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The study of variability in some wool traits in a coarse wool breed of sheep

Published online by Cambridge University Press:  27 March 2009

R. A. Guirgis
R. A. Guirgis
Affiliation:
Wool Laboratory, Department of Animal Production, Desert Institute, Matareya, Cairo, Egypt
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Summary

Wool samples from 47 Barki yearlings were taken from five positions during two years to study the variability in the fleece, the cause of variability and associations between different fleece traits. Statistical analysis has indicated the following significant points.

An antero-posterior gradient occurred in the different traits under study. When medullation was discarded, though it was of a low magnitude (3·9%), a reduction of 5·89% in the mean fibre diameter and of 18·33% in its standard deviation occurred.

The position most representative of the whole fleece varied with the trait. It is recommended to take three sampling positions forming a triangle, withers, mid-side and hip, to represent the Barki fleece.

The animals contributed the major part in the variability of mean fibre diameter (1), the standard deviation of fibre diameter (S.D.1), percentage medullation, mean fibre diameter after discarding the medullated fibres (2), the standard deviation of fibre diameter after discarding the medullated fibres (S.D.2), the contribution of medullation to the total variability, percentage fine fibres and percentage coarse fibres. The positions were the main contributor to the variability of percentage kemp fibres, staple length, medullation index and to a certain extent to that of the kemp score. The year played a significant part in the variability except for 2 and S.D.2.

The highest correlations with the standard deviation of fibre diameter were those of percentage medullation and kemp score. These three variables when considered separately accounted for 0·47, 0·35 and 0·31 respectively of the variability in S.D.

Equations were obtained to predict the standard deviation from both the mean fibre diameter and the percentage medullation and to predict the mean fibre diameter from the staple length and the kemp score. The coefficient of determination of the first set of equations ranged from 0·47 to 0·56 while that of the second set ranged between 0·07 and 0·51 for different positions.

Type
Research Article
Information
The Journal of Agricultural Science , Volume 80 , Issue 2 , April 1973 , pp. 233 - 238
Copyright
Copyright © Cambridge University Press 1973

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