Study of crimp expression and related characters in a New Zealand Romney flock

Abstract

A regular and precisely defined staple crimp is an important contributor to the appearance of the fleece (Henderson, 1968). It is also well recognised that young sheep have a fleece that is better than older sheep. In some instances the deterioration of the fleece starts at an early age and proceeds rapidly. This wool has been referred to as “doggy” wool. The main characteristic of “doggy” wool is a lowering of crimp frequency, through several stages according to severity, so that the wool has an irregular crimp, an unnatural lustre and a harsh handle (Ryder and Stephenson, 1968).

The fault has been widely reported in the Australian Merino. In one survey of the Eastern States of Australia no flock was found without some form of abnormal crimping. The fault was more prevalent in order sheep (Chapman and Short, 1964a).

“Doggy” wool is classified as rough fleece in Australia. Rough fleece in the Australian clip has increased in recent years to ¾ per cent of the total wool clip, the price gained being appreciably less than that of wools with more crimp. True “Doggy” wool is thought to make up at least ⅔ of the total rough fleece, the remainder being steely (copper deficient) wool (Chapman, 1964). There is no doubt that some wools, affected only slightly by crimp abnormality, are present in normal wool grades but have been devalued by the slight crimp upset.

An association was found between “doggy” wool production and the presence of capsules attached to an enlarged outer-root sheath of a varying proportion of follicles in the population (Chapman, Short and Hyland, 19860; Chapman and Short, 1965b). The incidence of follicles with capsules was found to increase with age (Chapman, Short and Hyland, 1960) and was associated with the production of short, straight, coarse fibres by affected follicles (Chapman and Short, 1965b). The presence of a number of these fibres in a staple of wool was found to upset the crimp form of the staple of wool was found to upset the crimp form of the staple (Aiken and Ryder, 1962; Chapman and Short, 1964a).

Burns and Clarkson (1950) had noted the presence of capsules attached to Romney wool follicles. These had also been noted in the New Zealand Romney by Henderson (1967).

The present experiment was designed to establish whether or not these capsules were present in any great numbers in the Romney, and with the Australian experience in mind , to try and establish a relationship between their presence and deterioration of crimp with age. If sheep with capsulated follicles were present in any great number and crimp deterioration was significantly associated with the presence of aberrant follicles, there would be justification for further work in this field. A large number of sheep with this fault could cause quite a serious devaluation in the New Zealand Wool clip.

Although only one flock was involved in the experiment reported , it is in the nature of a survey of the incidence of a possibly serious wool fault.