Supplemental Rumen-Protected Choline and Methionine for Lactating Dairy Cows
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Publisher:The Ohio State University
Series/Report no.:The Ohio State University. Department of Animal Sciences Honors Theses; 2006
The purpose of the experiment was to determine the effects of supplemental rumen-protected choline [Reashure® (REA)] and rumen protected methionine (Smartamine MTM) on the metabolism and performance of lactating dairy cows. Analyses were performed to measure both milk and plasma choline and nonesterified fatty acids (NEFA) and glucose in plasma. Milk samples were analyzed for fat, protein and urea nitrogen (MUN). The 56 lactating dairy cows were fed one of 4 diets at parturition: 1) control (duodenal flow of lysine:methionine (lys:met) 3.8; NRC, 2001), 2) 0.26% rumen protected choline (RPC) (REA fed at 60 g/d to provide 15 g/d of choline; lys:met 3.8; REA-L), 3) 0.52% RPC (REA fed at 120 g/d to provide 30 g/d of choline; lys:met 3.8; REA-H), or 4) 0.096% rumen protected methionine (Smartamine MTM; lys:met 3.0; MET). The diets were fed as a total mixed ration (TMR) for 13 weeks and were composed of 52% forage (76% corn silage and 24% alfalfa hay), 9% whole linted cottonseed, and 39% concentrates. The diets were 16.8% crude protein, 39.2% NDF, and 20% forage NDF. Thirty-one Holstein and 17 Jersey (48 total) cows completed the trial. Upon analysis, dry matter intake (DMI) (20.6 kg/day), milk yield (36.5 kg/day), milk fat (4.35%), and milk protein (3.14%) were found to be the same among all 4 diets. The MUN was the highest for REA-H (19.1 mg/dl) and intermediate for MET (18.1 mg/dl). Milk choline showed a significant increase for MET, but plasma choline and non-esterified fatty acids (NEFA) were not different for the diets. Plasma glucose was higher for both the control and MET diets than for either REA diet. Plasma methionine was significantly higher for the MET diet than for other diets. Milk choline was a better indicator for choline status than was plasma choline, and cows on the MET diet showed a higher milk choline concentration than did those on the RPC diet.
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