Cereal-based diets do not provide sufficient amounts of vitamins needed by poultry for optimum
performance and health. To decide on the appropriate supplemental amount for a particular vitamin,
it is necessary to have information both on the vitamin requirements of the various classes of poultry
for relevant production or health characteristics and on likely natural vitamin contents of the diet. A
suitable margin of safety must be contained in the allowance provided for the bird. This paper details
the vitamin requirements of various classes of chickens and turkeys. It quantifies the likely vitamin
contents of general types of diets and suggests supplemental allowances for practical diets.