Choline supply during negative nutrient balance alters hepatic cystathionine β-synthase, intermediates of the methionine cycle and transsulfuration pathway, and liver function in Holstein cows

Abstract

Although choline requirements for cows are unknown, enhanced postruminal supply may decrease liver triacylglycerol and increase flux through the Met cycle to improve immunometabolic status during a negative nutrient balance (NNB). Our objectives were to investigate the effects of postruminal choline supply during a feed restriction-induced NNB on (1) hepatic activity cystathionine β-synthase and transcription of enzymes in the transsulfuration pathway and Met cycle; (2) hepatic metabolites in the Met cycle and the transsulfuration pathway, bile acids, and energy metabolism; and 3) plasma biomarkers of liver function, inflammation, and oxidative stress. Ten primiparous rumencannulated Holstein cows (158 ± 24 d postpartum) were used in a replicated 5 × 5 Latin square design with 4-d treatment periods and 10 d of recovery (14 d/period). Treatments were unrestricted intake with abomasal infusion of water, restricted intake (R; 60% of net energy for lactation requirements) with abomasal infusion of water, or R plus abomasal infusion of 6.25, 12.5, or 25 g/d choline ion. Liver tissue was collected on d 5 after infusions ended, and blood was collected on d 1, 3, and 5. Statistical contrasts were A0 versus R0 (CONT1), R versus the average of choline doses (CONT2), and tests of linear and quadratic effects of choline dose. Activity of cystathionine β-synthase was lower with R (CONT1) and decreased linearly with choline. Hepatic glutathione was not different with R or choline, but taurine tended to be greater with choline (CONT2). Betaine and carnitine were greater with R (CONT1) and further increased with choline (CONT2). Concentrations of NAD + were greater with choline (CONT2). Cholic and glycol-chenodeoxycholic acids were decreased by R and choline, while taurocholic and tauro-chenodeoxycholic acids were not altered. Plasma aspartate aminotransferase and bilirubin were greater with R (CONT1) but decreased with choline (CONT2). Paraoxonase was lower with R and increased with choline (CONT2). Data suggest that enhanced supply of choline during NNB decreases entry of homocysteine to the transsulfuration pathway, potentially favoring remethylation to Met by acquiring a methyl group from betaine. As such, Met may provide methyl groups for synthesis of carnitine. Along with production data indicating that 12.5 g/d choline ion improved milk yield and liver fatty acid metabolism during NNB, the changes in blood biomarkers also suggest a beneficial effect of choline supply on liver function and oxidative stress.

Hepatic betaine-homocysteine methyltransferase and methionine synthase activity and intermediates of the methionine cycle are altered by choline supply during negative energy balance in Holstein cows

“…Postruminal delivery of choline was previously observed to increase the concentration of Bet in milk (de Veth et al, 2016) suggesting that Bet concentrations in milk likely increased in the present study as well. The fact that we detected a linear increase in hepatic Bet concentration with increasing choline supply (reported in a companion paper; Coleman et al, 2019) supports the idea that Bet production was increased with enhanced postruminal choline supply. Hence, an increase in Bet may have led to an increase in milk yield through its function as an osmolyte, pulling water to the mammary gland.…”

Role of nutraceuticals during the transition period of dairy cows: a review

“…For instance, the function of choline as a lipotropic agent can have positive effects on butterfat production, as it improves lipid metabolism, increasing the VLDL synthesis, availability of FA for the mammary gland, and its incorporation into phospholipid membranes around fat globules. The composition of milk fatty acids can be influenced by the increased availability of preformed fatty acids via VLDL, as well as the milk protein yield, mainly because choline serves as methyl source sparing methionine [85]. The main effects of RPC supplementation are indeed on liver function (Table 4), reducing fat deposition in the liver.…”

Hepatic one-carbon metabolism enzyme activities and intermediate metabolites are altered by prepartum body condition score and plane of nutrition in grazing Holstein dairy cows

“…The onset of lactation in dairy cows is characterized by well-known physiologic challenges including negative energy balance (NEB), inflammatory environment, and overproduction of reactive oxygen species (ROS), which leads to oxidative stress (Loor et al, 2013a,b). The latter in particular has been identified as an underlying factor of dysfunctional inflammatory responses (Abuelo et al, 2015), underscoring the importance of the transsulfuration pathway in keeping an adequate supply of antioxidants (Coleman et al, 2019;Vailati-Riboni et al, 2019).…”