Genetic variants of the bone morphogenetic protein gene and its association with estrogen and progesterone levels with litter size in Awassi ewes

Abstract

This research aimed to assess the genetic polymorphism of the BMP15 gene concerning sex hormone levels and birth type in Awassi ewes. The genome DNA of 138 Awassi ewes was isolated (52 ewes produced a singleton and 86 produced twins). The BMP15 gene exon-2 was amplifiable by polymerase chain reaction (PCR), so two genotypes were identified based on 141 bp amplicons: TT and TA. A sequencing reaction revealed a novel mutation, c.50980646T>A, in the TA genotype. This single nucleotide polymorphism (SNP) showed a high association (P≤0.01) with sex hormone levels and litter size, sheep containing this SNP had higher levels of sex hormones and larger litter sizes than sheep without it. Ewes with the TA genotype had a 1.89 litter size than their TT counterparts. Logistic regression confirmed that the c.50980646T>A SNP increased litter size. In conclusion, the c.50980646T>A SNP appears to be significantly related to reproductive traits (especially sex hormone levels and litter size) in Awassi sheep. With these results, mutations of the BMP15 gene are suitable for developing marker-assisted selection programs to increase Awassi sheep litter size.