Crossbred ewes can be managed successfully in a hill environment
Take Home Message: The use of larger, more productive crossbred ewes will improve lamb output in hill situations.
Where stocking rates are adequate, larger and more productive crossbred ewes can be maintained in the hill environment without deleterious consequences for survival or pregnancy rate.
That was the conclusion of a study, carried out by researchers in Wales from the Institute of Biological, Environmental and Rural Sciences at Aberystwyth University, ADAS and the Welsh Assembly Government, which set out to compare the survival and productivity of pure-bred Welsh Mountain ewes with a range of cross-bred ewe types maintained in a hill environment.
“The Welsh Mountain sheep is a numerically important breed in the UK, but its lambs are characterised by low slaughter weights and poor carcass conformation,” IBERS’ Basil Wolf told delegates at this year’s British Society of Animal Science annual conference.
“The reduction in stocking rates that is often associated with environmental conservation schemes, offers the potential for the use of larger ewes. Crossbreeding allows more rapid genetic change to be undertaken than would be possible from selection within breeds, and affords the potential to utilise heterosis and improve the quality of subsequent crosses with the Bluefaced Leicester,” he said, explaining the rational behind the team’s work.
During a three-year period, 600 Welsh Mountain ewes were mated each year to either Cheviot, Poll Dorset, Lleyn or Texel sires. Up to 50 ewe lambs per year were retained from each breed and a similar number of pure bred Welsh Mountain lambs were also retained each year from the farm flock.
These pure Welsh Mountain and crossbred ewes were mated by Suffolk rams and ewe performance was recorded over three parities. Ewes were weighed and condition scored on a scale of 1 (thin) to 5 (fat) at the start of the mating period. All ewes in their first parity (two years old) were housed for the final six weeks of pregnancy and fed grass silage and concentrates according to predicted litter size.
In subsequent parities only twin and triplet bearing ewes were housed, and single bearing ewes were maintained on pastures and fed grass silage supplemented with feed blocks until lambing.
After lambing, single bearing ewes were grazed on semi-natural hill pastures at a stocking rate of 1.5 ewes per ha, while twin rearing ewes were retained on improved perennial ryegrass based swards at up to 10 ewes per ha until lambs were weaned at 18 weeks of age.
“And we found that there were no significant differences between ewe types in pregnancy rates and survival to third lambing,” said Dr Wolf.
“Cheviot, Dorset and Texel crossbred ewes were approximately 8kg heavier than the Welsh Mountain. Lleyn cross ewes were intermediate in weight.
“And relative to the number of ewes that entered the flock, total litter weight weaned over three lamb crops was between 18.7kg and 31.3kg higher in crossbred ewe types than in the Welsh Mountain, although the relative contribution to this of litter size and individual lamb weaning weights varied between crossbreeds.
“The progeny of crossbred ewes were also heavier at birth and weaning than lambs from Welsh Mountain ewes. However, although crossbred ewes supported higher growth rates in early lactation, there were no significant differences in average daily gain from eight weeks old to weaning,” he added.
Presented to the British Society of Animal Science Annual Meeting, March 30 to April 1, 2009, Southport, UK.
Full details: Wolf BT, McLean BML, Davies OD, Griffiths JB: “Performance of crossbred Welsh Mountain ewes in the hill environment.”
Summary (pdf) Presentation_071wolf (pdf)
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