Monday, July 27, 2009

There are trade offs- look forward and consider all facets of improvement-Alpaca

I notice much written lately on the issue of AFD increasing over age. Neil mentioned that low variation between fibers (SD or CV) and low variation in AFD over the fleece were important factors (I think that is what you said).

Trials conducted with both sheep and alpacas have provided (inconclusive) evidence that these two traits resulted in a reduced AFD differential between weaning age and adult age (relatively speaking). I seem to recall a research paper that gave conclusive evidence of this, however, I can't locate it. These two traits are also reported to be highly heritable.

On another point, I noticed someone on this forum refer to secondary to primary follicle ratios resulting in increased fleece density (or something along these lines). I should point out that the relevant research shows that S/P ratios have very little correlation with fleece or follicle density and should not be used for this objective.

Finally, I would like to steel a couple more lines on this issue of fleece/follicle density that may be of interest to forum readers.

I am currently working on a paper that draws attention to accelerated genetic selection that focuses on increasing animal productivity (such as increased density).

A number of animal industries are now experiencing problems in this area. A European Safety Authority has found that genetic improvement for milk production in dairy cows has resulted in increased stress, nutrition and health problems. The report has found that the increase in milk production ' the major factor causing lameness, reproductive disorders, metabolic disorders and significantly higher nutritional demands.

Another example of problems associated with increased production levels involves beef cattle in Great Britain where caesarean section births are now relatively common due to increased calve size brought on by genetic selection.

I am not suggesting increased fleece density is a bad thing. What I am saying is that we are now finding out that increased productivity from 'highly focused' genetic selection such as follicle/fleece density needs to bear in mind the trade-offs. In other words, does your selection strategy take account of the long term negative effects brought on from carrying heavier fleeces and increased nutritional demands for producing denser fleeces.

I think this needs to be carefully considered before you encounter the serious problems experienced by other livestock industries.

Regards from 'down under'
Paul Vallely

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