Is precision livestock farming an engineer's daydream or nightmare, an animal's friend or foe, and a farmer's panacea or pitfall?

This paper reviews the development of precision livestock farming (PLF), from the view point of the engineer, the farm animal and the farmer; PLF is the principal means by which ‘smart’ sensors will be used in livestock farming. It considers the technological principles upon which PLF is based, gives several examples of PLF, considers which livestock processes are suitable for the PLF approach, addresses whether PLF constitutes technology push or market pull, and stresses the need for a prospective bioethical analysis of PLF. We conclude that PLF is an embryonic technology with great promise but one that requires considerable research and development before uptake.