Analysis of Oestrus and Hormonal Changes in the Progeny of 2 Genotypes of FecB Gene-Edited Sheep.

The FecB gene, the first gene identified for multiple births, can improve reproductive performance in sheep. We used the CRISPR/Cas9 editing system to obtain the FecB gene in Kazakh sheep and mated with unedited Kazakh sheep. After the genotypic screening of the progeny, four B+ and ++ Kazakh ewes, each 2 weeks old and healthy, and close to the same body weight, were selected to study oestrus and hormonal changes in the progeny population of FecB gene-edited Kazakh sheep. Our results showed that the FecB gene was moderately polymorphic (0.25 < PIC < 0.5) in the progeny population, was able to be stably inherited, and showed increased lambing numbers. The number of follicles and tiny follicles differed significantly (p < 0.05) between the 2 genotypes of ewes in the progeny population. Physiologically, FecB gene-edited sheep did not differ from wild-type sheep. Throughout the oestrous cycle, FSH, LH, and E₂ in serum hormones of both sheep genotypes showed variability (p < 0.05) between 72-360 h, 360-528 h, and 12-72 h, respectively, compared to other periods. The concentration of FSH and PROG in follicular fluid was much higher than that of LH and E₂ (p < 0.05). Overall, it is possible to make Kazakh sheep carry the FecB gene by CRISPR/Cas9 editing and stably inherit it into the progeny population. The enhancement of reproductive hormones by the FecB gene is beneficial to follicular development and ovulation and improves the reproductive efficiency of sheep.