Breed Plan Indexes and Information

By Jack Allen, Technical Director ABRI

Breeders performance recording cattle over many years have enabled the development of estimated breeding values (EBVs). EBVs allow breeders to compare the genetics of animals from both within and across herds. As more EBVs become available within a breed, the more information we have to describe the genetics of the animals.

British Simmental members have recorded a reasonable amount of information over time (Table 1).

While these figures are encouraging, the total amount of performance information is less important than how the animals are recorded. Between 1990 and 2003 inclusive, 117,521 animals have been added to the British Simmental database. Of these, 39% had a 200 day performance record (Table 2). Of these performance recorded animals, 76% had later weights recorded as well (eg 400 days). However, only 16% of these performance recorded animals had an ultrasound scan record. While this level of scanning is low, 75% of the sires in the BSCS published sires list had either been scanned themselves or had progeny scanned.

As more EBVs become available to describe the genetics of animals, selection indexes have been developed to simplify and optimise selection decisions. Selection indexes combine the genetics (EBVs) and economics (marketing and production costs and returns) to give the genetics of animals economic worth in the production system and market place.

Development of an index requires an understanding of the production system, the market requirements and returns, and the relationship of the EBVs available to the traits of interest in the breeding objective. For example, a 400 day weight EBV is a good indicator of carcase weight in a 16 month old animal (as we cannot directly measure carcase weight in a breeding animal). Similarly, scrotal size is an indicator of herd fertility – albeit with only a moderate correlation.

The power of the index is therefore driven by how well we can define the costs and returns of the production and market systems, as well as how well we can describe the genetics of the animals. The costs and returns of production and market systems are developed in close consultation with the Society.

The more accurate and complete the economic information available to develop the index, the more reliable the index is to the specific production system and market specifications. Similarly as more EBVs and more accurate EBVs are available to describe the genetics of the animal, the more reliable the index is on that animal.

Indexes allow EBVs to be balanced to best suit the production and market environments. Not only are the EBVs balanced against each other (eg calving ease versus growth to market weight), but also within the EBVs (i.e. optimal EBVs rather than extreme).

British Simmental have a Terminal Production Index available at present. The BSCS Terminal Production Index is targeted at sires to maximise returns on progeny at the abattoir at 16 months of age while maintaining some emphasis on calving ease.

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For further information or an introduction pack and quotation for Breedplan, please contact The British Simmental head office on Telephone 02476 696513, fax: 02476 696724 or email: information@britishsimmental.co.uk or Barbara Webster on telephone: 01738 622478 email: barbara@breedplan.co.uk

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