Abstract:

[Objective] The present study was conducted to assess the effects of FecB gene on lambing performance of Dorper sheep and Small Tail Han sheep crossbred ewes and production performance of their offsprings. [Method] The athwart cross fixed ewes produced by the crossbred sheep of Dorper rams and Small Tail Han ewes were used as the research objects. The FecB genotypes of different generations of the athwart cross fixed ewes were detected, and the lambing performance of those of varied FecB genotypes as well as the production performance of their offsprings were statistically compared. [Result] The genotypes of BB, B+ and ++ were observed in the F1, F2, F3 and F4 generations of the athwart cross fixed ewes, and the homozygous BB genotype frequency was elevated as the increase of generations of athwart cross fixation. The F1, F2 and F3 generations of the athwart cross fixed ewes of BB genotype had significantly （P<0.05） higher average litter size than their counterparts of B+ genotype, and the average litter size showed an upward trend as the increase of the BB genotype frequency. The average lambing rate of the F1 and F2 generations of the athwart cross fixed ewes was lower in comparison to that of the Small Tail Han ewes, while the F3 generation of the athwart cross fixed ewes had higher average lambing rate than the Small Tail Han ewes as well as the F1 and F2 generations of the athwart cross fixed ewes. In terms of the production performance of the neonatal offsprings, the birth weight of the offsprings produced by the F3 generation of the athwart cross fixed ewes of BB genotype was significantly （P<0.05） lower than that of the offsprings produced by their counterparts of B+ genotype, and no significant （P>0.05） differences in body height, body length and chest circumference were observed between them. In terms of the production performance of the weaned offsprings, the body weight, body length and chest circumference of the offsprings produced by the F3 generation of the athwart cross fixed ewes of BB genotype were not significantly （P>0.05） different from those of the offsprings produced by their counterparts of B+ genotype, while the former had significantly （P<0.05） lower body height than the later. [Conclusion] FecB gene significantly and favorably affects the lambing performance of the crossbred ewes of Dorper sheep and Small Tail Han sheep, and it has great application value in selection of polytocous ewes.

Key words: FecB gene, athwart cross fixed offsprings of Dorper sheep and Small Tail Han sheep, lambing performance, production performance