The Effect of Exogenous Somatotropin on Lactation Performance of First-Litter Sows

Abstract

To determine the effect of exogenous porcine somatotropin (ST) on lactation performance of sows, 24 first-litter sows were injected daily at 0800 with either 10 mg of recombinant ST or an equivalent volume of buffer between d 8 and 39 of lactation. Litter size was standardized to six (n = 2), seven (n = 8), eight (n = 6), or 10 (n = 8) pigs within each pair of sows by fostering pigs within a few days after parturition. Milk yield and composition of sows given ST was similar at all stages of lactation to that of control sows. Combining treatment data revealed that the milk yield of sows was related linearly (P < .01) to litter size and was described with the following equation: MY = 1.03 (±.7..