Fly activity is increasing as temperatures rise. Therefore, herd owners should be alert for summer mastitis with summer-calving cows and replacement heifers.

Walk through cows daily to pick up early signs of summer mastitis.

Problem cows will often lie more, isolate themselves from others and can be stiff when walking.

By the time you notice a swollen quarter, the damage is usually done and making a full recovery is less likely.


The risk is increased where cows and heifers graze near wooded areas or lie under trees and hedgerows to shade from the sun, as these areas are a haven for flies.

The same risks apply where dry cows graze close to stagnant waterways or open drains that have not been maintained.

As grass heads out, there tends to be more fly activity, so keep this in mind when managing swards over summer.


There are numerous options for prevention, all of which have merits and flaws. Using a pour-on fly repellent is common on suckler farms. However, follow-up applications are often necessary.

Extra handling can be a problem when dry cows are grazing outfarms without handling pens.

To make it easier to apply a repellent, offer cows a small quantity of concentrate (max 0.5kg/head) and pre-calving minerals.

When animals are herded together at the trough, the pour-on can be applied on the cows.

Garlic lick buckets can be effective, as are fly repellent ear tags.

However, the most effective cover is to use a combination of these preventative measures.

Stockholm tar can be used. But, again, it needs to be reapplied regularly, which is problematic on outfarms with no handling units, as well as being labour intensive.

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