Purified Chicken Growth Hormone (GH) and a Human Pancreatic GH-Releasing Hormone Increase Body Weight Gain in Chickens

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Abstract
Purified chicken GH (cGH) and a synthetic human GH-releasing hormone (hpGRF) were tested for the ability to improve growth performance in chickens. Purified cGH was given to 4-week-old cockerels at 5, 10, and 50 .mu.g/day for 14 days via daily iv injection. Body weights of chickens receiving 5 and 10 .mu.g/day cGH were significantly increased at 6 days by 13.5% and 11.2%, respectively, relative to control values. At 14 days, body weights averaged 8.1% and 7.7% greater than controls, but these values were not statistically significant. There was a slight stimulation of body weight gain in chickens receiving 50 .mu.g/day cGH. In general, cGH produces a transient stimulation of body weight gain in chickens. hpGRF was also given to 4-week-old cockerels for 14 days via daily iv injection at 0.1, 1.0, and 10.0 .mu.g/day. hpGRF at 0.1 .mu.g/bird daily increased body weight on day 14 (9.1% over the control value). The stimulating effects of hpGRF on body weight are also transient. The effects of cGH on serum somatomedin-C (SM-C) were examined. Serum SM-C concentrations were significantly elevated 24 and 36 h after injection of cGH. In conclusion, purified cGH and hpGRF appear to have some growth-promoting activity. The stimulatory effect of hpGRF on weight gain may be mediated via GH, and the stimulatory effect of cGH could be mediated through SM-C.