Australian farmers deciding which bulls to use in their herd can now select for resistance to mastitis along with other production and performance traits.

This is possible following the release of milk somatic cell count ABVs (Australian Breeding Values) by the Australian Dairy Herd Improvement Scheme in February 2002.

Mastitis causes high cell counts in milk. The level of mastitis (or cell counts in milk) in herds depends on the day-to-day management in the herd. However, the genetic make-up of cows also is a factor because some cows are naturally more resistant to infection.

Bulls with lower cell count ABVs will breed daughters who are more resistant to mastitis.

The benefits of adding genetic improvement to your mastitis control tool kit can be considerable. ADHIS estimates the difference between the best (-60) and worst (+60) bull for cell count ABV to be worth about $40 per cow per year.

Selecting for mastitis resistance when choosing semen is likely to come at little additional cost. It is definitely worthwhile including when you plan for the genetic improvement you want in your herd.

ADHIS has included cell count in the Australian Profit Ranking (APR), so if you use this index it now has mastitis resistance built in.

Remember that genetic management is a long-term strategy with long-term benefits and must be used in addition to good general mastitis management on your farm.

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