EFFECT OF A HOT ENVIRONMENT ON PERFORMANCE, CARCASS CHARACTERISTICS, AND BLOOD HORMONES AND METABOLITES OF PIGS TREATED WITH PORCINE SOMATOTROPIN

A study was conducted to compare the effects of a single 100-mg recombinant porcine somatotropin (rpST) implant on performance, carcass characteristics, and blood hormones and metabolites of 40 finishing pigs exposed to either a thermoneutral (TN; 18 to 21-degrees-C) or hot environment (H; 27 to 35-degrees-C) for 28 or 35 d. Pigs in H gained at a slower rate (P < .01) than pigs in TN. Control and rpST-treated pigs gained at similar rates in respective environments. The rpST-treated pigs consumed 13% less feed (P < .01) than the control pigs in both environments, and pigs in H consumed 19% less feed (P < .01) than pigs in TN. Feed efficiency for rpST-treated pigs was 15% better (P < .01) than that for control pigs; environment had no effect on feed efficiency. When slaughtered, pigs treated with rpST had less (P < .01) leaf fat and less (P < .01) 10th rib backfat than control pigs. Pigs in H had a lower (P < .01) final BW and less leaf fat and backfat than pigs in TN. The rpST and H had various effects on blood hormones and metabolites. The results demonstrated that the benefits of this form of rpST treatment achieved under TN were also achieved in H with no interactions between the hormone and environment.