Two mutations affecting the ovulation rate and litter size are segregating in Olkuska sheep population, FecX^O in the BMP15 gene, and the G7 site mutation in GDF9 gene. Homozygous carriers of both mutations are hyperprolific, contrary to the sterility observed in homozygous carriers of most other BMP15 and GDF9 mutations. The objective of this study was to assess frequency and phenotypic effects of both mutations. Blood samples were obtained from 740 individuals, 111 rams and 629 ewes, out of which 91 rams and 561 ewes were successfully genotyped for the BMP15 and GDF9 loci. The reproductive performance included a number of lambs born/born alive and a number of lambs reared until 60 days of age, and for a subset of ewe ovulation rates. The study proved a high frequency of the FecX^O mutation in two flocks that have been selected for many years for increased litter size (0.7–1.0 in breeding ewes and rams respectively), and a moderate frequency in another 19 private flocks (0.4–0.5). The frequency of the GDF9 mutation was low, with only 50 sheep out of 312 genotyped being carriers of the GDF9/G7 mutation, including three homozygous carriers. The FecX^O mutation in the BMP15 had a significant effect on both litter size and the ovulation rate. The single copy in heterozygous carriers increased litter size by 0.255 (0.063), while the effect of two copies in homozygous genotypes was +0.874 (0.081) lambs born. Due to the low frequency of the GDF9 mutation, it can only be preliminarily concluded that litter size has been increased in double carriers of both the BM15 and GDF9 mutation, which may suggest their additive interaction. The positive effect of both mutations supports their direct use in selection programmes.

中文翻译：

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奥尔库斯卡绵羊群体中BMP15和GDF9突变的频率增加其产仔数及其表型效应

影响排卵率和产仔数的两个突变在Olkuska绵羊种群中分离，BMP15基因中的FecX ^O和GDF9基因中的G7位点突变。与大多数其他BMP15和GDF9突变的纯合子中观察到的不育性相反，这两个突变的纯合子子是高产的。这项研究的目的是评估两个突变的频率和表型效应。从740名个体，111头公羊和629头母羊获得了血液样本，其中成功对BMP15和GDF9基因座进行了91头公羊和561母羊的基因分型。繁殖性能包括许多出生/活着的羔羊，以及一些饲养到60天龄的羔羊，以及部分母羊排卵率。研究证明FecX ^O的频率很高多年以来被选择用于增加产仔量的两个鸡群的突变（种母羊和公羊分别为0.7–1.0），另外19个私人鸡群的突变频率适中（0.4–0.5）。GDF9突变的频率很低，在312个基因分型中，只有50只绵羊是GDF9 / G7突变的携带者，其中包括3个纯合携带者。FecX ^OBMP15中的突变对产仔数和排卵率都有显着影响。杂合子携带者的单拷贝产仔数增加了0.255（0.063），而纯合子基因型中的两个拷贝的影响是+0.874（0.081）出生的羔羊。由于GDF9突变的频率较低，只能初步得出结论，BM15和GDF9突变的双携带者的产仔数都增加了，这可能表明它们具有加性相互作用。两种突变的积极作用都支持它们直接用于选择程序。