Semen extenders in caprine reproduction: Composition, application and future prospects

Abstract

Semen extenders are indispensable in the cryopreservation and Artificial Insemination (AI) of semen, playing a critical role in maintaining sperm viability, motility, and fertilizing ability during storage and transport. Semen extenders are composed of various functional components, including cryoprotectants (e.g., glycerol, DMSO), buffers, energy sources, membrane stabilizers like egg yolk or soy lecithin, and antibiotics, each contributing to the preservation of sperm structure and function during the freeze-thaw process. But goat semen presents unique challenges due to the presence of seminal plasma enzymes like phospholipase A and proteases, which interact negatively with extender components egg yolk and skim milk-based extenders, leading to reduced sperm quality. This enzymatic activity results in the formation of toxic by-products that compromise membrane integrity and motility.This review presents a comprehensive analysis of the composition, functions, and species-specific applications of semen extenders in goats, highlighting both challenges and recent advances in this domain. It explores species-specific extender formulations tailored to goat sperm physiology and the latest developments, including antioxidant-enriched and vitrification-based approaches to minimize oxidative and cryo-damage