Comparative Analysis of In Vitro Aging in Liquid‐Preserved Boar and Bull Semen Stored at 5°C and 16°C

BACKGROUND: Although the prolonged liquid preservation of porcine and bovine semen is an attractive alternative to cryopreservation, the quality of the semen deteriorates over time due to in vitro aging. OBJECTIVE: To investigate the in vitro aging of porcine and bovine sperm after prolonged liquid preservation at 5°C and 16°C. MATERIALS AND METHODS: /mL sperm) were divided into two portions, which were stored at 5°C and 16°C for 6 days. Basic sperm quality parameters, such as progressive motility, thermo-resistance after 30 (TRT30) and 120 (TRT120) min at 38°C, and sperm morphology, as well as advanced multicolor assays, were examined on Days 1, 3, and 6 to evaluate viability, acrosome integrity, plasma membrane fluidity, intracellular calcium levels, and mitochondrial membrane potential. The data analysis was done using a general linear model (GLM) with repeated measures. RESULTS: Compared to 5°C, boar semen showed significantly higher values for TRT120, viable and acrosome-intact sperm with low membrane fluidity and intracellular calcium (VAI-LMLC), and VAI with high mitochondrial membrane potential (VAI-HMMP) at 16°C. Bull semen demonstrated superior quality when stored at 5°C. The GLM revealed significantly higher values for TRT30, TRT120, morphology and VAI on Day 3 at 5°C compared to 16°C. Over the course of all storage days, the mean values of VAI-LMLC and VAI-HMMP were significantly higher at 5°C. DISCUSSION AND CONCLUSION: Although basic semen quality could be maintained for 6 days in liquid-preserved boar and bull semen, advanced semen quality parameters revealed differences in the in vitro aging of boar and bull sperm that were specific to species and storage temperature.