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Virginia Cooperative Extension - Knowledge for the CommonWealth


Dairy Pipeline: February 2007

Christina Petersson-Wolfe
Extension Dairy Scientist, Milk Quality & Milking Management
(540) 231-2160;


Along with Staph. aureus and Strep. agalactiae, Mycoplasma species are also contagious mastitis organisms that can be passed from cow to cow at the time of milking.

Mycoplasma can be cultured from multiple body sites of both healthy and sick cattle including the udder, respiratory tract, reproductive tract and joints. In particular,Mycoplasma bovis is most commonly associated with bovine mastitis.

The classic symptoms involved with Mycoplasma mastitis include multiple quarters involved, dramatically decreased milk production, cows appear otherwise healthy but have severe mastitis, milk secretion
has sandy or flaky sediments in watery or serous fluid. Bacteriologic culture of milk is required to diagnose Mycoplasma mastitis. The best way to do this is to culture suspect cows displaying the previously described symptoms. When a negative test result is obtained from an individual cow, this generally means the organism is not present. However, intermittent shedding of Mycoplasma has been reported and may lead to false negative results. Not all laboratories perform this type of culture because special techniques must be used to test for this organism.

Mycoplasma is most often associated with the introduction of new cattle to the herd and unfortunately no treatment is available. Therefore, in order to control this organism, a strict sampling procedure should be put in place prior to the purchase of animals. Bulk tank cultures from the herd of origin should be requested prior to the purchase of non-lactating animals or calves and individual SCC and milk cultures should be requested prior to the purchase of lactating animals.

Feeding waste milk to calves can also be a source of transmission. Aside from mastitis, M. bovis is also an important cause of respiratory disease in calves and feedlot cattle as well as ear infections in young calves and occasional abortions. Infected cows should be promptly culled to avoid spread within the herd. If this is not economically feasible, a strict segregation plan should be devised and followed.

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