EFFECTS OF A PORCINE SOMATOTROPIN IMPLANT ON TISSUE MINERAL STATUS OFFINISHING PIGS EXPOSED TO A THERMONEUTRAL OR COLD ENVIRONMENT

An experiment was conducted with 24 crossbred (Landrace x Yorkshire x Duroc) finishing pigs (mean BW 85 kg) to study the effects of a single 100-mg recombinant porcine somatotropin (rpST) implant on the tissue mineral status of pigs exposed to either a thermoneutral (TN; 18 to 21 -degrees-C, 50 to 55% RH) or cold (C; 5 to 15-degrees-C, 50 to 70% RH) environment until BW averaged 110 kg. The implants used in this study delivered an average 2.4 to 2.5 mg of rpST/d during the course of the study. Control pigs were implanted with a placebo. All diets were sup plemented with minerals at levels that either met or exceeded the requ irements of an 85-kg pig. At slaughter (mean BW 110 kg), tissues were collected and analyzed for selected macro- and microminerals. Pigs tre ated with rpST had higher (P < .05) Ca concentrations and total Ca in liver and kidney and higher (P < .05) Ca concentrations in muscle. Tot al P, Mg, Na, and K were all higher (P < .05) in the liver and kidneys of rpST-treated pigs. In general, rpST had little influence on Cu, Zn , and Fe in tissues. No consistent trend was evident in the response o f tissue minerals to environmental temperature. Results indicated that pigs treated with rpST and supplemented with adequate minerals accumu lated more minerals in certain tissues than did pigs not given rpST.