D. L. M. Gore1, T. K. Muasya1, T. O. Okeno1, J. N. Mburu2
1Animal Breeding and Genomics Group, Department of Animal Sciences, Egerton University, P.O. Box 536, Egerton, Nakuru 20115, Kenya
Corresponding author: email@example.com: Tel. 0743944492
2Department of Veterinary Surgery, Theriogenology and Medicine,
Egerton University, P.O. Box 536, Egerton, Nakuru 20115, Kenya
Breeding of goats requires proper selection of breeding bucks through consideration of their breeding soundness. Selection of breeding bucks is the most critical decision for improvement of a flock, and it largely depends on factors like scrotal circumference and semen quality. The objective of this study was to evaluate the effect of breed and age on scrotal measurements, semen characteristics and the correlations among these traits in dairy bucks raised under extensive system. Total of twelve (12) bucks were used for this study, six (6) from each breed of Toggenburg and Saanen and within each breed the bucks were further subdivided into two group based on age (young and adults) in 2 x 2 factorial design. Body weight, scrotal circumference and scrotal length were measured. Additionally, semen volume, mass motility and spermatozoa concentration were also evaluated. The data were analysed using analysis of variance with General Linear Model and correlation analysis was conducted using Pearson’s product-moment procedures of SAS (Version 9.0). The findings demonstrated that breed of bucks had no effect on body weight, scrotal circumference, scrotal length, volume and motility. However, Toggenburg bucks had higher spermatozoa concentration compared to Saanen bucks. Also the study found that, there was significant effect of age on all the parameters measured with exception of semen volume. In terms of correlations, there was significant positive correlation among body weight, scrotal circumference and scrotal length. There was however, low positive correlation between body weight and scrotal parameters with semen characteristics. It could be concluded therefore, that Toggenburg bucks could produce high number of total spermatozoa and as a result higher semen doses for artificial insemination purposes compared to Saanen bucks under extensive system. Also age should be taken into consideration when selecting breeding bucks. Moreover, selection of breeding bucks should not be based on scrotal traits only, but semen characteristics should also be considered.
Keywords: Toggenburg, Saanen, bucks, scrotal parameters, semen characteristics