Abstract #453

# 453
Supplementation of rumen-protected choline (RPC) to periparturient dairy cows improved cow and calf performance.
M. G. Zenobi*1, R. Gardinal1, B. A. Barton2, J. E. P. Santos1, C. R. Staples1, 1University of Florida, Gainesville, FL, 2Balchem Corp, New Hampton, NY.

Choline is a vitamin-like nutrient and a methyl donor involved in many physiological processes. Objective was to evaluate the effect of RPC supplementation (0 or 60 g/d of ReaShure, Balchem Corp., New Hampton, NY) during the periparturient period to multiparous Holstein cows consuming prepartum energy in either maintenance or excess amounts on performance. The RPC was top-dressed on TMR daily from −21 to 21 d postpartum (PP). Cows were fed prepartum high energy (1.63 Mcal NEL/kg DM; 58% corn silage) or controlled energy (1.40 Mcal NEL/kg DM; 37.5% wheat straw) diets in ad libitum amounts with or without RPC (n = 21–25 per diet). After calving, cows were fed a common diet (1.68 Mcal NEL/kg) balanced for methionine, apart from RPC supplementation, through 15 wk PP. Thereafter, experimental cows returned to the herd and milk yield measured daily through 40 wk PP. Data were analyzed by ANOVA for repeated measures using the MIXED procedure of SAS. Significance was declared at P < 0.05. Effects of RPC were independent of prepartum energy intake. Cows fed RPC tended (P < 0.10) to produce more milk during the first 15 wk PP (43.5 vs. 41.3 kg/d) and throughout the first 40 wk (37.1 vs. 35.0 kg/d). Cows consuming RPC were in a more negative energy balance at 2 and 3 wk PP without greater mean concentration of plasma NEFA or BHBA (0, 1, 2, 3, and 5 wk PP) or of liver triacylglycerol (1, 2, and 3 wk PP). Incidence of subclinical hypocalcemia (<8.5 mg of Ca/dL plasma) was reduced from 52.1 to 31.6% during the first 7 d PP by RPC supplementation. Rectal temperature, taken at 4, 7, and 12 d PP, increased linearly by 0.18°C for control cows but decreased linearly by 0.29°C for cows fed RPC. Yield of colostrum was not changed (9.9 vs. 8.5 kg) but concentration of IgG was improved by RPC (78.9 vs. 58.3 g/L for RPC and controls, respectively). Heifers born from dams fed RPC had better ADG (0.89 vs. 0.85 kg/d) from 2 to 12 mo of age. Pregnancy at first timed AI tended to be improved (41.3 vs. 23.6%; P < 0.10) but did not differ by 40 wk PP (69.8 vs. 62.5%). Supplementing RPC for 6 wk during transition had long-term benefits to Holstein cows and calves.

Key Words: choline, transition