Streptococcus agalactiae has, for the most part, been eliminated from most herds in many parts of the world. Eliminating the reservoir, the infected cow, is what did it. Mycoplasma sp., however, does not appear to exist in all parts of the world. Where it does, though, it is possible that transported cattle infected the local herds. According to researchers, one of the easiest and best ways to avoid the risk of infecting a herd is to quarantine all new cattle before introducing them to the herd.
Researchers have found that prevention is difficult when in today’s system, especially in light of importation standards and the rapid expansion of herds. This increases the risk of exposing naïve cattle to new Mycoplasma sp.
But it isn’t just the introduction of cattle that leads to Mycoplasma sp. In some cases, outbreaks have occurred even in herds that are closed off to the entrance of new cattle. To prevent a possible outbreak, researchers offer a few other suggestions, including maintaining the cow’s immune system and reducing its exposure to stress. While some researchers suggest using a vaccination, it has been noted that there is a severe lack of effective vaccinations against mycoplasma sp.
Controlling an outbreak
Since it is quite difficult for producers to prevent the entrance of Mycoplasma sp. into a herd, most rely on control. The first step in control is constant vigilance for the disease. Monitoring the bulk tank is an excellent measure for determining the presence of mycoplasma. One should note that false negative results are not uncommon, though. Three consecutive negative bulk tank cultures would indicate that the herd does not have the disease.
Once it has been determined that mycoplasma mastitis is present in the herd, the infected cow or cows should be identified. The best strategy to identify the cow with the disease would be to take composite milk in groups of five cows, pool the milk, and then culture the pooled milk. If such a pool yields a positive result, then milk from each individual cow in the pool of five should be cultured to determine which cow has the infection. Other strategies include constant observation.
According to researchers, dairy managers who take a zero-tolerance approach to the disease have been able to successfully kept the prevalence near zero with the practice of testing milk, followed by the immediate culling of mycoplasma positive cows. Culling is not always the best solution, though. Sometimes segregation should also be a consideration. Ultimately, though, the decision on how to approach control should be made by dairy managers in collaboration with other health professionals and should consider multiple strategies.