Breed differences in seminal plasma chemistry; Implications for
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Seminal plasma serves as a nutrient rich medium for spermatozoa to function and survive. Several components of seminal plasma have also been shown to aid in cryopreservation and post-thaw viability. Although functions and roles of seminal plasma have been studied at length, the actual biochemical composition of sperm cells is poorly understood. In the present study, intra-species comparison of lipids, carbohydrates, and proteins present in sperm were examined in the bovine. Experiments were done in an effort to determine how cryopreservation may be affected by altering the level of cryoprotectant present in a sample based on baseline seminal composition of that particular specie. A wide variety of bovine breeds were used, representing both British and continental beef breeds as well as dairy. A portion of each sample was centrifuged to remove the cellular portion of the sample and both aliquots weighed to determine the cellular component’s contribution to weight of the sample. Results demonstrated a significant weight gain in equal volumes of each animal’s seminal plasma once the cellular component was removed (P < 0.001). Samples were then subjected to protein, carbohydrate, and lipid analysis. Each sample was run under spectrophotometric assay and blood chemistry assay cartridges to compare and contrast testing techniques. Differences in testing technique were detected in triglycerides and total protein levels (P = 0.023 and P = 0.018). Further, breed differences were also shown to be significant (α = 0.05) in triglycerides, glucose, total protein, and fructose (P = 0.001, P = 0.001, P = 0.001, and P = 0.009). However, no significant differences were seen between breeds for cholesterol (P = 0.228), as well as no differences detected in testing technique in cholesterol and glucose (P = 0.648 and P = 0.884 respectively). A non-linear correlation was observed between volume weights and total protein and triglyceride levels (P = 0.047 and P = 0.003). Together, these data suggest a difference in seminal component of various breeds and potentially on an individual basis as well. Further study is needed in order to examine how differences in seminal plasma chemistry effect cryopreservation and if it is possible to adjust cryoprotectant level in an effort to improve post-thaw viability of cryopreserved bovine semen.