Effect of intramuscular injection of butafosfan and cobalamin on the quality of Fresh and Cooled Stallion Semen

The use of butafosfan in combination with cobalamin modulates many cellular metabolic functions in several species. Its use enhances productive and reproductive performance and reduces stress responses in animals. Despite all these attributes, so far there have been no controlled studies to evaluate the effects of butafosfan and cobalamin on the quality of stallion semen. The purpose of this study was to evaluate the action of butafosfan in combination with cobalamin on the quality of fresh and cooled stallion semen. Four healthy stallions were kept in the same place and under the same management conditions during the entire experiment. Stallions were randomly assigned to two treatment groups in a 2x2 crossover design. Group A stallions were treated with an intramuscular injection of butafosfan twice a week for 80 days, while group B did not receive any treatment. After that, both groups were not treated for another 80 days allowing a washout period for the treated group. Then, the groups were reversed, and group B was treated with butafosfan and group A acted as the control for another 80 days. Semen was collected twice a week, diluted in skim milk and evaluated for total sperm count, total and progressive sperm motility, membrane integrity (CFDA/PI staining) and membrane functionality (HOS test) at 0 and 24 hours after preservation at 5oC. Data were analyzed by comparing the values obtained from the treated stallions between the 60th and 84th days of treatment and the values obtained from the same stallion during the control period. The ejaculates of the washout period and between days 1 and 63 of treatment were not considered. A total of 85 ejaculates were analyzed by one-way ANOVA. Means were compared by the Tukey test at the 5% level of significance. No significant differences were observed in fresh and cooled semen regarding the total sperm count, total motility, progressive motility, membrane integrity and membrane functionality in the treated and control groups respectively. No interactions were detected in the fresh and cooled semen. The use of butafosfan and cobalamin in the stallions did not affect the seminal quality of young and fertile stallions. It can be used routinely and safely in these stallions. However, contrary to observations in humans and in bulls, the use of cobalamin did not improve semen parameters in these stallions.