Palm Kernel Meal Protein Hydrolysates Enhance Post-Thawed Boar Sperm Quality

SIMPLE SUMMARY: Semen cryopreservation is associated with the production of reactive oxygen species, which leads to lipid peroxidation of sperm membranes, resulting in a reduction in sperm motility and decreased fertilizing ability. We investigated the effects of bioactive peptides from palm kernel meal protein hydrolysates (PKMPHs) on sperm viability, motility, acrosome and mitochondrial function in frozen–thawed boar semen. PKMPH improved the total motility, progressive motility, viability, acrosome integrity, and mitochondrial function of sperm and diminished lipid peroxidation. Therefore, we suggest that PKMPH plays a crucial role as an antioxidant during the freezing of boar sperm. ABSTRACT: Boar sperm is sensitive to particular conditions during cryopreservation, resulting in an extreme reduction in fertilizing ability due to damage to the sperm membranes. PKMPH contains bioactive peptides that have antioxidant and antimicrobial activities. There is no information on the use of palm-kernel-meal-derived bioactive peptides for boar semen cryopreservation. This study aimed to examine the effects of bioactive peptides from PKMPH on post-thawed boar sperm quality. Boar semen ejaculates (n = 17) were collected and divided into six equal aliquots based on PKMPH concentrations (0, 1.25, 2.5, 5, 10, and 15 µg/mL) in a freezing extender. Semen samples were processed and cryopreserved using the liquid nitrogen vapor method. Thereafter, the frozen semen samples were thawed at 50 °C for 12 s and evaluated for sperm motility using a computer-assisted sperm analyzer and for sperm viability, acrosome integrity, mitochondrial function, and lipid peroxidation by measuring the level of malondialdehyde (MDA). The results demonstrate that the supplementation of PKMPH with 2.5 µg/mL afforded superior post-thawed sperm qualities, such as increased total motility, viability, acrosome integrity, and mitochondrial function by 10.7%, 12.3%, 18.3%, and 12.7%, respectively, when compared to the control group. PKMPH at a concentration of 2.5 µg/mL showed the lowest level of MDA (40.6 ± 2.0 µMol/L) compared to the other groups. In conclusion, adding PKMPH peptides at 2.5 µg/mL to the freezing extender reduced the oxidative damage associated with cryopreservation and resulted in higher post-thawed sperm quality.