Effects of Rumen Protected Methionine on Milk Yield and Milk Composition in Earlier Lactating Cow

A total of 12 mature healthy Holstein dairy cows of the nearly body weight (580±30) kg, milk yield (22.5±2.8) kg in the early stages of lactation were selected in this experiment. The cows were randomly divided into 2 groups, every group had 6 cows, every group had 6 repeats, and every repeat had I cow. Added 20 g protected methionine in earlier lactating cow food every day. The results showed that protected methionine increased milk yield by 10.83%, testing group milk yield was significantly different than that of control (P＜0.05);protected methionine increased milk fat by 5.98%, testing group milk fat was significantly different than that of control (P＜0.05);Milk protein increased by 2.15%, but had insignificantly different (P＞0.05);dry matter of milk had the tendency of decrease, but had insignificant difference (P＞0.05).