Understanding the roles of zinc in the liver is likely to lead to improved therapy of some clinical conditions. Zinc appears to stimulate protein synthesis in the liver where it increases the binding and inhibits the degradation of insulin. Stimulating or maintaining protein synthesis in the liver is crucial to the outcome of parturition, injury or hepatotoxin challenge. A critical liver protein in circulatory collapse is angiotensinogen. This paper describes the observations of animal responses, in a practical farm situation, to zinc medication.