Integrative assessment of gamete and embryo quality in porcine in vitro production: A comprehensive review

Despite significant progress in porcine in vitro embryo production (IVP), major challenges persist, particularly regarding the biological quality and developmental competence of gametes and embryos produced in vitro . The lack of standardised and objective evaluation criteria continues to limit the efficiency, reproducibility, and translational value of porcine assisted reproductive technologies (ART). This review provides a comprehensive synthesis of current methodologies used to assess oocyte, sperm, and embryo quality in pigs, integrating insights from other mammalian models to highlight common principles and species-specific challenges. Oocyte competence remains a key determinant of IVP success, yet its assessment is hindered by variable maturation efficiency, polyspermy, and inconsistent handling procedures. Emerging approaches such as advanced imaging, metabolomics, and single-cell transcriptomics show potential for non-invasive and dynamic evaluation of oocyte quality, but their routine implementation in routine practice requires further validation and inter-laboratory standardisation. Similarly, improving sperm assessment requires moving beyond traditional parameters such as motility and morphology toward integrative frameworks that incorporate molecular, biochemical, and imaging-based markers of functionality. The strong link between gamete quality and fertilisation outcomes highlights the need for harmonised protocols and validated species-specific biomarkers to ensure reproducibility across laboratories. At the embryonic level, the development of multiparametric, data-driven frameworks combining morphological, metabolic, and molecular indicators represents a pivotal step toward objective embryo quality assessment. Although artificial intelligence, high-throughput omics, and machine learning hold great promise, their adoption will depend on rigorous validation, cost-effectiveness, and standardisation to minimise operator-dependent variability and guarantee reproducibility. Ultimately, advancing porcine IVP will depend on integrating biological insights with technological innovations through non-invasive tools and robust quality control systems adapted to the species unique physiological characteristics. This convergence offers a pathway toward more efficient, reproducible, and predictive ART in pigs, with broad implications for animal breeding, genetic preservation, and translational biomedical research. • Persistent lack of standardised criteria limits reproducibility in porcine IVP systems. • Comprehensive synthesis of morphological, biochemical, and molecular quality markers. • Emerging non-invasive tools: imaging, metabolomics, and AI-based embryo assessment. • Proposal of a multiparametric framework for gamete and embryo quality control. • Harmonisation strategies to boost efficiency and translational value.