Production Responses of Dairy Cows Fed Various Amounts of Rumen-Protected Methionine and Lysine

Open Access
Publisher Website
Google Scholar
Abstract
A 3 .times. 3 factorial response surface design was used to study the effects of feeding rumen-protected methionine and lysine to dairy cows between 22 and 305 d of lactation. A total of 130 dairy cows at three universities were individually fed a corn silage and corn grain-based diet that contained either soybean meal or corn gluten meal and urea. An unsupplemented control diet plus nine treatment combinations of three amounts of rumen-protected DL-methionine (3.4, 7.8, and 12.2 g/d) and three amounts of rumen-protected L-lysine (5.9, 13.5, and 21.1 g/d) were fed at all locations. Plasma concentrations of methionine and lysine were increased when rumen-protected methionine and lysine were supplemented to the diets. Rumen-protected methionine and lysine did not affect feed intake by cows fed either the soybean meal or corn gluten meal and urea based diets. Milk protein percentage was increased, but milk and milk protein yields were not improved when diets containing soybean meal were supplemented with rumen-protected methionine and lysine. In contrast, milk and milk protein yields were improved when a diet that contained corn gluten meal and urea was supplemented with rumen-protected methionine and lysine. Health and reproduction measurements were similar for cows receiving all treatments.