Lysine and methionine in dairy cows’ nutrition

Abstract

Abomasal infusion of lysine alone or lysine with methionine was investigated in lactating dairy cows to assess whether these amino acids were limiting to milk production. Two Israeli-Holstein cows cannulated in the duodenum were utilized in a double reversal experiment for a 72-day period. Cows were fed total mixed rations containing 25% silage and 75% concentrate on a dry matter (DM) basis, with 15% crude protein of which were com source. Cows were infused continuously over a 12-day period with 21/d water, a solution of 30 g/d lysine, or a solution of 30 g lysine plus 8 g/d methionine. Infusion of lysine to cows resulted in a daily increase of 7.4% in DM intake, 9.1 % in milk yield, 13.3% in milk protein yield, and a 3.55% decrease in milk fat yield compared to control. Cows infused with lysine and methionine had increases of 11.8% in milk yield, 6% in milk fat, and 12.5% in milk protein production. Addition of methionine to the lysine infusion resulted in a 6% increase in milk fat, but no increase in milk protein.