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

Abstract

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 (.X^), the standard deviation of fibre diameter (s.D-i), percentage medullation, mean fibre diameter after discarding the medullated fibres (X 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 X 2 and S.D. 2 .The highest correlations with the standard deviation of fibre diameter were those of H lt 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. INTRODUCTIONdifferent characters and to study the cause of variability. Such information may indicate a Because of their uniformity, synthetic fibres possible way of improving this type of wool and represent a source of great competition to wool, of assigning it to its most suitable category for a fact which emphasizes the importance of reduc-industry, ing the variability in the natural product.The fleece of Barki sheep (Fahmy et al 1969) MATERIALS AND METHODS has a relatively high variability in wool fibre diameter. In an earlier study (R. A. Guirgis, Forty-seven yearling Barki sheep were used, unpublished) the mean fibre diameter was 33-94 fi 28 in 1969 and 19 in 1970, and wool samples were with a coefficient of variation of 46-11%, when taken from five positions (Guirgis, 1967): three samples were taken from different lots of fleeces, dorsal positions -withers, back and hip -and two However, no information is available on how the lateral positions -mid-side and breech. The traits variability in fleece traits is affected by ...

A review of morphological characteristics relating to the production and reproduction of fat-tailed sheep breeds

“…Significant positive correlations were found between grease fleece weight and fiber length and between number of crimps and fiber diameter. Wool samples from Barki yearlings revealed a tendency for posterior positions to have higher values Iñiguez et al (2009) dorsally and laterally in the mean diameter, percentage medullation, and percentage kemp fibers (Guirgis 1973). Fine fiber percentage showed a reversed pattern of gradient anterior positions having the higher values.…”

Wool Production and Characteristics, Physiological and Haematological Parameters and Level of some Metabolic Hormones in Barki Ewes Shorn in Autumn as Alternative of Spring Shearing

“…Then, fibers from each type were counted and their percentages were calculated. Medulation index (MI) was calculated by multiplying the percentage of each fiber type by the type score (1, 2, 3 and 4 are the scores given to fine, coarse, heterotype and kemp, respectively), summing the resulted values then dividing the sum by 10 according to the adopted equation by (Guirgis, 1973) as follow:…”

Effect of Adding Moringa Oleifera Residues to Rations on Some Wool, Skin and Leather Properties of Growing Barki Sheep = تأثير إضافة مخلفات المورينجا أوليفيرا للعلائق على بعض خصائص الصوف والجلد للأغنام البرقي النامية

“…Wool fibers contained very coarse fibers with medulla occupying more than 70% of the medullated fiber are classified as kemp and fibers contained medulla classified as coarse fiber, whereas other non-medullated fibers classified as fine or non-medullated fibers. Fiber type ratios were also calculated according to Guirgis (1973). Crimp frequency (CF) is calculated as the average number of crimps per one centimeter of un-stretched fibers.…”