According to the Food and Agriculture Organization of the United Nations, globally, approximately 56 billion land animals—including nearly 48 billion broiler chickens— are slaughtered for human consumption in a single year (Food and Agriculture Organization of the United Nations 2004), in addition to an untold number of aquatic animals. The numbers of individual animals raised and killed by the meat, egg, and dairy industries far surpass the number of animals with whom human beings have any other relationship—whether they be those seen as fabric, target practice, test tubes, companions, or sideshow spectacles.
Gavinelli, A., & Park, M. (2007). Farm animal welfare: In legislatures, corporate boardrooms, and private kitchens. In D.J. Salem & A.N. Rowan (Eds.), The state of the animals 2007 (pp. 129-141). Washington, DC: Humane Society Press.