|Buonomo F C, - MONSANTO AGRICULTURAL CO.|
|Yen J T,|
Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 7, 1994
Publication Date: N/A
Interpretive Summary: Administration of porcine somatotropin (pST) by a sustained release implant which effectively delivers PST for 6 wks without large daily fluctuations in circulating PST has been shown to be effective in promoting rate and efficiency of lean growth in gilts and barrows. The present study examined the growth, carcass, and sensory quality responses of a boars and gilts of a commercial type crossbred line and genetically lean and obese lines, pigs with very different growth characteristics and endogenous endocrine milieu, to the sustained release form of pST administration. Administration of pST via the implant resulted in decreased feed intake, increased rate and efficiency of gain and decreased deposition of backfat during each of the three two-week periods of the trial indicating the pigs did not become refractive or resistant to the growth promoting actions of pST. At slaughter carcass composition of the pST implant pigs was improved. Quantity of trimmed primal cuts produced by obese and crossbred gilts and boars, given 4 mg pST/d, was increased 10% or more. Loin chops were submitted to a sensory panel. No influence of pST treatment was detected in the traits of juiciness, pork flavor or off flavors. A minor influence on tenderness was measured in chops from obese pigs. The sensory panel detected a reduction in boar taint; i.e., chops became more acceptable, with pST treatment. Thus, treatment of pigs increased the efficiency of lean pork produced and had no or little influence on quality of the product in gilts. In boars the quality of the product was increased due to reduced boar taint in the product.
Technical Abstract: Previous studies have documented the efficacy of porcine somatotropin administered by sustained-release implant (pST-SR) in promoting rate and efficiency of lean growth in genetically lean and obese barrows and gilts. Studies have been extended to include contemporary crossbred boars and gilts. The study consisted of 18 treatment groups of three lines, two sexes, and three doses of pST; 10 Xbred and obese boars and gilts assigned per dose, 10 lean gilts assigned per dose and 6 lean boars assigned per dose. Pigs were implanted at 55.2 +/- .3 kg BW. Pigs received no implant, or one or two implants designed to deliver 2 mg pST/d (i.e., doses of 0,2 or 4 mg pST/d). At 14-d intervals feed consumption, BW and backfat were recorded. At the end of the 42-d trial the pigs were slaughtered and offal components weighed and carcasses were dissected into untrimmed and trimmed wholesale cuts. Loin chops were collected for evaluation of sensory attributes, including boar taint. Each 14-d period of the trial feed consumption was reduced, gains were unchanged or greater, and efficiency of live weight gain was increased. At slaughter, weights of the organs were increased and the weight of the trimmed primal cuts was increased in all line x sex groups with increasing dose of pST-SR. Treatment with pST-SR had no effect on juiciness, tenderness, pork flavor and off-flavors. The panel detected a reduction in boar taint in meat from boars. Administration of pST-SR, improved efficiency and quantity of pork produced by both boars and gilts of genotypes representing a diverse range of lean growth potential. In addition, pST-SR improved the acceptability of meat from boars.