More than 9 million cows compose the U.S. dairy herd. Repeated reimpregnation, short calving intervals, overproduction of milk, restrictive housing systems, poor nutrition, and physical disorders impair the welfare of the animals in industrial dairy operations. Once their productivity wanes, the cows are often weak as a result of high metabolic output. Typically, these “spent” dairy cows are culled and processed as ground beef. In their fragile end-of-production state, handling, transport, and slaughter raise additional welfare concerns.
The Humane Society of the United States, "The Welfare of Cows in the Dairy Industry" (2009). IMPACTS ON FARM ANIMALS. 20.