Longer-living ewes can make a major contribution to the improved
performance of English half-bred flocks, according to the final report
of the 10-year Longwool Improvement Project conducted on behalf of
the English Beef and Lamb Executive (EBLEX) and Hybu Cig Cymru/Meat
Promotion Wales (HCC).
Blue-faced Leicester ram
The project, undertaken by MLC with Defra, the Institute of Rural
Sciences, SAC and ADAS, has involved the detailed evaluation of
the performance of seven annual lamb crops from nearly 2,600 Scottish
and Welsh mule ewes bred from Blue-faced
Leicester rams of known
genetic merit for carcase quality. It has led to the development
of a sire selection index offering the opportunity to substantially
improve the overall performance of the 2.3 million mule ewes that
currently make up a third of the English breeding flock.
So valuable has the project shown ewe longevity to be, both economically
and genetically, that it forms the single most significant component
trait in the emerging Longwool Index.
The particular importance of ewe longevity in the Index stems
from four main elements – the economic importance of the
trait; the substantial variation that exists in it between breeding
rams; its reasonable heritability; and, the fact that it shows
little or no negative association with important growth and other
The project’s assessments of the reproductive performance
of ewes lambing between 2000 and 2006 show the average number of
lambs reared per ewe put to the tup increasing steadily to five
years of age, improving lamb output. At the same time, its economic
calculations highlight worthwhile cost savings from lower flock
replacement costs with increasing ewe survival rates, offset slightly
by lower cull ewe revenues.
At a ewe replacement cost of £75, the project establishes
the net benefit of a one-year improvement in flock average age
at a very considerable £11.20 per year per ewe lambing.
The project also identifies an actual variation of over 1.5 years
in the longevity of ewes bred by different rams, together with
a moderately high heritability of 30% (similar to many carcase
traits) suggesting that considerable progress can be made through
At the same time, the low and non-significant genetic correlations
established between longevity and growth and carcase quality traits
indicate this progress is unlikely to have adverse consequences
on these other important performance characteristics.
Practical advice on using the Longwool Index as part of flock
performance improvement efforts will be made available free to
English levy payers through the Sheep Better Returns Programme
as the new breeding tool is finalised for industry use. Full details
of the programme and associated EBLEX Lamb Action for Profit fact
sheets can be obtained at www.eblex.org.uk or
on 0870 2418829.
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