LAUSR

This study aimed to determine how melatonin (MT) and seminal plasma affected the freezability of buck sperm during the nonbreeding season. Semen was collected from eight bucks before (pre-MT) and after (post-MT) MT application in the nonbreeding season. Individual ejaculates were collected from the bucks, split into two equal groups according to the removal of seminal plasma (SP) (-) or nonremoval of SP (+). For washing, the groups of ejaculates were centrifuged, and the supernatant was separated, SP (-) and SP (+) ejaculates were diluted, then frozen. Semen samples were examined for sperm motility, plasma membrane integrity, defective acrosomes, DNA fragmentation, and mitochondrial membrane function at the native and post-thaw stages. When the general average post-thaw motility (p < 0.01), plasma membrane (p < 0.05), acrosome (p < 0.05), and DNA integrity rates (p < 0.05) and mitochondrial membrane potential (MMP) (p < 0.01) were evaluated, it was seen that MT administration caused a statistically significant improvement. The dramatic effect of nonremoval of seminal plasma on motility and plasma membrane integrity is more clearly observed in individual semen samples frozen in the pre-MT group (p < 0.05). Also, it was observed that removing seminal plasma in the post-MT group caused even milder post-thaw acrosome damage compared with the SP (+) group (p < 0.05). The effect of removing seminal plasma was not observed in terms of DNA integrity and MMP rates in pre- and post-MT groups. As a result, it was concluded that MT application and removal of seminal plasma in the nonbreeding season result in improvement in the freezability of buck semen.