COLUMBIA, Mo. – The expansion of individual dairy operations has made biosecurity a top priority of many producers.
Others may learn that priority the hard way.
Jeff Tyler of the University of Missouri School of Veterinary Medicine urges producers to “picture our dairy industry today, then recall the dairy operations we grew up with: 30 cattle, none purchased, no new or exotic diseases. The animals were born, lived and died on the farm. That is not the industry we see today.”
Biosecurity is defined as management practices that prevent the introduction of disease onto the farm or its spread within the farm, said Richard Randle, veterinarian.
“You’re involved in biosecurity every day, whether you know it or not.”
Many diseases are imported to the farm through the acquisition of animals, Tyler said. “When you buy a cow, you’re purchasing the entire disease history of the farm it came from. To assemble those large lots, you might have to import the disease history of 50 herds.”
An effective biosecurity plans requires understanding how each disease is transmitted and recognizing the appropriate points at which to intervene, Randle said. Common strategies include isolation, sanitation, diet and other management tools. “We can do a lot with plain old husbandry.”
When attacking a specific disease, the first step is to determine the host range and transmission method, Tyler said. The pathogen could live on the ground, on shoes, in feed, on shoes, in urine and in other animals as well as the cows.
“Some bacteria will live in the farm environment for years.”
A narrow host range favors control methods, he said. “If it only infects cows, and if you can identify the cows, you can cull the cows and get rid of the disease.”
To prevent the introduction of new diseases, quarantines and reliable testing are required. Newly purchased calves should be quarantined one or two months or even longer if Johne’s disease or BLV (bovine leukosis virus) is suspected, he said.
An eradicable disease must be treatable, respond to antibiotics and not be endemic in the farm environment, “so if we get rid of it, it won’t be reintroduced,” Tyler said. “There are a few diseases we can treat our way out of, but it’s a short list.”
Such management decisions depend largely on the operation. For instance, BLV symptoms are manifested only in mature cattle. In some large confinement facilities, the animals are not expected to live long enough to be affected.
Although there are licensed vaccines for more than 37 diseases of cattle, “no vaccine is 100 percent effective,” Randle cautioned. “But for a great many diseases, it is our best shot at managing the impact” with proper timing and booster shots.
While producers can increase animal resistance through immunization, nutrition sanitation and other management tools, there are also possibilities for increased resistance through genetics in the future.
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