Fish meal may be a commercial product mostly made up of fish that aren't used for human consumption; fish meal is usually wont to feed livestock in agricultural setting. Because it's caloric ally dense and cheap to supply, fish meal has played a critical role within the growth of factory farms and therefore the number of livestock it's possible to breed and feed. Fish meal is formed from the bones and offal left over from fish caught by commercial fisheries. The overwhelming majority of the fish from which fish meal is manufactured aren't used for human consumption; rather, fish meal is usually manufactured from by-catch. Fish meal takes the form of powder or cake. This form is obtained by drying the fish or fish trimmings, then grinding it. If the fish used may be a fatty fish its first pressed to extract most of the animal oil. The production of fish meal is controversial. It encourages corporate fisheries not to limit their yields of by-catch, and thus leads to depletion of ecosystems, environmental damage, and the collapse of local fisheries. And its role in facilitating the breeding and over-feeding of many pigs and chickens on factory farms is criticized by animal rights and animal welfare groups. Manufacturers of fish meal counter that fish meal's role within the feeding and breeding of many livestock results in the assembly of more food and therefore the feeding of millions of people around the world. Fish by-products have been used historically to feed poultry, pigs, and other farmed fish.