Effects of Novel Mutations in the Gene on Litter Size in Gobi Short Tail Sheep and Sonid Sheep.

Increasing the litter size in sheep is a primary objective in breeding programs, driving sustained interest in identifying candidate functional genes and molecular markers associated with fecundity. The known FecD mutation in the gene has been shown to regulate reproductive traits by influencing the ovulation rate of Davisdale sheep. However, the relationship between single-nucleotide polymorphisms (SNPs) in the and litter size remains unknown in Gobi short tail sheep and Sonid sheep. In this research, we found one novel variant and thirteen known variants through direct sequencing in Sonid sheep and Gobi short tail sheep and performed an association study in a large-scale population. The association analysis identified two SNPs (c.240C>T (rs159694506) and c.279C>T (rs159694508)) with significant litter size associations in Gobi short tail sheep ( < 0.01 ). In Sonid sheep, the c.240C>T (rs159694506), c.279C>T (rs159694508), g.41249772C>T (rs412130067), g.41249873A>C (rs425490800), g.41250357T>C (rs424307284), and g.41250358T>C (rs404651806) SNPs were significantly associated with litter size ( < 0.05 ). In addition, in GB sheep, the frequency of the litter-size-associated C allele at the c.240C>T (rs159694506) and c.279C>T (rs159694508) variants were significantly lower than that in Sonid sheep (SN), Mongolia sheep (MG), Ujimqin sheep (UM), Tan sheep (Tan), Hu sheep (Hu), and Small-tailed Han sheep (STH) populations. In SN sheep, the frequency of the litter-size-associated C allele at the c.240C>T (rs159694506) and c.279C>T (rs159694508) variant was significantly lower than that in the DPU. These findings provided valuable molecular markers pertinent to the fecundity of sheep, offering scientific evidence for the genetic improvement of these breeds.