Fleece weight deals with quantity; what about wool quality? In the 1950s wool was graded visually for sale, as it had been for decades. Research determined the quality characteristics which had the greatest influence on price; the number of crimps per inch was found to be of overwhelming importance. A higher number of crimps was thought to be associated with a finer fibre diameter, and diameter was stated by manufacturers to be the most important characteristic of wool, price rising with decreasing diameter. As measurements from wool laboratories accumulated, it became increasingly clear that not only was crimp a very inaccurate guide to fibre diameter, but also that it had a high negative correlation with fleece weight. Attempts to maintain quality through keeping a high crimp number would therefore greatly reduce any progress which could be made in raising fleece weight. Average fibre diameter, on the other hand, had only a low positive association with fleece weight, so control of quality through fibre diameter would not have such a retarding effect on raising fleece weight.

Fibre diameter should therefore be measured, but on what? Firstly, on rams only because of expense. But how? On a wool sample, obviously, but from where? Diameter varies from back to belly and from neck to breech, but extensive sampling showed that a measurement on the midside gives a reading close to the average of all.

Obviously all sheep could not be measured. The Merino industry had over the years developed a three-tiered breeding structure of closed parent studs, daughter and general multiplying studs drawing rams from one or more parent studs, and commercial flocks drawing rams from any one of the stud levels. Genetic gains made by the parent studs would be passed down to other levels; if these were not making optimum gains in production, those at other levels would necessarily suffer. If the studs, particularly the parent studs, could be persuaded to adopt the results of scientific research, this would be the cheapest way of achieving progress. The lack of increase in fleece weight from 1930 to 1950 was followed by a slight rise in later years, but results from selection experiments on research stations showed that the annual changes could be doubled or trebled if measurements were introduced into the selection process, particularly if diameter instead of crimp was used to measure quality.

Some studs did incorporate new techniques, but not all. Dissatisfaction with lack of information about progress in studs led in the 1960s to the establishment of cooperative (also called 'group') breeding schemes, whereby top ewes from a number of flocks were placed in a central nucleus from which rams were then drawn. The pioneer scheme in Australia was the Australian Merino Society, founded in WA by a group of sheep breeders led by Mr. T. Shepherd which now incorporates more than 2 million breeding ewes, spread over all States.

During the 1970s moves were made to replace visual appraisal by objective measurement in wool selling, with a vast amount of research on bulk wool, instead of on individual fleeces. By 1984 most Australian wool was sold by measured samples. This has led to a change of attitude on the part of breeders and, in 1983, a Performance Merino Breeders Association was formed, incorporating breeders who use measurement in their selection procedures. This Association held a sale early in 1984 at which all rams were sold on measured performance, and it is moving in future towards computerized selling on measured performance.

Australian Academy of Technological Sciences and Engineering