(AP) —Kansas cattle ranchers are on alert today. Merck is suspending sales of its cattle feed additive Zilmax in the U.S. and 
Canada while it studies a possible link between Zilmax and lameness in cattle.
Merck and Co. says that stopping sales will allow it to set up a study protocol and follow certain cattle to find out possible causes of lameness and other mobility problems. The company also plans to review other possible factors like nutrition and transportation of the cattle.
Zilmax is mixed into food and is used to bulk up cattle before they are slaughtered. Merck reported $159 million in U.S. and Canadian sales of Zilmax in 2012.
Tyson Foods said Aug. 9 that it would stop buying animals that were fed Zilmax, citing experts who said it may be causing cattle to become lame.