University of Missouri Extension livestock specialist Dona Funk says that the first thing you should think about when hearing of a cow or steer that went down is not mad cow disease; it’s polio.
 

Polio is rare in cattle but could become more common as more livestock producers feed cattle ethanol byproducts, which can have enough sulfur to cause polio in cattle.  Polio can be in an acute form that causes sudden death, or it can trigger staggering and blindness or cause animals to be down.
 

In addition to high sulfur, polio also can be caused by lead toxicity, salt toxicity, or thiamine deficiency.  The amount of sulfur and other chemicals in ethanol byproducts (dried distillers grain with solubles) varies among ethanol plants and among loads from the same plant.  Funk said farmers feeding ethanol byproducts to livestock should seek to have each load they get tested each month.  Most area farmers feed the byproduct in liquid form that is spread on hay bales in limited quantities, Funk said.
 

Most potential for polio could be in parts of Western Missouri that have elevated sulfur levels in the water.  Combine this with sulfur from another source and polio potential is increased, agreed Al Decker, Butler extension livestock specialist.
Although the National Research Council recommends that the maximum tolerable dietary concentration of sulfur in the ration on a dry matter basis should not exceed 0.4 %, Decker says that not all cattle getting that amount - or more - will develop clinical polio.  He cites research in South Dakota that indicate dietary sulfur levels of 0.7% or more of dry matter may cause polio in growing cattle.  Ruminant microbial populations - trace concentrations of ruminant pH - can impact sulfur production and absorption, he said.