Page 171 - January 2018

foals, and there’s a possibility to offset some of the value of that mare, and salvage something from a disaster by processing those ovaries,” he explains.
Owners seldom think about this, when going through the emotional trauma of los-
ing their mare. “If they can think about this, however, and can get the ovaries and send them somewhere that does ICSI, they still might have a chance of salvaging something. All too often, a week later they’ll say, ‘Oh my God! We could have had a chance for another baby!’ But it’s too late by then,” he says.
Semen ISSueS
Another issue people need to consider is that there can be quite a variation in semen. Some stallions are more fertile than others, and fertility can vary with fresh or frozen semen. “We’ve had multiple cases of stallions that
died and the owners had frozen semen, yet
it does not work to breed mares, but worked with ICSI. This was the case with Smart Little Lena. There was a lot of his frozen semen
still available after he died, but no one could make a Smart Little Lena baby. The owners bred many mares with no success, gave up and gave their semen away. One of the original syndicate holders sent me 90 straws of this semen and told me I could have it for nothing. He said that if I was ever able to get a foal or two I could just pay him $1000 or so for the breeding, but he didn’t want to keep the semen because he was tired of paying storage on it,” says Beck.
“From the very beginning of our ICSI work, this was some of the most fertile semen we’ve had, and we’ve made more than 25 Smart Little Lena pregnancies. A lot of them were from trials, like we are doing now, using differ-
ent media—aspirating oocytes from recipi- ent mares and injecting them, just to make embryos and see how well it works. We use Smart Little Lena for many of our trials just because it’s so good!”
There are also several issues with semen that can affect success rates for a normal breeding. “When we do a fertility exam on a stallion, we collect a sample of semen and look at it under a microscope. If nobody is swimming (no sperm actively moving) or if they are just swimming very slowly, or the percentage of sperm swim- ming is low, then that stallion automatically flunks the test,” says Beck.
“In a normal breeding, even with artificial insemination, the sperm has to be able to swim up the oviduct to meet the egg. But when we inject sperm directly into the egg, they don’t even have to be able to dog paddle; they don’t have to go anywhere.” Slow sperm can still fertilize an egg.
This raises another question. “When a stal- lion breeds a mare he deposits billions of sperm.
When doing a fertility exam on a stallion, a sample of semen is collected and looked at under a microscope. If there are no sperm actively moving, or just swimming very slowly, or the percentage of sperm swimming is low, then that stallion automatically fails the fertility exam.
It’s survival of the fittest. The strongest ones get to the egg. When we do ICSI, who knows what we are injecting! Maybe we’ll be produc- ing wimpy babies if we’re using wimpy sperm! So we actually do a swim-up test for sperm. You put the sample in a tube and leave it 15 minutes—and the strong ones will swim up off the bottom of the tube. You take your sperm sample from those at the top, to inject into an egg,” says Beck. In this way, theoretically the strongest in that group will be selected.
This only gives you the strongest swimmers. There are many other factors that play a role
in sperm fertility. “One important aspect is the acrosome, which is the little cap on the head of the sperm. This is the drill that goes through the outer shell of the egg,” he explains. If a sperm doesn’t have a good “drill” it won’t be able to fertilize the egg, even if it gets there first.
“Some stallions have wonderful-looking semen. The motility is 99.9 and they are swim- ming off the dish—but those sperm are not getting a single mare pregnant because they have acrosome defects. Sperm from these stallions can produce foals, however, if I do ICSI, because I drill through the egg and they don’t have to.
If the sperm have motility issues or acrosome defects, ICSI solves the problem,” he explains.
“Another stallion we’ve used is Dash For Perks. He was raised in Oklahoma and was a racehorse and then became a very popular barrel racing sire. The owner sold him to Brazil and kept a lot of frozen semen and had 50 frozen semen contracts, but couldn’t get any mares preg- nant with the frozen semen. So he sent me the semen and we got several foals the first year, so now he’s a very happy guy!” ICSI is definitely an option for stallions when everything else fails.
One important aspect is the little cap on the head of the sperm called the acrosome. This is the drill that goes through the outer shell of the egg. If a sperm doesn’t have a good “drill” it won’t be able to fertilize the egg, even if it gets there first.
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equine health