The Shift Toward Antibiotic‐Free Semen Extenders: Innovative Uses of Natural Substances in Ruminant Sperm Cryopreservation

ABSTRACT Advancing liquid storage and cryopreservation technologies for ruminant semen is fundamental to the sustainability and genetic progress of the global livestock industry. Current preservation strategies typically involve three thermal approaches: ambient temperature storage, chilled (5°C) preservation, and cryopreservation (−196°C). However, the efficacy of these methods is frequently undermined by bacterial contamination, which serves as a primary limiting factor that compromises spermatozoal integrity and reduces the shelf‐life of processed semen. The proliferation of bacteria within semen induces significant structural and functional degradation of the spermatozoa. While traditional antibiotic supplementation in cryopreservation media effectively reduces microbial loads, tightening global regulatory restrictions and the emergence of multi‐drug resistance have prompted a shift in preservation strategies. Consequently, the integration of natural bioactive compounds as antimicrobial alternatives offers a sustainable, cost‐effective, and ecologically sound approach for maintaining semen quality and biosecurity. This review critically evaluates the inherent limitations and challenges associated with traditional antibiotic supplementation in the cryopreservation media of various livestock species. Beyond evaluating current shortcomings, we explore the therapeutic potential of natural bioactive molecules as viable antimicrobial substitutes, with a specific focus on their synergistic effects on sperm functionality, ultra‐structural integrity, and metabolic parameters. Additionally, we examine the dynamics of the seminal microbiome, analysing how species‐specific traits, seasonal fluctuations, and environmental variables influence microbial profiles. Ultimately, this review synthesizes the application of natural alternatives as a sustainable and environmentally innovative paradigm for optimizing assisted reproductive technologies and enhancing the global biosecurity of germplasm preservation.