The performance and carcass composition responses of fishing swine to a range of porcine somatotropin doses in a 1-week delivery system

• Published in: Journal of animal science Vol. 69; no. 12
• Main Authors: Knight, C.D. (NOVUS International, Inc., St. Louis, MO), Kasser, T.R, Swenson, G.H, Hintz, R.L, Azain, M.J, Bates, R.O, Cline, T.R, Crenshaw, J.D, Cromwell, G.L, Hedrick, H.B
• Format: Journal Article
• Language: English
• Published: 01-12-1991
• Subjects: CARNE DE CERDO; CERDO; COMPOSICION DE LA CANAL; COMPOSITION DE LA CARCASSE; EFFICACITE ALIMENTAIRE; EFICIENCIA DE CONVERSION DEL PIENSO; GAIN DE POIDS; GANANCIA DE PESO; HORMONAS PITUITARIAS; HORMONE HYPOPHYSAIRE; INGESTION DE ALIMENTOS; PORCIN; PRISE ALIMENTAIRE; PROTEINAS; PROTEINE; RESISTANCE MECANIQUE; RESISTENCIA MECANICA; SEXE; SEXO; VIANDE PORCINE
• ISSN: 0021-8812; 1525-3163

Four experiments using 580 barrows and 580 gilts (Study 1) and seven experiments using 500 barrows and 500 gilts (Study 2) were conducted at various geographical locations in the United States to determine the dose response of a pelleted form of porcine somatotropin (pST) relative to ADG, feed/gain (F/G), and percentage of carcass protein. Average initial weights for Studies 1 and 2 were 67.6 and 72.6 kg, respectively, and four pigs/pen were slaughtered when they achieved weights of 106.5 to 111.0 kg. In Study 1, pigs were implanted subcutaneously with pelleted pST doses of 0, 12, 24, 36, or 48 mg/wk and self-fed a corn-soybean meal diet containing 13.75% CP. Study 2 included two control groups self-fed a diet containing either 13.75 or 17% CP with added lysine. The pST-treated pigs were administered 12, 24, or 36 mg/wk, and all were offered the 17% CP diet. The pST treatments in Study 1 resulted in a linear reduction (P 0.05) in average daily feed intake (ADFI) and a quadratic (P 0.05) improvement in F/G and percentage of carcass protein. The pST treatments in Study 2 resulted in a linear reduction in ADFI (P 0.05), a linear improvement in F/G, and a quadratic increase in the percentage of carcass protein (P 0.05). Average daily gain was not affected in either study with this form of pST. The greatest increase in efficiency of lean gain was observed with the 36-mg dose for both Study 1 (9.4%) and Study 2 (10.8%). In Study 1, the force required to shear cores of the longissimus muscle was increased linearly with pST treatment (P 0.05). There was a similar linear increase in Study 2 with pST treatment (P 0.05); however, there was also an effect of sex (P 0.05) on shear force (gilts barrows) that was similar in magnitude to that observed for pST treatment. Differences in sensory evaluation because of pST were minor and of the same magnitude as those observed between barrows and gilts. It was therefore concluded that weekly administration of pST improved F/G and percentage of carcass protein with no detrimental effects on palatability of cooked lean pork