The individual producer contemplating a production increase will consider the major component of cost the price of feed to be unaffected by his increased demands The action of that individual will not influence feed prices Consequently in evaluating increased returns in relation to increased costs the marginal cost of feed can be considered as almost perfectly elastic On an industry wide basis however an expansion in flock size increases feed requirements which could lead to a rise in feed prices The marginal cost curve for the industry as a result is less elastic than that for individual producers. (martin j.gerra,1959)