The millionaires club - to treat or not to treat?
With a bulk tank somatic cell count (BTSCC) you'd rather not talk about and your first herd test under your belt, you may be reflecting on whether to treat those cows with a high individual cow somatic cell count (ICSCC). Before making any decision to treat or not treat the millionaire ICSCC cows in the herd, ask yourself these questions.
1. Is treatment effective?
2. Is treatment economic?
3. Does treatment actually alter BTSCC?
If you can answer these questions positively the next decisions are:
1. Which cows and quarters shall you treat?
2. With what shall you treat them?
3. What route of treatment shall you use? (injection, intramammary or both)
Let's consider what's normal. The top 10% of herds may have 10-20% of ICSCCs above 150,000. The top 25% may be 15-20% above 150,000 and the top 50% may have 25-50% above 150,000. And this is at 30 to 180 days into lactation.
The prevalence of sub-clinical mastitis infection in the herd is proportional to the number of mastitis cases and their duration. Logically therefore, by reducing the number of sub-clinical cases and their duration, we should be able to lower the prevalence. However, identifying and treating ‘new' infections is of greater economic return than prescribing for high ICSCCs.
Selecting cows for treatment may be by using ICSCC, by using the rapid mastitis test and udder conformation, by identifying the pathogen or using the cows' age and history of mastitis. Each of these approaches has its limitations.
Using ICSCC alone will lead to not treating cows that may have benefited. For example using a million cell count cutoff will miss half of those cows with a Staph aureus infection. At the same time, 20% of cows will be treated unnecessarily. The RMT test will miss a third of the major pathogens. A third of positive RMT quarters will not grow any pathogens when cultured.
A current, and yet uncompleted, study of 11 herds with BTSCC greater than 200,000 selected cows for treatment with ICSCC over 500,000, and a positive RMT for quarter selection, measured bacteriological cure rates at 21 and 28 days post-treatment. Three treatment regimes of varying intensity and duration were applied. Bacteriological cure rates doubled with increasing duration of treatment.
Treating sub-clinical mastitis during lactation can be logical and economical. The decision to treat is best based on cow specific criteria. Treatment alone does not necessarily reduce the BTSCC once treated cows are returned to the vat. Cure rates increase with increased duration of treatment.
Treating sub-clinical mastitis may be economic under conditions of high stock value, low payout and high transmission rates. The economics of treatment beg close scrutiny. Your money may well be better spent in finding where new infections may be arising by having Totally Vets carry out a milking management check.
