If SD means anything to you, then you cant ignore this ! About 2 weeks ago, I posted comments on our page regarding the impact the season has had on fleece test results, particularly over the eastern part of Australia. Last summer was dry and extremely hot, followed by significant rainfall in autumn with consequent sharp increase in nutritious paddock feed. The result was a dramatic change in fibre diameter over the season, with microns plummeting, then skyrocketing. This had the effect of artificially increasing SD owing to the increased variation in diameter along the fibre. I should mention that normally, about 80% of variation (SD) is the genetically influenced variation between fibres in the sample. This genetically influenced variation is the most important aspect of SD. We have now completed some testing of crias that were born in autumn, and as I mentioned in my previous post, I have not seen anything like this. The dams were affected by the harsh summer with consequent impact upon the pre natal fibre of the unborn crias. The dramatic increase in available nutrition for mum over autumn saw her energy/protein rich milk turbo charge the nutrition reaching the crias fibre follicles causing the crias fibre to blow-out to levels I have not witnessed before - in some cases, changing the diameter over the season by a massive 14 microns. One case in point is the recent testing we carried out for Jenn and Rob Errey of Errydge Park Alpacas in Victoria. The attached midside profile from one cria shows the fibre climbing from 16 to 27.5 microns over the first fleece season. This huge blow-out had a negative impact on the overall variation (SD) which was recorded at 7.0 microns for the midside test. In order to extract this whopping environmental influence on the SD, we tested a 40mm snippet from the sample where we felt little variation along the fibre was experienced. This genetic test from the same cria is also attached. This test of the more flatter profiled section of the sample gave a far more respectable (and reliable) SD of 3.2 microns, less than half the midside SD. This 3.2 micron SD is more indicative of the breeding potential of the alpaca as it confines itself to the variation between the fibres and not the variation along the fibres. I will be watching the testing we do for other countries to see if a similar impact is occurring. In fact I am starting to see some similiar issues for a number of NZ alpacas we have recently tested. There is a lot more to learn from this, and consequently, Jenn Errey and myself will publish a co-authored paper detailing this issue and methods we can adopt to overcome the problem of SDs (& CEMs) being made virtually useless due to extraordinary seasons. I hope the paper will be available in October. If you have any questions in the meantime, please contact me ([email protected]) I will also cover this issue at the fleece workshop this Saturday at Buhai Hill Alpacas, near Brisbane. Paul Vallely AAFT
Posted on: Thu, 25 Sep 2014 06:32:42 +0000
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