Submitted to: World Poultry Congress Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 4/1/2004
Publication Date: 6/10/2004
Citation: Zhou, H., Mitchell, A.D., McMurtry, J.P., Ashwell, C.M., Lamont, S.J. 2004. Associations of single nucleotide polymorphism in insulin-like growth factor 1 gene with growth, body composition, skeleton integrity, and metabolic traits in chickens. World Poultry Congress Proceedings, p. 1-4. Interpretive Summary: Intense genetic selection of broilers has successfully increased growth rate and breast muscle percentage. However, physiological disorders, such as obesity and skeletal integrity, are increasing. To simultaneously improve production and fitness traits, molecular markers associated with both sets of traits may be useful. The objective of this study was to examine associations of a IGF1 gene promoter single-nucleotide polymorphism (SNP) with growth, body composition, fitness, skeleton integrity, and metabolic traits in a unique F2 cross of a contemporary outbred meat-type line by two inbred lines of chickens. This study showed that the IGF-1 gene is one of the genetic factors influencing growth, and could be used as a specific candidate gene for marker-assisted selection to improve poultry production efficiency in the future.
Technical Abstract: Production performance and fitness traits are often negatively correlated in chickens. Multi-trait selection to simultaneously improve both facets is difficult to achieve by traditional phenotypic selection. Genetic markers in genes linked to quantitative trait loci (QTL) affecting individual traits provide an alternate means to select for genetic improvement. A resource population was developed to study the genetics of growth and body composition. Broiler sires were crossed to dams of two diverse, highly inbred lines (Leghorn and Fayoumi), and the F1 birds were inter-mated by dam line to produce broiler-Leghorn and broiler-Fayoumi F2 offspring. Growth, body composition, skeletal integrity, and hormonal and metabolic factors were measured in the F2 population (n = 720). The measured traits included weight of body, breast meat, drumstick, shank, spleen, heart, liver, and abdominal fat; plasma circulating T3, T4, IGF-I, IGF-II, insulin and glucagon; length of tibia and shank; and bone mineral content and density of the tibia. Insulin-like growth factor-I was selected as a biological candidate gene (IGF1) for study. A nucleotide polymorphism (SNP) was identified between the founder lines in the IGF-I promoter region, and a PCR-RFLP assay was developed. A mixed model was used to statistically analyze associations of the IGF1 SNP with phenotypic traits within each F2 cross. The IGF1 SNP had very significant associations with most recorded traits in the broiler-Leghorn F2 cross, but little association in the broiler-Fayoumi cross. These findings suggest the linkage of the SNP to a QTL in IGF1 or a nearby gene, and potential application of the IGF1 SNP in marker-assisted selection to improve growth performance and fitness traits in the chicken.