Testicular and related size evaluations in Nigerian Sahel goats with optimal cauda epididymal sperm reserve

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 (52.5%) of the goats had optimal ESC which was associated with testicular weight of 59.90 ± 16.10 (31.4-86.2) kg, gonado somatic index of 3.51 ± 0.69 (2.0-4.5) g/kg and scrotal circumference of 19.07 ± 1.29 (17.0-21.8) cm. The ESC correlated better with age than body weight of the animals and correlated also with testicular and scrotal size variables and epididymal weights. The size variables of the scrotum and testis correlated with one another. 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.

Keywords: Optimal sperm output, testicular size, scrotal size, Sahel goat, Nigeria