Another study looked at the use of a new method, the Petrifilm-based on-farm culture system to determine infected quarters 24 hours before dry-off as criteria for dry treatment. In the study, cows identified with an infection were infused with an antimicrobial dry treatment and then an internal teat sealant was applied. Cows without infection only received the internal teat sealant. The use of an internal teat sealant has been shown to reduce the risk of new infections during the dry period.
Sixteen herds with SCC < 250,000 were used in this study. The Petrifilm-based on-farm culture system only failed to identify 4 percent of infected quarters. However, only 67 percent of cows that cultured positive with that method had at least one infected quarter according to standard culture methods. This is a new method that could be adopted by producers but which does add an additional step, complexity and expense.
In this study, selecting cows for treatment based on results of the on-farm culture method was just as effective in controlling mastitis as was blanket dry cow treatment as measured by the infection status at calving.
Both of these studies, in agreement with others, show that herds can control mastitis without treating every cow and every quarter at dry-off, and do so without an increased risk of infections or clinical mastitis in the next lactation. The key is in having practical and good selection criteria for cows that will not receive treatment.
Part 3 of this series, “Increasing the likelihood of success without blanket dry cow treatment” will discuss herd criteria and management that can help increase the likelihood of good results with anything less than blanket antimicrobial use. In the meantime, review the culture reports on mastitis in your herd to determine what organisms are causing mastitis in your herd.
Additional articles in this series:
- Is it time to reconsider blanket dry cow treatment programs?
- Increasing the likelihood of success without blanket dry cow treatment