EFFECT OF LAMBING POLICY AND EWE BREED CROSS ON WOOL GROWTH-PATTERNS AND WOOL QUALITY

The effects of lambing policy (June- or August-lambing) and ewe breed cross on midside patch wool growth and wool quality traits were studie d for 12 months. Three ewe crosses-Border Leicester x Romney (BR), Pol l Dorset x BR (PBR), and Suffolk x BR (SBR)-were used. Twenty ewes of each cross within each lambing policy and balanced for litter size had midside patches clipped at approximately 6-weekly intervals for 1 yea r from April. Annual ewe fleece production was measured at the October shearings preceding and following the trial. June-lambing ewes produc ed 0.6 and 0.4 kg more greasy and clean wool respectively than August- lambing ewes (P < 0.001). This extra wool production was not parallele d by a greater total wool growth from midside patches in June-lambing ewes throughout the 392-day measurement period. There was, however, a difference in the pattern of wool growth between the two groups. The s easonal decline in wool production that normally occurs over the winte r months in August-lambing ewes was reduced in June-lambing ewes. Asso ciated with the extra winter wool production in June-lambing ewes was a significant increase in mean fibre diameter (P < 0.05) and staple st rength (P < 0.001) when measured at the following October shearing. Wo ol from the June-lambing ewes was brighter and whiter (P < 0.05) than that from August-lambing ewes. There was no difference in wool bulk or resilience between the two policies. Of the ewe crosses investigated, the BR had the highest greasy wool production (4.4 +/- 0.1, 3.4 +/- 0 .1, 3.0 +/- 0.1 kg for BR, PBR, and SBR respectively, P < 0.001), mean fibre diameter (p < 0.05), and wool tensile strength (P < 0.001). The SBR had the lowest wool production, mean fibre diameter, and wool ten sile strength but the highest wool bulk. The practical implications of the increased winter wool production in June-lambing ewes are discuss ed.