supplemented with this hormone has been shown to increase milk yield and feed intake in crossbred dairy cow during early lactation. These effects of somatotropin in crossbred dairy goat, however, have been demonstrated only during late lactation. To investigate further that somatrotopin could produce the same effects during early lactation, the experiment was performed using crossbred lactating goats. One week after parturition, animals were randomly
divided into two groups (n=5). Recombinant bovine somatotropin (rbST, 250 mg suspended in 396 mg sesame oil for prolonged release action) or vehicle (396 mg sesame oil) was injected at day 7th and 22nd after parturition to each group of animals. After the first injection, supplementation with rbST did not increase milk yield significantly, however, milk yield from rbST supplementation group was significant higher than from control group after the second injection period (1.44 versus 1.22 kg/day). Based on the milk sample from day 30th-33rd after parturition (8 days after the second hormone supplementation), the compositions of milk did not difference between both groups. Although body weight of animals from each group was not different, rbST supplementation appeared to decrease dry matter intake per body weight (control versus rbST: 46.13 versus 42.34 and 46.56 versus 41.49 g/kg BW, respectively) and then increased feed efficiency for milk in both injection periods (control versus rbST: 0.98 versus 1.10 and 0.93 versus 1.21 kg of milk/kg DMI, respectively). In addition, administration with rbST enhanced the plasma glucose concentration in comparison with the control group. Our current data indicated that rbST increased feed efficiency for milk in dairy goat during early lactation period. Interestingly, an increased feed efficiency appears to come mainly from the reduction in dry matter intake.