新疆地区西门塔尔牛核心群选择

Selection of Nucleus Herd for Simmental Cattle in Xinjiang Area

【目的】多年来新疆地区西门塔尔牛的遗传改良取得一定的成效,但遗传评估工作开展较少。为加快西门塔尔牛的遗传进展,本研究通过对西门塔尔牛主要经济性状进行遗传评定、遗传趋势的分析、组建核心群并对比总性能指数(total performance index,TPI)选择和单性状选择的差异,旨在为今后制定和优化适合新疆地区西门塔尔牛的育种方案提供理论依据。【方法】本研究以新疆呼图壁种牛场1974—2014年出生的2 495头西门塔尔牛母牛生产性能记录、DHI测定记录、成母牛体重及外貌鉴定记录为研究对象,运用DMU软件采用AI-REML结合EM算法配合多性状动物模型对305 d产奶量(305MY)、乳脂率(MFP)、乳蛋白率(MPP)、乳糖率(MLP)、总固体(TS)、体细胞数(SCS)、成母牛体重(MCW)和外貌评分(TC)性状进行方差组分和育种值估计,并对305 d产奶量、乳脂率、乳蛋白率、体细胞数和成母牛体重性状进行遗传趋势分析,最终通过总性能指数公式对该牧场种公牛进行遗传评价及筛选核心母牛群。【结果】西门塔尔牛305MY、MFP、MPP、MLP、TS、SCS、MCW和TC的遗传力分别为0.39、0.15、0.12、0.12、0.32、0.09、0.60、0.19,305MY、TS和MCW属于高遗传力(h2>0.3),MFP、MPP、MLP和TC属于中等遗传力(0.1<h2<0.3),SCS属于低遗传力(h2<0.1)。对西门塔尔牛各性状遗传趋势进行分析,1974—2007年间305MY性状遗传趋势变化不明显,2008—2012年呈明显的上升趋势;1974—2006年间MFP和MPP这两个性状遗传趋势略呈下降的趋势,2007—2013年呈明显的上升趋势;1974—2000年间SCS性状的遗传趋势呈上升趋势,2001—2012年间遗传趋势总体呈下升趋势;1974—2007年间MCW性状的遗传趋势上下波动较大,2008—2011年间呈明显的上升趋势。根据中国西门塔尔牛总性能指数公式对种公牛、大群母牛群和在群母牛群进行育种值排队,其中排在第一位的公牛TPI值为552.45,排在前10位的公牛平均TPI值为383.41,从在群母牛中筛选出100头核心母牛群平均TPI值为214.91,100头核心群母牛305MY、MFP、MCW和TC表型值均值分别为7 095.10 kg、4.13%、696.53 kg和76.73,与在群母牛群平均表型值相比要高。通过对比不同分组305MY性状选择、MPP性状选择和TPI选择各性状育种值的差异,得出TPI选择要优于单性状选择。【结论】近年来西门塔尔牛305MY、MPF、MPP和MCW育种值明显增加,SCS呈下降趋势,进一步证明对西门塔尔牛选育及遗传改良取得了一定的成果。通过比较TPI选择和单性状选择的差异,证明了在生产实践中综合选择指数更实用,牧场可加大TPI值高的种公牛的使用程度,并以100头核心母牛群为基础,扩群,通过选择优秀的公牛进行繁育、扩群,从而达到提高全群西门塔尔牛生产指标的目的。

【Objective】In recent years,the genetic improvement of Simmental cattle in Xinjiang has achieved certain effects,however,the genetic evaluation work has been carried out less.In order to accelerate the genetic progress of Simmental cattle,this study aims to constitute and optimize the suitable breeding program of Simmental cattle in Xinjiang by using genetic evaluation,combined with genetic trend analysis to select nucleus herd and compare the results of TPI selection and single-trait selection.【Method】The research date including the production performance records,DHI testing,mature cow weight and type classification records of 2 495 Simmental cattles,were collected from Xinjiang Hutubi Herd farm during 1974 to 2014.The DMU software was applied together with AI-REML of EM algorithm and multiple-trait animal models to estimate the variance components and breeding values of 305 MY,MFP,MPP,MLP,TS,SCS,MCW and TC.The genetic trend analysis was perfromed in 305 MY,MFP,MPP,SCS and MCW.Finally,bulls and nucleus herd cows were selected by TPI.【Result】The results showed that Simmental cattle heritabilities of 305 MY,MFP,MPP,MLP,TS,SCS,MCW and TC were 0.39,0.15,0.12,0.12,0.32,0.09,0.60,0.19,respectively.305 MY,TS and MCW were high heritability(h2>0.3);MFP,MPP,MLP and TC were medium heritability(0.1<h2<0.3),and SCS was low heritability(h2<0.1).Genetic trend of 305 MY did not change significantly from 1974 to 2007,and appeared obviously increasing trend from 2008 to 2012.Between 1974 and 2006,genetic trends of MFP and MPP showed a slightly downward trend,and appeared obviously increasing trend from 2007 to 2013.Genetic trend of SCS appeared obviously increasing trend from 1974 to 2000,and an upward trend from 2001 to 2012 is shown.Genetic trend of MCW had a big fluctuation from 1974 to 2007,and appeared obviously increasing trend from 2008 to 2011.Breeding values for bulls and herd cows were ranked according to total performance index.The TPI value of the first bull was 552.45,and average of top 10 bulls was 383.41.Average TPI value of 100 nucleus herd cows was214.91.Average value of 305 MY,MFP,MCW and TC phenotype values of 100 Average TPI value of 100 nucleus herd cows were7 095.10 kg,4.13%,696.53 kg and 76.73,respectively,which was higher than average of phenotype value in herd cows.The breeding values appeared to be different among single-trait selection and TPI.It is concluded that TPI selection was better than single-trait selection.【Conclusion】Recently,gentic trends of 305 MY,MPF,MPP and MCW of Simmental cattle were appeared obviously increasing trend,and SCS was a downward trend,which further proved that breeding and genetic improvement of Simmental cattle had achieved certain results.By comparing the differences between TPI selection and single-trait selection,it is proved that selection index was more practical in production,and farm will use more bulls with high TPI values.And the population of cattle group will be expanded on the basis of 100 nucleus herd cows.By selecting excellent bulls for breeding and expanding group,the purpose was improved production of the whole group in Simmental cattle.