Farm animals are generally produced in large, industrial facilities that house thousands of animals at high densities; these are sometimes called factory farms. The industrial nature of these facilities means that many routine procedures or animal husbandry practices impinge on the welfare of the animals and could be considered as cruelty, with Henry Stephen Salt claiming in 1899 that "it is impossible to transport and slaughter vast numbers of large and highly-sensitive animals in a really humane manner". It has been suggested the number of animals hunted, kept as companions, used in laboratories, reared for the fur industry, raced, and used in zoos and circuses, is insignificant compared to farm animals, and therefore the "animal welfare issue" is numerically reducible to the "farm animal welfare issue". Similarly, it has been suggested by campaign groups that chickens, cows, pigs, and other farm animals are among the most numerous animals subjected to cruelty. For example, because male chickens do not lay eggs, newly hatched males are culled using macerators or grinders. Worldwide meat overconsumption is another factor that contributes to the miserable situation of farm animals. Many undercover investigators have exposed the animal cruelty taking place inside the factory farming industry and there is evidence to show that consumers provided with accurate information about the process of meat productions and the abuse that accompanies it has led to changes in their attitudes.