Most farmers are well aware of the frustration that is caused by cows that repeatedly develop clinical cases of mastitis during a lactation.

At what point should consideration be given to culling such a cow?

We know that culling infected cows that have had repeated clinical cases is a key strategy in mastitis control as it is the only way to eliminate some of these infections, but we also know that many infections will be cured either with lactating cow therapy or with dry cow therapy at the end of the lactation.

For guidance on how best to approach these decisions, we can refer to Countdown Downunder Farm Guideline 15.1 which tells us to “Consider culling any cow when you find her third clinical case for this lactation.”

Research has shown that treatment is less likely to be successful in cows that have had multiple clinical cases of mastitis, with reported cure rates of 75% for first cases, 45% for second cases and 12% for cows being treated for the third time.

So, not only do the chances of curing these clinical cases reduce with each additional case, but it is also likely that the cow may be a potential source of infection to the rest of the herd.

Whilst the final decision of whether to cull a cow will depend on other factors, such as the production of the individual cow, her genetic merit, her pregnancy status and the availability of sufficient replacements, it seems very logical that after three clinical cases in a lactation that her future in the herd should at the very least be questioned, even if she is not immediately culled.