The effect of exogenous anabolic steroids on certain body parameters and seminal characteristics of Boer goats
Initially 20 yearling Boer goat bucks (between 14 and12 months of age, with a mean body weight of 47 kg) were successfully trained for semen collection with the aid of an AV. Animals were randomly divided into two groups, one group (n=9) was treated weekly with an intramuscular injection of 25 mg (1 ml) Nandrolone Deca-Durabolin (Adcock Ingram, The Netherlands), while the second group of bucks (n=10), served as a control. The following body and other parameters were recorded for each buck at weekly intervals: Testicular size and testis volume (ml), weekly body weights (kg), body length (cm), shoulder height (cm), shoulder width (cm) and the canon bone circumference (cm). Weekly feed intake (kg) was also recorded for each animal to determine the feed conversion ratio (FCR). No significant differences were recorded during the entire period of the study period, regarding the mean body weight gain, ADG and FCR of the bucks in the treatment group and those in the control group. The ADG was similar for both experimental groups, due to the fact that the animals were in an advanced phase of the growth curve. During the last half of the treatment phase and the entire recovery phase, the treated bucks tended to be relatively heavier than those of the control group, however these numerical differences were not statistically significant. Similarly, no significant differences between the two groups (treated and control groups) were recorded for all the other body measurements (e.g. canon bone circumference, body length, shoulder width and shoulder height) considered in this study, with the exception of the scrotal circumference (SC) and volume (SV) during the study period. All these changes in certain body parameters were recorded which ultimately then relate to the growth performance. Semen was collected by a means of an artificial vagina, and different sperm analyses for, evaluating the semen quantity, sperm concentration, sperm motility and sperm morphology, percentage alive or dead sperm were performed, while semen pH using pH-indicator strips was also recorded. Thin semen smears were stained with eosin/nigrosin and evaluated under a microscope for overall viability (percentage live), morphology (percentage normal or abnormal), percentage mass motility and sperm concentration during the two experimental (treatment and recovery) phases. Throughout the entire (31 week period) trial, the semen quality of the treatment group and the control group were similar (P>0.05) for the two experimental groups. Despite a significant reduction in the testicular size, as indicated by the significantly (P<0.05) lower scrotal circumference and scrotal volume following exogenous testosterone treatment, none of the semen parameters measured in this trial (i.e. sperm mass motility, semen volume, semen pH, sperm concentration, percentage live and percentage normal sperm) were significantly affected by the steroid treatment. From the current results recorded, there tended to be an insignificant decline in sperm concentration, % live and % normal sperm changes - these could be attributed to changes in seasonality. The % normal sperm decreased by 7-8% during the observation period and approximately 60% of the abnormalities could be attributed to tail abnormalities - with both the mid-piece and sperm head abnormalities attributing 30% and 10% respectively. From the data generated, it would seem that a lack in significant differences of the body parameters in the treated animal could possibly be ascribed to the dose of hormone used, the age of the animals, the duration of treatment and the energy content of the diet fed.