Saturday, December 20, 2008

BAS Screening-Fleece testing

This site can give you the requirements an alpaca must meet to pas the BAS screening process.

Screening alpacas for the British Market place is not as easy as everyone thinks.
Not all alpacas will pass screening, even if they are National Champions does not guarantee the passing of the British Alpaca Industry Screening process. The reason being, when an alpaca is shown in the ring, there are a number of physcial traits that are not being checked, and that is not to say they should be checked, i am not saying that at all. The traits that are being tested for when screening is to try and aliminate all genetic faults,for instance- Kink or bend or a knob at the end of the tail. I explained the reason for this on a previous blog
more than 4 nipples, (no blind nipples, no double nipples), laxating patella, a closer examination on teeth- that they are central all aligned, (as to the slight angle, means that they could eventually throw a wry face), bent legs,
again on a previous blog link above, are a few of the major things that are checked for to pass screening. There are two screeners, one is for the physical traits, who is an accredited veterinarian that is employed by BAS, and the other a Judge, that was a breeder, but now is solely employed by BAS. Both screeners, are extremely professional, and i must say, their knowledge always knocks me over, that very simple things to someone else, is picked up, and then explained about the complexity and importance of the fault, most would miss. Elyse always assists the screeners, with the handling of the alpaca, and to make sure that the tape is in place for measuring the height of the alpaca, the scales are working right, and the area for the alpaca to be screened is clean, and all is reaThe judge screener, takes a midside sample, which he takes two samples. One sample is sent to a place in the USA called Yocum McCall, whilst other sample is kept as the reserve sample. There are sometimes alot of controversy over the screening process, as the screening process really is acceptable for alpacas in the age range of 18 months -2.5 yrs old.
Rarely are working (males or pregnant females) older than these ages will pass, and if they do pass, it means that these alpacas are very, good, to be able to meet the tough screening rules for a younger animal. Just recently, two 11 year old meales passed screening, which is a credit to the males, as they are holding such fineness, and these are the type of alpaca that should be used for genetic gain, and they can compete against

qualities of alpacas 9-10 years younger than them. The biggest contorversy of the screening is the fibre testing. We are told that the fibre length has to be 2 inches in length, which it makes ease of handling if it is, but it can be tested if length is slightly smaller than this length. Yocum McCall tests the cutting edge of this fibre sample. Which can throw the micron out anything up to 6 microns, and the SD out by 2-3, which will throw again the Cv out, (as this is a calculation of the Micron divided by the SD). Breeders ask why are they measuring just the cut edge, most fibre test will measure the length of the fibre and then averaged out along the

fibre length (although the above histogram is a good histogram, it does not explain exactly what i am talking about but you can see this a little), if you look at the graph on the right side, you will see a line, which is the measurement at the length of the fibre. So for instance if there is 12 months growth on the fibre, you will see, when the alpaca was shorn which is the beginning of the line on the left hand side, the fibre was 15 microns, (maybe also, he was shorn in the summer, when there is not as much goodness in the grass, or he had just been taken of his dam (which this bay had), which means he now does not have the goodness of his dams milk, and he takes a bit to adjust , which will drop the micron), but also envirpomental conditions can play on this, if there is not enough feed, then fineness will come from starving, or if too much feed, and high in protein, then the microns will go up. But when the fleece was shorn at the right hand side of the line on this graph, you will see that it measures higher, again, enviromental conditions can cause this, as the alpacas are shorn late spring, before the summer, when there is a lot of goodness, and plentiful grass, and so this will make his micron higher.
So if we are looking at an alpaca who is higher in micron, and they were screened in the end of spring, for einstance, the micron can be alot higher than the average of the fibre, and can make the difference of passing or not passing. The stress of the vendor and the purchaser whilst they are waiting for the screening results are often so high. So the question is often asked, why are they measuring the fibre at the cut edge, it is not fair.
I asked my fibre tester this question, as i wanted to understand it so much better.
Of course Elyse had already studied thismethoid at the Wool School, Geelong. And the reason is really very clever.
This is his answer-
While Yocum McCall are only able to measure the variation at one point along the staple, (fibre length) we can do it right along the staple giving a more accurate picture of both genetic and environmental influences. (we are able to separate the two – another post called genetic gain, which i will write so keep an eye out). I understand they are looking at variation in fibre diameter between the fibres in any given staple (fibre bundle) – this is a good indicator of genetic potential.

Taking a measurement across one section of the fibre will give you a measurement of variation between individual fibres – this is important as it does not allow environmental influences to affect the test. Once you accumulate a series of measurements along the fibres, then environmental influences will affect the readings.
The problem is that the different fibres within a staple grow at varying rates. That’s why the base is used because the difference in growth rate is not evident at the base. When you measure the variation at the tip, the varying degrees of growth rate will have an influence on the degree of variation between the fibres. At the tip, the variation between fibre is normally greater because at that point the fibres have been growing for different amounts of time.
Elyse says, it is a true measurement, and BAS is correct in screening the alpacas in this way.
as it is the only true measurement at that one time of the alpaca, that they can measure.
ONe alpaca, may grow 1 inch of fibre in 1 month, wehere another can grow only 1/2 inch of fibre in that one month, so you cannot measure the alpaca's potential and knowing exactly at what time the fibre growth was measured, this way you can.
At that one point of time, when the fibre was cut, at an even distance from the skin (against the skin), then it is the true measurement.
Another very important point my fibre guy said. It is the measurement to look for potential of genetic gain, and to the ability to throw that genetic gain to the next generation.

I hope i explained this well enough, and i look forward to any questions, or comments on this.
It is very complicated, but i can say from my experience, as being an assistant or handler for the screeners, that the very best alpacas pass screening, and the screeners, are completely unbiased. They have no idea who the alpaca is, who the owner is, on our farm, again they have no idea, as the alpacas are not on the property of origin. The screeners also take their honor and responsibility very seriously, and i respect the two screeners in AUstralia.
BAS have selected the best people to take on this very important process.....which ultimately will mean the very best alpacas from the Australian herd will be exported under this process.
Nothing in my experience with any genetic faults gets passed the screeners.

1 comment:

hilaryc said...

Thanks again for an informative post , Are you referring to the AAFT , who have a method to separate genetic vs environmental micron gain ? ( I wrote to him a few weeks ago, asking about it, and he sent a detailed reply plus copy of the paper from the website)

With the BAS screening, I can see that it is a true meeasurement at that particular point in time - but surely it still has the influence of environmental factors occurring at that time? But I would , as a breeder, prefer to present animals when they were less likely to have an environmental component to their micron count - do you get more alpacas being presented for screening in eg summer rather than late spring ( when the grass is good).

Once an alpaca is screened by the BAS - how long does that screening last before importation ( ie if they have once passed the screening,is that valid for life?)

A interesting point about older animals - in as much as if they pass the strict screening, it shows a goof ability to maintain their micron count - never hought of it like that.