奶牛体内超数排卵反应性状研究进展

A Review on in vivo Superovulation Response Trait in Dairy Cows

奶牛超数排卵与胚胎移植(multiple ovulation and embryo transfer,MOET)是现代奶牛养殖中的重要生物技术,MOET技术可加快牛群遗传改良速度。然而,不同供体母牛对超数排卵的反应(简称超排反应)存在较大差异,这限制了MOET技术的广泛应用。因此,探究供体母牛超排反应差异的形成原因并预测外源激素处理的效果,进而筛选合适的供体母牛是目前亟待解决的问题。母牛的超排反应受遗传影响,对母牛的超排反应性状进行选育或将大幅提高母牛超数排卵的效率。研究中通常将奶牛的超排反应性状定义为单次超数排卵获得的总胚胎数和可移植胚胎数,这类性状受季节、供体母牛月龄、超排程序及操作人员等非遗传因素的影响,是一类具有中低遗传力的新型繁殖性状,研究发现超排反应性状与多种调控繁殖激素表达及调控细胞生长分化的基因存在显著关联。在遗传育种领域,国内研究人员对奶牛超排反应性状的研究相对较少,目前仅有少量关于超排反应候选基因关联分析的报道。作者从性状定义、非遗传因素建模分析、遗传参数估计和候选基因挖掘鉴定等方面系统综述奶牛超排反应性状的研究进展,并对奶牛超排反应性状的遗传学研究和选育应用进行了展望。

In the modern dairy industry,the multiple ovulation and embryo transfer(MOET)is the key technology,which can significantly accelerate the genetic improvement of dairy population.However,there is a large variation in superovulation response among different donor cows,which is one of the major limitations for the widely applying of superovulation.Therefore,there is an urgent need to explore the causes of variation in superovulation response and to predict the effect of exogenous hormone treatment for donor cows so that suitable donors can be selected.In previous studies,it had been widely reported that the superovulation response trait is heritable in dairy cows,and that genetic selection can substantially improve superovulation efficiency.In general,superovulation response trait is defined as the total number of embryos as well as the number of transferable embryos.Superovulation response trait can be influenced by several factors,including season,donor age,procedure and operator.As a novel reproductive trait with low to medium heritability,it was found to be associated with several genes that regulate the expression of reproductive hormones and cell growth and differentiation.At present,there are relatively few studies on genetics and breeding of superovulation response trait in China,and only a few studies reported candidate genes associated with superovulation response trait.The author systematically reviewed the advance of superovulation response trait in dairy cattle,including the trait definition,modeling of non-genetic factors,estimation of genetic parameters,and identification of candidate genes.In addition,we also discussed the research methods and application of superovulation response trait in the future.