Submitted to: Domestic Animal Endocrinology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 11, 1999
Publication Date: N/A
Interpretive Summary: The regulation of growth and metabolism in meat-type poultry is poorly understood. A family of protein hormones termed the insulin-like growth factors has been demonstrated to be important to growth and metabolism in mammals. The study was conducted to gain information on the role of one of these growth factors, insulin-like growth factor-2 on circulating metabolites and hormones in the broiler chicken. The response to both human and chicken insulin-like growth factor-2 was investigated. In general, the metabolic and hormonal response to the two insulin-like growth factors was similar in any parameter monitored. It is evident from this study that insulin-like growth factor-2 plays an important role in regulating intermediary metabolism in broiler chickens. This information will be of interest to other scientists.
The purpose of this study was to compare the metabolic and endocrine responses of male broiler chickens to an intravenous injection of either chicken insulin-like growth factor-II (cIGF-II) or human insulin-like growth factor-II (hIGF-II). At 5 weeks of age, chickens were surgically implanted with a jugular cannula. Following an 8 hr fast, equimolar amounts of cIGF-II or hIGF-II (103 and 104 g/kg bwt, respectively) were infused. Control birds were infused with an equal volume of saline. Plasma samples were collected at selected intervals pre- and post-infusion and analyzed for various hormonal and metabolic parameters. Similar hypoglycemic responses (50%) were induced by both growth factors. GH levels were depressed following infusion compared to saline treated control birds. Regardless of treatment, plasma T3 and T4, declined during the sampling period as well as lactate concentrations. Plasma IGF-I and insulin were unaffected by either treatment. Significant increases in plasma glucagon and free fatty acid concentrations were observed, while triglyceride levels were unaffected. Significant elevations in plasma uric acid and calcium were noted following IGF-II treatment. Similar metabolic and endocrine responses were elicited by cIGF-II and hIGF-II.