26 March 1999

Managing genetic advances

NEW technology could increase genetic progress and bring extra cash into the sheep industry but it must avoid the pitfalls which have afflicted other livestock sectors.

The warning came from SACs head of genetics Geoff Simm speaking at this weeks British Society of Animal Science conference in Scarborough, North Yorks.

He said the leading sire reference schemes, which are most suited to adopt these procedures because of cost, need to progress carefully.

Dr Simm told delegates that new technology, such as greater use of computer tomography (CT) will improve selection accuracy for carcass traits and speed up genetic progress. This could be worth up to an extra 50% a year in cash benefits.

But he warned that the industry needed to be careful how these new approaches were used: "New techniques which accelerate genetic gain also tend to increase inbreeding and reduce genetic variation."

Relentlessly pursuing certain traits has caused problems in other livestock industries and is something the sheep industry must ensure doesnt occur. "Lack of fertility in dairy cows and leg problems in pigs and poultry are examples of this.

"The sheep industry needs to be ahead of the game and avoid these problems. That means having a balance, and not selecting animals only on economically important traits but also others such as mothering ability and lamb survivability," he said.

However, Dr Simm said that many breeds could still improve carcass conformation further and there was no need to change breed goals yet. "SRSs are at the tip of the iceberg of breed development; 25% of commercial lambs still grade too fat."

Dr Simm said that SAC is currently looking at modifying breed goals for some terminal sire breeds, such as how much selection emphasis should be placed on fat depth in Texels.

Texel Elite Sires secretary Peter Johnson said that some members feel there is undue emphasis on leanness. "But we have all the EBVs and can use these to select according to breed goals."

Sensible option

Dr Simm said that using the current selection system is still the most sensible option. "We have had two poor lamb finishing seasons which hasnt helped lambs finish properly. So we should be careful of rushing into decisions about changing the system."

New developments in scanning body fat and muscle compositionwill also be commercially available soon, SACs animal breeding specialist Mark Young told the conference. &#42