Productivity and cold resistance in ewes pre-lamb shorn by standard or cover comb

Abstract

The cover comb has been developed in New Zealand as a means of increasing residual fleece depth after shearing and so increasing the resistance of shorn sheep to cold-stress. The effects of pre-lamb shearing ewes with cover or standard comb, and of leaving ewes unshorn until after weaning, on their feed intake, productivity, and cold resistance were studied. Border Leicester x Romney ewes were divided into three groups balanced for pregnancy status, ewe age and liveweight. Two groups of ewes were shorn, by either cover comb or standard comb, on day 114 of pregnancy (P114) and one group left unshorn until weaning on day 84 of lactation (L84). Ewes were managed under the same conditions during pregnancy and lactation. Ewes shorn pre-lamb by cover comb had lower mortality from shearing to lambing, and lower organic matter intakes and biting rates at P123-126 than ewes shorn by standard comb. These parameters did not differ between ewes shorn pre-lamb by cover comb and unshorn ewes except biting rate which was greater in the cover comb-shorn group. Twenty days after shearing (P134), the liveweights of ewes were greater in the unshorn group than in the cover comb-shorn group (P < 0.05), which was in turn heavier (P < 0.05) than ewes shorn by standard comb. Midside clean wool growth rates were greater in standard comb- and cover comb-shorn ewes during the post-shearing period (to day 40 of lactation) than in unshorn ewes ( P < 0.05). Similarly, the yield and brightness of wool were superior (P < 0.05) in pre-lamb shorn groups. Lamb liveweights at birth, docking and weaning, and lamb survival, were similar between shearing policies. Rectal temperature (RT) was significantly (P < 0.05) lower in both pre-lamb shorn groups than in the unshorn group on day 3 post-shearing (S3), but by S5 only the ewes shorn by standard comb had lower RT. These results suggest that the greater amount of residual wool in cover comb- vs standard comb-shorn ewes provides a low cost practical method for reducing the two important disadvantages of pre-lamb shearing, namely increased cold-stress and feed intakes post-shearing.