Feeding Rumen-Protected Choline To Transition Dairy Cows
Objectives were to determine the effects of feeding rumen-protected choline (RPC) on hepatic tissue composition and hepatic lipidosis in dairy cows. Holstein cows, 46, 20 multiparous and 26 primiparous, were fed either 0 (n = 25) or 60 g of RPC to deliver 15 g/d of choline (n = 21; Reashure, Balchem) top dressed onto the diet once daily from 25 d prepartum to 80 d in milk (DIM). Blood was sampled at 1 and 14 d postpartum and analyzed for concentrations of 3-OH-butyrate (BHBA). Hepatic tissue collected by percutaneous biopsy at 9 DIM was analyzed for concentrations glycogen, triglycerides and dry matter (DM). Cows were categorized as having hepatic lipidosis if hepatic triacylglycerol concentration was > 5% on a wet basis. Data were analyzed using the Mixed and Logistic procedures of SAS and odds ratios (OR) and 95% confidence intervals (CI) were calculated. Concentrations of BHBA were similar (P = 0.53) for cows fed control and RPC at d 1 (1012.7 ± 137.5 vs. 836.6 ± 143.4 mMol) and d 14 (927.0 ± 137.5 vs. 926.3 ± 143.3 mMol) postpartum. Concentration of glycogen in hepatic tissue was similar (P = 0.35) for cows fed control and RPC (0.94 ± 0.15 vs. 1.14 ± 0.16 %). Similarly, concentration of triglycerides in the hepatic tissue did not differ (P = 0.31) for cows in the control and RPC diets (5.9 ± 1.2 vs. 4.1 ± 1.3%); however, concentrations of triglycerides on a DM basis tended (P = 0.10) to be greater for control than RPC cows (10.4 ± 1.7 vs. 6.0 ± 1.9%). Feeding RPC reduced the risk (OR = 0.23; 95% CI = 0.05, 1.06) of cows to have hepatic lipidosis (40.0 vs. 14.3%; P = 0.05). Concentrations of glycogen in hepatic tissue declined as concentrations of triglycerides increased (glycogen % = 1.251 – 0.04451 × triglycerides%; r2 = 0.11, P = 0.01). Feeding rumen protected choline reduced triglyceride concentration in liver DM tissue and the risk of hepatic lipidosis in early lactation dairy cows.