming RPL.

Evaluating variations in metabolic profiles during the dry period related to the time of hyperketonemia onset in dairy cows

Hyperketonemia (HYK) in early lactation can have a different impact on health and productivity depending on the timing of HYK onset. While specific metabolites measured during the dry period may serve as biomarkers of HYK, the correlations between metabolites represent a challenge for the use of metabolic profiles dataset, and little has been explored on HYK. This exploratory cohort study aimed a) to characterize the correlations among metabolites measured during the late dry period in dairy cows, and b) to identify biomarkers in the late dry period associated with the onset of HYK at the first (wk1) and second (wk2) week of lactation. Individual blood samples from 440 Holstein dairy cows were collected at 21 ± 3 days before expected parturition. From each sample, 36 different metabolites were measured in serum and plasma. Hyperketonemia was diagnosed in wk1 and wk2 of lactation based on the blood concentration of beta-hydroxybutyrate (BHB > 1.2 mmol/L). Principal component analysis (PCA) was performed to reduce metabolites to a smaller number of uncorrelated components. Multivariable logistic regression models were applied to assess the associations between principal components (PC) and HYK at wk1 only (HYK+ wk1), wk2 only (HYK+ wk2), or both weeks (HYK+ wk1-2). The incidence of HYK was 16.2% in the first week, 13.0% in the second week, and 21.2% within the first two weeks of lactation. The results of PCA highlighted 10 PCs from which two were associated with HYK+ wk1 as compared with cows without HYK during the first two weeks of lactation (non-HYK); the PC a2 led by bilirubin and non-esterified fatty acids (OR = 1.29; 95%CI: 1.02-1.68), and the PC a5 led by alkaline phosphatase (ALP) and gamma-glutamyl transferase (GGT) (OR = 2.77; 95%CI: 1.61-4.97). There was no evidence of an association between any PC and HYK+ wk2 (vs. non-HYK cows). Cows with elevated PC a5 (led by ALP and GGT) in the dry period were 3.18 times more likely to be HYK+ wk1 than HYK+ wk2 (OR: 3.18, 95%CI: 1.34-8.73; P = 0.013). Overall, the main hypothesis generated by our exploratory study suggests that cows with biomarkers of liver dysfunction (ALP, GGT, bilirubin) assessed by PCA at 3 weeks before calving are more likely to develop HYK during the first week of lactation compared to the second week. In addition, results suggest that cows with HYK in both of the first two weeks of lactation had an overall metabolic disbalance during the onset of the late dry period, which based on PCs, encompass biomarkers related to glucogenic and ketogenic metabolic pathways as well as liver dysfunction and fatty liver. Further research is needed to determine the underlying mechanisms associated with the different adaptations between cows that develop HYK during the first and second week of lactation.

The Impact of Biotechnologically Produced Lactobionic Acid in the Diet of Lactating Dairy Cows on Their Performance and Quality Traits of Milk

Dairy processing is one of the most polluting sectors of the food industry as it causes water pollution. Given considerable whey quantities obtained via traditional cheese and curd production methods, manufacturers worldwide are encountering challenges for its rational use. However, with the advancement in biotechnology, the sustainability of whey management can be fostered by applying microbial cultures for the bioconversion of whey components such as lactose to functional molecules. The present work was undertaken to demonstrate the potential utilization of whey for producing a fraction rich in lactobionic acid (Lba), which was further used in the dietary treatment of lactating dairy cows. The analysis utilizing high-performance liquid chromatography with refractive index (HPLC-RID) detection confirmed the abundance of Lba in biotechnologically processed whey, corresponding to 11.3 g L^-1. The basic diet of two dairy cow groups involving nine animals, Holstein Black and White or Red breeds in each, was supplemented either with 1.0 kg sugar beet molasses (Group A) or 5.0 kg of the liquid fraction containing 56.5 g Lba (Group B). Overall, the use of Lba in the diet of dairy cows during the lactation period equal to molasses affected cows' performances and quality traits, especially fat composition. The observed values of urea content revealed that animals of Group B and, to a lesser extent, Group A received a sufficient amount of proteins, as the amount of urea in the milk decreased by 21.7% and 35.1%, respectively. After six months of the feeding trial, a significantly higher concentration of essential amino acids (AAs), i.e., isoleucine and valine, was observed in Group B. The percentage increase corresponded to 5.8% and 3.3%, respectively. A similar trend of increase was found for branched-chain AAs, indicating an increase of 2.4% compared with the initial value. Overall, the content of fatty acids (FAs) in milk samples was affected by feeding. Without reference to the decrease in individual FAs, the higher values of monounsaturated FAs (MUFAs) were achieved via the supplementation of lactating cows' diets with molasses. In contrast, the dietary inclusion of Lba in the diet promoted an increase in saturated FA (SFA) and polyunsaturated FA (PUFA) content in the milk after six months of the feeding trial.

Feeding rumen-protected lysine altered immune and metabolic biomarkers in dairy cows during the transition period

This experiment was conducted to determine the effects of feeding rumen-protected lysine (RPL; AjiPro-L Generation 3, Ajinomoto Health and Nutrition North America Inc.) from -26 ± 4.6 d prepartum (0.54% RPL of dietary dry matter intake) to 28 d postpartum (0.39% RPL of dietary dry matter intake) on immunometabolic status and liver composition in dairy cows. 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 4 dietary treatments in a randomized, complete block design with a 2 × 2 factorial arrangement of treatments. Treatments prepartum consisted of total mixed ration top dressed with RPL (PRE-L) or without RPL (PRE-C), and postpartum treatments consisted of total mixed ration top dressed PRE-L prepartum and postpartum, PRE-L prepartum and PRE-C postpartum, PRE-C prepartum and PRE-L postpartum, and PRE-C prepartum and postpartum in 300 g of molasses. Blood samples were taken on -7 ± 0.5, 0 ± 0.5, 7 ± 0.9, 14 ± 0.9, and 28 ± 0.5 d relative to calving. Whole blood samples were taken on -14 ± 0.5, -7 ± 0.5, 7 ± 0.9, and 14 ± 0.9 d relative to calving for oxidative burst and phagocytic capacity of monocytes and neutrophils. Liver samples were collected via a biopsy on -12 ± 4.95 and 13 ± 2.62 d relative to calving and analyzed for liver composition (triacylglyceride and carnitine concentrations), mRNA expression of hepatic genes, and protein abundance. Protein abundance was calculated by normalizing intensity bands for a specific protein with glyceraldehyde-3-phosphate dehydrogenase. Concentrations of haptoglobin and glutathione peroxidase activity in plasma were lower at d 0 for cows in PRE-L (102 µg/mL and 339 nmol/min per mL, respectively) compared with cows in PRE-C (165 µg/mL and 405 nmol/min per mL, respectively). Oxidative burst capacity in monocytes tended to be greater on d 7 postpartum for cows in PRE-L (65.6%) than cows in PRE-C (57.5%). Additionally, feeding RPL altered the mRNA expression in liver tissue prepartum [decreased INSR (insulin receptor), CPT1A (carnitine palmitoyltransferase 1A), and IL1B (interleukin 1 β)] and postpartum [increased IL8 (interleukin 8), EHMT2 (euchromatic histone lysine methyltransferase 2), TSPO (translocator protein), and SLC3A2 (solute carrier family 3 member 2); and decreased SLC7A1 (solute carrier family 7 member 1), SOD1 (superoxide dismutase 1), and SAA3 (serum amyloid A 3)] compared with cows not consuming RPL]. Additionally, cows in the PRE-C prepartum and PRE-L postpartum treatment tended to have greater protein abundance of mTOR postpartum compared with the PRE-C prepartum and postpartum treatment. Protein abundance of SLC7A7 (solute carrier family 7 member 7) pre- and postpartum tended to be greater and BBOX1 (gamma-butyrobetaine dioxygenase 1) tended to be less when RPL was consumed prepartum. In conclusion, cows that consumed RPL during the transition period had molecular changes related to liver composition, enhanced liver function indicated by greater total protein and albumin concentrations in plasma, and improved immune status indicated by decreased haptoglobin, glutathione peroxidase activity, and immune related mRNA expression.

The effects of maternal supplementation of rumen-protected lysine during the close-up dry period on newborn metabolism and growth in Holstein calves

This study aimed to evaluate the effects of rumen-protected lysine (RPL) supplementation during the close-up period on blood metabolites and calf growth. Forty multiparous Holstein dams were selected based on parity, body condition score, and expected calving date, and randomly assigned to a group: with RPL (n = 22) or without (control [CON], n = 18). RPL dams were supplied daily with 80 g of RPL from Day 21 before the expected calving date to parturition. Blood samples were obtained from the dams before the start of supplementation, 1 week before calving, and immediately after calving, and from calves immediately after birth and weekly until 8 weeks of age. Body weight measurements were performed immediately after birth in all calves and at weekly intervals until 8 weeks of age in female calves. No significant difference was observed in serum metabolite levels and plasma amino acid concentrations between the RPL and CON dams before supplementation, whereas plasma lysine concentrations tended to be higher in RPL dams immediately after calving (p = 0.07). Serum total protein levels (p < 0.05) were higher, whereas plasma total amino acid, total essential amino acid, total non-essential amino acid, and other amino acid concentrations were lower in the calves of RPL dams than those of CON dams (p < 0.05). There were no significant differences in calf birth weight between the two groups, although female calves of RPL dams (n = 7) had higher serum total protein (p < 0.05) and tended to have greater body weight (p = 0.09) from 1 to 8 weeks of age than those of CON dams (n = 11). Overall, RPL supplementation during the close-up period may increase placenta-mediated amino acid transfer to the foetus and enhance protein synthesis in the calf, leading to improved weight gain during the suckling period.

Multi-omics analyses reveal that the gut microbiome and its metabolites promote milk fat synthesis in Zhongdian yak cows

Background

Yak cows produce higher quality milk with higher concentrations of milk fat than dairy cows. Recently, studies have found the yak milk yield and milk fat percentage have decreased significantly over the past decade, highlighting the urgency for yak milk improvement. Therefore, we aimed to analyze how the gut microbiome impacts milk fat synthesis in Zhongdian yak cows.

Methods

We collected milk samples from Zhongdian yak cows and analyzed the milk fat percentage, selecting five Zhongdian yak cows with a very high milk fat percentage (>7%, 8.70 ± 1.89%, H group) and five Zhongdian yak cows with a very low milk fat percentage (<5%, 4.12 ± 0.43%, L group), and then obtained gut samples of these ten Zhongdian yak cows through rectal palpation. Gut metagenomics, metabolomics, and conjoint metagenomics and metabolomics analyses were performed on these samples, identifying taxonomic changes, functional changes, and changes in gut microbes-metabolite interactions within the milk fat synthesis-associated Zhongdian yak cows gut microbiome, to identify potential regulatory mechanisms of milk fat at the gut microbiome level in Zhongdian yak cows.

Results

The metagenomics analysis revealed Firmicutes and Proteobacteria were significantly more abundant in the gut of the high-milk fat Zhongdian yak cows. These bacteria are involved in the biosynthesis of unsaturated fatty acids and amino acids, leading to greater efficiency in converting energy to milk fat. The metabolomics analysis showed that the elevated gut metabolites in high milk fat percentage Zhongdian yak cows were mainly enriched in lipid and amino acid metabolism. Using a combined metagenomic and metabolomics analysis, positive correlations between Firmicutes (Desulfocucumis, Anaerotignum, Dolosiccus) and myristic acid, and Proteobacteria (Catenovulum, Comamonas, Rubrivivax, Marivita, Succinimouas) and choline were found in the gut of Zhongdian yak cows. These interactions may be the main contributors to methanogen inhibition, producing less methane leading to higher-efficient milk fat production.

Conclusions

A study of the gut microbe, gut metabolites, and milk fat percentage of Zhongdian yak cows revealed that the variations in milk fat percentage between yak cows may be caused by the gut microbes and their metabolites, especially Firmicutes-myristic acid and Proteobacteria-choline interactions, which are important to milk fat synthesis. Our study provides new insights into the functional roles of the gut microbiome in producing small molecule metabolites and contributing to milk performance traits in yak cows.

Dairy Cows Experimentally Infected With Bovine Leukemia Virus Showed an Increased Milk Production in Lactation Numbers 3–4: A 4-Year Longitudinal Study

Bovine leukemia virus (BLV) is widespread in global cattle populations, but the effects of its infection on milk quantity and quality have not been clearly elucidated in animal models. In this study, 30 healthy first-lactation cows were selected from ≈2,988 cows in a BLV-free farm with the same criteria of parity, age, lactation number, as well as milk yield, SCS, and composition (fat, protein, and lactose). Subsequently, these cows were randomly assigned to the intervention (n = 15) or control (n = 15) group, and reared in different cowsheds. Cows in the intervention group were inoculated with 1 × phosphate-buffered solution (PBS) resuspended in peripheral blood mononuclear cells (PBMC) from a BLV-positive cow, while the controls were inoculated with the inactivated PBMC from the same individual. From June 2016 to July 2021, milk weight (kg) was automatically recorded by milk sensors, and milk SCS and composition were originated from monthly performed dairy herd improvement (DHI) testing. Fluorescence resonance energy transfer (FRET)–qPCR and ELISA showed that cows in the intervention group were successfully infected with BLV, while cows in the control group were free of BLV for the entire period. At 45 days post-inoculation (DPI), the numbers of whole blood cells (WBCs) (P = 0.010), lymphocytes (LYMs) (P = 0.002), and monocytes (MNCs) (P = 0.001) and the expression levels of IFN-γ (P = 0.013), IL-10 (P = 0.031), and IL-12p70 (P = 0.008) increased significantly in the BLV infected cows compared to the non-infected. In lactation numbers 2–4, the intervention group had significantly higher overall milk yield (P < 0.001), fat (P = 0.031), and protein (P = 0.050) than the control group, while milk SCS (P = 0.038) and lactose (P = 0.036) decreased significantly. Further analysis indicated that BLV infection was associated with increased milk yield at each lactation stage in lactation numbers 3–4 (P = 0.021 or P < 0.001), but not with SCS and milk composition. Together, this 4-year longitudinal study revealed that artificial inoculation of BLV increased the milk yield in cows in this BLV challenge model.

Alterations in Skeletal Muscle mRNA Abundance in Response to Ethyl-Cellulose Rumen-Protected Methionine during the Periparturient Period in Dairy Cows

This study aimed to evaluate the effect of feeding ethyl cellulose rumen-protected methionine (RPM) on skeletal muscle mRNA abundance during the periparturient period. Sixty multiparous Holstein cows were used in a block design and assigned to either a control or RPM diet. The RPM was supplied from −28 to 60 days in milk (DIM) at a rate of 0.09% (prepartum) or 0.10% (postpartum) of dry matter (DM), ensuring a Lys:Met in the metabolizable protein of ~2.8:1. Muscle biopsies were collected at −21, 1, and 21 DIM. Thirty-five target genes associated with nutrient metabolism and biochemical pathways were measured via RT-qPCR. The mRNA abundance of genes associated with amino acid (AA) transport (SLC7A8, SLC43A2), carnitine transport (SLC22A5), insulin signaling (IRS1), and antioxidant response (NFE2L2) had diet × time effect (p < 0.05) due to greater abundance in RPM versus CON cows, especially at 1 and 21 DIM. Members of the AA transport (SLC7A8, SLC25A29, SCL38A9), fatty acid β-oxidation (ACADVL), vitamin transport (SLC5A6, SLC19A2), mTOR pathway (AKT1 and mTOR), antioxidant response (KEAP1, CUL3), CDP-Choline pathway and arginine metabolism had overall greater abundance (p < 0.05) in RPM versus CON cows. Overall, data indicate that RPM can alter nutrient metabolism in the skeletal muscle around parturition partly through alterations in mRNA abundance.

Feasibility of Supplying Ruminally Protected Lysine and Methionine to Periparturient Dairy Cows on the Efficiency of Subsequent Lactation

The objective of this study was to evaluate the effects of supplying ruminally protected Lys (RPL) and ruminally protected Met (RPM) to transition cows' diets on the efficiency of subsequent lactation. A total of 120 prepartum Holstein cows were assigned into four treatments blocked by the anticipated calving date, previous lactation milk yield, number of lactations, and body condition score and fed either RPL, RPM, or the combination (RPML) or control diet (CON) throughout the transition period (3 weeks before till 3 weeks after calving). From 22 to 150 days in milk (DIM), all animals (100 cows) were fed a combination of RPM and RPL (0.17% RPM and 0.41% RPL of DM; n = 25 cows/treatment) as follows; CON–RPML, RPM–RPML, RPL–RPML, and RPML–RPML. Milk production and dry matter intake (DMI) were measured daily; milk and blood samples were taken at 21, 30, 60, 90, 120, and 150 DIM. Supplemented amino acids (AA) were mixed with the premix and added to the total mixed ration during the experiment. DMI (p &lt; 0.001) and energy-corrected milk (ECM, p = 0.04) were higher for cows that were fed RPML–RPML than other cows. Compared with CON–RPML, yields of milk total protein, lactose, and nitrogen efficiency were increased (p &lt; 0.01), whereas milk urea nitrogen (MUN; p = 0.002) was decreased for other treatments. However, supplemental AA did not affect milk lactose percentage, fat yield, feed efficiency, or serum total protein concentration (p &gt; 0.10). Transition cows that consumed AA had a greater peak of milk yield (p &lt; 0.01), as well as quickly reached the peak of milk (p &lt; 0.004). There were differences in β-hydroxybutyrate concentration during the early lactation, with a lower level for AA groups (p &lt; 0.05), and the difference faded with the progression of lactation (p &gt; 0.10). Fertility efficiency as measured by pregnancy rate was improved by supplemental AA during the perinatal period (p &lt; 0.05). In conclusion, transition cows consumed RPM and RPL, increased post-calving DMI, milk production, milk protein yield, nitrogen efficiency, and improved fertility performance.

Supplementing Ruminally Protected Lysine, Methionine, or Combination Improved Milk Production in Transition Dairy Cows

The objectives of this study were to evaluate the effects of dietary supplementation of ruminally protected lysine (RPL), or methionine (RPM), and their combination (RPML) on the production efficiency of transition cows. A total of 120 pre-partum multiparous Holstein cows were assigned to four treatments based on previous lactation milk production, days (d) of pregnancy, lactation, and body condition score (BCS). Cows were fed a basal diet [pre-calving: 1.53 Mcal/kg dry matter (DM) and post-calving: 1.70 Mcal/kg DM] with or without supplemental ruminally protected amino acids (RPAA). Treatments were the basal diets without supplemental amino acids (CONTROL, n = 30), with supplemental methionine (RPM, pre-calving at 0.16% of DM and post-calving at 0.12% of DM, n = 30), with supplemental lysine (RPL, pre-calving at 0.33% of DM and post-calving at 0.24% DM, n = 30), and the combination (RPML, pre-calving at 0.16% RPM + 0.33% RPL of DM and post-calving at 0.12% RPM + 0.24 % RPL DM, n = 30). The dietary content of lysine was balanced to be within 6.157.2% metabolizable protein (MP)-lysine and that of methionine was balanced within 2.1-2.35% MP-methionine. Dry matter intake (DMI) was measured daily. Milk samples were taken on d 7, 14, and 21 days relative to calving (DRC), and milk yields were measured daily. Blood samples were taken on d -21, -14, -7 before expected calving and d 0, 7, 14, and 21 DRC. Data were analyzed using SAS software. There were significant Trt × time interactions (P < 0.01) for DMI pre- and post-calving period. The CON cows had lower DMI than RPM, RPL, and RPML, both pre-calving (P < 0.01) and post-calving periods (P < 0.01). Energy-corrected milk (P < 0.01), milk fat (P < 0.01), protein (P = 0.02), and lactose (P < 0.01) percentage levels were greater for RPM, RPL, and RPML cows compared to CON. Supplementing RPAA assisted in maintaining BCS post-calving than CON (P < 0.01). Blood concentrations of β-hydroxybutyrate decreased with RPM or RPL or the combination pre-calving (P < 0.01) and tended to decrease post-calving (P = 0.10). These results demonstrated that feeding RPL and RPM improved DMI and milk production efficiency, maintained BCS, and reduced β-hydroxybutyrate concentrations of transition cows.

Acremonium terricola Culture’s Dose–Response Effects on Lactational Performance, Antioxidant Capacity, and Ruminal Characteristics in Holstein Dairy Cows

Acremonium terricola culture (ATC) has similar bioactive constituents to Cordyceps and is known for its nutrient and pharmacological value, indicating the potential of ATC as a new feed additive in dairy cow feeding. The primary aim of this experiment was to investigate the effects of increasing amounts of ATC in diets on milk performance, antioxidant capacity, and rumen fermentation, and the secondary aim was to evaluate the potential effects of high doses of ATC. A total of 60 multiparous Holstein cows (110 ± 21 days in milk; 2.53 ± 0.82 parity) were assigned into 15 blocks and randomly assigned to one of four groups: 0, 30, 60, or 300 g/d of ATC per cow for 97 days. Data were analyzed using repeated measures in the Mixed procedure. Dry-matter intake was not changed (p > 0.05), while energy-corrected milk and fat-corrected milk yields increased linearly and quadratically, and somatic cell count in milk decreased linearly and quadratically (p < 0.05). The lactation efficiency and the yields of milk fat and protein increased linearly (p < 0.05). On day 90, serum catalase level, total oxidative capacity, glutathione peroxidase, immunoglobulin A, and immunoglobulin M concentrations were significantly higher in the 60 and 300 g/d groups than in the 0 g/d group (p < 0.05). ATC addition showed linear effects on total volatile fatty acid (VFA), acetate, branched VFA concentrations, and rumen pH (p < 0.05). Supplementing 60 and 300 g/d ATC significantly affected the bacterial composition (p < 0.05). The relative abundance of Christensenellaceae_R–7_group and Lachnospiraceae_NK3A20_group were significantly increased by 60 g/d supplementation, and the relative abundance of Erysipelotrichaceae_UCG_002, Acetitomaculum, Olsenella, and Syntrophococcus were significantly increased by 300 g/d supplementation (p < 0.05). ATC was effective in enhancing rumen fermentation and reducing somatic cell count in milk, thereby improving milk yield. The optimized dose of ATC was 60 g/d for lactating cows, and there were no risks associated with high doses of ATC.

Validation of 2 urine pH measuring techniques in a prepartum negative dietary cation-anion difference diet and the relationship with production performance

Negative dietary cation-anion difference (DCAD) diets have been implemented to combat hypocalcemia, a common peripartal disease in dairy cows; however, the extent of compensatory metabolic acidosis necessary and the subsequent effects on performance are still debated. Additionally, there is a need for an inexpensive, accurate method to measure urine pH on farm during the prepartum period to assess the extent of metabolic acidosis achieved by negative DCAD diets. Therefore, this experiment was conducted to determine the accuracy of Fisher pH sticks (pHF; ThermoFisher Scientific) and pHion balance test strips (pHI; pHion Balance) compared with a portable pH meter (pHP; Accumet AP115, ThermoFisher Scientific) in measuring urine pH (UpH) and the effect of UpH on pre- and postpartum dry matter intake (DMI), milk, and milk composition yields. Cows consumed a total mixed ration with a DCAD of -118 mEq/kg for 4 wk prepartum and 397 mEq/kg for 4 wk postpartum. Prepartum UpH measurements (n = 75) for each cow were averaged and used to classify cows in terms of urine pH as low (UpH ≤5.54; mean ± standard deviation; 5.44 ± 0.07), medium (UpH >5.54 and ≤5.90; 5.67 ± 0.09), or high (UpH >5.90; 6.42 ± 0.36). Cows were milked twice a day, and milk samples were taken on d 7 ± 1.3, 14 ± 1.4, and 28 ± 1.1 relative to calving. Milk yield and DMI were recorded daily and averaged weekly. Bland-Altman plots and Lin's concordance correlation coefficient (CCC) were used to assess the agreement between pHP and pHF or pHI (n = 375). Receiver operating characteristic curves were used to determine the threshold with pHF and pHI that best discriminated between UpH >5.75 and ≤5.75 compared with pHP, and area under the curve (AUC) was used to assess the accuracy. At the UpH threshold of 5.75 for pHF and pHI, the sensitivity, specificity, and AUC were 89.5 and 87.4, 99.1 and 97.0, and 0.94 and 0.92, respectively. The CCC was 0.93 for pHF and pHI, indicating near-perfect agreement with pHP. The UpH did not affect pre- or postpartum DMI. There was a tendency for a UpH × week interaction for milk yield, in which milk yields were less for cows in the low and medium groups. In conclusion, pHI and pHF are accurate measurements for UpH, and UpH did not affect DMI; however, when UpH was low or medium, milk yield was decreased at wk 1 postpartum.

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).

The crucial role of lysine in the hepatic metabolism of growing Holstein dairy heifers as revealed by LC-MS-based untargeted metabolomics

The objective of this experiment was to evaluate the effect of supplementing rumen-protected Lys based on a Lys-deficient diet on liver metabolism in growing Holstein heifers. The experiment was conducted for 3 months with 36 Holstein heifers (initial body weight: 200 ± 9.0 kg; 7-month-old). Heifers were randomly assigned to 2 diets based on corn, soybean meal, alfalfa hay, and wheat bran: control, Lys-deficient diet (LD; 0.66% Lys in diet), and Lys-adequate diet (LA; 1.00% Lys in diet). The results showed no difference in growth performance between the 2 groups (P > 0.05). However, there was a clear trend of increasing feed conversion rate with Lys supplementation (0.05 < P < 0.01). The serum urea nitrogen concentration was significantly decreased, and the aspartate aminotransferase-to-alanine aminotransferase ratio was significantly decreased by Lys supplementation (P < 0.05). Moreover, growing heifers fed a Lys-adequate diet had lower levels of urine nitrogen excretion and higher levels of the biological value of nitrogen (P < 0.05). Metabolomic analysis revealed that 5 types of phosphatidylcholine and 3 types of ceramide were significantly increased and enriched in sphingolipid metabolism and glycerophospholipid metabolism (P < 0.05). His, Leu, and Asp levels were significantly decreased in the liver following Lys supplementation (P < 0.05). In conclusion, Lys supplementation may promote the synthesis of body tissue proteins, as evidenced by significantly decreased amino acids in the liver and urine N excretion, it also improves hepatic lipid metabolism by providing lipoprotein precursors.

Effect of rumen-protected lysine supplementation of diets based on corn protein fed to lactating dairy cows

This trial tested whether rumen-protected Lys (RPL) supplementation would improve the nutritive value of rumen-undegradable protein (RUP) from corn protein. Thirty-two lactating Holstein cows were blocked by days in milk and parity into 8 squares of 4 cows each in replicated 4 × 4 Latin squares. Treatments provided all supplemental crude protein from: (1) soy protein (67% expeller soybean meal plus 33% solvent soybean meal); (2) a blend of soy and corn protein (33% expeller soybean meal, 17% solvent soybean meal, 25% corn gluten meal plus 25% distillers dried grains with solubles); (3) corn protein (50% corn gluten meal plus 50% distillers dried grains with solubles); or (4) corn protein plus RPL [diet 3 top-dressed with RPL (125 g/d of AjiPro-L Generation 1, supplying an estimated 20 g of absorbable Lys/d)]. Diets contained (dry matter basis) 22% alfalfa silage, 43% corn silage, 18% ground high-moisture and dry corn, 2.4% mineral-vitamin premix, 1.5 to 3.9% soy hulls, 15% crude protein, 30 to 32% neutral detergent fiber and predicted to contain equal rumen-degradable protein, RUP, and metabolizable protein. Cows within squares were randomly assigned to treatment sequences and fed diets for 4-wk periods before switching; production data and blood samples were collected during last 2 wk of each period. Data were analyzed using the mixed procedures of SAS. Intake was highest on diet 1, intermediate on diets 2 and 3, and lowest on diet 4; body weight gain was highest on diet 3, intermediate on diets 1 and 2 and lowest on diet 4. Intakes and body weight changes were reflected by differences in milk/dry matter intake, which was highest on diets 2 and 4 and lowest on diet 3. Milk yield was lower on diet 3 (44.3 kg/d) than on diets 1, 2, and 4 (average 45.8 kg/d) and protein yield was highest on diets 1 and 2 (average 1.35 kg/d), intermediate on diet 4 (1.30 kg/d), and lowest on diet 3 (1.25 kg/d). No effects of diet were detected on ruminal metabolites. Free nonessential amino acids and total protein AA were elevated in blood plasma on diet 3, reflecting reduced utilization for milk protein synthesis. These results indicated that 50% dilution of soybean meal RUP with that from corn protein did not reduce yield and that supplementing RPL to the corn protein-based diet increased yield 1.1 kg of milk/d and 50 g of true protein/d.