Genetic variants of the BMP2 and GDF9 genes and their associations with reproductive performance traits in Barki ewes

Abstract

• Two BMP2 variants and three GDF9 variants were identified in Barki ewes. • BMP2 variants were associated with TNLW and TWLW; however GDF9 variants were associated with twining rate, TNLB and TWLB. • Variation in ovine BMP2 and GDF9 affects reproductive performance traits of Barki ewes. The aim of this study was to investigate variation in the bone morphogenetic protein 2 ( BMP2 ) and growth differentiation factor 9 ( GDF9 ) genes, and ascertain whether it was associated with reproductive traits in Barki ewes. Records for conception rate of ewe, lambing number of ewe, lambing rate of ewe, twining rate of ewe, total number of lambs born per ewe (TNLB), total weight of lambs born per ewe (TWLB), total number of lambs weaned per ewe (TNLW), total weight of lambs weaned per ewe (TWLW) and ewe rearing ability were obtained for 296 Barki ewes. Polymerase chain reaction–single strand conformational polymorphism (PCR–SSCP) analyses were used to detect variation in exon 2 of BMP2 and exon 1 of GDF9 . The SSCP banding patterns for BMP2 revealed two variants ( A1 and A2 ), which contained one nucleotide sequence difference (c.962A > T). Three SSCP banding patterns ( C1 , C2 and C3 ) were observed for GDF9 and these contained two nucleotide-sequence differences (c.25C > T and c.260 G > A). Association analysis between the variation in BMP2 and GDF9 and reproductive performance traits revealed that BMP2 genotype was associated ( P < 0.05) with TNLW and TWLW, while GDF9 genotype was associated with twining rate of ewe ( P < 0.001), TNLB ( P < 0.001) and TWLB ( P < 0.05). This suggests that selection for the BMP2 and GDF9 genotypes might increase reproductive performance traits in Barki ewes.