Effect of cysteamine hydrochloride supplementation on the milk performance of dairy cow

•Level of plasma somatostation was reduced and growth hormone was enhanced by CSH.•Milk yield increased when the supplementation was increased to 30 and 45 g/d.•Milk protein content was increased by 8.2% for the CSH supplemented groups.•Supplementation of CSH at 30 g/d increased milk production of dairy cows.

Cysteamine (CS) can increase serum growth hormone concentrations and the growth performance of broiler, sheep, and pigs. However, information of CS supplementation on the milk performance of dairy cows is limited. An experiment was conducted to investigate the effect of dietary cysteamine hydrochloride (CSH) supplementation on lactation performance of dairy cows. Forty-eight multiparous mid-lactation Holsteins were fed a control diet or supplemented with 15, 30, or 45 g/d CSH preparation (cysteamine HCl 20%) for 63 d, including 7 d for adaptation. The base diet was formulated to meet the nutrient requirements of lactating dairy cows according to the Chinese feeding standard (China Standard NY/T 34,Feeding standard of dairy cattle 2004 Issued by Ministry of Agriculture of People's Republic of ChinaBeijing) and the DMI, milk yield, milk composition, and plasma parameters were measured. Milk yield was 7.1% and 6.3% higher for the two higher supplementation amounts (SEM=0.50, P<0.05), and milk protein content was 7.7%, 8.7%, and 8.1% higher for the three supplemented groups (SEM=0.077, P<0.05), respectively, than the control. Plasma urea N were lower for the 30 and 45 g/d CSH groups than for the control. Level of plasma somatostation was reduced and plasma growth hormone was enhanced in CSH groups compared with that of control (P<0.01). Supplementation of CSH preparation at 30 g/d increased milk production of dairy cows while 15 g/d has no positive effect on milk yield or milk efficiency.