上海地区荷斯坦奶牛体型性状、产奶性状和体细胞评分的遗传统计分析

[目的]探究荷斯坦奶牛体型性状(前乳房、后乳房、体躯容量、尻部、肢蹄、乳用特征、泌乳系统和体型总分)、产奶性状(产奶量、乳脂率、乳蛋白率、乳脂蛋比和高峰产奶量)和体细胞评分(SCS)之间的遗传相关性。[方法]统计2008―2012年间上海地区40个牧场的2 678头头胎泌乳奶牛的体型性状、产奶性状和SCS的鉴定记录,建立单性状和多性状动物模型,通过ASReml-R软件中的平均信息约束最大似然(AIREML)方法,估计上述性状的遗传参数。[结果]上海地区荷斯坦奶牛体型性状的遗传力变化范围为0.17(后乳房)~0.52(体躯容量),产奶性状的遗传力范围是0.13(乳脂蛋比)~0.59(产奶量),体细胞评分(SCS)遗传力为0.13。体型性状间和产奶性状间的遗传相关变化范围分别是0.10(尻部和后乳房)~0.90(后乳房和泌乳系统)和-0.57(产奶量和SCS)~0.99(产奶量和高峰产奶量)。大部分体型性状与产奶量之间为遗传正相关,体型总分与产奶量、乳脂率、乳蛋白率、乳脂蛋比、SCS的遗传相关系数(r)分别为0.61、-0.10、-0.21、0.06和-0.56;SCS与产奶量、高峰产奶量呈较强负相关,r分别为-0.57和-0.53,但是SCS与乳脂率、乳蛋白率之间为遗传正相关,r分别为0.40和0.46。[结论]加强体型性状的选择对奶牛产奶量以及乳成分的提高有利,也有利于降低体细胞数,增强个体乳房炎的抗性,体型性状的选择有利于奶牛整体健康和产奶性状的提高。
[Objectives]This study estimated the genetic correlations between eight type traits(fore udder,rear udder,frame capacity,rump,feet and legs,dairy character,mammary system,and final score),five milk production traits(milk yield,fat percentage,protein percentage,fat to protein ratio,and peak milk yield)and somatic cell score(SCS). [Methods]Data relating to type traits and milk production traits of 2 678 first-lactation Chinese Holstein cows were collected from 2008 to 2012 in 40 dairy herds in Shanghai. Heritability and genetic correlations between traits were estimated using single trait and multiple traits animal model by the method of AIREML using ASReml-R software. [Results]The estimated heritability was 0.13 for SCS and ranged from 0.17(rear udder)to 0.52(frame capacity)for type traits and from 0.13(fat to protein ratio)to 0.59(milk yield)for milk production traits. Genetic correlations among type traits ranged from 0.10(rump and rear udder)to 0.90(rear udder and mammary system)and ranged from -0.57(milk yield and SCS)to 0.99(milk yield and peak milk yield)among milk production traits. The genetic correlations of milk yield with most type traits were positive. Genetic relation coefficient of final score with milk yield,fat percentage,protein percentage,fat to protein ratio(F:P)and SCS were 0.61,-0.10,-0.21,0.06 and -0.56 respectively. SCS was genetically high unfavorably correlated with milk yield and peak milk yield(-0.57 and -0.53 respectively),but was positive with fat percentage and protein percentage(0.40 and 0.46 respectively). [Conclusions]Strengthening type traits selection is conductive to improving milk yield and milk composition,helps to reduce the number of somatic cells,and enhance individual mastitis resistance,suggesting that an improvement of overall health and milk production traits can be expected in next generation if type traits are paid more attention to