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  Discussion on High Ambient Temperature & Stallion Fertility
Author Message
Member:
judyhens

Posted on Wednesday, Jul 8, 2015 - 6:10 pm:

We are considering importing a stallion from Europe. We are going there in August to look at some ranches. The temperature where we are looking has been consistently in the triple digits lately (108 - 113 F), with no end in sight. We have learned over the years with our own stallions that high temperatures can adversely affect the quality of the collection. We need to keep them cool, hose them off, clean them out the night before and collect early in the morning to maintain >=75%+ active and forward moving collections when we consistently hit triple digits - and we never approach 113 degrees. This is compared to closer to 90% in the spring. Plus, we have a heavy outside mare load, so they are collected often. Our concern is whether or not extreme ambient temperatures will affect semen quality when we have a vet check done on the chosen stallion. Their breeding season has already shut down. Is there any research on this re: stallions? I know A & M did research on mares, and found that exercise in high ambient temperatures here in Texas did affect conception rates negatively. Anyway, what is your thought on this? Any insight would be appreciated.
Moderator:
DrO

Posted on Thursday, Jul 9, 2015 - 6:43 am:

Hello Judy,
I do not know of any work such work on stallions. It would not be surprising from several different standpoints that thermal stress might adversely affect semen quality. We do know sperm do best at slightly lower than body temperature and that fever can greatly affect sperm health. Beside the direct effects on the sperm, the stress on the stallions may also have an effect.
DrO
Member:
judyhens

Posted on Thursday, Jul 9, 2015 - 9:07 am:

I did find one article last night called Effects of heat stress on mammalian reproduction (Peter J. Hansen) which supports your comments. Its bottom line: "A rise in testicular temperature in mammals with external testes leads to reduced sperm output, decreased sperm motility and an increased proportion of morphologically abnormal spermatozoa in the ejaculate. Such effects can be observed (lists multiple reasons)...... or (when) body temperature is raised because of fever or thermal environment...." They do mention the horse in their examples. They also state that In the bull, where spermatogenesis takes about 61 days, alterations in semen occur about two weeks after heat stress and do not return to normal until up to eight weeks following the end of heat stress. What is the length of spermatogenesis in the horse?

The concern we have is, of course, wanting to document that the stallion we choose is reproductively sound since the importation is expensive and our goal is to import an excellent stallion to include in our breeding program. The one we are most interested in does have confirmed pregnancies this year, foals born this year, and 20 registered foals from the last few years. I don't want to pass up this horse because he doesn't test well with such high ambient temperatures. Nobody expected this. This heat is not normal in that part of Spain. We have a deposit up on the one we want pending vet check, x-rays, etc. Any suggestions re: other ways to evaluate stallion fertility? We are doing the Piro and other blood work now and having it sent to the states. Never expected to be in this situation....
Moderator:
DrO

Posted on Friday, Jul 10, 2015 - 9:42 am:

Recent pregnancy rates are probably the best indication of reproductive soundness. There is a correlation between testicular volume, measured by ultrasound or calipers, and the number of sperm per ejaculate but the particular numbers are breed specific and I don't currently have a source for the numbers.
DrO
Member:
judyhens

Posted on Monday, Jul 13, 2015 - 9:27 am:

Thanks! Those measures and the fact that we have confirmed pregnancies this year and lots of foals on the ground may be what we will have to rely on. We are hoping for things to cool down before we get there!
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