Effect of protected methionine supplementation on milk production and reproduction in first calf heifers

Abstract. Sixty Holstein heifers (30 days in milk) were used to examine the effects of protected methionine on milk production, milk composition and reproduction performance up to 100 days post-partum. Heifers were randomly divided into two dietary treatment groups (30 each) receiving either 14 or 16 % crude protein. Heifers of each treatment group were assigned into three subgroups with a daily supplementation of 0, 15 or 25 g/hd/d of rumen protected methionine. Diet fed was a total mixed ration consisting of fresh alfalfa, corn silage and a concentrate mixture. In addition, alfalfa hay was offered ad libitum during the whole experimental period.