From a marketing perspective, milk has about as squeaky clean an image as you'll find. But behind the smiling celebrity milk moustaches, is there a darker side to dairy? A Brian Ross Blotter investigation tonight pulls back the curtain on what critics call dairy "factory farms," featuring graphic video of disturbing deletion treatment of milk cows at the Willet Dairy in East Genoa, New York. The footage was shot by an investigator for the animal rights group Mercy for Animals posing undercover who was hired at the dairy as a mechanic. One clip shows the controversial process of tail-docking, pictured above and described fully in a Blotter report here. The other, embedded below, shows a cow in obvious pain as it horns are burned off. Lyndon Odell, CEO of Willet Dairy said that he prides himself on the conditions of his dairy and uses the latest technology to keep his cows healthy. He explained that tail-docking and burning off horns are common in the industry and are not abusive of the animals. Tune in tonight for the full investigation.