Last update: November 19, 2010 09:34:11 AM E-mail Print

 

Fibre diameter profile of summer and winter mohair of various age groups

of South African Angora goats

 

M.A. Snyman1 and N.M. Kritzinger2


1Grootfontein ADI, P/Bag X529, Middelburg (EC), 5900

2CMW, P.O. Box 3314, Port Elizabeth, 6056

Corresponding author:  Gretha Snyman

 


Fibre diameter is the single most important price-determining variable of mohair and is of critical importance in determining the eventual textile qualities and final manufacturing applications of mohair. Age of the Angora goat is probably the most important single factor determining the quality and quantity of mohair produced. Another aspect that has an influence on the price of mohair is the season of production. The aim of this study was to establish the variation in mean fibre diameter and its associated traits of summer and winter mohair of various age groups within South African Angora goat flocks. Data were recorded on mohair from adult ewes (21590 records), young goats (10923 records) and kids (11019 records) from 10 Angora goat producers from the summer 2000 until the winter 2004 shearing seasons. The following fibre diameter traits were determined with OFDA-procedures: fibre diameter (MFD; µm), coefficient of variation of fibre diameter (CV_MFD; %), standard deviation of fibre diameter (SD_MFD; µm), spinning fineness (SF_MFD; µm) and standard deviation of fibre diameter along the length of the staple (SD_ALONG; µm). From the results several conclusions can be drawn. There are large differences in MFD as well as the other fibre diameter traits measured among the various producers. There is a large overlap in MFD of adults, young goats and kids. Generally, winter adult mohair had a 0.8 µm higher MFD, a 0.5 % lower CV_MFD, the same SD_MFD and the same SD_ALONG compared to summer adult mohair. Theoretically it can be expected that the processing performance of winter and summer adult mohair will be similar. Winter young goat mohair had a higher MFD, higher SD_MFD, higher CV_MFD and higher SD_ALONG compared to summer young goat mohair. On top of the seasonal effect, an age effect also contributed to differences in fibre diameter profile. Summer kid mohair had a lower MFD, lower SD_MFD, higher CV_MFD and higher SD_ALONG than winter kid mohair. This could mainly be ascribed to an age effect. The frequency distribution of CV_MFD for summer and winter adult as well as young goat mohair differed very little, while there was a considerable difference between summer and winter kid mohair.