The use of crimp and staple length in the visual classing of stud Merino rams.

Abstract

THE USE OF CRIMP AND STAPLE LENGTH IN THE VISUAL CLASSING OF STUD MERINO RAMS MARY ROSE* SUMMARY In a Peppin Merino stud, all reserve and flock rams were sampled for fleece In addition to fleece weight, yield and fibre diameter measurement at 12 months. measurements which are usually made, crimp and staple length were measured and their means and distribution within the two classer's grades calculated. Reserve rams produced 18% more greasy wool and 17% more clean wool than the flock rams. Little difference was observed in yield but the average fibre diameter of reserves was 0.4 urn stronger than that of the flock rams. Reserves had (67.5 mm'+ 6.46), (74.8 mm t 7.40). in reserves (10.7 reserves. longer staples (70.7 mm + 7.00) than selected stud sires having even longer Crimps per inch were higher in flock + 1.43). Stud sires had fewer crimps flock rams staples rams (10.9 + 1.43) than (10.1 -+ 1.14) than Phenotypi c correlations were estimated for all characters measured and of s imilar orde r to those pub lished for 15-16 month old sheep. The classer placed considerable emphasis on fleece weight in his classing. Staple length has been shown to make a useful contribution in the visual assessment of rams with high clean fleece weight but crimp frequency was an unreliable guide to the fibre diameter of individual rams in the flock. INTRODUCTION A recent study of two Merino studs which measure all rams at classing has produced information on fleece weight, yield and fibre diameter in the classers' grades of rams (McGuirk et al. 1980). These workers showed that the two classers placed considerable emphasis on fleece weight in the selection of the reserve rams and that differences between grades in yield and average fibre diameter were generally not statistically significant. Classers use many characters in their visual assessment of rams. can be readily measured are staple length and crimp. Two which Classers endeavour to cull rams with short wool and consider length in choosing reserve rams and in sire selection. Length is an important component of wool weight; but since selection for high clean fleece weight would result in increased length, staple length is seldom measured. Many authors have shown that, over a wide range of wools, fibre diameter increases as number of crimps falls but the diameter corresponding to any one crimp may vary greatly both between flocks of the one strain and also between sheep within a flock (e.g. Lang 1947; Roberts and Dunlop 1957). However crimp and handle are the factors used in the visual appraisal of wool quality. It is apparent that as well as the relative emphasis a classer gives to each character and his efficiency of selection, the phenotypic correlations between fleece characters will greatly influence the success of his selection. * Wool Biology Laboratory, Department of Primary Industries, Yeerongpilly, Qld 4105. 428 Animal Production in Australia This paper examines the fleece weight, yield and fibre diameter for rams in one year in the Queensland stud reported by McGuirk et al. (1980), and the corresponding data on staple length and crimp. Estimates of phenotypic correlations between the fleece characters are also presented. MATERIALS AND METHODS The stud The stud was a Peppin Merino stud located in south west Queensland and joining approximately 5,000 ewes each year. In the year studied all rams were shorn as lambs and classed prior to the 12 month shearing when they carried about eight months' wool. In September 1976, 1,487 rams were classed and graded as reserves (279), flock rams (957) and culls (251). After measurement 28 stud sires were selected from within the classer's reserves using clean fleece weight and fibre diameter measurements as an aid but not staple length and crimp measurements. Measurements Greasy fleece weights were recorded for all rams but sampling and laboratory testing were confined to reserve and flock rams. Yield was estimated as the ratio of oven-dry clean wool (plus mineral ash) relative to the weight of the greasy sample, and clean fleece weight calculated. Average fibre diameter was measured using the Sonic A Fineness Tester. Measurements of staple length and crimps per inch were also made. Estimates of phenotypic correlations between the fleece characteristics measured were calculated. RESULTS The Table 1. production flock rams performance of the reserve, flock, cull rams and stud sires is shown in The reserve rams were 18% above the flock rams in greasy wool and 17% above in clean wool production. The greasy fleece weight of was 11% above that of the visual culls. There was little difference in yield between the grades measured but the average fibre diameter of reserve rams was 0.4 pm stronger than that of the flock rams. Although the study of the distribution of clean fleece weight by McGuirk et al. (1980) showed that the majority of high producers were in the reserves, there was still considerable variation in fleece weight among the reserves. TABLE 1 Relative productivity of the classer's grades and stud sires at 12 months (8 months' wool growth) Table 2 shows the distribution and mean staple length and crimps per inch 429 Animal production in Australia for the reserve and flock rams and the means for the stud sires. Estimates of variation are also given. Mean staple length of sires was greater than that of all reserves and reserves had longer staples than had the flock rams. TABLE 2 Distribution of staple length and crimps in reserve and flock rams Mean number of crimps in the flock rams was slightly fewer than for the reserves. Sires showed a further reduction in mean crimps. Estimates of the phenotypic correlations of the various fleece characters measured appear in Table 3. TABLE 3 Estimates of phenotypic correlations between fleece characters in reserve and flock rams at 12 months DISCUSSION The possible relevance of such results to the Merino stud industry as a whole has been discussed at some length (McGuirk et al. 1980). The emphasis given to fleece weight was considerably greater classer efficiency studies reported previously (Morley 1955; Riches 1955). In an early study Miller and Moule (1956) reported data for where the reserve rams produced less wool than the flock average. reason for the higher efficiency of the classer in this study may has wide experience and is a successful commercial classer familiar use of objective measurement. than in and Turner one stud One possible be that he with the Although it is not possible to assess the grade averages for staple length and crimp in relation to the whole flock it may be assumed from their distributions that the rams were a very even line visually, a majority of 430 Animal production in Australia animals falling into shorter wool than is a difference between some emphasis in his very few classes for each character. Despite this and the traditional for stud ram classing, the classer has achieved grades in both characters. This suggests that he places selection on each of these characters. Many of the estimates of phenotypic correlations were outside the ranges previously published for 15-16 month old animals (Turner and Young 1969) but they were of similar order. From these estimates it can be seen that the use of staple length would have contributed to the selection of higher clean wool producers in the reserves. Average fibre diameter of reserves was slightly higher than that of the flock rams. However in this stud all rams with diameters greater than two standard deviations above the mean are culled after measurement. Because of this, selection of sires with high clean fleece weight or slightly broader crimp did not result in sires with broader wool. Sires had a higher average clean fleece weight and broader crimp than the reserves but their average fibre diameter was 0.5 urn finer. These results confirm previous criterion in the visual selection of crimp may be unreliable in assessing in a flock. The measurement of fibre fleece measurement if wool quality is findings that staple length may be a useful rams with high clean wool weights while fibre diameter visually in individual rams diameter must be an essential part of to be maintained. ACKNOWLEDGEMENTS It is a pleasure to acknowledge the kind co-operation of the stud owner, the technical adviser and the stud classer. REFERENCES LANG, W.R. (1947). J. Text. Inst. 38: T241. McGUIRK, B-J., SCOTT, R., and ROSE, MARY (1980). Aust. J. Exp. Agric. Anim. Husb. (in press). MILLER, S-J., and MOULE, G.R. (1956). Aust. Vet. J. 32: 278. Z MORLEY, F.H.W. (1955). Agric. Gaz. N.S.W. 66: 400. RICHES, J.H., and TURNER, HELEN NEWTON (1955), Aust. J. Agric. Res. 6: 99. ROBERTS, N-F., and DUNLOP, A.A. (1957). Aust. J. Agric. Res. 8: 524.= TURNER, HELEN NEWTON, and YOUNG, S.S.Y. (1969). 'Quantitative?enetics in Sheep Breeding' (Macmillan Co. of Australia Pty Ltd: Melbourne). 431