Postmortem diagnosis of aspermatogenesis and hypospermatogenesis in the Nigerian Sahel goat by testicular and epididymal sperm cytometry

- Aspermatogenesis and hypospermatogenesis exist in Sahel bucks with gonadosomatic index values of <1-3 g/kg.
- Bucks with dyspermatogenesis have reduced numbers of spermatogenic cells due to the arrest of spermatogenesis at spermatogonia, spermatocyte or spermatid stage.
- Bucks with abnormal or optimal spermatogenesis can be discriminated by testicular size variables.

Apparently healthy male Nigerian Sahel goats (n = 125) aged 18-30 months old and weighing 10-25 kg were selected at slaughter by stratified quota sampling, into 5 groups of 25 each with varying testicular sizes, in order to investigate the occurrence of dyspermatogenesis. Testicular sizes were categorized as very small, small, medium, large and very large using gonadosomatic index values of <1, >1-2, >2-3, >3-4 and >4 g/kg, respectively. Left testes and epididymides were homogenized with formalized normal saline for sperm cell count by manual cytometry. Right testes were fixed in 10% buffered formalin and processed for histopathological examination. Cauda epididymal sperm counts of zero and <1.1 × 109 were used to diagnose aspermatogenesis and hypospermatogenesis, respectively. Dyspermatogenesis occurred in 59 (47.6%) out of 125 goats consisting of 37 (29.6%) and 22 (17.6%) with aspermatogenesis and hypospermatogenesis, respectively. Aspermatogenesis had higher (p < 0.05) incidence than hypospermatogenesis. Age was associated (p < 0.05) with occurrences of the lesion indicating linear trend (p < 0.05) with age. Very large testes did not have abnormal spermatogenesis. Aspermatogenesis occurred in very small (80%) and small (68%) testes, but hypospermatogenesis occurred in very small (20%), small (28%), medium (36%) and large (1%) testes. Testicular sizes varied (p < 0.05) due to the lesion and were associated (p < 0.05) with occurrences of aspermatogenesis and hypospermatogenesis as they influenced testicular and epididymal sperm counts. Seminiferous tubular epithelia indicated reduction (p < 0.05) in the number of germinal cells. In conclusion, dyspermatogenesis in the goats seemed to be caused by germinal cell maturation arrest and the occurrence of the lesion could be predicted by testicular size during selection of breeding sires.