Relationship between body morphometry in Bapedi rams and sperm characteristics measured using Computer-aided Sperm Analysis

Abstract

Ram fertility is not defined by a single trait. Quantifiable physical parameters that are correlated to fertilization capacity of sperm are required to advise farmers on ram selection activities. The objective was to investigate the relationship between body measurements and sperm traits of Bapedi rams conserved in situ and ex situ. Before semen collection and body measurements, body temperature was taken. Semen was collected from 33 rams (two ejaculates/ram weekly, with 2 d resting period, age = 2–6 y). Body weight (BW, kg), body measurements [body length, head length, head width, rump height, rump width, rump length, tail length, heart girth, and scrotal circumference (SC)]; and semen volume (ml), sperm concentration (billion/ml), and sperm motility parameters were measured using Computeraided Semen Analysis System (CASA®). The semen pH was measured using a microprocessor pH/mV/°C meter fitted with a glass probe. Body condition scores (BCS) of the rams were recorded on a scale of 1 to 5. Data were analysed using the PROC univariate procedure of SAS. BW of Bapedi rams was 38–57 kg in all groups. There was uniformity in all body measurements of Bapedi sheep regardless of method of conservation. Body temperature during semen collection; scrotal circumference; semen volume, pH, and concentration; sperm total motility; and kinematics in Bapedi rams using both methods of conservation were similar. Strong correlations between BW, BCS, and SC with semen volume were found. Rump length positively influenced sperm normality. BW, BCS, and SC can be included in the selection criteria for improving the reproductive performance of Bapedi breeding rams. Farmers can use SC and rump length to predict semen volume and sperm normality.