Possible risks associated with breeding easy care sheep include facial eczema, cold and inbreeding. Here, Dr David Scobie discusses these risks giving his informed opinion about the degree of risk.
Terms to discuss: facial eczema, inbreeding
Questions to consider:
Can you think of other possible risks of breeding easy care sheep?
Find out more about facial eczema – the cause, the effect and treatment.
Dr David ScobieAgResearch
Well we have seen some potential dangers in the north of New Zealand, we get a lot of disease called facial eczema, and when more areas of skin are exposed to the sunlight and those animals have eaten the fungus which will lead to facial eczema, we could have worse cases of facial eczema. That would be a bad welfare outcome and bad for productivity as well.
A lot of people worry that, if we breed wool off the extremities of the sheep, those animals will get really cold in snow storms and cold weather. It’s not actually true, because sheep like to be a lot colder than humans do, they start puffing and panting above about 10 or 12 degrees, so they like to be quite cold.
When you are talking about inbreeding, we could run into a problem where we have probably less than a couple of hundred sheep, and particularly with rams, we are just choosing 1 or 2 rams a year to mate with our flock. Now we have in the experimental flock. we minimise that by keeping 5 or 7 or 10 rams per year, and so we keep a mixture of genes. We are actually – in the animals that we develop – less chance of inbreeding than you have in an established Romney stud. Because some of the flocks we went to have been running for, one of them was nearly 100 years, a Border Leicester flock that had been running for 100 years. Those animals are actually in real danger of being inbred, because there is not that many Border Leicester sheep left in New Zealand, and many of them are related.
So there is a real danger of inbreeding that gene pool, and the first things that collapse when you start inbreeding are the immune system and the reproductive system. So you get less lambs and they are less likely to survive. Now, we have so many sheep in New Zealand that it hasn't really become a problem, but in our experimental flock, we used 13 different breeds and 9 different feral strains, and it will probably be another 20 years before we got to the stage where we would have all of those sheep so uniform that we had no genes of any other animal.
Acknowledgements:
Dr Clive Dalton, Woolshed 1
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