Litter Size EBVs Boost English Flock Performance
28/09/06

Using rams with high Estimated Breeding Values (EBVs) for litter size in replacement breeding can make a valuable contribution to improving the performance of English lowland flocks, according to figures produced by MLC’s Signet Breeding Services on behalf of the English Beef and Lamb Executive (EBLEX).

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Detailed 2005 crop records gathered from a lowland flock show the daughters of the five rams with the highest litter size EBVs producing 13 more lambs per 100 ewes than those of the five rams with the lowest EBVs for the trait.
Table: Impact of Litter Size EBV on Lambs Produced in a Commercial Flock (2005 crop)

Assuming an 80% lamb survival rate to sale, this could easily add an extra £5/ewe/year to flock output; worth more than £800 per ram over the productive lifetime of his female offspring retained in the flock.

Where producers have a breeding objective to increase lambing %, using high litter size EBV rams will be invaluable. However, EBLEX advises producers to focus their attention on a number of other critical aspects of flock management in parallel to maximise the extent to which the improvement in lambs born is translated into increased lamb output at sale.

These include:

• Using rams which also have high maternal ability EBVs to optimise milk output and other mothering characteristics in their offspring;
• Managing tupping to ensure optimum ewe and ram fertility;
• Ensuring ewes and rams are in optimum condition for tupping, avoiding overfat ewes.
• Scanning ewes to identify twin and triplet-bearing stock for preferential feeding in the run-up to lambing and as an aid to rapid fostering;
• Bringing replacement ewes and ewe lambs into the flock vaccination programme for clostridial diseases and pasturella pneumonia in the autumn.
• Giving ewes booster vaccinations for clostridial diseases and pasturella pneumonia 4-6 weeks before lambing - including ewes and lambs not in lamb.
• Ensuring every lamb receives sufficient colostrum in the first 4-6 hours of life;
• Fostering any lambs that require it as soon after birth as possible;
• Castrating and tailing lambs no sooner than 24 hours after birth;
• Giving ewes and lambs sufficient time for mothering-up before moving them; and
• Maintaining effective measures to prevent lamb infections, like disinfecting buildings and equipment, and treating navels with iodine.

Further practical guidance on managing ewes and lambs to minimise lamb losses is available free to levy payers through the Lamb Action for Profit resource at www.eblex.org.uk.

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