Effects of rumen-protected choline (RPC) supplementation to periparturient dairy cows did not depend upon prepartum energy intake

Abstract Text: Objectives were to evaluate the effect of prepartum energy intake on performance of dairy cows supplemented without or with RPC (0 or 60 g/d ReaShure, Balchem Corp., New Hampton, NY). At 48 days prior to calculated calving date, 93 multiparous Holstein cows were assigned to 1 of 4 treatments. Cows were fed prepartum high energy (HE; 1.63 Mcal NEL/kg DM; 58% corn silage) or controlled energy (CE; 1.40 Mcal NEL/kg DM; 43% wheat straw) diets in ad libitum amounts with or without RPC. The RPC was top-dressed daily from 21 days prepartum to 21 days postpartum. After calving, cows were fed the same diet balanced for methionine, apart from RPC supplementation, through 15 weeks. Liver tissue was collected for biopsy at -14, 7, 14, and 21 days relative to calving. Data were analyzed by ANOVA for repeated measures using the MIXED procedure of SAS. Cows fed the HE diet consumed energy at 24% above requirement whereas cows fed the CE-based diet consumed energy at 0.7% above requirement during the last 15 d prepartum. Cows fed RPC tended (P<0.10) to produce more milk (43.5 vs. 41.3 kg/d) and energy-corrected milk (44.2 vs. 42.0 kg/d) without increasing DM intake (23.7 vs. 23.2 kg/d) and tended to have greater mean body condition (3.32 vs. 3.24) during the first 15 wk postpartum. Over the first 40 weeks postpartum, feeding RPC in transition increased milk yield of cows (n=91) fed HE (37.4 vs. 33.4 kg/d) or CE diets (36.5 vs. 36.1 kg/d) prepartum (RPC by prepartum energy diet interaction, P=0.16). Cows fed the CE compared with the HE diet consumed more feed postpartum (24.0 vs. 22.9 kg/d, P<0.01) but did not produce more milk (43.1 vs. 41.6 kg/d). Thus, postpartum cows fed the CE diet prepartum were in less mean negative energy balance (P<0.05) and tended to have lower (P=0.10) mean NEFA and had lower (P<0.01) mean BHBA concentrations in plasma compared with cows fed HE diets prepartum. Mean postpartum concentration of liver triacylglycerol was greater (P<0.05) for cows fed the HE compared with the CE diet (10.7 vs. 8.3% DM) whereas RPC had no effect on hepatic triacylglycerol (Control=9.0 vs. RPC=9.9%DM). Compared with an HE diet, feeding a CE diet prepartum improved energy balance and DM intake postpartum. Feeding RPC during the transition period increased yield of milk for 40 weeks regardless of prepartum energy intake.

Keywords: choline, transition, wheat straw