Preliminary observations on seasonal changes in the fleeces of unshorn Merino sheep.

Abstract

PRELIMINARY OBSERVATIONS ON SEASONAL CHANGES IN THE FLEECES OF UNSHORN MERINO SHEEP By M. L. R YDER *' Summary Fibre shedding is being studied in monthly skin annually, and two sheep left unshorn. The incidence may possibly be greatest in spring. Twenty monthly and the unshorn sheep have missed shearing twice, but reduced their wool growth rate. I. INTRODUCTION samples from two sheep shorn of shedding is very low, but samples have been examined, these have not shed more, nor This investigation was designed first to show the effect of leaving Merino sheep unshorn, in particular to determine whether the extra length of wool grown wili act as a stimulus for fibre shedding; and, second, to gain information (from the shorn control sheep) of the normal incidence of fibre shedding in the Merino. The investigation follows previous work on the incidence of shedding in British breeds (Ryder 1957), and on moulting in the wild Mouflon sheep (Ryder 1960). Since the investigation commenced, Lyne ( 1961) has published observations on the incidence of shedding in the Merino, and Margolena ( 1960) has failed to find any shedding in spring and autumn samples from the Rambouillet. II. METHODS Four fine-woolled ewes were selected in March 1960. Sheep 4 (5 years old j and sheep 10 (4 years old) have been kept as controls and shorn annually. Two more ewes, 69 and 92, two years old, were obtained with about six months growth of wool. These have been left unshorn as the experimental sheep. All the ewes, except 92, have borne a lamb in the springs of 1960 and 1961. Monthly skin and wool samples are being taken, and the approximate staple length is being measured each month. The skin samples are being sectioned both horizontally and vertically, and examined for follicles showing fibre shedding. III. RESULTS AND DISCUSSION Table 1 shows the length of wool grown before, and since, the observations began. It is clear that the sheep were initially producing wool at different rates, and they have continued at the same individual rates. Sheep 10 seems to be the greatest producer; sheep 4 and 69 seem to be comparable, and unshorn sheep 69 has not shown any. reduction in rate of growth. However, the rate of growth in sheep 92, the other unshorn sheep, seems to be slowing slightly, in that there were negligible increments during the four months ending with October 1961, the last sample before the time of writing. * School of Rural Science, University of New England, Armidale, New South Wales. 46 TABLE 1 STAPLE LENGTH (MM) ~Sheep 4 Sheep 10 Sheep 69 Sheep 92 April 1960 80 February 1961 70 80 llO- 40 = 70 95 - 35 = 60 October 1961 50 Total 120 145 120 97 40 35 65 160- 110 = 50 130- 95x35 1 shorn f i unshorn (100 mm = approximately 4 in) 95 I TABLE 2 INCIDENCE OF SHEDDING Shorn Unshorn Sheep 10 Sheep 69 __. ----I__ _-Sheep 92 March 1960 April May June July August September October November December January 1961 February March April May June July August September October No. of months with shedding: Sheep 4 + + + + + I -./ -- + + c- i- L i+ 8 -A- 10 - Table 2 shows the times at which fibre shedding occurred. Owing to the difficulty of determining the incidence of shedding, which is extremely low, as found by Lyne ( 1961) , only the presence or absence of shedding has so far been recorded. Lyne ( 1961) apparently noted only empty follicles, but in the present study, brush ends, empty follicles (distinguished by their collapsed lumen, and changes in the sheaths), and regrowing fibres, i.e., any stage of shedding, have 47 been recorded. Even so, the incidence is apparently lower than that found b;l Lyne. In no sample were more than a few shedding follicles found, i.e., an incidence of far less than 1 per cent. This makes it difficult to give an exact figure for the incidence, compared with that in British breeds, in which a definite proportion, usually greater than 1 per cent. of follicles shedding, is found. It is intended to adopt Lyne' scoring system as the investigation proceeds. A monthly s shedding incidence of less than 1 per cent. indicates that each individual follicle has a growing phase greater than eight years. Although Lyne claims to have found no seasonal trends, his graphs show peaks in spring and autumn. So far, in the present study, the greatest amount 01 shedding has occurred from late winter (August) to early autumn (March), with some variation between sheep in the months that shedding occurred. British breeds and the wild sheep shed most in late winter, with a smaller peak in late summer. The present work suggests a similar pattern. The shedding that took place in other months was also observed in British breeds, and in the Mouflon, in which quantitative work showed it to be insignificant. IV. REFERENCES A. G. ( 1961) .-The postnatal development of wool follicles, shedding, and skin thick ness in inbred Merino and Southdown-Merino crossbred sheep. Aust. J. Biol. Sci. 14: 141-56. R G O L E N A , L. A. (1960) .-Season and comparative activity of wool follicles. Anat. Rec. 138: 368. D E R, M. L. (1957).-A survey of the follicle populations in a range of British breeds oE sheep. J. Agric Sci. 49: 275-84. D E R, M. L. (1960).-A study of the coat of the Mouflon O v i s musimon with special reference to seasonal change. Proc. 2002. Soc. Lond. 135: 387-408. LYNE, M R R A Y Y