Michael (1)
prostonik_7 (1)
Okay, so Skin Biopsy testing has been going on in the U.S. for a few years now, what do we think of it?
EXPENSIVE ! …..I know about $300 per SB……….Im with you there.
The average alpaca scores around a 38 follicles sq/mm. An exceptionally dense alpaca has above 65 follicoles sq/mm.
Personally , we have not done any Skin Biopsy tests, but plan on biting the bullet soon and testing some of our herdsires, and a few of our important females.
What has convinced us to get the testing done?
We have several friends that have been getting these tests done regularly for the last few years, and they all seem to come away with the same surprising observations.
Since reviewing the scientific data of SB tests, most of our breeder friends conclude that
Human hands cannot accurately determine density of an alpaca.
What they once thought was dense is NOT, and what they thought was not dense is now very dense!
These particular breeders making this statement are very experienced breeders, all of whom have a minimum of 13 years in the industry, some are past AOBA judges. They claim that with the help of the SB test results, they are making significant changes in their breeding programs. One breeder had Stud A breeding most of his herd because he thought he was VERY dense (Stud A test was approx 45 fol/sq.mm). Stud B was not used much because he was not dense. ( Stud B test results of approx 80 fol/sqmm), The 24 year alpaca breeder and past AOBA judge reversed his breeding males. He became a believer in the SB tests.
Other breeders are mentioning similar storys.
Okay, I can accept all of this. Technology triumphs again!
But this brings up another interesting point. If human hands cannot accurately determine density, why are we permitting judges to attempt such feats in the ring? Well, obviously we need to have judges attempt to figure out density in the ring, but what are the judges doing to catch up with this technology?
Hopefully some judges will comment.
My thought is that eventually, with the help of SB tests, experts will learn other visual fleece characteristics that correlate to high SB numbers………
I think that eventually, we all will all be capable of determining accurate density with the use of our eyes.
Don — there’s one thing about SB’s that people don’t talk about… the fact that it may not be a representative sample of the animals’ blanket. I have yet to find any studies that conclusively show that a skin biospy taken at a relatively random location on the animal’s body can be a true measure of that animal.
How do we know that the area chosen for the SB wasn’t just unusually dense or not dense? Or for environmental reasons some of the folicles are dead?
personally, I think a better statistical measure will be something that measures fleece weight per AFD/SD. In other words, which would you rather have:
A. a stud who’s got 15 lbs of blanket at 22 micron, SD 4
B. a stud who’s got 12 lbs of blanket at 18 micron, SD 6
C. a stud who’s got 10 lbs of 20 micron, SD 3
my preference would be C — most weight for the lowest/most consistent fleece.
thoughts?
Dani
I’d
Hi Dani,____Im aware of some breeders that are indeed collecting data to test the consistency of skin biospys between random sample on the body. Nothing official yet, but they are seeing little change between the random samples. Im sure that Norm will be sharing his results soon. The bigger difference seems to be coming between the two sources actually perfoming the tests._______
Dani,
As far as your formula to help measure a more meaningful alpaca fiber SCORE, Its a nice idea for internally comparing fleeces in one's herd. We do this in our heads currently, lol….. Absolutely!, weight, fineness, and consistency are all equally important factors when deriving a meaningful number to help evaluate your herd and breeding decisions regarding fiber production.____However, when examining the idea of EPD fiber data, until you can get , a predictable, reliable, and repeatable method of exactly what fleece you are measuring ie. neck and blanket, legs and blanket, blanket only, blanket minus chest, etc…, the data collected will be meaningless to each farm. __I heard that ARI's collection of fiber weight data will entail weighing the alpaca before and after shearing. This number will be turned in for the fleece weight. When you look at all the variables that will impact the data, like peeing/pooping during shearing, whether or not some will shear legs and some will not, a significant error will be introduced into the data and will not be meaningful to me.____Just some of my thoughts_
>When you look at all the variables that will impact the data
Oh, I know — GIGO (garbage in – garbage out) at it's finest. If, as you mention in your other post, SB's do turn out to be a valid sample of the entire animal, then i think that could turn into a useful measure — as long as we take into account resting folicles, dead folicles, etc. So SB is a measure of potential production.
Fleece weight, on the other hand, is a measure of actual production, and both will have their uses.
Dani,
You state that the SB is taking from a relatively random site on the alpaca. Skin biopsies are to be taken in a very specific spot on each alpaca tested.
Wouldn’t the histogram’s from alpacas A, B, and C in your example above be taken from relatively random sites? Histograms from different sites on each alpaca could yield very different results.
I think that the SB as well as the histogram are to be used as tools. The more tools you use, the more informed you are.
Just my thoughts.
Marcee
>Skin biopsies are to be taken in a very specific spot on each alpaca tested.
They provide good direction — but how many people are able to correctly follow the directions?
>Histograms from different sites on each alpaca could yield very different results
My point about SB's. Both YM & Ian give specific examples on where to take the fiber sample. How many of us are good at doing that?
That's not to say I don't think that SB's could be a useful tool. But since there will be variables in location of the test site, as well as questions about how representative the sample is of the whole animal, there will be errors in the results. I realize there will be errors in using fleece weight as well — so I'm still struggling on what's the right collection of tools to have in my toolbelt.
Dani
Hi Don,
I would never purchase a male anymore without skin biopsy results. And I am doing biopsies on my foundation dams as well. How else would I be able to accurately assess the performance of my breeding decisions? Ribbons? In addition to density, I get Secondary to Primary ratios as well as the SD between primary and secondary fibers. I've taken the adage to heart that 'my arm is not a scale and my eye is not a microscope.' Remember Nationals? I stood in a yearling male class and was told by the judge that while my entry was 'the finest, most uniform and had the best handle in the class', the male lacked density. That remarked caused some head scratching from the audience. Norm Evans confirms through a biopsy that my boy's density is 81. That's the upper 0.5% of tested males. My boy was finer, softer and more uniform that the rest and didn't win – so 'perceived' density must be really important to our judges. Ian Watt's results will be available shortly, as well. I believe that as our alpacas are bred to be finer and finer, density gets much more difficult to assess in the ring – and even in a fleece class. I call this 'the curse of Snowmass,' since their incredibly fine and uniform animals get docked for fleece weight. Check out their research on their website.
"My girl sheared at 22 pounds' is a meaningless marketing ploy to me. Who wants 22 pounds of 30 micron rug material?
Remember when judges use to criticize animals for medullation? Then they were told they could neither see nor feel medullation and better change the terminology? Perhaps density analysis should be left to the laboratory now and not to the show ring.
Give me a herd with lingering fineness and a decent blanket weight. How do I get there? An extremely dense animal cannot blow out – the closeness of the follicles preclude thick fibers and lack of uniformity. Fast growing fiber (an easy at home measurement and calculation) coupled with good density that is being passed on through proper breeding decisions gives me my toolkit.
Great post, Jim.
I agree with your comments and definately FEEL for you at Nationals. Ive been struggling with that same question," Should judges even try to make sense of the density in the ring?" As more and more breeders get SBs done, they are gonna look like fools making comments like "Not DENSE" and be talking about an 80 fol/sq.mm.
I would love a judge to make a comment on this subject. How are they planning on dealing with this?
Are Ian and Norm Evans the only ones that have the capabilities to do the biopsy testing?
Yes, Ian and Norm are the only ones. Both do quality work, but their approach and results differ.
Here is Dr. Norm Evans's explanation of skin biopsies.
Some breeders have requested information on how to use the results of fiber biopsies. The results of your biopsies, when coupled with the histogram, should give good direction to your breeding program if you wish to follow it.
The useful tools you get are 1) Density, 2) Secondary to primary ratio, 3) Sebaceous gland presence and density, 4) Secondary fiber medullation, and 5) Fiber cluster shape, symmetry, or infrastructure, and 6) Micron variation of the secondary and primary fibers.
1) Density is the number of follicles per square mm of skin. Based on about 1800 biopsies, the average for huacayas is about 39.75. About 270 Suris have averaged 38.75 follicles sq mm. Superior breeding stock that seem to win in the show ring is 55-60+.
2) The secondary to primary ratio is the number of smaller micron desirable fibers to each primary fiber or guard hair in each bundle. The average that I have seen on about 1800 huacayas is about 8.75 to 1. The average S/P on about 270 Suris is also 8.5 to 1. It seems that near 10 to 1 is desirable for the perception of better bundle structure in the show ring. However, I am aware of a 5 X color champion that is 5.2 to 1 with a density over 70, so there are exceptions. I count 25 fiber clusters and average that number for the S/P average so it may not agree with the picture scan.
3) The sebaceous gland presence has not been mentioned until 2006. I have followed the progress of alpacas on fiber nutrients in my research for the past 5 years. I saw that some responded more rapidly than others. After the biopsies, I see that it is the ones with gland presence that responded better. After evaluating family lines, I see that these glands are appearing to be highly genetic. These glands provide a nutrition pathway to the fiber and are a very strong factor responsible for brightness and luster. When several judges started using this approach, looking for well nourished fleeces, I saw that I was headed in the right direction.
4) Secondary fiber medullation was thought to be bad. In fact, some say that all alpacas with secondary medullated fibers should be eliminated from the gene pool. The fact is that would take 98% of the Huacayas and Suris from the United States gene pool. The average that I see on biopsy is about 40-50% secondary medullation. The judges are actually rewarding it in the ring because higher secondary medullation relates to more defined bundle structure which gives the fibers the perception of strength and form. In fleece shows however, the apparent feel from secondary medullation is not as desired.
5) Fiber cluster shape, symmetry, structure, or infrastructure is highly genetic but can be destroyed by sickness or infection. Ideally, we want all clusters to have an even distribution of fibers. Clusters that uniformly have 10 to 12 fibers are preferable to having one bundle with15 fibers beside a bundle with 8 fibers and another bundle with 11 fibers. This irregularity on the inside does not give the judges a good perception because of the irregularity on the outside. The fact is we can predict this before you ever select your breeding. Look for tight symmetrical clusters of the same size and shape on your biopsy rather than irregularly shaped clusters with uneven fiber numbers.
6) Micron size and variation of the secondary and primary fibers gets a lot of press. Most all opinions agree that it is highly desirable to breed toward primary and secondary fibers that are healthy and near equal in size as measured in microns. The primary fibers (guard hairs) are usually straight, much larger, and have a prickle factor that is unpleasant to human skin. The 250 X scan of your biopsy gives a good indication of the micron variation on your particular alpaca. I count and measure 100 secondary and 50 primary fibers (depending on the specimen density) and show a typical view on this scan. This calibration is usually rather close to the histogram results where many more fibers are evaluated. Both are to be used as tools in selecting breedings. Our goal is to breed in the direction that both fibers are acceptable in size and as near equal in size as possible. Micron size appears strongly genetic but can be altered by sickness, weather extremes, nutrition, and other factors. The average variation that I see to date is 7.9 microns and any thing under 5 to 5.5 microns seems very desirable and genetically strong.
How do we use this info? You breed strong points to weak points in your selection process. To excel as a herd, some animals will simply not help to strengthen the gene pool. This is the reason for knowing the stats on the females as well as the males, if you really want to more rapidly potentate your genetics. In about 30% of the cases, where both females and males are biopsied, the females actually have superior genetic characteristics to the males that they are bred to. Every farm that I visit seems impressed with how their crias are improved compared to previous years. This certainly is the case and we notice that the show ring is becoming much more competitive. Much of this success can be a compliment to breeder management in the selection of males utilized as well as to improved nutrition. Close observation of the programs enjoying much success have utilized the above tools in breeding selection.