Effects of shearing time and time of lambing on wool growth and processing characteristics

Abstract

Wool growth rate, seasonal pattern of fibre diameter, clean fleece weight, quality and the processing characteristics of wool were measured on medium-wool Merino sheep shorn in March (autumn) or October (spring) coupled with March or June lambing. These four management systems were compared under two nutritional regimes in the medium rainfall area of Western Australia. The sheep grazed annual pastures only, or had lupin grain and stubble during summer in addition to the pasture. The study ran for two shearing periods. Time of shearing was the dominant factor. Sheep shorn in March produced 14% more clean wool and fewer tender fleeces than sheep shorn in October. The autumn wool had a lower yield, higher fibre diameter and when processed had a higher card loss, lower percentage noil and lower top and noil yield. However, mean fibre length in the top was substantially higher and the variation in fibre length lower. Vegetable matter was higher in autumn shorn wools. There were some interacting effects of lambing time and type of feed regime. Sheep fed lupins had lower yielding wool but this effect was more pronounced in June lambings and was reflected in differences in top and noil yield. From measurements of wool growth rate, it was found that the extra wool was produced in autumn after shearing, due possibly to stimulated appetite that cannot occur after spring shearing because the sheep are too fat.

Effect of lambing policy and ewe breed cross on wool growth patterns and wool quality

“…The results are contrary to those reported for Australian conditions where autumn-Avinterlambing ewes produced a higher proportion of tender (low tensile strenth) wools (Kenny & Davis 1975;Arnold et al 1984;Foot & Heazlewood 1988). However, in the Australian situation, unlike the trial reported here, nutrition during the autumn may be limiting and this would contribute to lower wool growth, and hence a higher proportion of tender wool in the autumn-lambing ewes than in spring-lambing ewes.…”

“…Australian researchers, however, have reported no differences in wool production between winter (June/July)-and spring (August/September)-lambing ewes (Allden 1956;Kenney & Davis 1975;Arnold et al 1984). The breeds used in those studies were Merino or Merino crosses and the lack of a policy effect on wool production is perhaps a reflection of the Merino's relative aseasonality of wool production.…”

“…Morris et al (1993) observed a greasy wool production advantage of between 0.1 and 1.1 kg to June-lambing ewes compared with August-lambing ewes. Fitzgerald (1976) found an 11 % difference in wool production between winter (June/July)-and spring (August/September)-lambing ewes but other researchers have found no difference (Allden 1956;Kenney & Davis 1975;Arnold et al 1984). Several studies have shown that an autumn/winter lambing policy can increase the proportion of tender fleeces (Kenney & Davis 1975;Arnoldetal.…”

On-farm factors affecting physical quality of Merino wool. 1. Nutrition, reproduction, health and management

“…Time of shearing did not affect SS in this study, but others have shown the converse is true while also altering the position of break when SS is measured (Douglas, 1989;Adams et al, 2000). VM contamination is influenced by the timing of shearing (Warr et al, 1979;Arnold et al, 1984;Adams et al, 2000).…”

Reproductive performance of ewes grazing lucerne during different periods around mating

“…This is consistent with a limited effect of reproduction on wool variables under suitable nutritional conditions (Robertson et al, 2000), although under poorer pasture conditions, the value of wool produced may be reduced as a result of the larger nutritional demands of ewes bearing twin foetuses. Although the staple strength of wool was not reduced by the lucerne treatments, the greater variability of along-staple fibre diameter for ewes which grazed lucerne indicates that there may be an increased risk of lower staple strength if the time of shearing differed (Arnold et al, 1984) due to alteration of the fibre diameter profile. This is consistent with the trend (Table 5) for staple strength to differ between treatments.…”