牛DGAT1基因的K232A取代等位基因分布频率及对部分胴体性状的影响

Alleles distribution frequency of K232A substitution at DGAT1 gene and their effect on partial carcass traits in beef cattle

为研究肉牛与体脂相关的胴体性状的数量性状座位,利用单链构象多态性方法检测了牛DGAT1基因K232A取代的2个等位基因K和A在实验群体中的分布频率,并分析了基因型对4个肉牛群体部分胴体性状的影响。结果表明,编码赖氨酸的等位基因K在地方黄牛品种鲁西牛、晋南牛、秦川牛和杂交牛利木赞牛×鲁西牛群体中的分布频率分别为0.75、0.39、0.40和0.35,在南阳牛中的分布频率最高,为0.83。在本研究中,牛DGAT1基因的K232A取代对背膘厚度(P=0.88)、大理石花纹等级(P=0.13)和肌内脂肪(P=0.19)没有显著影响,但与腔油重/胴体重、嫩度显著相关,KK型和KA个体外脊肌肉剪切力低于AA型个体(P=0.037),而腔油重/胴体重明显高于AA型(P=0.045),而且KK型个体有更高的净肉率(P=0.018)。研究显示,编码赖氨酸的等位基因K在鲁西牛和南阳牛中分布频率高于秦川牛和晋南牛及已经报道的国外牛种,牛DGAT1基因的K232A只与腔油重/胴体重、嫩度和净肉率相关。该实验相关性分析结果还有待在更大的群体中验证。

To detect QTL for the body fat-related carcass traits in beef cattle, the single strand conformation polymorphism assay was used for investigating the K232A substitution in DGAT1. Animals from 4 beef cattle populations （32 Luxi, 28 Jinnan, 32 Qinchuan and 26 Limousin × Luxi cattle） were used to estimate allele frequencies and gene substitution effects on several beef carcass traits. Another population, 39 Nanyang cattle, unrecorded for carcase traits, was sampled to analyze allele frequencies. The frequencies for the lysineencoding variant（allele K）were 0.7.5, 0.39, 0.38, 0.32 in Luxi, Jinnan, Qinchuan and Limousin × Luxi cattle respectively, but 0.83 for Nanyang cattle. The substitution had no marked effect （P 〉0.0.5） on backfat, marbling score and intramuscular fat. Intestinal fat/Hot carcass weight and tenderness were affected by the genotype （P 〈 0.0.5）. Individuals with genotype KK and KA had higher （P = 0.045） intestinal fat weight/Hot carcass weight rate and lower Shear force （P = 0. 037） than individuals with genotype AA. Significant association was observed between polymorphism and net meat percentage （P = 0.018）, individuals with genotype KK had higher net meat rate. The present study showed that allele K frequency was higher in Luxi and Nanyang than in Qinchuan, Jinnan and other reported foreign breeds, and the K232A Substitution only affected Intestinal fat/Hot carcass weight, tenderness and net meat rate. Further study should be performed to confirm the correlation analysis results.