Variation in and Sampling of Alpaca Updated: January 2007 ISSN 1329-8062 Bruce McGregor, Attwood Introduction
diameter of fibres growing from primary and secondary skin follicles in an alpaca may be more than 20 µm. Many
Evaluating the attributes of alpaca fleeces subjectively by
medullated fibres in alpaca fleeces are more than 10 µm
eye is difficult and unreliable as alpaca fleeces show large
coarser than the mean fibre diameter (McGregor 1999a).
variations in attributes. In addition, our eyes (and brain) are limited in their ability to discern fibre diameter, the
Along the fibre
average of other attributes and the extent of naturally
Changes occur in the fibre diameter, dust, grease and
occurring contaminants. Alpaca fleeces are also affected
vegetable matter content as the fleece grows during the
by environmental conditions, in particular humidity, but
year. In the example shown in Figure 1 (McGregor 1999b)
also by storage conditions. These same limitations apply
diameter varied from a low of 21 µm to a maximum of 27
µm. During the first few months of life the mean fibre
To assist in the commercial trading of fibre for textile
diameter ranged from 21 to 23 µm (15 to 11 cm) and then
processing, a range of testing procedures have been
increased to 25 to 27 µm (10 to 4 cm) before declining to 21
developed to help reduce the errors associated with
to 22 µm. Nutritional changes, weaning, rapid growth, the
subjective assessment. These testing procedures are
affects of disease and reproduction all influence fibre
approved by the International Wool Textile Organisation
(IWTO) as the basis for the international trade in wool and other animal fibres. The IWTO Technical Committees take this task very seriously and convene international meetings to assess new or suggested changes to protocols based on new information, new technology or better scientific methods and analyses. Associated with objective tests are a range of errors related to the sampling and testing procedures. With objective testing it is possible to quantify the likely extent of the errors associated with the testing procedures employed.
To help breeders evaluate alpaca fleece attributes the
starting point is understanding the types of variation found
Figure 1.Changes in the mean fibre diameter along a staple from
in and between fleeces; the most appropriate method of
a tui alpaca sampled in November (McGregor 1999b)
sampling alpaca fleeces; and the application of this
Different positions within the fleece
information for evaluating fibre test results. This article is
Fibre length, fibre diameter, incidence of medullated
based on research conducted in Australia.
fibres, grease, suint, dust and vegetable matter
This Agriculture Note discusses the sources and extent of
contaminants vary with the position in the fleece. These
variation within the alpaca fleece and suggestions are
variations are discussed in greater detail in this Agnote.
made as to the most appropriate method of sampling alpaca fleeces.
Differences between animals and herds
Within a herd of animals, between herds and between
Variation in animal fleeces
properties, alpacas will differ in their fibre diameter
The variation in the attributes within the fleece of animals
attributes and in their level of grease and other
contaminants. This is discussed elsewhere for Australian alpacas in greater detail (McGregor and Butler 2004,
Within a staple
Most of the variation in fibre diameter occurs between
Briefly, mean fibre diameter (MFD) of alpaca fibre was
fibres within a staple. The difference between the fibre
influenced by farm, year, age, breed, live weight and
State of Victoria, Department of Primary Industries Variation in and Sampling of Alpaca Fleeces
colour of fibre. The influence of farm and age are shown in Figure 2. MFD increased to 7.5 years of age.
Figure 2. Responses of mean fibre diameter to age at shearing after adjustment for year, live weight, colour of fleece and breed on five different farms (modified from McGregor and Bulter 2004). Each symbol represents a different farm
Coefficient of variation of fibre diameter (CVD) was
influenced by farm, year, age, breed, and colour of fibre.
Figure 3. Location of the saddle, neck and fleece components Impact of variation in animal fleeces that form the pieces (front legs including apron, belly and back
The large variation in animal fleeces affects fibre
legs) in alpacas and the site for mid side sampling.
preparation (fleece classing), fleece value, processing and
Table 1. Variation in attributes of Alpaca fleece
the interpretation of fibre testing results.
measured from mid side samples and fleece component grid samples including mean fibre diameter Variation due to position in alpaca (MFD) and coefficient of variation of MFD (CVD). Sampling site CVD Clean washing Components of the alpaca fleece
The physical attributes of alpaca fleeces vary considerably
over the body. During the preparation of alpaca for sale, the fleece is commonly divided into three components:
# Within attributes, sampling site values with a different superscript are significantly different.
According to standard industry practice, the skirtings
The fibre from the mid side site was 1.2 µm finer than
consist of the fibre shorn from the belly, the top of the
fibre from the saddle and neck, 3.7 µm finer than the mean
back legs, the top of the front legs and apron (area between
for the entire fleece and 10.1 µm finer than fibre from the
front legs and neck) providing it is free of guard hair
pieces. Fibre from the saddle was 2.4 µm finer than the
mean for the entire fleece and 8.8 µm finer than fibre from
The site used for taking mid side samples, which is
discussed in the next section, is part of the saddle
There was a large variation in the over the body. The CVD
of mid side fibre was 2.7% lower than fibre from the
Variation in fleece attributes
saddle, 3.8% lower than the mean for the entire fleece and 4.3% lower than for neck fibre.
Australian alpaca fleeces show large differences between the attributes of fibre from the mid side, saddle, neck, and
The significantly lower clean washing yield of the mid
the remainder of the fleece (pieces) and the mean for the
side and neck compared with that of the saddle and pieces
entire fleece (Tables 1 and 2, Aylan-Parker and McGregor
shows that the distribution of dust, dirt and grease content
are not equally distributed over the body of alpacas.
In these alpacas there was significant variation in the mean fibre diameter over the body and this variation was associated with high variation in the coefficient of variation of fibre diameter (CVD).
State of Victoria, Department of Primary Industries Variation in and Sampling of Alpaca Fleeces Table 2. Variation in medullated fibre attributes of white
diameter and other fibre attributes will be seriously over
Alpaca fleece measured from mid side samples and fleece component grid samples.
The mid side sample mean fibre diameter has been
Sampling site Incidence by Medullated fibre
reported in Merinos and Alpacas to actually test finer than
number# % diameter µm
the average for the whole fleece. In the study of the
Merino wool, this was particularly so for the finer sheep in the population. It was suggested that in Merino sheep this
was due to intense selection over the years for finer fleece
based on the mid side sample rather than selection for a
finer entire fleece (Stadler and Gillies 1994).
# Within attributes, sampling site values with a different
While the mid side sample is highly correlated with the
superscript are significantly different.
mean fibre diameter of wool top (wool processed up to the
The incidence of medullated fibres at the mid side site was
spinning stage), the mid side sample can be finer and the
8.7% less than in the saddle, 10.8% less than the mean of
differences may not be consistent (Fleet et al. 1993). This
the entire fleece and 20.1% less than in the pieces. Similar
suggests that the mid side sample may not be a reliable
differences were seen in the diameter of medullated fibres.
predictive tool for the diameter of top.
In summary, for each fleece attribute, fibre at the mid side
Some of these differences may be due to the effect of fibre
site had lower values than fibre from the saddle and the
breakage and subsequent loss during carding and noil
mean of the total fleece. For each fleece attribute, except
for clean washing yield, the saddle had lower values than
Grid sample method
fibre from the pieces and the mean of the total fleece.
Grid sampling has been used for more than 20 years. The
grid sample includes differences due to position within the
There are two main methods of fleece sampling available
fleece and so can detect variations in the fleece that the
for alpaca breeders: the mid side and the grid sampling
mid side sample does not detect. For example, Butler et al.
methods. Each method has it own advantages and
(1991) found that processed wool top produced from
Merino wool was better predicted by grid sampling than by mid side samples.
Mid side sample method
Grid sampling is the best method for taking samples from
Since 1947, the accepted method for testing sheep wool
cashmere goats as the mid side sample overestimates the
has been to take a mid side sample (Turner et al. 1953).
commercial yield of cashmere and underestimates
The mid side sample has been used to test characteristics
cashmere fibre diameter (McGregor 1994).
of importance such as fibre diameter, fibre population,
Method used for grid sampling
staple length, density of fibres per unit area and staple crimp.
In sheep, the theory behind using a mid side sample is that
1. laying out the shorn fleece to be tested on a flat
a mid side sample test result is close to the mean of both
surface, ideally on a table measuring about 3 m2. The
the top to underside and the front to rear variation found in
a fleece. For this to be true the mid side sample has to be
2. take 16 to 32 random grab samples from the surface of
either mini-cored or tested after carding.
entire fleece. To help this process it is common for
If a mid side sample is tested after butt cutting, as is
breeders to lay a physical grid over the fleece and to
common in the United States of America, then this
take a sample from each grid. A suitable grid can be
assumption is incorrect. A butt cut is a fibre sample taken
made from plastic garden trellis mesh with a mesh
only at the end of the fibre closest to the skin. A butt cut
size of approximately 10 cm x 10 cm. The idea is to
sample does not include any of the along the fibre
take unbiased samples by pulling a tuft of sample
variation or differences due to position within the fleece.
Location of mid side sample Potential benefits of using grid sampling
The site for taking the mid side sample in sheep is located
Grid sampling can be completed while the next alpaca is
over the third last rib, halfway between the mid-line of the
being shorn or can be undertaken after a fleece has been
belly and the mid-line of the back (Figure 1).
The mid side site is convenient to use for sampling
Grid sampling avoids the problems found with core
because it can be easily located during shearing and can
sampling of entire fleeces. Core sampling is time
even be shorn without removing the entire fleece.
consuming but does include variation due to position within the fleece. However core sampling cuts staples in
Problems with mid side sampling
the fleece thus reducing the fibre length.
In alpacas, if the mid side sample is taken to close to the belly, it may include fibre that is really part of the pieces component. If this happens the test results for mean fibre
State of Victoria, Department of Primary Industries Variation in and Sampling of Alpaca Fleeces Sampling and testing variability
difficulty in sampling and measuring these fibres. Contamination of saddle fleece samples with fibres from
If repeat samples are taken from a fleece, differences in the
the pieces and by coloured fibres will also increase the
reported test measurement will usually be reported. These
differences are related to two main causes.
Variation between samples Evaluating and undertaking alpaca fibre
Each sample submitted for testing is different. These
differences are related to the variation in animal fleeces
Use of mid side sample
discussed earlier but in this case are due to sampling variation. Samples are also frequently sub-sampled once or
The mid side sample was found to be an appropriate
twice and variation also occurs during these processes.
sample from which to predict the mean fibre diameter and the clean washing yield.
Variation between tests
The mid side sample does not measure a large enough area
Variation occurs between tests. This variation can be
of the fleece to detect sufficient variation in mean fibre
related to preparation of the sample and the operation of
diameter coefficient of variation (CVD) or in the incidence
the equipment. Each sample tested by the equipment is
different, so some differences in the reported measurement are to be expected. Scientific test laboratories regularly
Use of the saddle grid sample
monitor their testing procedures to ensure the reliability of
Breeders wishing to improve CVD and/or spinning
fineness measurements of the alpaca saddle, in the most efficient way, should use the saddle grid sample, since the
Interpreting test results
mid side sample is not as accurate for use in the selection
Alpaca growers need to be aware that each test has an
inherent error related to the variability associated with
Breeders using either mid side samples or saddle grid
sampling and testing procedures. This measurement error
samples to improve total fleece CVD, will improve neck
exists even if only one sample is taken and measured.
CVD at the same time with similar effectiveness.
Some growers have submitted fleece samples to different
The saddle grid sample was found to be the appropriate
fibre testing services and expressed criticism at the
sample to predict the incidence of medullated fibres in the
“difference in results” they receive. Such an outcome is to
be expected. But do these “different” results really differ?
Sampling procedure Sampling variance in Australian alpaca
The large 95% confidence limits for all the tested fibre
By determining the sampling variance, the 95 percent
attributes indicate that alpaca breeders and advisers need
confidence limits can be calculated for a particular
to consider taking suitable duplicate measurements and
sampling and testing procedure. The sampling variance
other precautions during breeding and animal selling
and confidence limits for mid side and saddle grid samples
has been measured in Australian alpacas (Table 3, Aylan-Parker and McGregor 2002).
Using the confidence limits
The sampling variance for the alpaca fibre mean diameter
The 95% confidence limits for mean fibre diameter (± 1.6
attributes are similar to values reported for Merino wool.
µm) show that alpaca breeders and advisers need to exercise
Except for clean washing yield, the sampling variance for
caution when interpreting absolute fibre test results. This
saddle grid samples was generally 2 to 4 times greater than
data indicates that breeders cannot confidently distinguish
the sampling variance for mid side samples. As a
between animal test results where the mean fibre diameter
consequence, for most fleece attributes, the 95%
differs by less than 1.6 µm. See examples below.
confidence limits for the saddle grid sample were about
There is only a 5% chance that two alpacas with the
double those of mid side samples (Table 3).
following mid side test results are different:
Table 3. The 95% confidence limits for fibre attributes measured from mid side or saddle grid samples in Australian alpacas.
Small differences in MFD are unlikely to be valid grounds
Attribute Mid side Saddle
upon which to discriminate against animals. This
interpretation has even greater weight when using saddle
grid samples to select animals, as the sampling variance for these samples is at least twice that of mid side test
Differences between years and properties
It is not valid to compare the fibre testing results obtained among properties or between years unless special
Sampling variance for the incidence of medullated fibres
precautions are taken during the collection and analysis of
in saddle grid samples was very high, possibly due to the
data. Large between year differences in the environment
State of Victoria, Department of Primary Industries Variation in and Sampling of Alpaca Fleeces
will affect alpaca fibre attributes (McGregor 2002) and
McGregor, B. A., 1994. Animal Production in Australia,
property and year affects can interact (See Figures 2 and 3,
McGregor and Butler 2004). Thus during the design of
McGregor, B.A., 1999a. In “Australian Alpaca Fibre:
genetic improvement programs, arrangements must be
Improving Productivity and Marketing” pp. 6 – 46.
made to account for these influences if serious attempts are
RIRDC Research Paper Series No. 99/140. (RIRDC:
to be made at identifying real genetic differences.
Correct fibre classing
McGregor, B.A. (1999b). The influence of environment,
It is essential that alpaca fibre be harvested and prepared
nutrition and management on the quality and production of
for sale in accordance with the guidelines laid down by the
alpaca fibre. Proceedings National Conference Australian
industry. Correct fleece preparation is needed prior to the
Alpaca Association, pp. 88–94. (Australian Alpaca
taking of saddle grid samples. These guidelines can change
from time to time. New guidelines can be obtained from
McGregor, B.A., 2002. Comparative productivity and
grazing behaviour of Huacaya alpacas and Peppin Merino sheep grazed on annual pastures. Small Ruminant Conclusions Research 44: 219 – 232.
If alpacas are to be selected for characteristics such as low
McGregor, B.A., 2004. Natural variations in alpaca fleeces
mean fibre diameter and high fleece weight then the mid
and interpretation of fibre tests. Proceedings National
Conference Australian Alpaca Association, pp. 85-90.
If alpacas are to be selected for low mean fibre diameter
(Australian Alpaca Association: Mitcham, Victoria)
coefficient of variation, low incidence of medullated fibres
McGregor, B.A., 2006. Production, attributes and relative
and other characteristics of medullated fibre, then the
value of alpaca fleeces in southern Australia and
saddle grid sampling technique is recommended.
implications for industry development, Small Ruminant
Alpaca breeders and advisers need to exercise caution when
Research 61: 93-111.
interpreting absolute fibre test results. Evaluation of fibre
McGregor, B.A., 2006. The affect of age, fleece weight,
attributes among alpacas should take into account the 95%
fibre diameter and live weight on the relative value of
confidence limits of the sampling procedure.
Australian alpaca fleeces. Proceedings National Conference Australian Alpaca Association, pp. 108-112.
(Australian Alpaca Association: Mitcham, Victoria).
The financial support of the Rural Industries Research and
McGregor, B.A. and Butler, K.L., 2004. Sources of
Development Corporation and the Australian Alpaca
variation in fibre diameter attributes of Australian alpacas
Association is gratefully acknowledged. Ms. J. Aylan-
and implications for fleece evaluation and animal
Parker, Ms. A. Howse and Mr. C. Tuckwell are thanked
selection. Australian Journal of Agricultural Research55: References and further reading
Stadler, W. and Gillies, R.I., 1994. Wool Technology and Sheep Breeding, 42: 319-26.
Aylan-Parker, J. and McGregor, B.A., 2002. Optimising sampling techniques and estimating sampling variance of
Turner, H.N., Hayman, R.H., Riches, J.H., Roberts, N.F.
fleece quality attributes in alpacas. Small Ruminant
and Wilson, L.T., 1953. Division of Animal Health and
Production Report No.4 (Series S.W.-2), 92 pp. (CSIRO: Melbourne).
Butler, K., Dolling, M., Marland, D.J., Naylor, G.R.S., Phillips, D.G. and Veitch, C., 1991. In “Proceedings Fibre
The previous version of this note was published in
Diameter Review Conference”, 54 pp. (CSIRO: Belmont,
Fleet, M.R., Foulds, R.A. and Lampe, F.J., 1993. Wool Technology and Sheep Breeding, 41: 307-16.
The advice provided in this publication is intended as a source of information only. Always read the label before using any of the products mentioned. The State of Victoria and its employees do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this publication. State of Victoria, Department of Primary Industries
Circuit ISRAEL - IORDANIA - EGIPT Date de plecare: 26.01.09 / 16.02.09 / 09.03.09 Ziua 1: Bucuresti - Tel Aviv - Jerusalem/Bethlehem Intalnire cu reprezentantul agentiei la ora 18:00 la aeroportul international Otopeni pentru cursa Tarom spreTel Aviv. Decolare la ora 20:40 si sosire la Tel Aviv la ora 23.15. Transfer la Jurusalem/ Bethlehem si cazare. Ziua 2: Jerusalem Dupa micul deju
Coastal Plains Community Center Proposal Due Date: 4:00 P.M. CST, August 3, 2012 This RFP is issued by COASTAL PLAINS COMMUNITY CENTER (CPCC), a Community Mental Health and Mental Retardation Center and a governmental unit of the State of Texas under the provisions of Vernon’s Texas Codes Annotated, Health and Safety Code, Chapter 534, as amended, (the “Center”), for the purposes of