Abstract
This investigation was prompted by the discovery that lard or a mixture of 5 fatty acids—palmitic, stearic, oleic, linoleic, and linolenic—promoted growth of Agria affinis (Fall.), using chemically defined diets. Feeding tests with these fatty acids plus palmitoleic and arachidonic acids showed that, individually, oleic acid had the greatest effect. This was independent of any effects of biotin or cholesterol. Palmitic and stearic acid also increased the growth rate to a lesser extent. Interactions were found between oleic and paImitic, oleic and stearic, and palmitic and stearic acids. The data were inadequate to determine precise requirements, but if the diet contained an optimum amount of oleic acid (0.2%), the addition of between 0.044 and 0.132% of palmitic acid, or between 0.04 and 0.12% of stearic acid, or any combinations of the two in these ranges, resulted in growth equal to that when using the complete mixture. Linoleic, linolenic, palmitoleic and arachidonic acid apparently are not required.