Evaluation of Border Leicester × Romney (BR), Poll Dorset × BR, and Suffolk × BR ewes for out-of-season lambing

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

“…These two policies were studied because they were those previously shown to result in different annual ewe fleeceweights (Morris et al 1993) and because the June policy reflects what might be considered a likely "early lambing policy" in the lower North Island (Muir et al 1989). By definition, the comparison of two such policies inevitably involves a confounding between the effects of stage of production, feed allowance/ quality, and photoperiod.…”

“…Reid et al (1988) reported that autumn-lambing ewes produced up to 0.1 kg more greasy wool than those lambing in the spring. 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).…”

“…The ewe crosses were Border Leicester x Romney (BR), Poll Dorset x BR (PBR), and Suffolk X BR (SBR). A detailed description of the origin of these ewes and location of the trial is given by Morris et al (1993). Mating of the June-lambing ewes commenced on 5 January 1988 and was accomplished using progesterone-impregnated controlled internal drug-releasing devices (CIDR Type G, AHI Plastic Moulding Company, Hamilton, New Zealand) and high ram:ewe ratios (1:10) (Knight et al 1989).…”

“…a 2 x 3 factorial design). Ewes were randomly assigned to a lambing policy (June versus August) before mating at 18 months of age (Morris et al 1993) and remained assigned to that policy throughout the trial until shearing in October 1989. Midpoints of lambing were 5 June and 20 August for the two policies.…”

“…In particular, the study was designed to identify times of the year at which marked differences between the policies in wool growth were observed which might account for corresponding differences in annual fleeceweight previously observed (Morris et al 1993).…”