The Accidental Smallholder Forum
Livestock => Sheep => Topic started by: Bramblecot on October 02, 2013, 07:41:09 pm
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I know very little about genetics but ??? but realise it is bad practice to breed closely related animals. What is considered too close in sheep breeding? I will not use my ram on any of his progeny but in future years will one of his sons be too close to future generations? Ideally I would like to keep a closed flock - but will this mean running 2 separate lines within the flock. Confused :-\ . Advice please.
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I'm like you in that I don't know much about it. I do know farmers who will put offspring back to father once, and then no further. I'd been reading recently to try and find out for ourselves as we have now arrived at a stage after a few years where it has become trickier to avoid in-breeding. The idea of it is not something we are comfortable with but it does feel helpful to find out about it from an objective stance. I found this which is only a blog, not a text book but it seems quite neat and at least might start a debate.
"Just as incest in humans leads to genetic defect risks, closely related sires and dams can have defective lambs. One defective gene is normally recessive, but if lambs inherit two copies of a defective gene that runs in the family, they may have serious abnormalities. Inbreeding problems can occur in a small flock that uses its own rams, or gets in rams from another flock which has similar family bloodlines. The maths are complicated, but in simple terms a sheep should not be bred to its parent or offspring, its sibling or half sibling, the sibling or half sibling of its parents or offspring, or the progeny of any of these siblings and half siblings. The closest relationship should be half-grandson to half-granddaughter"
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I had one off my rams daughters get tupped by him (accidentally) and she raised to 2 healthy lambs the easiest way is to keep changing the ram bloodlines 2 crops off lambs then he goes or don't retain his ewe lambs. There is lots off ways it can be done there has proberly been hundreds off thousands off lambs out off closey related sheep and no problems
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I was looking into this recently and found this very useful article:
http://www.signetfbc.co.uk/documents/content/sheepbreeder/managing_inbreeding.pdf (http://www.signetfbc.co.uk/documents/content/sheepbreeder/managing_inbreeding.pdf)
Basically you want an inbreeding coefficient less than 6.25% (I think when they say less than they mean less than or equal to). But if you do have a mating that is above this then do it carefully, and check all the offspring carefully and be prepared to cull. If you do do it, then you definitely want to out-breed the following year.
If the offspring are destined for meat then I don't see there being a problem. I'm in-breeding one animal this season purely for my own convenience and those offspring won't be kept for breeding.
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I try to buy in as unrelated a ram as I can, looking at least four generations back. The rams from well regarded flocks are always popular but they have often been bred and fed for showing and I want robust, milky, docile, long-lived ewes that lamb by themselves and raise twins every year, not a pretty face!