12 September 1997

ADC aiming to add somatic cell counts to sire proof data

KEEN to reduce somatic cell counts and mastitis incidence? Then why not visit the Animal Data Centre in the Spotlight on Profit exhibit on avenue M.

Next Febraury the ADC will include cell count information in dairy sire proofs. This will allow producers to add somatic cell counts to the list of traits on which they base sire selection. ADC geneticist Gordon Swanson believes that using SCCs as a selection tool will help reduce mastitis. ADC research has shown that SCCs have a heritability of 12%. Although not as high as production, at 35%, a favourable correlation between SCC and mastitis incidence justified its use as a selection trait, says Mr Swanson.

Studies in Scandinavia had demonstrated that bulls with the lowest transmitting ability for SCC produced daughters with the lowest incidence of mastitis.

SCC data would be expressed as % transmitting ability and Mr Swanson expects that the very best bulls for SCC would score -30% and the worst +30% – but 95% of bulls would be between  10%.

"For example, a bull with a PTA of -10% for SCC is expected to pass on a 10% reduction in cell count, and a bull with a PTA of +10% for SCC is expected to pass on a 10% increase," explains Mr Swanson.

"PTAs for SCC will be of most value in herds with high cell counts. Selecting a bull with a negative PTA for SCC will help these herds achieve lower cell counts and reduce risk of masititis.

"But SCC PTAs are not as heritable as yield and should only be used as a secondary selection aid. Lower heritability also means more daughter information is required on SCCs compared with yield to provide the same reliability." &#42

ADC geneticist Gordon Swanson:"PTAs for SCC will be of most value in herds with high cell counts."

For full details of next weeks European Dairy Farming Event, including FWs competition in the Spotlight on Profit exhibit, dont miss our supplement in this issue.