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

Abstract

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 β-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.

Immune cells phenotype and bioenergetic measures in CD4+ T cells differ between high and low feed efficient dairy cows

“…When these cells encounter pathogens or microbial components like lipopolysaccharide, the upregulation of CD14 + cells can lead to enhanced phagocytosis, cytokine production, and activation of these myeloid cells as part of the innate immune response 19 . Even though all mid-lactating cows were healthy in this study, an increased expression of T cells, B cells, or monocytes suggest a state of activation and readiness for migration to infected tissues, which plays a crucial role in mounting effective immune responses against pathogens or antigens, and these findings are aligned to gene expression data of Caputo et al 15 . Studies conducted on low and high RFI pigs showed no discernible difference in immune response when exposed to a viral challenge 20 .…”

“…In a previous study conducted in our laboratory, healthy mid-lactating cows were categorized based on RFI into HE (low RFI = − 1.73 kg/d) or LE (high RFI = + 1.72 kg/d), and RNA seq results indicated that the molecular control of gene expression in liver and muscle tissue were associated with immune function, and differed according to RFI ranking 15 . It was observed that several highly expressed genes involved in the activation of the innate and adaptive immune response were upregulated in HE cows ( LYZ , AOAH , CLEC7A , GIMAP8 , GIMAP6 , MARCO , and CD180 ) compared to LE cows 15 . In the present study, the increased expression of CD14 + cells were observed within CD11b + monocytes in HE cows compared to LE cows.…”

“…Considering the substantial glucose utilization by immune cells during an immune response, it is possible that cows with different feed efficient status could partition nutrients differently, ultimately influencing feed efficiency and RFI. Preliminary evidence indicated that HE mid-lactating cows showed an increased expression of genes associated with both innate and adaptive immune responses in liver and muscle tissues compared to least feed efficient (LE) cows based on RNA sequencing analysis 15 . This work proposed that HE cows might exhibit a phenomenon of immune readiness even in the healthy state; however, the activity of immune cells in high and low RFI cows and how it potentially contributes to energy sinks and feed efficiency were not directly evaluated in that study, warranting further investigation 15 .…”

“…Preliminary evidence indicated that HE mid-lactating cows showed an increased expression of genes associated with both innate and adaptive immune responses in liver and muscle tissues compared to least feed efficient (LE) cows based on RNA sequencing analysis 15 . This work proposed that HE cows might exhibit a phenomenon of immune readiness even in the healthy state; however, the activity of immune cells in high and low RFI cows and how it potentially contributes to energy sinks and feed efficiency were not directly evaluated in that study, warranting further investigation 15 . Ferronato et al 16 investigated the relationship between divergent RFI and immunometabolism in healthy Italian Simmental calves and demonstrated that HE calves had reduced blood markers related to oxidative stress and systemic inflammation compared to LE calves, supporting that the immune system might be a potential component to explain variability in feed efficiency in dairy cows.…”

Behavioral consistency of competitive behaviors and feeding patterns in lactating dairy cows across stocking densities at the feed bunk

“…Individual TMR ingredients were collected weekly and dried by forced air oven (Isotemp Oven, Fisher Scientific, Waltham, MA) at 55°C for 48 h (concentrates in triplicate, forages in quadruplicate), composited by week and analyzed by a commercial laboratory (Dairyland Labs, Inc., Arcadia, WI) as described previously ( 20 ). In brief, samples were analyzed for DM determined by National Forage Testing Association method 2.1.4, crude protein (method 990.03), neutral detergent fiber (method 2002.04), acid detergent fiber (method 973.18), lignin (method 973.18), ether extract (method 920.39), ash (method 942.05), water-soluble carbohydrates, and starch.…”