| PCR-SSCP and DNA sequencing techniques were applied to detect the genetic variation of GHR gene, GHRH gene, TG gene and 5'end of TG gene in 136 Qinchuan cattle and 105 Nanyang cattle. The associations between these polymorphisms and growth and development traits were analyzed using the general linear model (GLM). Results were obtained as follows:1. Association of polymorphisms of GHR gene with growth traits in Qinchuan cattle and Nanyang cattleA polymorphism of GHR gene was first studied in Qinchuan and Nanyang cattle. Three SSCP alleles, named allele A, B, and C were detected, and the frequencies of alleles A/B/C were 0.5956/0.2905/0.1140 respectively in Qinchuan cattle and 0.5619/0.3000/0.1381 respectively in Nanyang cattle. This locus was at Hardy-Weinberg equilibration in both cattle breeds. Then, the PCR fragments with different genotypes were sequenced, the results showed: the mutations A>C and T>C were found respectively in position 7419 and 7471 in genotype AA individuals; the mutations C>T, A>C and T>C were found respectively in position 6931, 7419, 7471 in genotype BB individuals; the mutations C>T, C>T, G>T, A>T, C>T, and T>C were found respectively in position 6931, 6970, 7152, 7264, 7319, 7471 in genotype CC individuals.The associations between genotypes and growth and development traits showed: In Qinchuan cattle breed, body weight, hip width, rump length with genotype AB were higher than those with genotype BC(P<0.05), and heart girth with genotype AB was higher than those with genotype AC, BC(P<0.05). In Nanyang cattle breed, body weight in born with genotype AC was higher than those with genotype BC(P<0.05), and withers height, body length, body weight in 6 months age, body length, body weight in 12 months age, body weight in 18 months age, withers height, body length, body weight in 24 months age with genotype AB were higher than those with genotype BC(P<0.05), among which body weight in 24 months the difference was remarkable(P<0.01); heart girth in 18 months age with genotype AB was higher than those with genotype CC(P<0.05); body weight in 18 months age with genotype AB was higher than those with genotype AA, BB, AC also(P<0.05), and the difference was remarkable between those with genotype AB and those with genotype AC(P<0.01); withers height in 24 months age with genotype AA, CC, was higher than those with genotype BC also(P<0.05), and the difference between those with genotype AA and those with genotype BC was remarkable(P<0.01); body weight in 24 months with genotype AB was higher than those with genotype AA, BB, AC also(P<0.05), and the difference between those with genotype AB and those with genotype AC was remarkable(P<0.01).2. Association of polymorphisms of GHRH gene with growth traits in Qinchuan cattle and Nanyang cattleA polymorphism of GHRH gene was first studied in Qinchuan and Nanyang cattle in. Two SSCP alleles, named allele A and B were detected, and the frequencies of alleles A/B were 0.8778/0.1222 respectively in Qinchuan cattle and 0.8476/0.1524 respectively in Nanyang cattle. This locus was at Hardy-Weinberg equilibration in both cattle breeds. Then, the PCR fragments with different genotype were sequenced, the results showed a mutation T>C in position 4308 was found in genotype AB individuals..The associations between genotypes and growth and development traits for gene GHRH proved no differences in Qinchuan cattle, but some differences were found in Nanyang cattle, which were that hucklebone width in 6 months age, body weight in 6, 12, 18 and 24 months age, body length in 18 months age with genotype AB were higher than those with genotype AA(P<0.05), among which the difference of body weight in 18 months age was remarkable(P<0.01).3. Association of polymorphisms of 5'end of TG gene with growth traits in Qinchuan cattle and Nanyang cattleA polymorphism of 5'end of TG gene was first studied in Qinchuan and Nanyang cattle. Two SSCP alleles, named allele A and B were detected, and the frequencies of alleles A/B were 0.3015/0.6985 respectively in Qinchuan cattle and 0.2714/0.7286 respectively in Nanyang cattle. This locus was at Hardy-Weinberg equilibration in Nanyang cattle, but not in Qinchuan cattle. Then, the PCR fragments of the individuals from different genotypes were sequenced, the results showed mutations G>C, G>T, and C>T in position 355, 630, 671 respectively in genotype AA; mutaions G>T, T>A, C>T in position 390, 513, 671 respectively in genotype AB.The associations between genotypes and growth and development traits for 5'end of TG gene proved that: In Qinchuan cattle, withers height, height at hip cross, hucklebone width with genotype BB were higher than those with genotype AB(P<0.05),among which the difference of hucklebone width was remarkable(P<0.01); hip width with genotype AA was higher than those with BB and AB(P<0.05), the difference between those with AA and those with AB was remarkable(P<0.01). In Nanyang cattle, hucklebone width in 6 months age with genotype BB was higher than those with genotype AA(P<0.05); withers height, body length, heart girth and body weight in 6 months age, heart girth in 12 months age, body length and heart girth in 18 and 24 months age with genotype BB were higher those with genotype AA and AB(P<0.05), and difference between withers height, heart girth, body weight in 6 months age, heart girth in 12, 18, 24 months age with genotype BB and those with genotype AA was remarkable(P<0.01).4. Association of polymorphisms of TG gene with growth traits in Qinchuan cattle and Nanyang cattleA polymorphism of locus in TG gene was first studied in Qinchuan and Nanyang cattle, Two SSCP alleles, named allele A and B were detected, and the frequencies of alleles A/B were 0.8235/0.1765 respectively in Qinchuan cattle and 0.6476/0.3524 respectively in Nanyang cattle. This locus was not at Hardy-Weinberg equilibration in both cattle breeds. Then, the fragments of the individuals from different genotypes were sequenced, the results showed mutations T>C, G>C, and A>G in position 906, 920, 959 respectively in genotype AA; mutations G>C and A>G in position 920, 959 respectively in genotype AB.The associations between genotypes and growth and development traits for gene TG proved that there were no differences in both cattle breeds, except that body length with genotype AB was higher than those with genotype AA in Qinchuan cattle(P<0.05).
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