Alpaca Fleece Micron Measurement
Cashmere Connections has been purchasing Alpaca Fleece based on subjective measurement. Some growers
have objected to the fibre assessments given because they have test results from mid side fleece samples
which differ from Cashmere Connections' view.
This paper attempts to answer two questions.
- How useful is a mid side sample test in ascertaining the value of a fleece?
- How good is Avtar at estimating the production value of a fleece?
The use of mid side samples to evaluate fleeces for breeding purposes is questionable (see papers below).
When interloting fleeces for processing, mid side samples are definitely inappropriate.
© Charles Esson. No rights reserved.
Huacaya and Suri alpacas (n = 120) of varying age, live weight (LWT) and sex (female, male) were selected randomly from
four farms in southern Australia. At shearing, fleeces were divided into four components: saddle (S), neck (N), pieces (P; front
and back legs, belly, apron) and the midside sample (MS). Components were weighed, sampled using the grid sampling
technique and fleece attributes measured: clean washing yield (CWY), mean fibre diameter (MFD), coefficient of variation of
the MFD (CV(D)), incidence of medullated fibres (Med), mean medullated fibre diameter (MedMFD) and coefficient of
variation of the MedMFD (MedCV(D)). The MS and saddle grid sample (SGS) were used to create models to predict the fleece
attribute of the total fleece (TF), saddle and neck fibre. For each fleece attribute MS had lower values than SGS and TF
(P < 0:005) and SGS, except for CWY, had lower values than the P and TF (P < 0:005). The means were: MFD MS 27.5 mm, S
28.8 mm, N 28.7 mm, P 37.6 mm, TF 31.2 mm; CV(D) MS 24.3%, S 27.0%, N 28.6%, P 30.6%, TF 28.1%; CWY MS 90.2%, S
91.4%, N 88.9%, P 92.8%; Med 24.4%, S 33.1%, P 44.5%, TF 35.2%; MedMFD MS 32.7 mm, S 34.4 mm, P 41.1 mm, TF
36.0 mm; MedCV(D) MS 19.4%, S 22.3%, P 25.9%, TF 23.4%. The MS was found to be an appropriate sample from which to
predict the MFD and CWY. CV(D) was only satisfactorily predicted by the SGS (r = 0:88), with the exception of the neck
fleece, for which neither the MS nor SGS could provide an accurate predictive model. The MS did not sufficiently account for the
variation in Med (r = 0:73 - 0.79). The SGS gave accurate prediction of Med (r = 0:98). Sex effects were detected in models for
TFMFD, NMFD and TFCV(D). LWT effects were detected in models for NMFD, NCV(D) and TFMedMFD. SGS often gave a
more accurate prediction of a fleece attribute but it requires the removal of the entire fleece, whereas MS can be removed by
shearing a small area or can be removed during shearing with a minimum of effort. Sampling variance for SGS was generally two
to four times greater than the sampling variance for MS with the 95% confidence limits (CLs) for SGS being about double those
of MS for most parameters except for clean washing yield (CWY) which were similar. Sampling variance for the incidence of
medullated fibres in SGS was very high. The large 95% CL for all the tested fibre attributes indicate that alpaca breeders and
advisors need to consider taking suitable duplicate measurements and other precautions during breeding and animal selling
programs.
© Crown Copywrite. For use for educational and research purpose only.
To help breeders evaluate alpaca fleece attributes the
starting point is understanding the types of variation found
in and between fleeces; the most appropriate method of
sampling alpaca fleeces; and the application of this
information for evaluating fibre test results. This article is
based on research conducted in Australia.
© State of Victoria, Department of Primary Industries
Sources of variation in fibre diameter attributes of Australian alpacas and implications for fleece
evaluation and animal selection were investigated using data collected in the years 1994-97, from 6 properties in
southern Australia. Data were analysed using REML (multiple regression analysis) to determine the effect on mean
fibre diameter (MFD) and coefficient of variation of MFD (CV(FD)) of age, origin (property), sex (entire male,
female), breed (Huacaya, Suri), liveweight, fibre colour, individual, and interactions of these effects. The mean
(n = 100) age (range) was 4.2 years (0.1-11.9), liveweight 72.0 kg (12.0-134 kg), MFD 29.1 um (17.7-46.6 um),
CV(FD) 24.33% (15.0-36.7%).
A number of variables affected MFD and CV(FD). MFD increased to 7.5 years of age, and correlations between
MFD at 1.5 and 2 years of age with the MFD at older ages were much higher than correlations at younger ages.
Fibre diameter "blowout" (increase with age) was positively correlated with the actual MFD at ages 2 years and
older. There were important effects of farm, and these effects differed with year and shearing age. Suris were coarser
than Huacayas with the effect reducing with increased liveweight; there was no effect of sex. Fleeces of light shade
were 1 um finer than dark fleeces. CV(FD) declined rapidly between birth and 2 years of age, reaching a minimum
at about 4 years of age and then increasing; however, CV(FD) measurements on young animals were very poor
predictors of CV(FD) at older ages, and the response of CV(FD) to age differed with farm and year. Suris had a
higher CV(FD) than Huacayas on most properties, and MFD, liveweight, and sex did not affect CV(FD). Fleeces of
dark shade had higher CV(FD) than fleeces of light shade in 2 of the years. It is concluded that there are large
opportunities to improve the MFD and CV(FD) of alpaca fibre through selection and breeding. The potential benefit
is greatest from reducing the MFD and CV(FD) of fibre from older alpacas, through reducing the between-animal
variation in MFD and CV(FD). Sampling alpacas at ages <2 years is likely to substantially decrease selection
efficiency for lifetime fibre diameter attributes.
© CSIRO 2004
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