Abstract: 【Objective】 The aim of this study was to explore the relationships between GHSR and GHRL gene and body weight & size traits, and search the molecular genetic markers related to goat growth traits.【Method】Guizhou white goat and Guizhou black goat were chosen as subjects, the DNA pooling was constructed and the technology of direct sequencing of PCR products and PCR-SSCP were used to detect the single nucleotide polymorphism of GHSR and GHRL genes, and its association of polymorphisms and different genotypes and combined genotypes with growth traits was analyzed by SPSS(18.0). Meanwhile, the bioinformatics analysis of GHSR gene was conducted by online software.【Result】The result showed that two SNPs (G200A and T628C) were detected in exon 2 and 3′UTR but no SNPs in exon1 and 5′UTR of GHSR gene, respectively. G200A was a sense mutation site and devided into three genotypes GG, GA and AA by PCR-SSCP. Genotype GG was the dominant genotype and allele G was dominant allele with the frequencies of 0.6731 and 0.5243 in Guizhou white goat and Guizhou black goat (♀) groups instead of allele A in Guizhou black goat (♂). All populations were moderate polymorphic in G200A site (0.25＜PIC＜0.50). G141A was found in intron 2 and two sense mutation sites (T78C and C14T) were identified in exon2 and exon4 of GHRL gene, respectively. There were two genotypes (CT and CC) in C14T site, genotype CC was the dominant genotype, which the frequency were 0.7692, 0.9417 and 0.9390, allele C was dominant allele with the frequency of 0.8846, 0.9709 and 0.9695, respectively. These populations were low polymorphic (PIC＜0.25). χ² test indicated that SNPs(G200A and C14T) fit with Hardy-Weinberg equilibrium in the population (P＞0.05). Correlation analysis revealed that G200A site was significantly associated with body weight, body height, body length and hucklebone width (P＜0.05), GG genotype was superior genotype. Additionally, body weight, body height and chest girth of individuals of Guizhou black goat (♂)with genotype CC was significantly higher than those with genotype CT(P＜0.05) in C14T site. Meanwhile, the combined genotype was significantly associated with body height and chest girth, the individuals with CCGG genotype had significantly better body height than that of genotype CCAA (P＜0.05). Bioinformatics analysis indicated that no core promoter regions and CpG island were found but a CAAT-box and several important transcription factors in 5′UTR region of GHSR gene. G200A had led to the change of secondary structure of mRNA. The secondary structure of protein was mainly α-helix (48.90%). Tertiary structure and transmembrane helix prediction showed that GHSR protein was a membrane protein.【Conclusion】The results revealed that SNPs and combined genotype of GHSR and GHRL gene had effect on growth traits in goat, G200A and C14T sites could be used as effective genetic markers for goat molecular breeding.

Key words: GHSR gene, GHRL gene, genetic variation, growth traits, correlation analysis