Sir: Your article on genetic engineering, "Is this the work of man or nature?" (20 November) asks if there are any limits to what people can, and should, do to animals to further human ends. There certainly are, and I think they can best be defined by the Farm Animal Welfare Council's "Five Freedoms", which are equally applicable to all animals used by mankind for his advantage. They are:
1. Freedom from thirst, hunger and malnutrition.
2. Freedom from discomfort.
3. Freedom from pain, injury and disease.
4. Freedom to express normal behaviour.
5. Freedom from fear and distress.
A group of animals specifically created to develop cancer would not be free from discomfort, pain, disease or distress, and I doubt if they would be able to express normal behaviour.