It is now October, most of the spring herd has calved, you've done silage, and you may have done one, or maybe two herd tests since the start of calving.
So, is there anything to worry about?
Well, maybe there is a group of freshly calved cows that you've seen on your herd test with high cell counts! Or even worse, it could be some first calf heifers with high cell counts!! All that work rearing these heifers, and now they are infected!
What can be done? Should these cows & heifers be treated?
The first step is to check each of them to ensure that they are not actually clinical cases of mastitis that have not been detected. Remember the definition of a clinical case requiring treatment provided by Countdown is –
A case of clinical mastitis which requires treatment occurs when there is heat, swelling or pain in the udder, or there are changes in the milk (wateriness or clots) that persist for more than three squirts of milk.
If a cow meets this definition, then she is a clinical case - so treat her!!
If not, then it is important to recognise that these are subclinical infections – the decision process is not quite as simple!
As a general rule, it has been shown that the treatment of subclinical mastitis infections in Australia is likely to be unrewarding. Commonly these cases either do not respond well, or relapse after a period of time following treatment.
This is not surprising as the recent Mastitis Pathogen Survey in SE Australia showed that the most common cause of subclinical infections in Australia is Staph aureus, and Staph is renowned for being difficult to cure at any time!
However, the second most common cause of subclinical infections in the survey was Strep uberis, and there has been some trial work suggesting that subclinical infections due to Strep uberis may be treated with reasonable success in early lactation.
Hence, at Dairy Focus, we will consider treatment of these animals if they meet a few criteria –
- It is early in their lactation.
- There are culture results suggesting the infections are likely to be due to Strep uberis.
- They are not chronically infected cows with a history of high cell counts or clinical cases in a previous lactation.
If you have cows that meet the criteria and you are considering treatment, what might that treatment protocol look like?
Will you use intramammaries, or injectables? What length of treatment should be given?
The most expensive treatment is the treatment that doesn't work – you lose money on drugs, discarded milk and labour - so clearly, this would be the time to discuss the situation with your vet and/or mastitis adviser.
They will be in the best position to advise on whether treatment of these cows is likely to be a good option in your herd, and if so, what might be the best treatment protocol for you - there are products that are particularly suited to this situation.
A successful treatment is when the cow's cell count returns to below 250,000 cells/ml, and then remains there!
In this case, we can say that the cow is now more likely to be uninfected, and the risk of her breaking down into a clinical case, and/or spreading infection to other cows in the herd is dramatically reduced.
If the cell count does not return below 250,000 (and remain there), then we have not been successful, as the cow is likely to be still infected (and therefore remains a risk of spread to other cows in the herd). And your next opportunity to make a significant difference to this cow is probably not until drying-off!
Before undertaking treatment programs such as this, we like to be confident that spread of infection on the farm is well controlled (see Dairy Focus Mastitis Risk Assessment) - after all, it would be a waste to successfully treat these cows, only to find they become reinfected due to a high level of spread in the herd!
In summary, provided cows meet certain criteria, there may be a reasonable opportunity to successfully treat subclinical infections in early lactation in some herds.