Biosecurity, Brucellosis and Johne�s Disease
Dr. Clell V. Bagley, D.V.M.
USU Extension Veterinarian
Recent regulatory changes on Brucellosis vaccination requirements will decrease regulatory intervention and provide for greater freedom of animal movement. This will also place more responsibility for prevention directly on the individual producer. Be sure you have and follow a biosecurity plan to keep Brucellosis out of your herd. Biosecurity is just a plan, implemented to keep an infectious, living (bio) disease organism away (security) from your animals.
Currently none of the dairies in Utah has any Brucellosis infected animals in them. Utah has been free for many years and continued monitoring has not disclosed any infected herds (dairy or beef). That puts you as Utah producers in a very good position. But, Brucellosis has NOT yet been eradicated from the United States. There are still a few infected cattle herds in other states and there are infected bison and elk in the Yellowstone Park area.
The action of the Utah Legislature removes mandatory Brucellosis vaccination and this will allow greater freedom for animal movement. However, that action also removes some regulatory protection that has been in place and transfers the responsibility to you as individual producers. You have a greater personal responsibility to compensate for this as you purchase (or bring in) any cattle. If you do not have a biosecurity plan (a specific disease prevention plan) and follow it, you will put your own herd and your neighbors� at risk. For example, if you purchase a load of �put-together� heifers from out of state, how do you know one of them is not a Brucellosis carrier? Or, if you have your own heifers custom fed at a feedlot, what assurance do you have that an out-of-state Brucellosis carrier is not fed just across the fence from your animals (with the potential to spread it to yours)? Isolation and testing of new animals are key elements of your biosecurity plan for Brucellosis.
A similar situation exists with Johne�s Disease except that probably one-fourth of our Utah herds are already infected with it and we just don�t know it because we haven�t looked that hard for it yet. In most other states where they have looked for it in dairy cattle, that is what they have found it (estimate of 22% of herds nationally). If your herd is already infected, then perhaps you could say you don�t have to worry about bringing it in. But then you will want (for economic reasons) to begin some on-farm control (biosecurity) to reduce its spread and costs.
A major challenge with Johne�s Disease in purchased animals is the long incubation period and the fact that they may be shedding massive numbers of the causative organism in their feces and still not appear ill nor show positive reactions on the tests currently available. So, you could buy a load of heifers, even test negative and then 4-6 years later have your herd fall apart with Johne�s Disease. This becomes an even greater threat as some other states implement regulations to help clean up their problem. For example, Wisconsin has implemented a law of �implied warranty� so all cattle offered for sale are implied to be free of Johne�s Disease unless accompanied by test results or a disclaimer stating that the cattle are NOT warrantied to be free. Wisconsin dairy producers who are interested in controlling the disease will not buy cattle that are unwarranted. So, those unwarranted cattle may be sold to dealers who then resell them out of state (perhaps to you in Utah).
Since the individual animal test is not very sensitive for Johne�s, it is best to purchase from herds which have been testing the whole herd and know they are free of Johne�s. The herd status and herd tests are much more reliable than are individual animal tests.
It is also important to consider other potential sources for Johne�s Disease. For example, you are a good neighbor and use your loader to help a fellow dairyman move some manure. It just happens that there is Johne�s Disease in his herd. Then your loader comes home and is used to load feed for your herd. In the process, your own herd becomes widely infected and it continues to spread before you become aware that it is present.
Biosecurity plans are best designed for the specific farm situation and for the specific diseases that are most important for you to control. There is not one �recipe� that will fit all situations. Involve your veterinarian in helping to plan the program and then you, as manager, take primary responsibility for enforcing it on your operation. Other diseases besides Brucellosis and Johne�s that you should plan to prevent include: contagious mastitis (Staphylococcus aureus, Streptococcus agalactia, and Mycoplasma); Hairy Heel Warts, TB (tuberculosis) and persistent carriers of BVD (bovine virus diarrhea). There are also other diseases for some producers to consider and make plans to prevent.