On the occurrence of growth inhibiting substances in rye

The cause of the decreased food intake and lower growth rate of animals fed on rye was investigated. With rats it was proved that the causative agent was soluble in petroleum ether and acetone. The growth inhibitor was identified as a mixture of 5-n-alkyl resorcinols with odd numbered side-chains of 15-23 C atoms, and of smaller amounts of 5-alkenyl resorcinols.No difference in growth inhibition could be detected from the wheat resorcinols found by Wenckert et al. But the effect of synthetic 5-n-pentadecyl resorcinol was only 50-60 % of that of the grain resorcinols, however. This could not be due to alkenyl resorcinols in wheat and rye, because hydrogenation of the grain resorcinols did not alter the growth inhibition.A fluorometric method for the analysis of 5-alkyl resorcinols was developed. By this method and thin-layer chromatography the alkyl resorcinols could be found in the pericarp. So the resorcinol content of rye proved to be proportional to the surface area of the grain and thus dependent on grain size.Young rats were more susceptible to grain resorcinols than older ones. The decreased food consumption of resorcinol-fed rats was not caused by any unappetizing taste of rye oil or rye resorcinols.The growth of pigs on rations containing 50 % rye oil or an equivalent amount of rye oil, was 11-12% lower than on a 50% barley ration. No differences in harmfulness could be detected between fresh rye and rye stored for a year.