Effects Of Feeding Rumen-Protected Choline (RPC) On Lactation And Metabolism
S. Lima*, and J. E. P. Santos, M. F. Sa Filho, L. F. Greco, F. Susca, V. J. A. Magalhaes, J. Garrett Veterinary Medicine Teaching and Research Center, University of California Davis, Tulare, Balchem Corporation, Animal Nutrition & Health, New Hampton, NY.
Objectives were to determine the effects of feeding RPC on lactation and metabolism in dairy cows. In Experiment 1 (E1), 369 cows were fed 15 g/d of PC (Reashure, Balchem) from 25 d prepartum to 80 d in milk (DIM). In E2, 578 primigravid cows were fed 15 g/d of RPC in the 21 d prepartum. Blood as sampled from 80 cows in E1 and 47 cows in E2, and analyzed for concentrations of nonesterified fatty acids (NEFA) and glucose at 1, 14 and 21 IM. Blood from all cows was analyzed for concentrations of 3-OH-butyrate (BHBA) at 1 and 14 DIM. Subclinical ketosis was considered when BHBA was greater than 1.0 mMol/L. Hepatic tissue from 46 cows in E1 sampled at 8 DIM was analyzed for concentrations glycogen and triglycerides. Body condition was scored at enrollment, 1, 30, 60, and 90 DIM in E1, and at enrollment and calving in E2. Monthly yields of milk and milk components in E1 and weekly yields of milk in E2 were measured for 90 DIM. Prepartum DM intake was similar (P>0.15) between treatments and averaged 12.5 and 10.5 kg/d for E1 and E2, respectively, but intake tended (P = 0.10) to be greater for cows fed RPC (23.9 vs 22.6 kg/d) in E1. In E1, yields (kg/d) of 3.5% FCM (44.6 vs 42.8), ECM (40.1 vs 38.5), and milk fat (1.61 vs 1.52) were greater (P<0.05), and of milk (43.1 vs 42.1) and true protein (1.21 vs 1.17) tended (P=0.08) to be greater for RPC than control. Energy output in milk was greater (P=0.03) for RPC than control (30.0 vs 28.8 Mcal/d), although milk NEL content was similar and averaged 0.70 Mcal/kg. In E2, milk yield tended (P=0.07) to be greater for RPC than control (28.7 vs 27.9 kg/d). Body condition was improved (P =0.01) postpartum for RPC in E1. Concentration of glucose tended to be greater (P=0.10) in E1 and of NEFA was smaller (P=0.05) at calving in E2 for RPC compared with control. Prevalence of subclinical ketosis tended (P=0.07) to be smaller at calving in all cows (28.5 vs 37.2%) and was smaller (P=0.05) in multiparous cows (22.1 vs 40.0%) fed RPC in E1, but did not differ between treatments in E2. Feeding RPC improved lactation and metabolism of dairy cows, but benefits were enhanced when it was fed prior to and after calving.
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