Objective The Paper aims to explor the relationship between single nucleotide polymorphisms (SNP) of 5'-flanking and Intron 1 in growth hormone (GH) gene and the comb traits of Ningdu yellow chicken, and find molecular markers for the comb traits selection of local chicken breeds.

Method The comb trait data at seven different week age of 499 Ningdu yellow chickens were recorded including comb height, comb length, comb thickness, wattle length, wattle thickness and number of comb teeth. These traits were associated with SNPs in the 5'-flanking and Intron 1 regions of GH gene using statistical analysis system (SAS).

Result A total of 13 SNPs were significantly associated with comb height trait (P < 0.05), including C1272225T, G1272611A, C1271211T, C1270902T, A1270769G, G1270640C, T1270578C, G1270503C, T1270451C, C1270032T. A1270769G was significantly correlated with the comb height traits at seven different week age. G1272611A was significantly associated with the comb height traits at five different week age. A total of 10 SNPs were significantly associated with comb length trait (P < 0.05), including C1272225T, G1272611A, C1271211T, C1270902T, A1270769G, G1270640C, T1270578C, G1270503C, T1270451C, C1270032T. C1271211T was significantly correlated with the comb length at six different week age. G1272611A was significantly correlated with the comb length at five different week age. The locus G1272611A was significantly associated with both comb length and height trait at five consecutive weeks, which had two genotypes in this population, GG and GA, comb height or length of GG genotype individuals were significantly higher than those of GA genotype.

Conclusion G1272611A could be used as a candidate molecular marker for selection of Ningdu yellow chicken comb traits.