Study On Growth Characteristic And Molecular Markers In Guyuan Local Cattle And Its Hybrid F₁ Offspring By Limousin

Growth traits of 309 Limousin×Guyuan cattle were determined in this study. Four Growth Models were used to analysis the growth traits of Limousin×Guyuan cattle in Guyuan region. Growth traits of 196 cattle in Guyuan were determined and associated with GH gene polymorphism. Finishing and slaughtering performances of 24 cattle in Guyuan were determined, and were associated with MYF5 gene polymorphism. Main results are as follow:1 Growth traits of Hybrid F1 offspring of Limousin×Guyuan cattle Growth traits of 97 four-month old Guyuan local cattle and Limousin×Guyuan cattle were determined. Significant difference was found between Guyuan local cattle and Limousin×Guyuan cattle in body weight, body length, chest girth, body height, hip height, waist width, rump length, BPI (P<0.01). No significant difference was found in Hucklebone width of bull (P>0.05), and significant difference was revealed in Hucklebone width of cow (P<0.05). 37 Limousin×Guyuan cattle were determined when boring. Body weight: bull 32.95 kg, cow 31.24 kg. It respectively increased 40.81%, 38.88% compared with Guyuan local cattle."Heterosis"was very distinct.2 Study on Growth Model of Limousin×Guyuan cattle in Guyuan. Four growth model were used to analysis the growth traits of Limousin×Guyuan cattle. Brody model was the most suitable one. The body weight equations were: bull, Y=533.8637×(1–0.9141×e-0.0416×t), cow, Y=285.9270×(1–0.8999×e-0.1372×t).3 Association between GH Gene Polymorphism and Growth Traits of Guyuan cattle 345 bp PCR products including intron3 of the GH gene of 196 Guyuan cattle were amplified, genotyped by PCR-SSCP and sequenced. A c→t mutation was found at 1162bp of the GH gene complete sequence. Two genotypes were found: AA and AB. Frequencies of A and B alleles were 0.8608 and 0.1392, respectively. The genotype distributions of this loci were in Hardy-Weinberg disequilibrium (P<0.05). Polymorphic information content of this population was 0.2109. No significant difference was found between AA and AB genotypes. Three genotypes were found as AA, AB and BB when detecting GH 3'UTR by HaeⅢ. Frequencies of A and B alleles were 0.6126 and 0.3874, respectively. The genotype distributions of this loci were in Hardy-Weinberg equilibrium (P>0.05). Polymorphic information content of the population was 0.3620. Significant differences were found among these three genotypes. AA genotype showed better performance in Body height, Hip height, Hucklebone width, Body weight and BPI than the other two.4 Associations between MYF5 Gene polymorphism and Finishing and Slaughtering performance of local cattleThree genotypes, AA, AB and BB were found in 196 Guyuan local cattle and Limousin×Guyuan cattle by detecting Myf-5-TaqI polymorphism. Frequencies of A/B alleles were 0.3429/0.6571 and 0.3611/0.6389. Polymorphic information content of the two populations were 0.3491/0.3550. Slaughtering performances of 24 local cattle were determined. No significant difference was found in 24 months old population (P>0.05). In 24 months old population, several slaughtering performances (body weight, BPI, Renal weight, Renal Fat weight, Carcass weight, Carcass hind leg width) showed significant difference among the three genotypes (P<0.05). Significant difference was found in eye muscle area (P<0.01). AA genotype showed the better performances.