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.

Pasture management to minimise the detrimental effects of pre‐lamb shearing

“…Treatment effects were consistent across years as indicated by non-significant treatment x year interactions. However, climatic conditions were less extreme than in a previous study (Dabiri et al 1995a) in which up to 14% of shorn ewes died of cold stress and differences between standard comb-and cover comb-shorn ewes were more marked than in this study.…”

“…40 However, there were no effects of shearing treatment on organic matter intakes of late pregnant ewes in the present study. This does not agree with studies of non-pregnant and lactating ewes (Wodzicka-Tomaszewska 1964;Webster & Lynch 1966;Elvidge & Coop 1974), in which increased feed intake occurred one week following shearing, but is consistent with many experiments involving late pregnant ewes whether housed in pens (Rutter et al 1972;Symonds et al 1986) or at pasture (Parker et al 1991;Dabiri et al 1995aDabiri et al , 1996. The fact that shearing treatment increases feed intake in non-pregnant and lactating ewes, but not in late pregnant ewes, suggests that this difference is accounted for by the different physiological states of the ewes.…”

“…This is difficult to achieve in practice because during the winter, when pre-lamb shearing is normally carried out, pasture growth and availability is limited. Furthermore, in many studies of pre-lamb shearing at pasture, responses in feed intake were not evident until some weeks after shearing (Parker et al 1991;Dabiri et al 1995aDabiri et al , 1996. This raises the question of whether high feed allowances immediately after shearing are in fact important.…”

“…We have shown that the cover comb, which leaves a greater depth of fleece stubble than the standard comb, has advantages as a method to reduce the detrimental effects of shearing (Holmes et al 1992;Dabiri et al 1995aDabiri et al , 1995b. Since ewes shorn by cover comb generally exhibit greater resistance to cold stress than ewes shorn by standard comb (Dabiri et al 1995a(Dabiri et al , 1995b, it might be expected that a high feed allowance after shearing would be less important for the former group than for the latter.…”

“…Since ewes shorn by cover comb generally exhibit greater resistance to cold stress than ewes shorn by standard comb (Dabiri et al 1995a(Dabiri et al , 1995b, it might be expected that a high feed allowance after shearing would be less important for the former group than for the latter.…”