Ruminant Nutrition: Gut Physiology, Fermentation, and Digestion

摘要

Objectives were to determine the effects of rumen-protected choline(RPC) on hepatic composition and plasma metabolites in cows inducedto develop fatty liver. The hypothesis was that RPC would reduce triacylglycerol(TAG) and increase glycogen contents in liver. Pregnant,nonlactating parous Holstein cows (n = 110) were blocked by BCS (4.02± 0.5) at 232 d of gestation and assigned randomly (22/treatment) to receivecholine chloride (CC) supplemented as RPC with either a low (L,28.8% CC) or high concentration (H, 60.0% CC) in the RPC product.The amounts supplemented were 0 (CON), 12.9, or 25.8 g/d of cholineion resulting in 5 treatments, CON, L12.9, L25.8, H12.9, and H25.8 fedfor 14 d. Cows were fed for ad libitum intake on d 1 to 5, and restrictedto 50% of the NEL required from d 6 to 14. Intake of metabolizable methioninewas maintained at 20 g/d for the 14 d. Liver was sampled on d 6and 13 and analyzed for TAG and glycogen. Blood was sampled throughoutthe experiment. Data were analyzed by ANOVA with mixed modelsusing the MIXED procedure of SAS. Contrasts included the effects ofcholine (CON vs. L12.9+L25.8+H12.9+H25.8), source (L12.9+L25.8vs. H12.9+H25.8), amount (L12.9+H12.9 vs. L25.8+H25.8), or the interaction(L12.9+H25.8 vs. L25.8+H12.9). Supplementing RPC reducedhepatic TAG and increased glycogen contents without affecting plasmaconcentrations of NEFA or BHB (Table 1). Increasing the dose of cholineion from 12.9 to 25.8 g/d further reduced TAG and increased glycogencontents. Choline improved hepatic composition of cows in negativenutrient balance independent of changes in plasma metabolites.