QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Cogburn, L. A. Articles by McMurtry, J. P. Search for Related Content PubMed PubMed Citation Articles by Cogburn, L. A. Articles by McMurtry, J. P.

Growth, Metabolic and Endocrine Responses of Broiler Cockerels Given a Daily Subcutaneous Injection of Natural or Biosynthetic Chicken Growth Hormone^1,2,

Delaware Agricultural Experiment Station, Department of Animal Science and Agricultural Biochemistry, College of Agricultural Sciences, University of Delaware, Newark, DE 19717-1303 ^* Animal Sciences Institute, Agricultural Research Service, U.S. Department of Agriculture, USDA-BARC, Beltsville, MD 20705

The effects of daily injection of natural chicken growth hormone (ncGH) or recombinant-derived chicken growth hormone (rcGH) on growth, heat production rate, plasma hormone levels and body composition were determined in rapidly growing broiler chickens. Beginning at 3 wk of age, eight broiler chickens were given a daily injection of either bicarbonate buffer (control), 100 or 200 µg ncGH/kg body wt, or 200 µg rcGH/kg body wt for 14 d. Blood samples were taken preinjection and 4 h postinjection on d 7 and 14 of chicken growth hormone (GH) treatment. Compared to preinjection levels, plasma GH levels at 4 h postinjection were significantly (P < 0.05) elevated by daily injection (per kg body wt) of 100 µg ncGH (2.3-fold), 200 µg ncGH (5.5-fold) or 200 µg rcGH (6.4-fold). Although exogenous chicken GH treatment failed to increase body weight gain, ncGH injections did increase (P < 0.05) body fat content to 117% that of the control group. Daily injection of chicken GH did not alter plasma levels of immunoreactive insulin-like growth factor-I (IGF-I), thyroid hormones, insulin, glucagon or glucose. Feed efficiency, heat production rate and respiratory quotient were also not affected by chicken GH treatment. Plasma levels of nonesterified fatty acids were elevated (P < 0.05) by treatment with 200 µg ncGH/kg body wt. In contrast to domestic mammals, it is apparent that exogenous chicken GH can not be used to increase lean body mass or improve productive efficiency in chickens. Our results indicate that exogenous chicken GH exerts a strong lipogenic, rather than lipolytic, action in rapidly growing broiler cockerels.

KEY WORDS: • chicken growth hormone • growth rate • feed efficiency • heat production rate • body composition • insulin-like growth factor-I • insulin/glucagon molar ratio • thyroxine 5'-monodeiodinase activity • chickens

¹ Supported by grants from International Minerals and Chemicals Corp. and the Delaware Research Partnership.

² Published as Miscellaneous Paper #1180 from the Delaware Agricultural Experiment Station.

Manuscript received 5 March 1989. Revision accepted 7 April 1989.