The Accidental Smallholder Forum
Livestock => Sheep => Topic started by: Womble on June 25, 2015, 10:20:46 am
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The topic of Embryo Transfer came up on another thread, but I didn't want to derail it.
Could someone possibly explain to me how this works? I'm interested because when we went to buy some Zwartbles recently from a flock disperal sale and the owner told me that any that weren't bought would be sold to another farmer who wanted them for embryo transfer.
I took this to mean that embryos would be implanted into the Zwartbles, but I didn't really get what was wrong with the original owner of the egg carrying the lamb herself? I wondered if it was something to do with breeding terminal sire rams who can't be born naturally, but can anyone explain?
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Nail on head.
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Sometimes it's to put a big lamb in a ewe that's bigger than its natural mum, yes.
Sometimes - more often, I think - it's to create more offspring from one really good tup (and really good ewes which are hormonally flushed, too) than could be achieved [more] naturally.
And both together, of course. Huge numbers of offspring from a smallish nucleus of excellent (depending on your definition ;)) meat sheep, embryos carried and lambs born to and raised by other sheep with good capabilities in the lambing and rearing departments.
Same thing's been happening in double-muscled cattle for a while, Jerseys are often used as the recipient / surrogate mother as they have a very wide pelvis and produce fabulous milk which will make a great job of the calves. More recently, however, the calves have become so darned large (being limited only by the size of the Jersey's birth canal, not that of their genetic mother) that they now do elective caesarians rather than risk the calf getting stuck. So now there are no limits on how large a calf they can breed, except maybe the Jersey's stomach muscles... The vet has told us that 2 caesarians is as many as a cow can have, so if that's still true, then the Jerseys are presumeably used twice. :idea: I've no idea whether they ever implant multiple calves...
(Derailing a bit, but this is why my not-for-breeding Jersey heifer is becoming boxed meat this weekend, and didn't get sold alive.)
I accept it with misgivings when it's about saving a rare breed or bloodline, and with slightly more misgivings when it's about bringing in 'improved' bloodlines, but start to feel very uncomfortable when the surrogate mothers are more capacious than the natural mothers (for the reasons given above in the Jersey story) and when it is used as a regular breeding practise, when it feels too much like using ewes as a unit of production - real 'factory farming'. (Echoes of that pig unit in the 70s. *:shudder:*)
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In a related comment... AI in sheep is an invasive procedure, unlike in cattle. So the move towards a lot of AI, even in 'common' breeds like the Scottish Blackface, troubles me. I understand, from someone who worked as a shepherd with SB flocks that were impregnated this way, that the ewes can only be served this way twice, and are then no use for breeding. *:shudders again, for the same reason:*
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http://www.paragonvet.com/breeding-sheep_breeding-embryo_transfer__e_t_ (http://www.paragonvet.com/breeding-sheep_breeding-embryo_transfer__e_t_)
Hope this helps
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Thanks all, and for the link WBF.
It doesn't sit well with me though, I have to say. I mean, is there no aspect of nature we won't mess about with for profit?
Recipient ewes are programmed as above prior to E.T. They should be in good health and selected for ease of lambing and mothering ability. We recommend programming 6 recipient ewes per donor ewe. Any changes in management or stress should be avoided before and after E.T to allow embryos to implant.
There are residential facilities available at Newbiggin where donor and recipient ewes can be programmed and managed at your convenience.
They're not computers for goodness sake!?
Downloading embryo now....... embryo accepted. Congratulations, Ewe are now pregnant :o.
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Womble say you had some medium ewes and you had wonted to get very good stock you could get straws of pedegre stock and get the vet to implant the staws in youre sheep in spring you would have supper stock all the same.
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Thanks VF, but I wasn't wanting to TRY E.T, I just wanted to understand it better.
Traditional artificial insemination is at least easy to understand, and I can see why it would give me access to better male bloodlines than I could otherwise afford. However, we already have a pedigree tup who points out that his semen should be perfectly adequate for our modest needs, and is also willing to do the implanting bit himself for free. He claims this will save me no end of bother, not to mention a few flasks of liquid nitrogen! ;D
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Not to mention Ace is nearly the same size as womble...so may well win any arguments... :-D :-D :-D
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And the ewes can take the tup year after year after year...
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So far looked at E.T. in women / dogs /cats / pigs / cattle / sheep /horses / goats ( intresting one of rare Spanish ibex implanted in domestic goats ) llamas / camels / big cats and so on , all for various reasons . IF you had ewe cost 10,000 and a ram costing 50,000 which might only produce 2 lambs per year but by E.T maybe 20 per year ??
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No ewe should cost £10,000. It's a racket. And it doesn't sit well with the public who see tups being sold for £100,000.
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IMO AI and ET used to improve/increase your flock with excellent lines are good tools to use in pedigree breeding - but of couse with common sense as to the welfare of the recipient ewe/nanny.
I have used laprascopic AI in my goats with no ill effect, and would - if I had a fantastic female - be tempted to do ET from her as well. Hoping to do lap AI again this year for my goats - my only chance to use really good males from a few different bloodlines.
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No ewe should cost £10,000. It's a racket. And it doesn't sit well with the public who see tups being sold for £100,000.
OFF post , but market forces dictate prices eg world records texel ram lamb £231,000 sheepdog £10,000 Hereford bull $600,000 limousin heifer £131,000 goat kid $170,000 lamb $260,000 racing pigeon £260,000 race horse 5 MILLION GNS 20yrs or so a Suffolk ram sold for £50,000 and the owner sold offspring for a total of £250,000
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Luck money ;)
And insurance... :innocent:
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In the borders there is a farm that has the world record Ram and also 3 more that cost over 90000 some stock .And all the 300 ewes are the same of 1 ram .
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One hears of tups being bought for silly money by a consortium, stripped for AI, then dying.
Wonder if the insurance payout recognises the revenue from the semen... :innocent:
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Problem is more long term, in my view. If the same semen is used on many ewes, no matter how good the ram, then you're narrowing the gene pool. I think our understanding of genetics is just beginning. Who knows how many valuable traits were lost when scrapie testing was introduced? If you look at the genetics of black-and-white dairy cattle the same sire names crop up again and again.
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All the more reason to be supporting the RBST, and keeping the old breeds going so we've a gene pool to go back to.
But of course, RBST are another big user of embryo transfer... :thinking:
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AI is common here in Jersey (not sure on ET) because the whole island is essentially a closed herd. Now the semen ban is lifted, its meant genetics that left the island years ago can be brought back and has helped to protect the herd a bit more.
Foot and Mouth was terrifying with the potential it had but AI has made it much less risky if something similar happens again
I do think though that ET might have been more common before the ban was lifted because there are definitely less desirable bloodlines within the herds that have less value in milk and money terms, now these girls are being put to british blue and angus but previously I don't know.
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I know from my browsing of an Icelandic Sheep keepers group that in the States they use AI quite a lot to maintain diversity in their flocks. And I can see the attraction too here as there are so few bloodlines if you want to keep the offspring 100% Icelandic. They also use AI to select for the leader gene which is very important when dealing with the sort of predators they are up against. They mostly get the semen from Iceland it seems. Although I can see the advantages, I must say I would rather have an animal than a straw of fluid.
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As I understand it, they use AI almost exclusively in Iceland. The reason being that there were some problems with disease spreading between flocks, so now there is no movement of rams.