Evaluation of dietary betaine in lactating Holstein cows subjected to heat stress

Abstract

Betaine (BET), a natural, organic osmolyte, improves cellular efficiency by acting as a chaperone, refolding denatured proteins. To test if dietary BET reduced the effect of heat stress (HS) in lactating dairy cows, multiparous, lactating Holstein cows (n = 24) were blocked by days in milk (101.4 ± 8.6 d) and randomly assigned to 1 of 3 daily intakes of dietary BET: the control (CON) group received no BET, mid intake (MID) received 57 mg of BET/kg of body weight, and high dose (HI) received 114 mg of BET/kg of body weight. Cows were fed twice daily and BET was top-dressed at each feeding. Cows were milked 2 times/d and milk samples were taken daily for analysis. Milk components, yield, feed ..