The Accidental Smallholder Forum
Livestock => Sheep => Topic started by: Lizt on May 08, 2011, 05:27:54 pm
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Just wondering why (it would appear) the biggest of twins is born first - I would expect it to be more random. Anyone know?
Liz
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because there the strongest and push other out the way maybe?
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thanks dm82 but I'm not convinced its that simple.. You'd think the biggest (heaviest) would naturally be the bottom one in the womb and there fore come second. Do the lambs actively participate in birth? I thought the mother did all the work? Perhaps they come out in order of 'doneness" for survival reasons!
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The vet told me that if the twins are very different sizes, it can be because the ewe was carrying triplets but one died. How the vet described it was that she might have had two foetuses in one horn and one in the other, then one of the pair died, so the remaining one in that horn was already destined to be a smaller lamb and has all its plumbing (to get nutrition from mum) accordingly. The single in the other horn takes advantage of competing only with one other lamb and not two and grows bigger than it would have been able to had all three foetuses survived.
Not sure whether this throws any light on why the bigger one comes first but I thought it was interesting!
I have never particularly noticed that the first lamb is always the larger but cannot specifically recall a lambing in which a smaller lamb came first. I can recall triplets where the middle lamb was the smallest.
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Ours have no definite order. I've just looked at my weight list, triplets first smallest(ram) second (ewe) last biggest (ram).
3 sets of twins where heaviest born first and 3 sets of twins where heaviest born last.
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Thanks Sallyintnorth and elissian - very interesting and your weight records (e) confirm that it is in fact random.