Questions like these are certainly important. However, there is a tendency
to overlook the role of the individual farmer and his style and skills
in stockmanship. Both research and practical experience suggest that in a
population of farms with similar production systems, there is often a great
variation in production efficiency. Similarly, there is great variation in the
welfare of the animals or in the loss of nutrients to the environment; a
variation which is often comparable in magnitude to the mean variation
between systems