Abstract
Testicular sizes of animals are important for identification of those with adequate sperm production. The aim of this study was to define the testicular and related size estimates that would be associated with optimal cauda epididymal sperm counts (ESC) in Sahel goats based on postmortem evaluations. A stratified quota sample population of 125 male goats inclusive of all testicular sizes was taken at a slaughterhouse in Maiduguri, Nigeria. The bucks were aged 18–30 months and weighed 17.04 ± 2.99 (12–25) kg. Body, testicular, and epididymal weights of each goat with other related size measurements were estimated. ESC was determined from homogenized tissue using a manual cytometer. At the cut-off ESC of >1.1 × 109 sperm heads, 66 (52.80%) of the goats had optimal ESC which was associated with testicular weight of 59.90 ± 16.10 (31.40–86.20) g, gonadosomatic index of 3.51 ± 0.69 (2.00–4.50) g/kg, and scrotal circumference of 19.07 ± 1.29 (17.00–21.80) cm. The size variables of the scrotum and testis correlated with one another and with the ESC. These findings provide data that may be used to anticipate adequate antemortem sperm reserve based on testicular size during preliminary selection of sires for breeding from a sexually mature Sahel buck population.
Highlights
The breeds of goats in Nigeria are either dwarf (West African Dwarf type, WAD) or long-legged (Sahel type)
One hundred and twenty-five apparently healthy male Sahel goats in good body condition aged 18–30 months and weighing 10–25 kg, presented for slaughter at the metropolitan abattoir, Maiduguri, Nigeria, were selected by stratified quota sampling to capture those with various testicular sizes from small to large sizes with bilateral symmetry and the rightsided testis was consistently used for the study
Gonadosomatic index (GSI) correlated with Testicular weight (TW) (r = 0.80) and Epididymal weight (EW) (r = 0.77) as well as Scrotal circumference (SC), scrotal length (SL), Testicular longitudinal length (TLL), and Testicular mid-circumference (TMC) (r = 0.58–0.80) but failed to correlate significantly (p > 0.05) with TSC (r = 0.22) and epididymal sperm counts (ESC) (r = 0.25)
Summary
The breeds of goats in Nigeria are either dwarf (West African Dwarf type, WAD) or long-legged (Sahel type). Reference values of testicular size and sperm cell counts in cauda epididymides of Nigerian goats at postmortem or after castration, based on adequate number of reference individuals, were not accessible, but such values ought to be available to indicate normal variations observed in healthy populations so that it would be possible to identify individuals having abnormal values in unhealthy conditions [18]. Four postpubertal WAD goats at 5 months of age weighing 8.90–11.00 kg in the early dry season had cauda epididymal sperm reserve of 1.57 ± 0.32 (1.20–1.90) × 109 [9]. At the age of 12–14 months and weighing 19.52 ± 1.25 kg, 15 WAD goats were reported to have cauda epididymal sperm reserve of 1.46 ± 0.26 (1.20–1.70) × 109 [15]. Increasing age and body weight positively correlated with testicular sizes
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