Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/17/2006
Publication Date: 2/1/2007
Citation: Zhou,H., Evock-Clover, C.M., McMurtry, J.P., Ashwell, C.M., Lamont, S.J. 2007. Genome-Wide linkage analysis to identify chromosomal regions affecting phenotypic traits in the chicken. IV. Metabolis traits. Poultry Science. 86:267-276. Interpretive Summary: The study of circulating protein hormones and metabolites has long been of interest to the animal agricultural community. Initially these efforts focused on determining the underlying hormonal basis of disease and eventually defined the functional pathways for how numerous hormones affect metabolism. It is this information that sparked the interest in hormonal regulation of metabolism in poultry whose growth, feed efficiency, and health are of significant economic importance to the poultry industry. Little is known about the natural genetic variation present and its contribution to the variation in normal circulating hormone levels. The current study was conducted to investigate the natural variation present in the genomes of a novel broiler chicken resource population to determine if quantitative trait loci exists for circulating insulin, glucagons, glucose, lactate, insulin-like growth factors, and the thyroid hormones. The results of this study demonstrate that several positional candidate genes for metabolic traits are biologically associated with the regulation of metabolic pathways for insulin and the thyroid hormones. This information would be of interest to other scientists and poultry geneticists.
Technical Abstract: This study is a comprehensive genome analysis to detect QTL affecting metabolic traits in chickens. Two unique F2 crosses generated from a commercial broiler male line and two genetically distinct lines (Leghorn and Fayoumi) were used in the present study. The plasma glucagons, insulin, lactate, glucose, T3, T4, insulin-like growth factor I (IGFI) and IGFII level at 8 wk were measures in the two F2 crosses. Birds were genotyped for 269 micro satellite markers across entire genome. The program QTL express was used for QTL detection. Significance levels were obtained using the permutation test. For the ten traits, a total of 6 and 9 significant QTL were detected at 1% chromosome-wise significance level, of which 1 and 6 were significant at the 5% genome-wise level for the broiler-Leghorn cross and broiler-Fayoumi cross, respectively. Most QTL for metabolic traits in the present study were detected in Gga2, 6, 8, 9, 13, and Z for the broiler-Fayoumi cross. Phenotypic variation for each trait explained by all QTL across genome ranged from 2.73% to 14.08% in the broiler-Leghorn cross and from 6.983% to 21>15% in the broiler-Fayoumi cross. Several positional candidate genes within QTL region for metabolic traits at 1% chromosome-wise significance level are biologically associated with the regulation of metabolic pathways of insulin, T3, and T4.