Productive, biochemical, behavioral, and feeding parameters of Holstein cows treated with two formulations of recombinant bovine somatotropin

Abstract

ABSTRACT This work aimed to compare the efficiency of two commercial recombinant bovine somatotropin (rbST) formulations on productive, metabolic, behavioral, and feeding parameters of mid-lactation Holstein cows. Eighteen secondiparous cows were randomly assigned to two groups to be treated with injectable rbST (rbST-Fast, Boostin ® , MSD Saúde Animal; and rbST-Slow, Lactotropin ® , Agener União Saúde Animal). Cows were rbST-treated during five cycles of 14 days each, totaling 70 days. Blood samples were collected thrice in each cycle to assess metabolic markers. Daily, automatic feeders and individual monitoring collars measured behavior and feed intake. Milk samples were collected weekly to evaluate milk composition and somatic cell count. The rbST-Fast group had higher milk production ( p = 0.03) and tended to present greater feed intake ( p = 0.07). In addition, animals treated with rbST-Fast had higher ( p < 0.01) concentrations of non-esterified fatty acids (NEFA) and tended ( p = 0.09) to have lower serum glucose values. As for the variation in body weight, cows treated with rbST-Fast lost approximately three times more weight ( p < 0.01) than rbST-Slow cows. Regarding milk components, cows from the rbST-Fast group produced milk with a higher lactose content ( p = 0.05). In conclusion, rbST-Fast treated cows produced more milk, had higher feed intake, and showed a higher degree of lipid mobilization, demonstrated through the higher body weight loss and higher NEFA concentrations.