Submitted to: Journal of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: March 4, 1997
Publication Date: N/A
Technical Abstract: Insulin-like growth factor -I (IGF-I) effects on chicken growth and development are poorly understood. This study examined the effect of IGF-I on protein synthesis rates in various tissues in the male broiler chicken. At three weeks of age, osmotic minipumps were subcutaneously implanted in the scapular area. Chickens were infused with either chicken IGF-I (450 æg/kg bwt/day) or saline. After 5 days of treatment the chickens received a flooding dose of [3H]-phenylalanine and were sacrificed 20 min later. Wing vein blood samples were taken at 5, 10 and 20 min post-infusion. The following tissues were removed and frozen for analysis: pectoralis muscle, gastrocnemius muscle, heart, liver, and small intestine. Total protein synthesis measurements were made using the double-label technique. There were no significant differences in absolute or relative body growth rates over the treatment period. Tissues weights did not differ between treatment groups. However, chickens that were treated with IGF-I had muscle protein synthesis rates were increased above those of saline controls. Since over this time period growth rates did not differ between the treatment groups, the rates of protein breakdown in the IGF-I treated group must have increased. This data demonstrates that IGF-I way have a direct effect on muscle protein synthesis and degradative rates.