An animal disease that cuts productivity is threatening Iowa’s dairy herds. Johne’s Disease can weaken animals and make them quit giving milk and get so thin they have to be sold off for slaughter. Scott Niess is president of the Iowa Dairy Association and says the cattle disease could be as serious as the swine virus that closed state borders to some hog sales for years. Niess says it’s a big issue and could become as big a challenge as the now-achieved eradication of pseudorabies. Niess is a dairy farmer in Osage, in Mitchell county, and he and his wife milk about 55 cows. He says the disease gets into your dairy herd and if you don’t take steps to control it “It will control you and put you out of business.” He says there are products and management techniques to control it. Niess says auction barns are a crossroads for spread of the disease, often by animals that were headed for slaughter. Animals infected with the disease may seem fine, and some dairy farmers sell the cow as a cull animal but the buyer may take it back to another farm for continued use as a dairy animal. That herd is then infected, and he says a regulation is needed to stop that. The Iowa State Dairy Association is proposing legislation to do that. A professor of microbiology from ISU this week told producers at an informational meeting that for every animal found sick with Johne’s disease there are five to fifteen other cows in the herd that are infected but appear healthy.