The Effects of Different Sex-Linked Dwarf Variations on Chinese Native Chickens

Variants in chicken growth hormone receptor (GHR) gene lead to sex-linked dwarf (SLD) chickens, but effects of different variants are distinct. In this study, 11 SLD chicken breeds or strains including 3 Chinese native breeds and 8 breeding strains were studied in order to investigate the effects of different sex-linked dwarf variations on growth performance. The results showed that there were three reasons which could lead to dwarfism in the 11 breeds or strains. Firstly, an about 1.7 kb deletion of growth hormone receptor (GHR) gene leads to dwarfism in Jiangxi dwarf chicken, strains GF24, GF26, N308, N309, and N310. Secondly, a T354C mutation in exon 5 of the GHR gene leads to dwarfism in strains N301 and N305. Thirdly, an unknown variant leads to dwarfism in Guizhou Yellow Dwarf chicken and Yixing Bantam chicken. In addition, all individuals of N303 had the 1.7 kb deletion of the GHR gene, and additionally, some of them also carried the T354C mutation. As far as the performance of individuals were compared among T354C homozygote, deletion homozygote, and heterozygote carrying both T354C and deletion, it was found that the T354C's impacts on body weight of Chinese chickens were maximum, the body weight of chickens with homozygote T354C was 92.12% of those with heterozygote, and the difference of the body weight between deletion homozygote and heterozygote was not significant. There was no significant difference of shank length among three genotypes.