Polymorphism Analysis of FecB and BMP15 Genes in Kenguri and Kenguri × NARI Suwarna Sheep
Abstract
Sheep production in India is constrained by low reproductive efficiency, with litter size being a major limiting factor in improving productivity. Prolificacy in sheep is largely regulated by fecundity genes such as Booroola fecundity (FecB/BMPR1B) and BMP15, which directly influence ovulation rate and litter size. The present investigation was carried out to detect polymorphisms in these two genes in Kenguri and Kenguri × NARI Suwarna (F1) sheep maintained at the Livestock Research and Information Centre, Veterinary College, Bidar. Blood samples were collected from 30 Kenguri and 30 crossbred sheep. Genomic DNA was isolated using the phenol–chloroform method and evaluated for purity and concentration. PCR amplification was performed using specific primers to amplify a 190 bpfragment of FecB and a 434 bpfragment of BMP15. The PCR products were subjected to restriction fragment length polymorphism (RFLP) using AvaII and StuI restriction enzymes, respectively, and separated by agarose gel electrophoresis. In Kenguri sheep, the FecB locus was monomorphic, with all animals showing the wild-type (++) genotype. However, in the Kenguri × NARI Suwarna (F1) crossbred population, three genotypes were identified: BB (0.16), B+ (0.50), and ++ (0.34). The corresponding allele frequencies were B = 0.41 and + = 0.59. A Chi-square test for Hardy–Weinberg equilibrium revealed significant deviation (χ² = 7.82, p < 0.05) in the crossbred group, indicating possible selection pressure, genetic drift, or non-random mating. At the BMP15 locus, no polymorphism was detected, and all animals across both populations were found to be monomorphic for the wild-type allele. The results clearly demonstrate the successful introgression of the FecB allele through crossbreeding with the NARI Suwarna strain, thereby enhancing the genetic potential for higher prolificacy in Kenguri sheep. These findings provide molecular evidence supporting the role of targeted crossbreeding in improving reproductive traits. The absence of variability at the BMP15 locus suggests that FecB plays a more prominent role in this population.
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Introduction
The livestock sector is an important sub-sector of Indian agriculture, contributing significantly to rural livelihoods and national GDP. Although the share of agriculture in the national GDP has been declining, the livestock sector has shown steady growth, contributing about 3.9% to total GDP and nearly 24% to agricultural GDP). Among livestock, sheep occupy an important position, contributing meat, wool, and skin. India has more than 65 million sheep, yet per-animal productivity remains low, mainly due to poor reproductive efficiency.
Prolificacy, or the ability of ewes to produce multiple offspring per lambing, is a key trait influencing mutton production. However, most indigenous Indian breeds are characterized by low twinning rates, thereby limiting productivity (Jain et al., 2006a). The discovery of fecundity genes has opened new opportunities for improving reproductive traits through marker-assisted selection (MAS). Among these, FecB (BMPR1B) and BMP15 are the most studied. Mutations in these genes are known to increase ovulation rate and litter size in several prolific breeds such as Booroola Merino, Garole, and Husheep (Mulsant et al., 2001; Wilson et al., 2001; Davis, 2005).
Kenguri is a medium-sized sheep breed of northern Karnataka, valued for mutton production but known to have very low prolificacy. By contrast, NARI Suwarna, a crossbred strain developed by introgression of the FecB mutation from Garole sheep into Deccani sheep, has demonstrated a 33% increase in productivity due to higher litter size (Appannavar et al., 2010). Crossbreeding of Kenguri with NARI Suwarna offers potential to introduce the FecB mutation into the Kenguri population. Therefore, the present study was designed with the objective of detecting polymorphisms in FecB and BMP15 genes in Kenguri and Kenguri × NARI Suwarna (F1) sheep using PCR-RFLP, and to estimate genotypic and allelic frequencies along with Hardy–Weinberg equilibrium.
Conclusion
This study confirms the absence of the FecB mutation in purebred Kenguri sheep and its successful introgression into Kenguri × NARI Suwarna (F1) sheep. The presence of three genotypes at the FecB locus in crossbred animals, along with significant deviation from Hardy–Weinberg equilibrium, suggests ongoing selection pressure. The BMP15 locus was monomorphic in both populations. These findings provide a molecular basis for incorporating FecB-based marker-assisted selection inbreeding strategies aimed at enhancing reproductive efficiency in Kenguri sheep. Future studies involving larger populations and direct association with reproductive performance traits are essential to validate these findings and ensure sustainable genetic improvement.
CONFLICT OF INTEREST Author declares no conflict of interest.
