Identifying Key Genetic Factors Influencing Reproductive Performance in Dairy and Meat Sheep Breeds of the Mediterranean Region

This study aimed to detect genetic variations in key genes (BMPR1B, BMP15 and GDF9) that influence crucial reproductive traits, such as lambing rate and litter size in sheep. Understanding the genetic basis of these traits is essential for developing more efficient breeding strategies and selecting superior breeding stock, ultimately contributing to improved reproductive efficiency across different sheep breeds, production purposes and farming systems. We examined polymorphisms in the above genes across 500 adult ewes from three Mediterranean countries. The studied breeds included high-yielding dairy (Sarda), dual-purpose with a meat focus (Awassi) and medium-to-low dairy and meat breeds (Slovenian Bovška, Istrian Pramenka and Jezersko-Solčavska). Genetic variations were analysed and correlated with reproductive efficiency, including the interval in days from ram introduction to lambing based on lambing dates. This was used to assess the potential influence of these genes on follicular maturation and oocyte developmental competence. The analysis identified 15 polymorphisms distributed differently among the breeds, with the Sarda exhibiting 11 SNPs and the Awassi 13. The Slovenian breeds showed distinct genetic variation patterns potentially linked to their production goals. However, no significant association was observed between the identified polymorphisms and the analysed reproductive traits. Further studies on other genes regulating bone morphogenetic protein expression, such as the Gremlin 1 (GREM1) gene, may provide additional insights into the genetic mechanisms underlying reproductive traits.