Milk Production and Composition in Cows and Goats Fed α-Ketoisocaproate

To examine whether alpha-ketoisocaproate supplementation affects milk production, 10 goats were fed either 0 or 1.1% calcium-alpha-ketoisocaproate for 2 wk and 12 cows were fed either 0 or .75% Na alpha-ketoisocaproate for 3 wk. Supplementation with alpha-ketoisocaproate increased milk fat content, milk fat yield, and 4% FCM yield in cows by an average of 5, 10, and 8%, respectively, for the treatment period. In cows, response of milk fat yield to alpha-ketoisocaproate was 120 g during wk 1 of treatment but diminished to 55 g by wk 3. Milk yield and milk protein yield tended to be greater in cows fed alpha-ketoisocaproate, but milk production efficiency and body weight were not altered by treatment in either species. Supplementation with alpha-ketoisocaproate had no significant effect on fatty acid composition of milk but tended to increase the percentage of C10 and C12 fatty acids. In goats, supplementation with alpha-ketoisocaproate had no significant effect on milk production or composition, but trends toward increased milk fat and protein content were observed. Results indicate that alpha-ketoisocaproate acutely stimulates milk fat production in lactating cows and that this effect seems to diminish with time.