中国美利奴羊(新疆型)无角类型培育理论依据及测交试验结果

The Theoretical Foundation and Result of Test Cross in Breeding of Poll Chinese Merino(Xinjiang Type)

绵羊角的有无是由或主要由一个基因位点(Locus)上的三个等位基因(H、h′、h)所决定。三个等位基因的遗传方式是:H为显性无角基因,对h为完全显性,即Hh基因型均表现无角性状;h为隐性有角基因,即hh基因型均表现有角性状;h′为一个频率很低的基因,对h为不完全显性,即h′h基因型仍表现为有角性状;但H对h′基因为不完全显性,即Hh′基因型可能出现角痕(角突或角基)。而h′h′基因型公羊表现为小角、发育残缺不全的矫型角,母羊表现为无角。培育无角羊的关键是选择使用无角公羊,通过测交试验能确定无角公羊基因的纯合度,从而决定如何使用。

The presence or absence of horns can be attributed to the action of three alleles at an autosomal locus, H,h＇ and h. Poll allele H is dominant completely to horned allele h , and the phenotype of Hh is hornless; h is recessive, and the phenotype of hh is horned; h＇ with a lower frequency is dominant incompletely to h, the phenotype of h＇h is horned; H is dominant incompletely to h＇, the phenotypes of Hh＇ could be a small protuberance. The key of breeding poll merino is to select the poll rams by test cross.