140 The relationship between morphometric characteristics and semen parameters in Bapedi rams

Abstract

Bapedi is a fat-tailed, hardy, and disease-tolerant breed of sheep that is indigenous to South Africa. The Bapedi sheep breed is facing genetic degradation due to nonselective cross-breeding and irregular mating; therefore, breeding strategies for urgent conservation of Bapedi sheep are crucial. The aim of the present study was to investigate the relationship between body measurements and semen traits of Bapedi rams conserved in situ (conserved in their natural habitat) and ex situ invivo (live animals conserved outside their natural habitat). Semen was collected twice per week from 33 rams aged 2-4 years (four ejaculates per ram) using an electroejaculator. Body measurements (rump height, body length, scrotum circumference (SC), scrotal width, and scrotum length (cm)), body condition score (BCS; scale of 1-5), bodyweight (BW; kg), rectal temperature (°C), semen volume (mL), spermatozoa concentration (billionsmL−1), and motility parameters were measured using a computer-aided semen analysis system. Data were analysed using analysis of variance and the general linear models of SAS (SAS Institute Inc.). The Pearson correlation coefficient in SAS was used to determine the relationship among variables. There was uniformity in all body measurements of Bapedi sheep regardless of the conservation method (P>0.05). There were no significant differences in body temperature during semen collection, SC, semen volume, semen pH, semen concentration, spermatozoa total motility, and kinematics in Bapedi rams between methods of conservation (P>0.05). Pearson correlation revealed moderate significant relationships between semen volume and BW, BCS, and SC (r=0.315, 0.638, and 0.381, respectively). Rump length had a moderate correlation (0.566) with normal spermatozoa (P<0.05). It was concluded that Bapedi sheep are still a uniform breed regardless of their decreasing numbers. The BW, BCS, and SC must be considered in the selection criteria for improving the reproductive performance of Bapedi breeding rams because they were positively correlated with semen volume. It is recommended that more studies be done to correlate body measurements, testicular morphometry, and semen parameters in this breed.