September 28, 2012
In some circumstances, this can be a very handy trick of the horse-breeding trade.
By Dr. Robert O. Gilbert
Do you have a promising colt? Not sure if you would be better off keeping him intact? Do you feel torn between the desire to preserve his breeding potential and the convenience of working with a gelding? One way to do both is to freeze semen, store it and wait to see how the gelding performs in his athletic career. If you need only a modest amount of frozen semen, it may not be necessary to train the stallion for semen collection, but simply to obtain sperm from his reproductive organs after castration. Similarly, if a stallion's life is cut short by an accident or acute illness, it may be possible to obtain sperm after death and successfully freeze it. (This procedure is less likely to be successful if the stallion has had a prolonged illness or suffered age-related reduction in fertility before death).
Sperm can be obtained from the tail of the epididymis – this is the organ attached to the testis, into which sperm pass after their production in the testis. It functions to support sperm as they mature and acquire the ability to fertilize oocytes, or eggs. The epididymis also serves as the major storage organ for sperm before ejaculation. Transit time for sperm through the epididymis is about two weeks. By the time they reach the tail of the epididymis, they have achieved the ability to fertilize and are held in “suspended animation” as a reservoir for ejaculation. It is this feature that is exploited to allow recovery of sperm from dead stallions or post-castration. Read the rest of this entry »