The effects of feeding varied levels of low- and high-gramine yellow lupin seeds (LG and HG, respectively), and of synthetic gramine added to the diets in amounts ranging from 0.15 to 1.2 g per kg were investigated in one experiment on growing chicken and in two experiments on growing rats. The comparison of LG and HG lupin and the effect of 0.5 g gramine per kg of LG diet were determined in a growth-balance experiment with pigs. Organ weights and histology, blood parameters and activity of liver enzymes were determined. The response to HG lupin and gramine concentration varied among the species, the rats being more affected than chicken; no adverse effects of HG lupin or gramine were found in growing pigs. The common reaction of rats and chicken to the high levels of gramine (native or synthetic) was the decrease of feed intake and body gain. The increase of the relative weight of liver or kidney, changes in hematological parameters and liver enzymes were found only in rats. The estimated NOAEL (no-observed-adverse-effect level) of gramine was about 0.3 g/kg diet for rats, 0.65 g for chicken and at least 0.5 g for growing pigs.