Reproductive performance and fertility traits in Madrasin cattle: The influence of growth differentiation factor-9 gene expression on reproductive tract size, cervical mucus characteristics, and fertility rate

Background and Aim: The growth differentiation factor-9 (GDF-9) gene is recognized as a critical regulator of ovarian function and fertility in cattle. However, its role in crossbred populations, particularly Madrasin cattle (Madura × Simmental cross), remains underexplored. Understanding the genetic underpinnings of fertility traits in this crossbreed could provide valuable insights for improving reproductive efficiency in Indonesia’s livestock sector. This study aimed to investigate the relationship between GDF-9 gene expression and reproductive traits, specifically reproductive tract size (RTS), cervical mucus characteristics, and fertility rate, in Madrasin cows. Materials and Methods: A total of 20 Madrasin cows (aged 2–5 years) were evaluated. GDF-9 expression levels were assessed through polymerase chain reaction, and samples were categorized into “Strong Expression” (G1) and “Dimmed Expression” (G2) groups based on amplicon band intensity. Reproductive tract dimensions were recorded through rectal palpation, while cervical mucus quality was analyzed using five parameters: appearance, viscosity, spinnbarkeit, pH, and fern pattern. Fertility was determined by the non-return rate (NRR) following artificial insemination. Statistical analysis was conducted using analysis of variance with a significance threshold of p < 0.05. Results: Cows in the strong GDF-9 expression group exhibited significantly larger uterine horn diameters and greater ovarian height than the dimmed group (p < 0.05). Cervical mucus from G1 animals displayed higher scores in appearance and spinnbarkeit, although only appearance was statistically significant. NRR was notably higher in G1 (p < 0.05), suggesting enhanced fertility in cows with elevated GDF-9 expression. Conclusion: GDF-9 gene expression in Madrasin cattle is positively associated with RTS and fertility-related cervical mucus characteristics. These findings suggest that GDF-9 could serve as a promising genetic marker for improving fertility and breeding outcomes in crossbred cattle populations. However, the study’s limited sample size and exclusion of environmental factors warrant further investigation to validate the utility of GDF-9 in broader genetic selection strategies.