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Title: GROWTH, BODY COMPOSITION AND ENDOCRINE RESPONSES TO CHRONIC ADMINISTRATION OF INSULIN-LIKE GROWTH FACTOR I AND/OR PORCINE GROWTH HORMONE IN PIGS

Author
item Klindt, John
item Yen, Jong Tseng
item BUONOMO, FRANCES - MONSANTO AGRICULTURAL CO
item Roberts, Andrew
item Wise, Thomas

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/18/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: During the later phases of the finishing period of swine fat deposition exceeds protein deposition. The current study investigated the effect of exogenous administration of insulin-like growth factor-I (IGF-I), alone and in combination with exogenous porcine growth hormone (pGH), on growth rate and composition during a 28 day treatment period. IGF-I is a growth factor produced by many tissues in response to increased serum concentrations of GH. It is thought that IGF-I may be a useful agent for modifying growth rate and compostion in meat animals. Administration of pGH increased gain 43%, feed efficiency 60%, carcass protein accretion 88% and trimmed lean cuts 16%, while, IGF-I administration increased gain 22%, carcass protein accretion 33%, and trimmed lean cuts 5%. There was little difference in responses to administration of the combination of IGF-I plus pGH and pGH alone. The actions of pGH on growth of pigs cannot be mimicked by administration of IGF-I at a dose which produces serum IGF-I concentrations which are not dissimilar. These results provide little indication that IGF-I has potential as a growth modifier for use in finishing of market hogs.

Technical Abstract: The actions of insulin-like growth factor I (IGF-I), alone and in combination with pGH, on growth and endocrines and metabolites important in growth were investigated in peripubertal age Meishan barrows. Pigs were assigned to 4 treatments. C, buffer; IGF-I, 66 ug rhIGF-I/kg BW daily; pGH 33 ug rpGH/kg BW daily; and IGF-I+pGH. IGF-I was administered in 2 daily injections and pGH was injected once per day. Treatments were administere for 28 d. Feed intake, BW and backfat were recorded and blood samples collected weekly. At slaughter organ and primal cut weights were recorded. Offal and half the carcass were ground for chemical analysis. Serum concentrations of IGF-I on d 7,14,21 and 28 in the IGF-I, pGH and IGF-I+pGH groups were increased 80, 156 and 174%, respectively, compared to the control group. Administration of pGH increased gain 43%, feed efficiency 60%, carcass protein accretion 88% and trimmed lean cuts 16%, while, IGF-I administration increased gain 22%, carcass protein accretion 33%, and trimmed lean cuts 5%. There was little difference in responses to administration of IGF-I+pGH and pGH alone. With administration of IGF-I, serum concentrations of IGF-I achieved were not dissimilar to those with pGH administration; however, the growth and carcass responses were reduced. The actions of pGH on growth of pigs was not mimicked by administration of IGF-I at a dose which produced significantly increased serum concentrations of IGF-I.