Document Detail

Insulin-like growth factor (IGF)-I but not IGF-II promotes lean growth and feed efficiency in broiler chickens.
MedLine Citation:
PMID:  9593647     Owner:  NLM     Status:  MEDLINE    
The efficacy of exogenous IGFs to stimulate growth and modulate protein and fat deposition was examined in a number of broiler chicken lines. From around 600 g body weight the chickens received a continuous infusion of vehicle (0.1 M acetic acid), human recombinant IGF-I or [Gly1]IGF-II at 300 microg/kg body weight per day, or a combined infusion of 150 microg/kg/day of each IGF for 2 weeks. Experiment 1 used commercial broiler female chickens and included measurements of nitrogen balance, Ntau-methylhistidine excretion and muscle protein synthesis rates. In Experiment 2 the same treatments were applied to three experimental lines of chickens selected for high food consumption (relatively fat), high food utilisation efficiency (relatively lean), or at random (control). IGF-I, but not IGF-II, significantly increased growth rate and food utilisation efficiency by around 10-15% in each experiment, an effect which was consistent across all genotypes. Nitrogen balance was significantly increased by IGF-I in Experiment 1 as was carcass nitrogen content in Experiment 2, indicating that the increased growth was in lean tissue. Carcass fat was consistently reduced in chickens receiving IGF-I and was related to the levels of circulating IGF-I (r2 = 0.30, P < 0.01) but not triiodothyronine. Protein synthesis rates were unaffected by treatment and could not account for increased growth rate. However, there was a significant reduction in Ntau-methylhistidine excretion indicating a reduced rate of muscle protein breakdown in IGF-I-treated chickens (1. 56%/day vs 2.05%/day for IGF-I-treated vs controls, P < 0.05). The efficiency of feed utilisation was inversely related to the rate of protein breakdown (r2 = 0.25, P < 0.01). In conclusion, these experiments are the first to report an enhancement of growth and food utilisation efficiency by broiler chickens receiving exogenous IGF-I. Our results show that IGF-I may be important in controlling the growth and efficiency of food utilisation of young chickens at least in part by modulating the rates of protein breakdown.
F M Tomas; R A Pym; J P McMurtry; G L Francis
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  General and comparative endocrinology     Volume:  110     ISSN:  0016-6480     ISO Abbreviation:  Gen. Comp. Endocrinol.     Publication Date:  1998 Jun 
Date Detail:
Created Date:  1998-08-27     Completed Date:  1998-08-27     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0370735     Medline TA:  Gen Comp Endocrinol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  262-75     Citation Subset:  IM    
Copyright Information:
Copyright 1998 Academic Press.
Cooperative Research Centre for Tissue Growth and Repair, CSIRO Division of Human Nutrition, Gouger Street, Adelaide, South Australia, 5000, Australia.
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MeSH Terms
Animal Nutritional Physiological Phenomena*
Blood Glucose / drug effects
Body Composition / drug effects
Chickens / blood,  growth & development*
Infusion Pumps, Implantable / veterinary
Insulin / blood
Insulin-Like Growth Factor I / administration & dosage,  metabolism,  pharmacology*
Insulin-Like Growth Factor II / administration & dosage,  metabolism,  pharmacology*
Organ Size / drug effects
Proteins / drug effects,  metabolism
Triiodothyronine / blood,  drug effects
Reg. No./Substance:
0/Blood Glucose; 0/Proteins; 11061-68-0/Insulin; 67763-96-6/Insulin-Like Growth Factor I; 67763-97-7/Insulin-Like Growth Factor II; 6893-02-3/Triiodothyronine

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