Abstract
Colostrum is a critical nutrient source that provides passive immunity to dairy calves. Choline is a trimethylated molecule that is frequently supplemented in the diet to periparturient dairy cows to support postpartum health and performance. Whereas choline and its metabolites have been characterized in milk, the effects of dietary rumen-protected choline (RPC) supplementation on choline metabolites in colostrum from dairy cattle have yet to be explored. Therefore, the objective of the present study was to assess the effects of dietary supplementation and dose of RPC on colostrum yields, quality, and choline metabolites. Parous Holstein cows were blocked by calving month and randomly assigned within block to receive 45 g/d (20.4 g/d of choline ions) of RPC (CHOL45, n = 22), 30 g/d (13.6 g/d of choline ions) of RPC (CHOL30, n = 20), or no RPC (control, n = 19) starting 24 d before expected calving. The effects of dietary supplementation and dose of RPC were assessed on colostrum yields, component yields, somatic cell score (SCS), quality (as assessed by Brix), and choline metabolites. Data were analyzed using a linear mixed model with the fixed effects of treatment, parity, and the 2-way interaction and the random effect of block. Regardless of dose, dietary RPC supplementation increased colostrum yields and protein yields. No effects of dietary RPC supplementation were found on colostrum component percentages, SCS, or colostrum quality. For choline metabolites, treatment interacted with parity for phosphocholine where colostrum from second-parity CHOL45 and CHOL30 cows had greater concentrations of phosphocholine than colostrum from second-parity control cows, but no treatment effect was seen in the colostrum from 3+ parity cows. Dietary choline supplementation, regardless of dose, increased trimethylamine N-oxide concentrations. Dietary choline supplementation did not affect the concentrations of choline, betaine, glycerophosphocholine, sphingomyelin, phosphatidylcholine, or total choline in colostrum. In conclusion, dietary choline supplementation increased phosphocholine concentrations in colostrum from second-parity cows, enhanced trimethylamine N-oxide concentrations, and increased colostrum yields without affecting colostrum quality.