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Title: THE EFFECT OF INSULIN-LIKE GROWTH FACTOR-I (IGF-I) ON PROTEIN SYNTHESIS RATES IN THE MEAT-TYPE CHICKEN

Author
item Czerwinski, Susan
item CATE, JENNIFER - 1265-35-00
item FRANCIS, G - ADELAIDE, AUSTRALIA
item Brocht, Donna
item McMurtry, John

Submitted to: Comparative Biochemistry and Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/4/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: 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. Chickens were infused with either chicken IGF-I 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. Skeletal muscle weights (pectoralis and gastrocnemius) weights were significantly decreased with IGF-I treatment, while ventricular weight was significantly increased. Liver weights were similar between treatment groups. However, chickens that were treated with IGF-I had gastrocnemius muscle protein synthesis rates were increased above those of saline controls. There was no effect of IGF-I on protein synthesis rates of the pectoralis muscle, liver , heart, or small intestine. Since over this time period growth rates did not differ between the treatment groups, skeletal muscle rates of protein breakdown in the IGF-I treated group must have increased, while ventricular degradative rate decreased.

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. Chickens were infused with either chicken IGF-I (450 :g/kg BW/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. Skeletal muscle weights (pectoralis and gastrocnemius) weights were significantly decreased with IGF-I treatment, while ventricular weight was significantly increased. Liver weights were similar between treatment groups. However, chickens that were treated with IGF-I had gastrocnemius muscle protein synthesis rates were increased above those of saline controls. There was no effect of IGF-I on protein synthesis rates of the pectoralis muscle, liver , heart, or small intestine. Since over this time period growth rates did not differ between the treatment groups, skeletal muscle rates of protein breakdown in the IGF-I treated group must have increased, while ventricular degradative rate decreased.