The Accidental Smallholder Forum
Livestock => Sheep => Topic started by: Anke on November 07, 2010, 06:56:17 pm
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Hi, I have just got my new tup in, but he hasn't got scrapie genotyped. I was wondering if it was worth doing, and have tried to find some relevant documents on the DEFRA website, but not finding anything that seems to give more detailed info. Is there some papers or similar anywhere on the we that explain it all a bit more detailed?
Does anyone know which combinations are safe? My older tup is ARR/ARQ and I have got also some ARR/ARR ewes. All my pedigree sheep are Shetlands (white) but I also have a number of crosses (not scrapie tested).
What does it usually cost per test? I am not going to join the scheme I think.
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Don't think anyone bothers now, do they?
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The National Scrapie Plan was ended a couple of years ago, because the science behind it is shakey. No genotype is now considered to be more 'safe' than another. Shetland Sheep are sometimes still scrapie tested because the disease itself has been a big problem on the Shetland Islands, so that is where the first testing was done. The Shetland Sheep Soc uses a slightly different 'typing' system to the NSP, in that they talk of R1, R2 and so on, whereas the NSP refers to 'Type 1', Type 2' and so on.
As I said, the science behind it all is now outdated, but previously it was thought that sheep with an ARR in their genotype were resistant to developing scrapie, whereas those with a 'V' ie valine were very susceptible. So ARR/ARR was type 1 and supposedly the most resistant, but type 5 VRQ/VRQ was extremely susceptible. Type 4 was I think ARR/VRQ - I wonder which one won out there - ARR or VRQ? It was also found that most primitive sheep had type 3 genetics ie types such as AHQ and ARH. Testing showed up some surprising results, when ARR appeared in some primitives, implying blood from other breeds where ARR is more typical. An example of this was that Hebrideans were found to have about 20% of sheep with one or more ARR. Not surprising as it is accepted that Hebs had close contact with Jacobs, which are predominantly ARR, in the old parkland flocks. However, some Soays were also found to have ARR which definitely shouldn't have been there.
More worrying was that many good sheep were removed from the breeding flock, especially amongst coloured Shetlands, because of their genotype, and many second rate animals were bred from purely because they had ARR genotypes.
To discuss whether or not to have your sheep scrapie genotype tested, please contact the Shetland Sheep Society for the latest advice. The SSS will also be able to put you in touch with the labs which do the work. As well as paying the lab, you would also have to pay the vet to draw blood from each sheep.
The only time having your sheep scrapie genotype tested is worth the effort now is if you want to export to Europe or N Ireland and Eire.
The NSP was based on the premise that scrapie in sheep could be passed on to cattle and humans, but this is now discounted.
For quality Shetland rams, you are better to go for an 'approved ram', which has been examined by the society inspectors and passed as of good breeding quality.
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Hi, fleecewife I have a couple of questions re hebredians. if I may.
is the reference to jacobs because of the prescence of dominant black in the breed or is there a known connection?
why are hebredians black? I understand the breed was ressurrected from park animals were they just kept as they were ornamental or was there another reason?
just curious
thanks
I do test for scrapie genotype. not because of any programme nor any particular need as I don't select on genotype but am interested to know. heterozygous types are generally thought to be at greatest risk of scrapie this goes for ARR classic scrapie resistance and also for varient scrapie with other genotypes being more resistant
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Hi Kanisha. Complicated question ! Hebs were first selcted, it is thought, as black individuals from the general Scottish multicoloured type back in the 1880s. To breed true of course they had to be recessive black, although some people believe there may be a brown type carried under that. It is known that Hebs and Jacobs were then present in some parkland flocks at the same time, in the late 19th and early 20th centuries. There are no records of interbreeding, just an assumption that it probably happened. Now about 20% are dominant black - according to some estimations, but they are just that, estimations. The scrapie testing with it's 20% or so of type 2 with the occasional type 1 seemed to support that theory. Jacobs are dominant black, but so are Black Welsh Mountain (mainly), and there is a rumour that certain Heb breeders in the early years of the RBST may have used BWM to add size and horn strength to Hebs. But who am I to spread rumours :o So there is very little supporting evidence for anything, just assumptions and possibilities. One thing which is certain though is that Hebrideans were not brought across to Britain by the Vikings as they were here long before that - or multihorned, (probably multi coloured) sheep were, from archaeological evidence.
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Hi Fleece wife thank you all makes sense to me except if jacobs were used there is the not insignificant problem of white spotting..............a recessive so even if it doesn't show in the first generation its likely to come back to bite you. I am intrigued you place so much importance on the scrapie genotype as supporting cross breeding with jacobs. I would have thought its entirely possible the varience in genotype could have taken place with the general scottish multicolours? Ouessants are getting on for as much as 60% ARR as opposed to ARQ ( ignore UK population of ouessants as these are of dutch origin and the dutch wiped out all their odd scrapie genotypes ( and still do) coz they don't like anything that isn't ARR/ARR) The main flock of reference to me goes back uninterupted and closed flock since the 1900's and this year just tested one of their ewes ARR/ARR
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White spots crop up every now and then and are not registerable. This could be from Jacobs or it could be naturally present within the ancient Scottish multicoloureds (some of which would have been piebald). There is much discussion about it but without getting the genome for the various breeds we can't resolve it. Doesn't stop there being several different fiercely held opinions, as in every realm of human activity ;D
During the days of the NSP it was found that the northern shorttailed breeds (which is what I meant when I said primitives) were generally type 3 ie with neither ARR nor valine. Hebs had no valine but did have ARR, so the assumption was that there was a recent mixing of blood with a breed or breeds which carry ARR naturally. Oddly, Castlemilk Moorits were found to be exclusively type 3. The other nst breeds were found to have varying percentages of ARR, and these were again assumed (by NSP) to be from recent admixtures of blood from other breeds. Are Ouessants nst s or do they originate from longtailed sheep?
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Hi, fleece wife very interesting; ouessants are Nsts they are classed on the age of index by geneticists as the oldest french breed. although the ouessant breed is a construct the origin of the sheep is the breton noir of which it would be impossible to find many if any that might not have been crossed out as the black sheep of the region is so indigenous everyone sees them knows them and doesn't think anything of them. the ouessants were kept seperately as they long ago earned the title of worlds smallest sheep and curiosity of visitors to the region being so small. although it is widely acknowledged they are just the island population of the regions black sheep;
I am as certain as its possible to be that the roots of this breed in the region lie further back in the UK's populations of primitive sheep but at a time when the celtic regions ( cornish is understood by bretons and welsh has the same roots) were trading with each other. cornwall and brittany are very closely linked. it isn't by accident la grande bretagne is opposite la bretagne....
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I suppose that can only be determined by looking at the genomes of the various contenders, as with the Hebs. One day it's going to have to be done, but probably not during a recession and when we are being told that the national diet will have to move increasingly towards a vegetarian one, because of all the greenhouse gasses our livestock produce. All the more reason to preserve our rare breeds, whatever their origins.
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have you heard of the age of index? it was a very interesting study done by JJ lauvergne ( of his time one of the foremeost geneticists who worked alongside adalsteinsson who did the work on determining the agouti patterns in shetlands.) it uses morphology to determine a breeds point of development along an evolutionary scale.like the definition of a short tail but uses considerably more points of reference each one a determinant for a breeds point along an evolutionary scale; it would be hard to breed back any breed from a longtailed sheep to get a sheep meeting the definition of nst not to mention from the evolutionary scale there would be too much that was off for all the other criteria. I would love to do a genome project just tell me where to get the testing done. I'm happy to fund a study in ouessants myself. in the meantime the age of index is a good starting point;
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Hi Kanisha. I met Stefan Adelsteinsson 10 years ago (we talked about colour patterns in cats as well as Shetland sheep), but I don't recall hearing of JJ Lauvergne. The immediate flaw that springs to mind would be that cross-breeding of longtailed sheep with shorttailed sheep can produce offspring with either long or short tails, and presumably the same holds for other features, so any admixture of 'alien' blood could skew the results. (Think of Hebs which are nsts, but they have fairly long tails, nearly to the hock, so morphologically they appear to be longtailed) Also the example of, was it Merino sheep which have been isolated on a NZ island for many generations, and have reverted to being coloured rather than white, coloured being a primitive characteristic, shows that reverse evolution/adaptation can occur. But now I come to think of it I have seen the age index you mention, can't remember the context. I seem to remember it has some unexpected, or at least counter-intuitive, associations. I'm going to have to find where I saw it now!! I think rather weirdly that it was something to do with spinning.
I think they are working on sheep genomes somewhere, possibly Soay at Edinburgh, but I could be misremembering that. Also probably on OZ and NZ breeds, that being where the money and interest are. It would be interesting to know which breeds' genomes have been mapped so far, and how close we are to being able to identify the different breeds accurately. I would think that the points of difference between the various breeds would be minute, though hopefully significant. But Ouessants, having been recognised as distinct, would seem to be ideal candidates to work on - presumably they will be establishing base lines using very distinct breeds. I'll see if I can find out more about how far sheep genome research has progressed, and which universities are doing it.
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Hi Fleecewife. If you haven't heard of JJ Lauvergne heres a bit of his work;
http://granit.jouy.inra.fr/productions-animales/1991/Prod_Anim_1991_4_4_06.pdf
http://www.biomedcentral.com/content/pdf/1297-9686-9-2-151.pdf
http://www.biomedcentral.com/content/pdf/1297-9686-8-2-153.pdf
http://www.gse-journal.org/index.php?Itemid=129&option=com_article&access=doi&doi=10.1051/gse:19810303
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2726201/pdf/1297-9686-2-3-249.pdf
just a taster he was quite prolific.
would be interested to hear of any counter intuitive thinking .
maybe this is what you are thinking of?
http://wwwbibli.vet-nantes.fr/theses/2002/lallemand02_100/part1.pdf
yes the hebredians are interesting are you saying they are back bred from long tails?
as for merinos and their reversion to coloured they still don't fulfil the criteria for primitive sheep by a loooong way; you would have had to sit there with a list of criteria ( assuming that those in the 17th/ 18th/19th century knew what those criteria were (not yet established) and then breed for them on all levels. if you read the study ( I have included it for you) they you will be able to see how these criteria came about. and that heterozygous types are not part of the criteria.
I knew that my theories of agouti grey had punctured the pride of some in the shetland world but I had no idea they would be this threatened by the theory wow I must be hitting close to the bone ;D I hope as a result of my experiments this year to really get to grips with the colour theory ;D love to have more details on any genome testing that can be done.
how do you explain hebredian tails?
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strange if its not needed anymore. we had a really nice ram lamb this year a spotty shetland with a couple of colours and we even had difficulty giving him away. he was just to good to eat. people demanding that they want the scrapie results for him oh and wanting a list of parents. some people are really difficult. sorry im not spending 50 quid to give him away. next year any ram lambs will just be eaten. the scrapie testing did remove a lot of coloured shetlands and the more primitives shetlands thats why the multiple horned shetlands are very rare now.
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Hi Shetland Paul. Most people who are breeding seriously do expect their stock to be registered, but there are also breeders around who have unreg stock, but more difficult to contact. I think that in Shetland scrapie testing is still important in the effort to eradicate the disease because of its serious effect on the sheep. The NSP was set up to try to eradicate the disease in mainland Britain for the sake of the supposed health of humans, not of sheep.
I had thought that the multi-horned Shetlands were rare before scrapie testing started, but perhaps not. There is a chap down in England breeding multihorns, but he has a big problem with split eyelids. If only there were more for him to introduce fresh blood, but finding the odd one in Shetland from such a distance then importing it is difficult. But at least he's trying.
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Hi Kanisha. My, that's a lot of reading ! I will take a look when the sun isn't shining ;D
To try to explain the Heb tails look at the more primitive Shetlands (eg from Foula), which all come from the same nst stock as Hebs - they too have longer (but not 'long') tails. The fluke shaped tails of the ideal Shetland might be the result of breeding selection since the 1927 standard was written. Within Hebs there are those with shorter tails, although never fluke shaped. On the other hand, Soays always have tiny short tails. The actual length is I think less important than the number of vertebrae, which is 14 in nsts and more but variable in Longtailed sheep. A bit like giraffes which have seven neck vertebra as do humans, but definitely not the same neck length ;D When grading Hebs, we look at tail length - tails must not reach the hock. We don't however count vertebra in the tail, as that can only really be done post mortem. But no I'm not saying that Hebs have Long tails in their ancestry, although it's possible given the proximity of Jacobs, BWM etc in parklands. (People also kept zebra in parklands at that time - there is a picture of one pulling a small trap :o)
No, I mentioned that crossing long tailed sheep with short tailed sheep can result in either long or short tailed lambs to illustrate that the morphology of an individual animal might reflect previous cross breeding or an influx of alien blood. However, I shall read all you have sent me and see if it is the same as I was dimly remembering before I comment any more, as I am perhaps thinking of a different thing.
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Yes I much prefer a more balanced approach and tail vertebrae is a more interesting and relative means of measurement. ouessant breeders have never placed any importance on the fluke tail and its significance to shetland owners as a sign of cross breeding is a breed specific issue., outcross a ouessant to anything else and the biggest indicator of cross breeding will be size. Hence a ouessant breeder doesn't go anywhere without his measure or his knee. ( they should all be below the knee level.) the texts are in french but the study from nantes is lengthy ( there are multiple parts just change the number in the end of the url. ) very in depth and very interesting still puts the ouessant as the oldest breed in france and untouched by modern intervention. due in a large part to its geographic location; interesting to note that one of the main indicators used in the nantes study for breed age is size the population of the breton noir is also listed and height measured in many zoo technical manuels from the 17th century onwards again because of the rusticity of the sheep in this region. There are more than enough indicators to confirm the origins of the ouessant in the region and its authenticity as a Nst its just that sometimes people aren't used to seeing variation as anything other than a sign of cross breeding. what if I was to give you another considered by some *outrageous* explanation for dominant black in hebredians.............
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<<what if I was to give you another considered by some *outrageous* explanation for dominant black in hebredians.............>>
Oh go on then ;D
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Hang on to your hat! I will assume you have a good understanding of basic colour genetics.
standard explanation for dominant black is that it switches ( in laymans tems) the dominance from the agouti locus to the brown locus. It is a single switch ie its either dominant black ( whatever is at the brown locus dominates) or its standard agouti dominance.
the only fly in the ointment to this has been those breeds that behave as whites but have black markings like the scottish blackface. Genetically this has not been possible to explain if agouti is full on to white, expression of eumelanin isn't possible. All the studies to explain sheep colour have been based on this assumption. Including the very tidy agouti heirarchy as seen and ably demonstrated in the shetland. with the more recent (2008) understanding of the mechanism in white sheep thanks to the genome project it was able to show that there was a duplication in the agouti signaing protein sequence that does allow the *possibility* for expression of eumelanin in a white sheep Instead of one agouti signaling protein there are two sat next to each other.
Instead of a switch you now have possibility for a mechanism for co-dominance between agouti and extension. This can appear in a variety of forms depending on the expression of that co-dominance, each family or breed of sheep showing these genetics has its own pattern and the patterns are progressive if you select always for the most patterned ( darkest) individuals I call them spreading patterns) so the scottish black face is a much reduced black pattern on a white sheep . I made the proposal that agouti grey was not an agouti pattern but this type of co-dominance between agouti and extension only much futher towards the greater expression of extension. In some case this shift towards extension can go further and become extension dominant and the odd ED sheep arrives in an otherwise "normal" flock. I made this proposal after struggling for a long period to understand the development of pattern in ouessants a breed which traditionally only comes in white and black and the experiments I have done to study this development.
This would be exactly the same mechanism as is seen in suffolks. Now instead of the shetland having exclusivity, its genetic mechanism is shared with many UK breeds of sheep ( This proposal has caused outrage!) However just say this was the case and that in the genetic soup before breeds were fully characterized within the scottish populations of sheep there was a mechanism for producing dominant black that may explain those hebredians that were selected as black ( we all know you can't tell by looking which are recessive and which are dominant black)Then the notion of assuming ED was as a result of crossing to a jacob or a black welsh mountain isn't necessarily the only answer. I leave it to you to work out if the breeds history allows this development but the mechanism is there.
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Hi Kanisha. Very interesting ! Yes, I think the breeds history would allow for the possibility of this mechanism. It is only 130 years or so since Hebs were part of the greater multicoloured Scottish tanface landrace type. Would you not though also expect to see th same mechanism in, say, black Soay, North Ronaldsays, etc? In fact is someone in N America not studying that very question with Soays?
As genetics, whilst being extremely interesting, is not my main hobby, I find it difficult to keep up with the latest studies and knowledge, so thank you for bringing that one to my attention.
Now, can you explain White Hebrideans please? I understand that it is beleived that they can be genuine (ie there is a mechanism to explain how they can pop up every now and then) although the HSS still does not allow registration. Whites were registerable under the RBST but not since the HSS took over. We have a white Heb ewe we bought several years ago but have always assumed that she was a cross.........You can see her on our website www.scothebs.co.uk
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Hi Fleecewife. Black soay are recessive blacks this is as result of a non functional promoter to the agouti signaling protein studies have shown this to be the case in black soays on hirta. The study came out not that long after the study into white sheep so was very relevant. studies in NA soays depend on which ones they are studying they may or may not be relevant some are acknowledged to have been crossed out to US breeds.
The north ronaldsay is a good question. Has anyone given you an explanation for their colouration or the mode of inheritance? everytime I ask I get blank looks. However as a breed they are very relevant.
OK firstly the explanation I have given is far from being accepted by the genetics community but its working for me and that is important because it is quite a complex inheritance;and I am looking for the theory to fail in order for me to have to rethink things.
to take first the scottish blackface a breed which in terms of pattern and colour is very stable there is very little variation within the breed until you cross them out. I would not expect a dominant black to pop up in this breed without being a mutation they are to far towards a white sheep to get a huge shift to ED.
the north ronaldsay are more variable but quite a stable population in that they are all closely related, would anyone one know/ notice if one went as far as ED? is anyone breeding them looking for definative colour patterns or characteristcs? I was told of one breeder who claimed to have a recognisable mouflon ( black and tan or soay) pattern crop up only to be told by the breed society it was a cross. I asked to have contact details for the breeder and was blanked.... yet the breed society couldn't tell me the colour inheritance of the breed; ( the mouflon pattern is relevant but lengthy to explain)
as for whites hebredians; Blondie is for me fascinating although white she shows marked colouration and that for me is what I spend a lot of time looking at all those funny little patterns in white sheep. she could only show up as a true white hebredian if there was dominant black and somewhere along the line a genuine white hebredian line was continued but if you say that up until recently they were accepted then its entirely possible ( as much as not) that she is genuine. I am only able to look closely at ouessants its hard enough getting good testimony from breeders over their oddities in this breed let alone other breeds and it takes people who are comfortable with questioning the acceptance of breed characterisitics in such black and white terms but my theory would offer an explanation for both genuine dominant black hebredians and the white hebredian line. whether or not you could prove it is another matter..... do you know her parentage and history?
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<< Blondie......do you know her parentage and history? >>
Unfortunately not, as she is not registered. We know the Hebridean flock she came from and we also bought several black Heb ewes from them at the same time - one of those a few years ago produced white twins but we assumed fence hopping was to blame as at that time we had a white Shetland tup. There were apparently four flocks which regularly produced white Hebs but in the face of opposition from the HSS they gave up trying to get them recognised. This was before we joined the HSS ourselves so all I know is by hearsay. I think that the flock we bought Blondie from was one of the four, so the chance of her being genuine is fairly high. As well as the dark nose, she also has one or two tan markings which she passes on to her crossbred lambs. If bred to a black Heb, she produces black lambs indistinguishable from pure Hebs, so we always cross her. Obviously if we had time and space we would do some experiments, but we don't.
I don't know enough about Ronnies to be able to help there. I know a couple of people who breed them, and I know that their fleeces are wonderfully soft to spin, but beyond the general history of the breed I have no insight.
As you will have seen on our website, we breed Soays for black - the piebalds popped up from two blacks but are a new venture. As well as black we also get moorit lambs, which you would expect.
I think Lawrence Alderson feels now that white Hebs can be explained without the presence of dominant black, but I need to make further enquiries.
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Hi, does she always produce black lambs when bred to the hebredians?
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When we first bought her as a three year old she was already in lamb to a pure Heb and had a single perfect black lamb. The previous owners had previously bred her to a pure tup and had had black lambs they said. After her first lambing we always crossed her to a white shetland and she would have a single enormous white lamb. This year we are not breeding her.
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Hi Fleecewife , interesting but not possible to draw any conclusions from.
Re other way to get white from black.
the other mechanism is white spotting which is a recessive and at times it can be hard to tell a white sheep from a black sheep with white spotting except when you have tan markings and then you are dealing with a white sheep as tan cannot be expressed in the prescence of white spotting - which is a total failure of the colour cells to produce colour; Blondie is a genuine white sheep whether she is genuine hebredian is a different question.
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Ah so the tan markings are significant. Blondie remains a mystery, but I will see if I can find out more through Lawrence Alderson, as he is the one who has said that it is explainable. This question is significant to the Hebridean breed, because of the change of policy from registering whites under the RBST, to not registering them under the HSS. At the same time, registrations of polled and topknotted animals was also not allowed, but now they are, as the current HSS committee recognises the need to preserve the ancient characteristics of the breed before they are lost forever.
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Yes and to get back to my original point there has been a kind of breed snobbery with regard to variation instead of conserving and understanding the variation some breeds view any deviation from the ideal as an indication of cross breeding. hence the issues with tails. and of course more relevant to this thread the mistaken idea that concentrating exclusively on one single genotype as providing protection from scrapie. nature favours variation for breed strength and yet you still meet people who will only accept ARR/ARR
One point to make re blondies black lambs if she was heterozygous for white ( which one would have thought more than likely) she should have by the law of averages produced as many white as black lambs for her former owners when put to hebs unless of course his flock had dominant black present which could also hide white...........but that doesn't mean you'd get the same results with your flock.
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Blondie's dam was a normal black Heb - but then so allegedly was her sire. But depending on the reason for her being white, she could I suppose be homozygous recessive, if this proposed mechanism allows that. I am a bit pushed for time at the moment but I will try to find out more.
With Hebs, we have a breed desciption, not a standard, so it allows for variation within that description - it's something we defend to the hilt and it has allowed us to save the rarer traits at the last minute.
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I can see where Lawrence alderson could try to explain white hebs using white spotting and yes this would result in a homozygous recessive piebald lamb. ( I'm not saying I agree but as a mechanism its theoretically possible. )
however Blondie isn't as a result of white spotting her colouration excludes that. I would have thought the easiest way would be to get blondie DNA tested. it can be done to determine parentage quite easily these days.she would then be either as a result of dominant black hiding a white or a cross fence liaison. Testing wouldn't prove or disprove Aldersons ideas but leaves two possible explanations for whites in hebs and of course will settle blondie. The complication in Aldersons theory is that there is dominant black in Hebs but as white spotting isn't hidden by dominant black you should get the two cropping up independantly of each other.