Reproduction potential of farm animals is mainly determined by selection of appropriate strategies that benefit the reproductive performance. The aims of the study were first to evaluate the effect of selenium (Se) supplementation on attainment of puberty and reproductive performance of Saanen bucks and secondly, to evaluate the effect of selenium supplementation on semen yield and quality of Saanen bucks following two semen collection methods and induced stress. The study consisted of three experiments. For experiment 1, goats were allocated into two treatment groups: treatment and control. The treatment group were dosed with sodium selenite at three months interval. In experiment 2, the two groups from experiment one were further subdivided into two groups each based on semen collection method (artificial vagina - AV or electro ejaculator - EE) leading to four groups (Se + AV, Se +EE, Control + AV, Control + EE). For experiment 3, the major two groups (selenium supplemented and control) were subdivided into two groups each based on induced stress (injected with adrenocorticotropic hormone -ACTH) and not, leading to four groups (Se, Se + ACTH, ACTH and control). For the last two experiments, selenium supplementation was done at two months interval. ACTH was administered at three weeks interval. The phenotypic parameters were evaluated every two weeks. For all experiments semen was collected bi-weekly from bucks and evaluated for volume, colour, sperm motility, concentration, viability and morphology. Blood samples were collected at two weeks interval to determine selenium concentration and reproductive hormones. Data collected was analysed using GLM procedures of SAS (2012) and the means were separated by Duncan test. Supplementation with selenium significantly (P < 0.05) improved body weight, testicular measurements and decreased age at puberty. Selenium supplementation led to significantly (P < 0.05) greater ejaculate volume, semen colour and pH, high sperm motility, concentration and viability in the present study. There were lower (P < 0.05) percentages of morphological abnormal sperm from the selenium supplemented bucks than the control. There were also a lower percentage of primary sperm abnormalities from the selenium treated group, compared to the control. The electro-ejaculator method of semen collection had a greater ejaculate volume regardless of the selenium supplementation. The interaction of selenium supplementation and electro-ejaculator method of semen collection showed that when bucks are supplemented with selenium, the electro-ejaculator technique lead to a creamy semen appearance. The electro-ejaculator technique had an advantage of leading to a lower percentage of tertiary sperm abnormalities. Selenium supplementation also reduced the detrimental effects of stress on semen characteristics. Supplementation with selenium lessened the effects of induced stress, improved luteinising hormone and testosterone concentrations. Selenium supplementation enhanced serum blood glutathione peroxidase activity and lowered cortisol level in bucks. The results of the present study confirmed that male goat kids supplemented with selenium attain puberty with enhanced pubertal characteristics. It was observed that if selenium is supplemented and semen is collected frequently, both the electro-ejaculator and artificial vagina semen collection methods yield acceptable semen parameters and, consequently lead to improved semen quality of Saanen bucks.
Dissertation (MSc Agric)--University of Pretoria, 2017.