Improved reproductive outcomes and metabolomic profiles in swine induced by red light-treated semen†

This study investigated the effects of red light-emitting diodes (LED) light exposure on boar semen quality, sperm metabolism, and reproductive performance in sows. A total of 60 semen samples were collected from Duroc boars and randomly assigned to 6 light treatment procedures and a control. Among these, Procedure #1 (red light for 13 min-dark for 10 min-red light for 13 min) significantly improved sperm motility indicators, particularly reducing the amplitude of lateral head displacement and enhancing beat-cross frequency over time (P < 0.05). Flow cytometry analysis revealed that this procedure preserved mitochondrial membrane potential and acrosome integrity. A large-scale field trial involving 1499 sows across four breeds demonstrated that insemination using red light-treated semen (Procedure #1) significantly increased pregnancy and delivery rates in Large White and Yorkshire sows, along with higher litter birth weight, total number born, and number born alive (P < 0.05). Untargeted liquid chromatography-tandem mass spectrometry metabolomics identified 60 differential metabolites and revealed distinct clustering between treated and control groups. Enrichment and receiver operating characteristic analyses highlighted key altered pathways, including retinol metabolism, fatty acid degradation, sphingolipid metabolism, and arachidonic acid metabolism. Metabolites such as vitamin A, palmitoylcarnitine, psychosine, and prostaglandin E2 showed potential as biomarkers of red-light exposure. These findings suggest that optimized red LED exposure enhances boar semen quality and sow reproductive outcomes by modulating sperm motility and metabolic profiles, offering a novel strategy to improve reproductive efficiency in swine production.