title: Administration of porcine somatotropin by sustained-release implant: growth factor and metabolic responses in crossbred white and genetically lean and obese boars and gilts.
abstract: Differences in endocrine and metabolic responses to porcine somatotropin administered by daily injection or sustained-release implant (pST-SR) have been previously observed in genetically lean and obese, gilts and barrows. The current study extended those findings by examining responses to pST-SR in gilts and boars of a contemporary crossbred line, as well as lean and obese lines. Pigs were treated with 0, 1, or 2 pST-SR implants inserted subcutaneously behind the ear. The osmotically driven pST-SR implants delivered 2 mg of recombinant pST/d. Pigs were bled on d 0, 7, 14, 28, and 42 after implantation. Sera were assayed for pST, insulin-like growth factor (IGF)-I, IGF-II, IGF-binding protein-2 (IGFBP-2), insulin, glucose, and blood urea nitrogen (BUN). Circulating pST concentrations were increased in a dose-dependent manner (P < .001) in the pST-SR treated pigs, but remained elevated (P < .05) only in the 4 mg of pST-SR/d group on d 42. Significant effects of line, dose, time, line x dose, and time x dose were noted for IGF-I. Serum IGF-I was elevated in a dose-dependent manner over the 42-d period in all pST-treated swine. Examination of the line x dose x time interaction indicated that the IGF-I response to pST-SR was greatest in the obese line compared with the lean and crossbred lines. Conversely, serum IGF-II responded to pST-SR to the least extent in the obese pigs. Circulating IGFBP-2 concentrations were reduced by pST-SR, but were not affected by line. The BUN concentrations were reduced by pST-SR. An interaction of line x dose x time (P < .001) indicated that the response was greater in the obese line. Line x dose x time interactions were also noted for insulin and glucose concentrations, which were elevated by pST-SR in a dose-response manner in all lines, but to a much greater extent in the obese pigs.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Animal Sciences Division, Monsanto Co., St. Louis, MO 63198, USA.
authors.forename: F C
authors.initials: FC
authors.lastname: Buonomo
authors.forename: J
authors.initials: J
authors.lastname: Klindt
authors.forename: J T
authors.initials: JT
authors.lastname: Yen
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D001806:Blood Urea Nitrogen; D001947:Breeding; D002352:Carrier Proteins / Q000097:blood; D003692:Delayed-Action Preparations; D004305:Dose-Response Relationship, Drug; D004343:Drug Implants; D005260:Female; D013006:Growth Hormone / Q000008:administration & dosage* / Q000097:blood; D007328:Insulin / Q000097:blood; D018971:Insulin-Like Growth Factor Binding Protein 2; D007334:Insulin-Like Growth Factor I / Q000032:analysis; D007335:Insulin-Like Growth Factor II / Q000032:analysis; D008297:Male; D009765:Obesity / Q000235:genetics / Q000378:metabolism / Q000662:veterinary*; D013552:Swine / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D013997:Time Factors
chemical_list: D001786:Blood Glucose; D002352:Carrier Proteins; D003692:Delayed-Action Preparations; D004343:Drug Implants; D007328:Insulin; D018971:Insulin-Like Growth Factor Binding Protein 2; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D013006:Growth Hormone