Wool Fineness in Eight Sampling Regions on Yearling Rambouillet Ewes

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Abstract
Analyses are presented for fiber diameters of wool obtained from ten Rambouillet yearling ewes, sampled from eight body regions: withers, back, rump, shoulder, side, hip, thigh and belly. Three locks of wool from each region were taken, and each lock was cross-sectioned at three levels: near the base, at the middle and near the tip. Four groups of 50 adjacent fiber diameters were measured in each cross-section, making a total of 14,400 fiber diameters for each sheep or 144,000 for all animals. There appears to be a trend in average fineness from the smallest average diameter at the withers, shoulder, back and side, to larger average diameters at the rump and belly, to the coarsest fibers at the thigh. Differences between sheep, regions, locks, cross-sections and groups were examined to determine the minimum number of locations and number of fibers that would adequately characterize a fleece and so describe a working index for selection of experimental breeding sheep. An increase in the number of fibers measured beyond 100 to 200 decreases the standard error but slightly, which indicates that measuring the fibers from more than one cross-section at a particular region and level is not efficient sampling technique. Increased accuracy can most efficiently be obtained by increasing first the number of regions sampled and then the number of levels along the fiber. Samples from one level and two regions are required to obtain a standard error of 0.692 which is consistent with the range usually observed in fine wool sheep. It was found that samples from the shoulder, side and thigh rank sheep in approximately the same order as samples from the eight regions. For comparing individual fleeces several regions and levels must be sampled to make differences of from two to three microns significant at the 5% level. In comparing fleeces from groups of sheep, such as progeny by different sires, results show that at least ten sheep per group are required to make a difference of one micron significant for a reasonable number of regions and levels. Copyright © . .

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