Castration of stallions is a simple surgical procedure with little risk. Sperm are produced in the testes, mature and stored in the epididymis, from where they are excreted through the vas deferens during ejaculation. The testicles, epididymis, part of the spermatic cord and testicular covering are removed from the stallion. After that, already at the gelding, sperm production is immediately stopped, but the recently castrated horse is still responding to the mares.

This is due to the presence of an ampoule, a sperm reservoir at the end of the vas deferens. Because the ampoule is not removed during marinating, the gelding can potentially cover the mare for up to one month after castration. But a month later, the sperm that remained in the vial during castration no longer exists. Continue reading →