澳系进口荷斯坦牛IL8基因遗传多态性与体细胞评分及泌乳性状的关联分析

Genetic Polymorphism of IL8 Gene and Its Association with Milk Traits and SCS in Holstein Imported from Australia

以海丰奶牛场来自72个公牛家系588头胎澳系进口荷斯坦牛为试验材料,分析白介素8(Interleukin-8,IL8)基因2个突变位点对日产奶量、乳脂率、乳蛋白率、305d产奶量、305d乳脂量、305d乳蛋白量及体细胞评分(SCS)7个性状的影响,寻找可用于生产应用的分子标记。用PCR-SSCP技术对IL8基因的遗传多态性进行分析,采用最小二乘模型分析多态位点与各泌乳性状及SCS的相关性。结果表明,IL8基因5′侧翼区序列-180位点发生了G→A的突变,检测到GG、GA和AA 3种基因型,频率分别为0.226、0.476和0.298,等位基因G和A的频率分别为0.464和0.536;该位点突变对305d脂肪产量有显著影响,而对其它泌乳性状及SCS均无显著影响。GG基因型305d脂肪产量显著高于GA基因型(P<0.01),而AA基因型305d脂肪产量与GG、GA基因型之间无显著差异(P>0.05)。IL8基因2 789发生A→G的突变,共检测到GG、GA和AA 3种基因型,频率分别为0.297、0.506和0.197,等位基因G和A的频率分别为0.550和0.450;该突变位点对测定日乳脂率、乳蛋白率、305d校正奶量和SCS有显著影响(P<0.05)。AA基因型乳脂率极显著高于GA、GG基因型(P<0.01);AA基因型乳蛋白率极显著高于GA基因型(P<0.01);GG基因型的体细胞评分(SCS)极显著高于GA、AA基因型(P<0.01);对于305d校正奶量而言,GA基因型显著高于AA基因型(P<0.05)。IL8基因遗传突变对澳系进口荷斯坦牛泌乳性状和乳房炎抗性有较大的遗传效应,可用于其分子标记辅助选择。

The effect of two mutations in Interleukin-8 （IL-8） gene for 588 Holstein cows from 72 bull families of Haifeng dairy cattle farm imported from Australia were investigated on 7 milking performances： tested day milk yield, milk fat percentage, milk protein percentage, 305 d corrected milk yield, 305 d milk fat yield, 305 d milk protein yield and somatic cell score （SCS）. The aim was to explore molecular marker in the breeding of dairy cattle. The polymorphism of IL8 gene was detected by polymerase Chain reaction-single strand conformation polymorphism （PCR-SSCP） technique. The association between polymorphic sites of IL8 gene and milking performances , SCS was analyzed by the least square mean model. The results showed that a mutation from G to A was identified in the 5′ upstream of -180（G/A）, the genotypic frequencies of GG, GA and AA were 0.226, 0.476 and 0.298, respectively. The gene frequencies of G and A were 0.464 and 0.536, respectively. No significant effects of mutation were observed on milking performances and SCS except on 305 d milk fat yield. The 305 d milk fat yield for GG genotype was higher than GA （P〈0.05）. A mutation from A to G was identified in 2 789 of IL8, and the genotypic frequencies of GG, GA and AA were 0.297, 0.506 and 0.197, respectively. The gene frequencies of G and A were 0.550 and 0.450. This mutation showed significant effects on tested day milk fat percentage, milk protein percentage, 305 d corrected milk yield and SCS. The AA genotype had greatly significant higher milk fat percentage than GG and GA genotypes （P〈0.01）. Milk protein percentage for AA was greatly significant higher than that GA （P〈0.01）. GG genotype had greatly significant higher SCS than GA and AA （P〈0.01）. 305 d corrected milk yield for GA was significant higher than AA （P〈0.05）. The polymorphisms of IL8 gene had a greatly genetic effects on milking traits and mastitis resistance, so this gene could be a useful genetic marker for Holstein cows imported from Australia.