COINCIDING with the latest bull proofs issued by AHDB Dairy, a new mastitis genetic evaluation has been launched to give an indication of a bull’s ability to transmit mastitis resistance on to his daughters. 

It is expressed on a scale of -5 to +5 and, as with the somatic cell count predicted transmitting ability (PTA), negative figures are desired. 

Marco Winters, head of animal genetics for AHDB Dairy, explained: “The degree to which any animal can be improved through breeding depends on the heritability of the trait being improved and how reliably we are measuring that trait.

“In the case of the new mastitis evaluations, we have used extensive national records from all of the UK’s milk recording organisations to assess the degree to which each bull’s daughters are able to resist mastitis and, from that information, we have established every bull’s breeding pattern.”

By using this information, it is estimated that the heritability of mastitis is about 4%, on a par with several traits capable of being improved through breeding and higher than some making good genetic progress, including female fertility. 

“This means we are confident dairy producers can improve the mastitis rates in their herds through breeding which – although a slow and long-term process – reaps rich rewards over the generations,” added Mr Winters.

The existing SCC PTA will continue to be published alongside the new mastitis PTA evaluation since, although similar, the two traits are not identical.

The new mastitis PTA can be seen in action in the latest bull proofs, see the April 8 and April 15 issues for more.