Post Number: 3
|Posted on Monday, March 03, 2008 - 08:34 pm: ||
Our stallion, who is 4 this year, has a peculiar issue with his semen. Last year his volume was always in the low 20's, concentration consistantly 400. The odd part is this. The 1st 2 times we collected him, everything was normal, and motility was 95%. The next 4 collections, upon microscope exam, no sperm were moving! The 1st time this happened, we were panicking. We had to ship that day, and there was no more time, to collect him again. Couple of days later, we collected him, again, not one sperm was moving, not even a twitch. So we added some extender, and within seconds, they were all fully awake! We did our first collection this year, and it was the saem deal, the only difference is he gave a volume of 40! Any ideas of why his semen does this? Obviously, we aren't in trouble, as we did get every mare in foal, the first go around, but it is interesting.
Post Number: 1748
|Posted on Tuesday, March 04, 2008 - 10:25 am: ||
It is not unusual to see very concentrated semen show poor motility until extended. The first two times you collected him it probably took a little longer, and the more you tease a stallion prior to collection, the greater the volume of ejaculate. The increase in volume however is an increase in secondary sex gland secretions (seminal plasma and gel), not sperm-rich fraction, so one gets a lower concentration (same number if sperm in a higher volume = lower concentration). That's probably why you could see movement in the first couple of ejaculates, but then once he got the hang of the routine, he got down to work faster and you got lower volume.
Something to be aware of is that if highly concentrated semen that is demonstrating this tendency is not extended with reasonable alacrity, the sperm will quite often die fast. Hence, get the collection done and head right into the lab and extend 1:1 with warmed extender, then worry about doing all your evaluations. If you are using a mechanical counter, be aware that you need to remove a small sample of the raw semen to do your counts. Once the semen is extended the counters do not work accurately. If using a hemacytometer, you don't need to worry, and can count the extended semen. Note too that at very high or low concentrations, the mechanical counters are even less reliable than they normally are (the are never as consistently accurate as the hemacytometer).
The increased volume this season may be a reflection of (a) his not having been collected recently, so not having a higher number of retained sperm to ejaculate; or (b) he's a little older and more mature (you don't mention his age), and therefore producing more sperm.
Points to be aware of in case the above is not the reason:
There may be a seminal plasma toxicity issue, that you are reversing with the addition of the extender. If this is the case, quick addition of the extender is essential to avoid toxicity damage and death of the sperm;
If you are seeing a large number of tail-less sperm (i.e. just heads) in the early ejaculates, you may be looking at an accumulator stallion that is not clearing dead sperm daily in his urine. If this is the case, you need to collect him regularly (perhaps 2 or 3 times a week) even if you do not need the semen to keep him cleaned out so that you have good quality ejaculates available when you need them.
Post Number: 4
|Posted on Tuesday, March 04, 2008 - 08:19 pm: ||
Thanks Jos, for the information. We always make sure to extend the semen immediately, as this seems to do the trick for his semen. We have the ARS densimeter, so we quickly take out the raw sample first. His semen is very intact and extremely progressive, and always has been. Last year we collected him only once per month, he was 3 then. We do use the Inra 96 with him, as his motility dropped rapidly with everything else. We bred A Saddlebred mare with semen that was 58 hours old, and it was still 50% progressive, she got in foal, with one insemination. We don't tease with him or use a mare at the mount as he is rather scared of them. This last collection, I forgot to mention that we did have to collect him twice in an hour as the first time, he was more interested in the sunshine, and we didn't get a decent collection, so most likely, that's why we got a larger volume maybe. I am fairly new at AI, I have done live cover handling for many years, so the scientific side of it all is a never ending learning experience.