Performance, carcass composition, and blood hormones and metabolites of finishing pigs treated with porcine somatotropin in hot and cold environments
1993
Becker, B.A. | Knight, C.D. | Veenhuizen, J.J. | Jesse, G.W. | Hedrick, H.B. | Baile, C.A.
Two experiments were conducted to assess the ability for recombinant porcine somatotropin (rpST)-treated pigs to perform and cope with the demands of hot and cold environments. In the first experiment, finishing pigs were exposed to either a thermoneutral (TN; 18 to 21 degrees C) or a hot environment (H; 27 to 35 degrees C) for 35 d. In the second experiment, pigs were exposed to a TN or cold environment (C; 5 to 15 degrees C). The rpST delivered by a 6-wk prolonged-release system had no effect on ADG, whereas both H and C reduced ADG by 29.4 and 11.8%, respectively. In the first experiment, rpST-treated pigs consumed 17.6% less feed than control pigs, whereas rpST-treated pigs in H consumed 24.4% less feed than rpST-treated pigs in TN. Overall feed/ gain ratios through the first 4 wk of both studies were improved by 21.8 and 14%, respectively, by rpST (P < .05) and were 24.3% poorer in C (P <.05) than in H. The changes in blood concentrations of pST, IGF-I, and IGF-II associated with rpST were not influenced by the different environments. Total body composition of rpST-treated pigs had increased amounts of protein (P < .05) and decreased amounts of fat (P < .05); H further reduced fat (P < .05). The C resulted in reduced protein content (P < .05). No evidence of thermal imbalance due to rpST was found as assessed by rectal temperature, respiration rate, and heat production estimated by indirect calorimetry and chemical analysis.
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