Information on daily nutrient requirements is more complete for farm animals than for horses, pets and man. Very little is known, particularly in man, horses and pets of the relationship between nutrition and longevity. Therefore, a slightly higher intake of essential nutrients would appear to be preferable, the more so as the body can readily remove any surpluses. This also holds true for man and animals in suboptimum living conditions. Inadequate information on this relationship in man as well as the current concern of the consumer regarding the safety of his food are the reasons for which animal production should be very cautious regarding the use of additives and drugs. Investigations on the effects of nutrition on longevity and resistance, immunity, food-intake regulation and other complicated problems should be directed towards understanding and require thorough and extensive preliminary studies covering all species of animal, including man. Animal husbandry as a whole contributes materially to world food production because of its use of many feeds which are unacceptable to or cannot be utilized by man. Further possibilities of increasing the conversion of feed into food are presented. However, ensuring an optimum world food supply to defeat famine not only involves the technical problems referred to but also has several economic and sociological aspects and requires united international efforts.