Effect of heat treatment (toasting) on protein degradability in the rumen was evaluated for four organic concentrates (field beans, soyabeans, blue lupin and peas) in simple cross-over experiments with rumen and intestinally fistulated cows. For soyabeans, field beans and blue lupin, heat treatment numerically increased duodenal flow of amino acid N (AAN) due to an increase in flow of undegraded feed AAN. For peas the increase in duodenal flow of undegraded feed AAN was counterbalanced by a similar decrease in microbial AAN synthesis, probably due to sub-optimal rumen ammonia concentrations. Heat treatment had no overall effect on microbial efficiency.