级进杂交绵羊微卫星基因杂合度与生长性能的关系

利用10个微卫星基因座对陶赛特绵羊及其与新疆细毛羊级进杂交一代、二代和三代4个绵羊群体进行了遗传学检测，计算出各个群体的平均杂合度和平均生产性能的数值，分析群体杂合度与生产性能间的相关系数和变化趋势。结果表明：随级进杂交程度的增加，群体的杂合度逐渐降低，趋向于陶赛特群体的杂合度；微卫星标记杂合度与各个时期的体重、体高、体长和管围间呈正相关，其中杂合度与各个时期的体长呈显著正相关，而与各个时期的胸围呈负相关。微卫星基因杂合度对各个时期生长性能的相关效应在不同级进杂交群体问存在一定的差异。由此得到3点启示：（1）基因杂合度与生长性能间不是简单的相关关系；（2）级进杂交可使有害基因与中性标记连锁遗传，从而部分或全部抵消杂合优势的表现，甚至出现杂合劣势；（3）不同时期基因间的互作对于性状的作用是不一样的。

Relationship between microsatellite marker heterozygosity and growth capability in grading crossing sheep

The polymorphism of 10 microsatellites was analysed in the Dorset sheep and its grading crossing offspring F_1,F_2 and F_3 crossed with Xinjiang Fine Wool.Average heterozygosity and average growth capability,the correlation index and changing trend between microsatellite marker heterozygosity and growth capability were calculated in each group.The results showed that the average heterozygosity was gradually decreased and was regress to the value of Dorset according to grading crossing increasing.There was a significantly positive correlation between the microsatellite marker heterozygosity and body size in every phases,and negative to heart girth.There was a variable effect of the microsatellite marker heterozygosity on growth capacity in different grading crossing group.This suggests as following:(1)There is not a simple relationship between the microsatellite marker heterozygosity and the sheep growth performance.(2)Some deleterious alleles might be linked with neutral markers in the course of grading crossing and it can represent heterotic vigor or heterotic deficiencies among descendants in some cases.(3)There is variable influence of gene interactions on its trait in different stage.