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Evaluation of N-Hydroxymethyl-DL-Methionine-Ca and Di-Hydroxymethyl-L-Lysine-Ca in a Blended Corn Based Ration for Lactating Cows¹

Department of Animal Sciences, New Hampshire Agricultural Experiment Station, University of New Hampshire, Durham 03824

ABSTRACT

Five lactating cows were fed ad libitum a ration of 67% corn silage and 33% concentrate and 2.2 kg hay per head daily in a 5 X 5 Latin square to evaluate five treatments: 1) negative control, 2) 64 g/day di-hydroxymethyl-L-lysine-Ca, 3) 24 g/day N-hydroxymethyl-DL- methionine-Ca, 4) 64 g/day di-hydro-xymethyl-L-lysine-Ca and 24 g/day N-hydroxymethyl-DL-methionine-Ca, and 5) 638 g/day formaldehyde-treated sodium caseinate. Nitrogen supplements were blended with the corn silage and concentrate at time of feeding. Dry matter of the basal ration contained 11 to 12% crude protein. Mean daily milk yields were 27.4, 26.9, 26.1, 27.1, and 29.9 kg for the respective treatments. Yields of milk, milk protein, and milk fat and efficiency of feed conversion to 4% fat-corrected milk were greatest with formaldehyde-treated casein. Amino acid derivatives had no effect on feed intake, milk production, milk composition, or utilization of dietary nitrogen. Concenrations of methionine and lysine in plasma, relative to the other indispensable amino acids, were not different among treatments. We suggest that the low pH of the ration resulted in considerable dissociation of the derivatives prior to consumption.

¹ Scientific Contribution Number 1054 from the New Hampshire Agricultural Experiment Station.

² Department of Dairy Science, Virginia Polytechnic Institute and State University, Blacksburg 24061.