Seminal plasma and serum fertility biomarkers in Ossimi rams and their relationship with functional membrane integrity and morphology of spermatozoa

Abstract

This study aimed to explore some fertility biomarkers in seminal plasma (SP) and blood of rams with different field fertility, based on their conception and lambing rates. Ejaculates were collected from fertile (n = 20) and subfertile (n = 10) Ossimi rams by electroejaculation for 16 replicates. Each ejaculate was analyzed for volume and sperm characteristics before centrifugation at 12,000 × g for 30 min at 4 °C to collect SP. Blood samples were collected from all rams and centrifuged to collect serum which was frozen stored at – 30 °C until analysis. Seminal and serum levels of superoxide dismutase, nitric oxide, testosterone, thyroxin and malondialdehyde as well as seminal fructose and serum glucose were determined. Ovine SP proteins were extracted and separated by gel electrophoresis. Both ejaculate volume (P < 0.05) and % hypo-osmotic swelling test (HOST)-positive spermatozoa (P < 0.001) were greater in fertile than subfertile rams. On the other hand, stimulation time (P < 0.05) and % abnormal spermatozoa (P < 0.0001) were greater in subfertile than fertile rams. Intriguingly, seminal and serum levels of superoxide dismutase, nitric oxide, testosterone and thyroxin as well as seminal fructose and serum glucose were greater (P < 0.05) in fertile than subfertile rams. On contrary, seminal and serum malondialdehyde were higher (P < 0.01) in subfertile than fertile rams. The proportion of HOST-positive spermatozoa has positive association (P < 0.05) with seminal and serum levels of superoxide dismutase, nitric oxide, testosterone and thyroxin as well as with seminal fructose and serum glucose and negative association (P < 0.001) with malondialdehyde content, while % abnormal spermatozoa was positively correlated (P < 0.05) with only malondialdehyde content either in serum or SP. Noteworthy, protein band of 14 kDa was prominent in fertile rams and faint to absent in subfertile rams. In conclusion, determination of seminal and/or serum superoxide dismutase, nitric oxide, testosterone, thyroxin and malondialdehyde as well as seminal fructose and serum glucose might be beneficial in assessment of male fertility during breeding soundness examination. Moreover, SP protein of 14 kDa might be a candidate of fertility-associated protein in ovine SP at least for the Ossimi breed.