Undercover videos produced by animal rights groups are fueling a debate over the need for new laws to regulate the treatment of American dairy cows.
The graphic videos include one made inside a huge New York dairy operation where cows never go outside, have the ends of their tails cut off in painful procedures without anesthesia, and are seen being abused by one employee who hits a cow over the head with a wrench when it refuses to move.
An investigator for the group Mercy for Animals worked at the New York dairy farm, Willet Dairy, one of the largest in the state, for two months as a mechanic.
"These animals are really treated as little more than milk-producing machines," said Nathan Runkle, executive director of Mercy for Animals. "The overall environment at this facility was really a culture of cruelty and neglect."
Portions of the video will be played in reports to be aired this evening on ABC World News with Diane Sawyer and later on Nightline.
The practice of cutting off the ends of the tails of dairy cows -- known as tail docking -- is found in about half of American dairy farms, according to a 2002 U.S. Department of Agriculture report, although a dairy industry trade group says it is in decline.
The practice was banned in California last year and a bill to prohibit tail docking was introduced last week in the New York legislature.
"Science has shown repeatedly this practice is barbaric and totally unnecessary," said Jennifer Fearing, California director of the Humane Society of the United States, which helped push the passage of legislation in Sacramento.
The dairy trade group says tail docking helps prevent cows from spreading manure and filth with their tails in barn conditions.
"I don't think it would help to create an army of tail police to go around and check whether some cows have portions of their tails cut off," said Chris Galen of the National Milk Producers Federation.