After Merck's ($MRK) feed additive Zilmax was pulled from the market on side effect concerns last year, the company embarked on a comprehensive review. The results are in, and Merck has concluded the product is safe when consumed as detailed on the label. But reports of hoof loss and pneumonia originally prompted the recall last August, and a fair number of cattle deaths have been linked to the product, so persuading the livestock industry that they should embrace the additive could be a challenge. Industry giants such as Tyson ($TSN) and Cargill are still refusing Zilmax-fed cattle. Article