Adding bovine seminal plasma prior to freezing improves post-thaw bull sperm kinematics but decreases mitochondrial activity.

Variations in fertility between bulls with comparable sperm quality could be due to differences in their seminal plasma (SP). The aim of this study was to investigate the effect of adding bovine SP from bulls of known fertility to SP-free sperm samples. After removal of SP by Single Layer Centrifugation, resuspended sperm pellets were treated with SP from high or low fertility bulls at 0% (control), 1%, or 5% before freezing. Sperm quality was evaluated after thawing. Data were analyzed using Proc MIXED, SAS®. Bovine SP at 1% or 5% SP1 and SP5, respectively, decreased average path velocity, curvilinear velocity, and amplitude of lateral head displacement whereas wobble and linearity were increased. In addition, the proportion of spermatozoa with high mitochondrial membrane potential (MMP) was lowest for treatment with SP5 compared to SP1 and control. The proportion of SP did not affect other parameters of sperm quality. Thus, adding 5% bovine SP produced a favorable effect on some sperm velocity parameters but had an unfavorable effect on MMP. There were no differences in effect between SP from high and low fertility bulls.

ABBREVIATIONS: AI: artificial insemination; BCF: beat cross frequency; CASA: computer-assisted sperm analysis; IVF: in vitro fertilization; MMP: mitochondrial membrane potential; SLC: single layer centrifugation; SP: seminal plasma.