Controlling flied around stock at this time of year is important to prevent cases of summer mastitis from occurring.
As we move into the summer months and temperatures increase, so too does the number of flies.
Seeing flies around stock is not unusual. But it is important to remember that they could potentially lead to an increase in disease or infection within some of the herd.
Summer mastitis
One of the biggest concerns of having large amounts of flies around dairy stock is summer mastitis.
Summer mastitis is caused by the organism Actinomyces pyogenes, along with a number of other organisms that either enhance its activity or allow infection to develop.
This form of mastitis is very severe and causes udder damage, high temperatures and toxaemia. The infected quarter becomes swollen and hard, and when stripped it will be foul smelling.
The extract may appear clear or with soft to cheese-like curds and as damage progresses there may be traces of blood.
An infected quarter is generally lost and treatment is focussed on saving the animal and preventing pregnancy loss.
Prevention
There are a number of measures that can be taken to prevent summer mastitis in your cows and heifers.
The use of pour on or other products should be used to control flies near or around stock. These products should be used as instructed to ensure maximum effectiveness.
For heifers there is also the option of using Stockholm tar – which is used on the teats to prevent infection.
One of the major drawbacks of using Stockholm tar however, is that it must be applied to the udder at least once a week.
However, if the heifers are on the home block it does offer an opportunity to start parlour training the heifers and get them used to the environment.
For heifers, dry cows and even milking cows, you may need to be more cautious about where they are grazing.
Paddocks or fields with a large amount of trees or tall weeds are more likely to lead to infection than others.
The trees and weeds can provide cover for flies and thus increase the likelihood of an animal picking up an infection.
Prevention is important as most animals that are affected by summer mastitis end up losing the teat or are unable to produce milk from it.