Shearing ewes at housing boosts performance
Getting out the clippers at housing has positive knock-on benefits for lamb birth and weaning weights, writes Dr Tim Keady
Many flock owners who are now preparing to house their ewes are asking if shearing ewes at housing make sense financially and from a management perspective.
The price that producers receive for wool has declined dramatically in the past year. Consequently, the return from the fleece will not cover the cost of shearing in most cases.
However, a series of studies carried out at Athenry would suggest that shearing ewes at housing does make sense. Shearing ewes, which lamb in March, at housing has many advantages. The aim of this article, the seventh in the current series, is to present results from studies on the taken in Athenry on how shearing at housing affects subsequent animal performance.
Shearing at housing
Three studies have been undertaken at Athenry which have evaluated the effects of shearing March-lambing ewes, at housing in December, on their subsequent performance and the performance of their lambs from birth until weaning.
In each of these studies, ewes were housed either unshorn, or shorn and fed ad-lib grass silage. For the six weeks prior to lambing, ewes carrying singles, twins and triplets each received a total of 12kg, 20kg and 25kg concentrate, respectively.
Ewes rearing singles and twins, and their lambs, were turned out to pasture post lambing and grazed as one flock until weaning, without concentrate supplementation.
Ewes that were rearing triplets were turned out to pasture post lambing and managed as a separate flock and received 0.5kg concentrate daily for five weeks post lambing.
Lambs that were reared as triplets had access to concentrate, up to a maximum of 300g daily, until weaning.
Effects on animal performance
The effects of shearing ewes, who are due to lamb in March, at housing on subsequent lamb performance are presented in Table 1.
Shearing at housing did not alter ewe condition score at lambing. However, shearing the ewes at housing increased silage intake.
The difference in silage intake between the shorn and unshorn ewes was similar from housing until lambing.
Lambs born from ewes that had been shorn at housing were 0.6kg heavier at birth and 1.9kg heavier at weaning. Whilst shearing at housing increased lamb birthweight, it did not affect the incidence of lambing difficulty or mortality.
The increased birthweight of the lambs from ewes shorn at housing was due to increased silage dry matter intake which was partly a reflection of cold stress immediately post shearing, and more importantly, a reflection of reduced heat stress in late pregnancy and an extended gestation period. The increase in lamb weight at birth (0.6kg) was trebled (1.9kg) at weaning at 14 weeks of age.
The increase in lamb weight at weaning obtained due to shearing ewes at housing is the same response as would be expected from providing 19kg of creep concentrate to each lamb prior to weaning, which is equivalent to a cost of approximately €5/lamb. Shearing at housing (cost €2.50/ewe) is equivalent to a saving in creep concentrate of approximately €8/ewe for ewes rearing 1.7 lambs.
Previous studies at Athenry have shown that an increase in lamb weaning weight of 2kg reduces the age at slaughter by approximately two weeks.
Effects on fleece weight
Season of shearing affects the weight of wool harvested. The effect of season of shearing on fleece weight is presented in Table 2 below. Shearing ewes at housing increased the weight of wool harvested by 0.3kg/ewe relative to shearing in May.
The recommended space allowance for unshorn ewes depends on floor type and ewe weight.
For example, the recommended space allowance for ewes housed on slats and straw bedding is 1.1 and 1.2m2 for 70kg ewes; and 1.2 and 1.4m2 for 90kg ewes.
The floor area required by shorn ewes is up to 20pc less per ewe. Thus shearing ewes at housing enables more ewes to be housed in a given area.
Ewes shorn at housing are easier to monitor during late pregnancy and post lambing.
Shearing ewes at housing occurs during a period of low labour demand for flock management and consequently spreads the annual work load more evenly.
Shearing at other times
Some producers opt to shear their flocks in the autumn prior to joining the ewes with rams.
Two studies were undertaken, one at Athenry and the second on a large commercial farm, to evaluate shearing either four weeks prior to joining (September) or at housing (December) relative to the traditional time (early summer).
All ewes at each site were kept in one flock throughout the grazing and mating seasons, and were housed in mid-December and offered the same diet.
The results of these studies showed that shearing the ewes in autumn resulted in approximately 60pc of the benefit in lamb birthweight observed when shearing was at housing.
Shearing in the autumn prior to the joining period reduced fleece weight by 0.5kg; there was no beneficial effect on litter size (a claim that is sometimes made).
Dr Tim Keady is Principal Research Scientist at the Animal and Grassland Research and Innovation Centre, Teagasc, Athenry, Co Galway.
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