However, according to Animal Heath Ireland, while once-a-day milking does not of itself appear to significantly increase the incidence of intramammary infection, it can increase the SCC of individual cows and thus the bulk tank SCC.

It says high SCC cows should not be ignored –a plan of action should be in place to deal with them, before they infect clean cows in the herd, and increase bulk tank SCC.

According to the AHI these are the best options for dealing with these high SCC cows:

1. Reduce their risk of spreading infection

Aim to achieve best practice in hygiene and milking routine
Segregate: Mark the high SCC cows, and milk them last. If you are milking a large herd, you may find it easier to just run these cows as a separate herd, and milk them last.

2. Cure any existing infections

While this may appear to be the most logical option, remember that cure rates can range from 20-80% depending on various factors. Consider the following questions before reaching for that treatment:

What bacteria is involved?
How long has the cow been infected?
What lactation number is the cow?
How many quarters are infected?
Is the cow still milking, or about to be dried off?

3. Remove the source of infection

Dry off individual quarters i.e. simply stop milking it, do NOT use a dry cow tube
Consider culling if the cow is a repeat offender i.e. high SCC in two consecutive lactations.