Age-related changes in the testicular and epididymal sperm parameters in the African greater cane rat (Thryonomys swinderianus, temminck, 1827)

Abstract

This study investigated age-related changes in the testicular and epididymal sperm characteristics and spermiogram profiles in fifteen African greater cane rats (Thryonomys swinderianus) of different age-groups; pubertal: 5 – 11 months, adult: 12 – 30 months and aged: > 30 months, obtained from commercial cane rat farm, Badagry, Lagos State, Nigeria. Following a ventral abdominal incision of anaesthetisized cane rats, testes and epididymides were exteriorized for the determination of spermatozoa morphology, motility, concentration, live-dead ratio and morphometry. Spermatozoa head from pubertal cane rat onwards were ovoid in shape and lack visible acrosomal hook. From pubertal to aged cane rat, percentage abnormal sperm cell was not significantly different (p>0.05). Sperm morphometric parameters (sperm length and width or diameter, midpiece length, tail length and complete spermatozoa length) were not significantly (p>0.05) different with age. There was consistent remarkable increased epididymal sperm motility in the adult cane rat relative to other groups. Testicular and epididymal sperm counts were markedly elevated in the adult relative to other age groups. However, both the testicular and epididymal spermatozoa live-dead ratio were not significantly different (p>0.05) from pubertal to aged cane rat. This study has demonstrated that sperm motility and concentration were remarkably elevated in adult cane rat. Therefore, cane rat breeders are advised to utilize adult rat in breeding.

Keywords: Sperm characteristics, Spermiogram, Testis, Epididymis, Cane rat, Thryonomys swinderianus