Influence of porcine somatotropin on the phosphorus requirement of finishing pigs: II. Carcass characteristics, tissue accretion rates, and chemical composition of the ham.
We investigated the effects of recombinant porcine somatotropin (pST) on the requirement for P to maximize lean tissue accretion and to minimize fat tissue accretion in two experiments using finishing pigs. Corn-soybean meal diets with varying levels of P were fed, and Ca was adjusted to maintain a Ca:P ratio of 1.1:1. In Exp. 1, 96 pigs were fed dietary P concentrations of .35, .45, and .65% from 75 to 109 kg BW. One-half of the pigs were injected daily with 4 mg of pST. Administration of pST increased (P < .05) percentages and accretion rates of lean tissue, bone, skin, water, and protein, but it reduced (P < .05) those of fat tissue and lipid. Increasing dietary P had little effect on chemical composition or accretion rates in untreated pigs, but it increased (P < .05) ash percentage and accretion in pigs treated with pST. Experiment 2 consisted of 66 pigs fed six dietary P concentrations (.35, .50, .65, .80, .95, and 1.10%) from 72 to 114 kg. One-half of the pigs were injected daily with 4 mg of pST. Percentages and accretion rates of lean tissue, bone, skin, water, and protein increased (P < .05) with pST, but those of fat tissue and lipid were reduced (P < .05). Increasing dietary P increased accretion rates of bone and skin (linear, P < .05), lean tissue, water, protein, and ash (quadratic, P <.05), and it reduced (quadratic, P < .05) that of lipid in pigs treated with pST. Dietary P level did not consistently affect percentages or accretion rates of tissues or chemical components in untreated pigs. In most instances, pigs treated with pST required higher dietary P levels and greater daily intakes of P to maximize lean tissue and protein deposition and to minimize fat tissue and lipid accretion than untreated pigs. These results indicate that finishing pigs treated with pST require higher dietary percentages of P to maximize carcass lean deposition as compared with untreated pigs.
Carter
S D
SD
Department of Animal Sciences, University of Kentucky, Lexington 40546, USA.
Cromwell
G L
GL
D000821:Animal Feed; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001823:Body Composition / Q000187:drug effects / Q000502:physiology*; D002118:Calcium; D005527:Food, Fortified; D013006:Growth Hormone / Q000494:pharmacology*; D008460:Meat / Q000032:analysis*; D009751:Nutritional Requirements; D010758:Phosphorus; D011994:Recombinant Proteins / Q000494:pharmacology; D013025:Glycine max; D013552:Swine / Q000254:growth & development*; D003313:Zea mays
D011994:Recombinant Proteins; D010758:Phosphorus; D013006:Growth Hormone; D002118:Calcium