Liver and Muscle Transcriptomes Differ in Mid-Lactation Cows Divergent in Feed Efficiency in the Presence or Absence of Supplemental Rumen-Protected Choline.

Improving dairy cow feed efficiency is critical to the sustainability and profitability of dairy production, yet the underlying mechanisms that contribute to individual cow variation in feed efficiency are not fully understood. The objectives of this study were to (1) identify genes and associated pathways that are altered in cows with high- or low-residual feed intake (RFI) using RNA sequencing, and (2) determine if rumen-protected choline supplementation during mid-lactation would influence performance or feed efficiency. Mid-lactation (134 ± 20 days in milk) multiparous Holstein cows were randomly assigned to either supplementation of 0 g/d supplementation (CTL; n = 32) or 30 g/d of a rumen-protected choline product (RPC; 13.2 g choline ion; n = 32; Balchem Corp., New Hampton, NY, USA). Residual feed intake was determined as dry matter intake regressed on milk energy output, days in milk, body weight change, metabolic body weight, and dietary treatment. The 12 cows with the highest RFI (low feed efficient; LE) and 12 cows with the lowest RFI (high feed efficient; HE), balanced by dietary treatment, were selected for blood, liver, and muscle analysis. No differences in production or feed efficiency were detected with RPC supplementation, although albumin was greater and arachidonic acid tended to be greater in RPC cows. Concentrations of ß-hydroxybutyrate were greater in HE cows. Between HE and LE, 268 and 315 differentially expressed genes in liver and muscle tissue, respectively, were identified through RNA sequencing. Pathway analysis indicated differences in cell cycling, oxidative stress, and immunity in liver and differences in glucose and fatty acid pathways in muscle. The current work indicates that unique differences in liver and muscle post-absorptive nutrient metabolism contribute to sources of variation in feed efficiency and that differences in amino acid and fatty acid oxidation, cell cycling, and immune function should be further examined.

In utero choline exposure alters growth, metabolism, feed efficiency, and carcass characteristics of Holstein × Angus cattle from weaning to slaughter.

Feeding rumen-protected choline (RPC) to late gestation dairy cows has potential to affect growth in offspring. The objective of this study was to evaluate the effects of in utero choline exposure on the growth, feed efficiency (FE), metabolism, and carcass quality of Angus × Holstein cattle. Multiparous Holstein cows pregnant with male (N = 17) or female (N = 30) Angus-sired calves were enrolled 21 d prepartum and randomly assigned to one of four dietary treatments varying in quantity and formulation of RPC. The treatments included a control with 0 g/d supplemental RPC (CTL), supplemental RPC fed at the recommended dose (RD) of 15 g/d from either an established RPC product (RPC1RD; ReaShure; Balchem Corp.) or choline ion from a concentrated RPC prototype (RPC2RD; Balchem Corp.), or a high dose (HD) of RPC2 fed at 22 g/d (RPC2HD). From 2 to 6 mo of age, calves were group housed and offered 2.3 kg grain/hd/d (42% CP) with ad libitum grass hay, and stepped up to a complete finishing diet by 7 mo (12.0% CP; 1.34 Mcal/kg NEg). Weight and height were measured monthly. Animal FE was measured in individual pens for 35 d at 8 mo. Feed intake was measured daily, and blood was obtained on day 18 during the FE period. Afterwards, cattle were group housed and offered a free-choice finishing diet until slaughter, where carcass yield and quality characteristics were measured. Mixed models were used in PROC MIXED (SAS, 9.4) with the fixed effects of treatment, sex, time, their interactions, and the random effect of calf. Month was the repeated measure, and preplanned contrasts were used. Blood and FE data were analyzed with the fixed effect of dam choline treatment, calf sex, and the interaction. Increasing dose of RPC tended to increase weight over the entire study period. Feeding any RPC increased hip and wither height compared with CTL, and increasing RPC dose linearly increased hip and wither height. Treatment and sex interacted on DMI whereby increasing RPC intake linearly increased DMI for males but not females. Compared with control, feeding any RPC decreased plasma insulin, glucose, and an insulin sensitivity index (RQUICKI). In utero choline exposure increased kidney-pelvic-heart fat and marbling score. Mechanisms of action for intrauterine choline exposure on offspring growth, metabolism, and carcass characteristics should be explored as they have direct implications for profitability for cattle growers and feeders.

Common nutritional and management programs implemented during gestation in dairy cattle also have positive outcomes for offspring growth, health, and well-being. Recent work has demonstrated that supplementing rumen-protected choline (RPC) to dairy cows for several weeks before calving increases growth and feed efficiency (FE) of their calves. Considering the recent industry trends of breeding dairy cows with beef semen, any potential growth and FE advantages imparted by prenatal RPC supplementation of the dams could help increase value of the resulting beef × dairy calves. The objective of this study was to evaluate growth, FE, and carcass characteristics of beef × dairy calves from dairy cows supplemented with RPC before calving. Feeding RPC to dairy cows before calving increased offspring weight and height through 9 mo of age. In utero exposure to choline also improved markers of insulin sensitivity of the offspring while being fed with a high-energy diet. Dam dietary RPC supplementation increased offspring kidney, pelvic, and heart fat at slaughter, and also increased marbling score. Considering the importance of marbling in carcass quality, the potential of RPC to positively influence offspring performance could be beneficial for further enhancing value of beef × dairy cattle at slaughter.

Prepartum supplementation of conjugated linoleic acids (CLA) increased milk energy output and decreased serum fatty acids and ß-hydroxybutyrate in early lactation dairy cows.

Prepartum supplementation with conjugated linoleic acid (CLA) may influence lipolysis and hyperketonemia in dairy cows. The objective of this study was to examine the effect of prepartum CLA supplementation on lactation performance and serum fatty acids (FA) and ß-hydroxybutyrate (BHB) in early lactation dairy cows, and secondarily on reproductive performance. Multiparous cows were enrolled in the study at 18 days prior to expected calving date, and randomly assigned 100 g/day of Lutrell Pure (BASF, Ludwigshafen, Germany; 75% FA), providing 10 g/day of each CLA isomer (trans-10 cis-12 and cis-9 trans-11 CLA) or equivalent amount of rumen inert fatty acids as control (78 g/day of Energy Booster 100; Milk Specialties Global, Eden Prairie, MN). Treatments were top dressed daily to individual cows from enrollment to calving and all cows were offered the same ration. Blood samples were collected on the first day of supplementation, 10 days prepartum, and 1, 7, 14, and 30 days postpartum. Hyperketonemia was defined as serum BHB ≥ 1.2 mM. Milk yield was recorded daily until 60 days postpartum and averaged weekly. Milk samples were obtained weekly for component analysis. Prepartum CLA supplementation tended to increase serum concentration of cis-9, trans-11 CLA and increased trans-10, cis-12 CLA prepartum. Cows supplemented with CLA had increased milk protein yield and tended to have increased milk fat yield and milk yield, which together resulted in greater energy content of milk. Cows supplemented with CLA had lower serum FA on day 1 and 7 postpartum and overall lower serum BHB postpartum, which resulted in decreased prevalence of hyperketonemia on day 14 postpartum. There were no differences in body condition score change, other health disorders, or reproductive outcomes by treatment. Together, these findings indicate that prepartum CLA supplementation may be a plausible strategy to positively influence postpartum performance.

Regulation of inflammation, antioxidant production, and methyl-carbon metabolism during methionine supplementation in lipopolysaccharide-challenged neonatal bovine hepatocytes.

Supplementation of methionine (Met) may improve immunometabolic status, specifically during a period of inflammatory stress. The aim of the present study was to establish an inflammation model using primary neonatal bovine hepatocytes and to examine the effects of increasing concentrations of dl-Met and a maintained Met to lysine (Lys) ratio on hepatocyte inflammatory responses, antioxidant production, and Met metabolism during lipopolysaccharide (LPS) challenge. Hepatocytes isolated from 4 calves were maintained as monolayer cultures and exposed to 0, 10, or 40 µMdl-Met and 100 µM Lys (0Met100Lys, 10Met100Lys, or 40Met100Lys) or 10 µMdl-Met and 25 µM Lys (10Met25Lys). Cells were exposed to each treatment for 16 h and then challenged with either 0 or 100 ng/mL of LPS for 8 h. In the absence of LPS, glutathione (GSH) was not altered by 10Met100Lys or 10Met25Lys but was increased by 40Met100Lys. With LPS challenge, GSH concentration was decreased with 40Met100Lys and tended to be decreased with 10Met100Lys. Hepatocytes receiving 10Met100Lys treated with 100 ng/mL of LPS showed an inflammatory response with increased mRNA expression of tumor necrosis factor (TNFα), IL-6, IL-1ß, and interferon gamma, which was accompanied by increased nuclear factor κB inhibitor and serum amyloid A3 mRNA. The treatment 40Met100Lys was effective for preventing the LPS-induced increase in expression of the above genes except TNFα. Similar preventative effects were observed for 10Met25Lys; however, it did not prevent the LPS-induced increase in TNFα or IL-6 mRNA. Lipopolysaccharide challenge decreased mRNA expression of key genes controlling the transmethylation and Met regeneration pathways, which was not prevented by Met supplementation. The data suggest that bovine hepatocyte cultures can be used as a biological model to study the inflammatory cascade via an LPS challenge. Supplementation of Met prevents the LPS-induced hepatocyte cytokine expression and is associated with elevated intracellular GSH concentration.

The effect of increasing concentrations of dl-methionine and 2-hydroxy-4-(methylthio) butanoic acid on hepatic genes controlling methionine regeneration and gluconeogenesis.

Metabolizable methionine (Met) concentrations can be increased by feeding rumen-protected dl-Met or the isopropyl ester of 2-hydroxy-4-(methylthio) butanoic acid (HMBi). Hepatic responses to increasing concentrations of metabolizable Met as a result of supplementation of different Met sources have not been comparatively examined. The objective of this experiment was to examine the regulation of key genes for Met metabolism, gluconeogenesis, and fatty acid oxidation in response to increasing concentrations of dl-Met or 2-hydroxy-4-(methylthio) butanoic acid (HMB) in bovine primary hepatocytes. Hepatocytes isolated from 4 Holstein calves less than 7d old were maintained as monolayer cultures for 24h before addition of treatments. Cells were then exposed to treatments of dl-Met or HMB (0, 10, 20, 40, or 60 µM) in Met-free medium for 24h and collected for RNA isolation and quantification of gene expression by quantitative PCR. Expression of betaine-homocysteine methyltransferase (BHMT), 5-methyltetrahydrofolate-homocysteine methyltransferase (MTR), and 5,10 methylenetetrahydrofolate reductase (MTHFR) genes, which catalyze regeneration of Met from betaine and homocysteine, decreased linearly with increasing dl-Met concentration. We observed similar effects with increasing HMB concentration, except expression of MTHFR, which was not altered. Expression of Met adenosyltransferase 1A (MAT1A), which catalyzes the first step of Met metabolism to generate S-adenosylmethionine (SAM), a primary methyl donor, was decreased with increasing dl-Met or HMB concentration. Expression of S-adenosylhomocysteine hydrolase (SAHH) was decreased linearly with increasing HMB concentration, but not altered by dl-Met. Increasing concentrations of dl-Met and HMB decreased cytosolic phosphoenolpyruvate carboxykinase (PCK1) expression, but did not alter the expression of mitochondrial phosphoenolpyruvate carboxykinase (PCK2) or pyruvate carboxylase (PC). Expression of glucose-6-phosphatase(G6PC) decreased linearly with increasing HMB concentration, but not altered by dl-Met. Neither dl-Met nor HMB altered the expression of carnitine palmitoyltransferase 1A(CPT1a). These findings demonstrate reduced necessity for Met regeneration with increased Met concentrations in the medium, regardless of the Met source. The lack of upregulation of gluconeogenesis indicates that increased dl-Met or HMB is not prioritized for glucose synthesis in primary bovine hepatocytes.