Supplemental rumen-protected choline and methionine for lactating dairy cows
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Series/Report no.:CFAES Undergraduate Research Forum, 2006
The purpose of the experiment was to determine the effects of supplemental rumen-protected choline [ReashureÂ® (REA)] and rumen protected methionine (Smartamine MTM). Analyses were performed to measure both milk and plasma choline, nonesterified fatty acids (NEFA) and plasma glucose and milk samples were sent out to be analyzed for milk fat, milk protein and milk urea nitrogen (MUN). 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, Adisseo, Antony Cedex, France; lys:met 3.0; MET). The diets were fed as a 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. 31 Holstein and 17 Jersey (48 total) completed the trial. Upon analysis, DMI (20.6 kg/d), milk yield (36.5 kg/d), milk fat (4.35%) and milk protein (3.14%) were found to be the same between all 4 diets. 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 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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