Production of food has to be cost-effective. Slaughter and transports of the animals are not always carried through in a way that is the most considerate towards the animals. Bad hygienic conditions have sometimes caused animal diseases and contagiousness. Principles on animal welfare have not always been followed. At the same time people in Europe have raised a consciousness of the needs and wishes of animals.
Animals have to be treated in a way that is ethically and morally acceptable.
A sustainable development also includes a recognition of animal rights. Animals have a value of their own. As human beings we are not entitled to exploit animals. There are laws relating to the production of animals. Each society has to legislate for the prevention of cruelty to animals.