Equine chorionic gonadotropin (eCG) and GDF9 gene on the reproductive performance of Katahdin sheep

Abstract

Objective. To determine the influence of equine chorionic gonadotropin (eCG) application and the presence of exon 2 of the GDF9 gene on reproductive variables in Katahdin sheep in the transition period. Materials and methods. 63 sheep with average age and weight of 2.83 ± 0.89 years and 45.32 ± 5.44 kg, respectively, were used. A 2x2 factorial arrangement under a completely randomized design was used, where the factors and levels were: the absence or presence of exon 2 of the GDF9 gene and the application or not of the eCG hormone in the synchronization protocol. Results. The application of eCG showed a significant favorable effect on the reproductive behavior of sheep, but not for the presence of exon 2 of the GDF9 gene. Treatments T2 and T4 were superior in the variables % of gestation, % of lambing, fertility and prolificacy with respect to T1 and T3. The best reproductive response was obtained with the application of eCG regardless of the presence or absence of the gene. Conclusions. This study shows evidence of the null interaction of exon 2 of the GDF9 gene and eCG to improve the reproductive performance of sheep. The application of eCG is recommended in estrus synchronization protocols for Kathadin sheep in the transition period. Faced with the few genomic reports on Katahdin ewes, evidence is shown of the need to carry out other research on genetic variants and their relationship with reproduction in sheep.