Hi, I'm Bryan Beachy, a Western Oregon sheep farmer who since 1987 has been working on a project(or study) to learn how to artificially inseminate(AI) sheep. Over the years, I've learned enough about ovine reproductive functions to enable transcervical AI in sheep. I wrote a paper about my study titled "Discoveries in ovine reproductive physiology and a new method of transcervical insemination for sheep" which can be found at the above button "6/17/2019 Sheep AI Paper". Although my study isn't finished, it has gone far enough to get sheep producers started with AI; so I'm sharing my discoveries now because I'm getting old and I don't want this information getting lost should fate pull my plug: sheep producers have been waiting too long as it is for an AI industry of their own. Hopefully, I'll be adding my progress to this website with more papers and how-to videos. For now, my paper is at the above button, the highlights of my study are below this paragraph, a brief version of my study is below the highlights, and my comments are below the brief version.
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Highlights of study
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- Ovine closed cervix syndrome is caused by phytoestrogen poisoning.
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- An estrous ewe in optimal health has an open cervix.
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- The reproductive tract of a ewe has a defense mechanism.
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- Two way chemical communication occurs between a ram's penis and ewe's cervix.
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- Mimicking ovine natural processes enables transcervical insemination.
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- Much of the information in this study may apply to other species: goats, cattle, etc.
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My study in brief
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Two factors have made AI for sheep problematic. The first is a ewe's sensitivity to phytoestrogen poisoning(clover disease) which causes cervical dysfunction(closed cervix syndrome). The second is the ewe's species defense mechanism which gives her the ability to snap her cervix shut.
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I found that ewes raised in a low legume environment who wintered on alfalfa hay and summered on pure grass pasture with zero legumes came into heat with an open cervix. However, when my plastic viewing probe touched the cervix, it would snap shut. I also found that inserting anything of a larger diameter than a ram's penis(such as a speculum) into a ewe's vagina caused her to close her cervix. Also, that any kind of rousting of a ewe, associated with catching, penning, haltering, or pushing her into a chute, caused her to close her cervix. So a better method of sheep handling was called for.
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By using a haltered teaser ram as bait, it was easy to lure estrous ewes into a pen, shrink the pen and crowd the ewes close to the ram, then halter the ewes and tie them to the pen wall next to the ram, then open the pen and examine the ewes. This method of handling did not cause any ewes to close their cervix; even the wildest ewes in the barn were agreeable.
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I made a different video probe of 10 mm stainless tubing, curved to approximate the angle between a ewe's cervix and vagina, and covered on its distal end with a thin layer of semi absorbent foam. When the foam was saturated with mucus from the ram's penis, this probe easily penetrated the ewe's open cervixes to the uterus, providing a pathway for an AI gun that was curved to match the probe.
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I swabbed a sample of cervical mucus from an estrous ewe and applied the swab to the tip of the ram's extended penis. This caused the ram to make a forward thrust involving further penis extension and a back hump, followed by the penis tip curling down and back against itself and continuing in this motion until the entire glans was inverted 180 degrees.
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I found that different cervical states caused different styles of coital mating behavior in rams during breeding season. When breeding a ewe with closed cervix syndrome, the ram mounts the ewe and makes multiple rapid thrusts. But, when breeding a ewe with an open cervix, the ram mounts the ewe, then shifts his weight from one hind foot to the other hind foot several times, then makes a single forward thrust which he holds in place for several seconds before dismounting. These different mating styles make an easy visual reference for stockmen to be aware of their ewe's cervical state during breeding season.
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Comments
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I am well aware that telling sheep farmers they need to get rid of their clover is not going to win me any popularity contests. However, please consider I'm not the first to report on reproductive ills in sheep associated with phytoestrogen poisoning. My favorite study of this problem was written by Davenport in 1967 and is available at:
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It's open access, and won't cost you a thing to read it.
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This is probably a good place to put a story that I edited out of my original paper for making the paper too long and I was afraid no one would read it. In the early years of my study our sheep ran on pastures(including summer pastures) containing clover. During that time selecting for twinning ability was frustrating at best. It seemed so random. We only retained daughters that were twins but we didn't make much progress. The best lambing percentage we got was 175%, but most years it was closer to 150%. That all changed within a few years of moving the flock to the summer pasture containing zero legumes. The environmental cause of single lambs had been removed, and the genetic cause of single lambs became glaringly obvious. With the removal of one family line from the flock, single lambs from mature ewes became a thing of the past, and lambing percentages rose to 200 to 220%. Our daughter selection criteria then changed from trying to raise lambing percentage, to keeping it in check since most of our ewes weren't very good at counting above two and we didn't like bottle feeding bums.
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Recent USDA statistics show average lambing percent in USA at 105%. The year before it was 110%. For an animal that was designed to have twins, that's horrible. Even for farmers who don't care about AI; an increase in lambing percentage of 30 to 100% would pay for a heck of a lot of clopyralid and 2,4-D.
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A ewe's species defense mechanism will seem like a real pain in the neck to a beginning AI technician. However, a better understanding of how sheep function, what ewes want at breeding time, and learning how to handle them accordingly, makes the job a lot easier. In some ways sheep are easier to AI than cows; at least you don't have to stick your hand up their butt. And we can be thankful that sheep do have a defense mechanism. If they didn't, their ancestors would likely have been bred out of existence long ago by the ancestors of goats.
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My last comment is for Chris Spitzer. Chris, if you're reading this, I apologize for taking so long to figure it out. Do you remember the Romeldales my wife sold you that you were supposed to get 200% lambing rates from, and after you got them home you were mad because they only delivered 150%? Well the answer is quite simple. It wasn't genetics or crooked salesmanship; it was because your summer pastures had clover, and ours didn't.
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