Nutritional and toxicological evaluation on rats of earthworm (Eisenia fetida) meal as protein source for animal feed

Abstract

The nutritional value of earthworm (Eisenia fetida) meal was studied with laboratory rats. A group of 20 rats was fed an experimental diet with inclusion of earthworm meal at 100 g protein kg −1 level and compared with a control group fed a diet containing casein to the same protein level. The results showed that the values of protein efficiency ratio and net protein ratio were not significantly different ( P < 0.05) for both diets. The long-term toxicological evaluation of worm meal in feed was performed with an experimental diet containing 200 g earthworm protein kg −1. The study did not reveal any deleterious effect on the rats' health, showing good reproductive and lactation performance throughout the four generation period. The organ examination showed normal weights for liver, kidney, heart, spleen, lung, suprarenal and thyroid. Only the gonads of rats fed earthworm meal were significantly heavier ( P < 0.05) than those of the control rats. Histological examination of the organ tissues showed mostly normal features for all generations of rats fed the experimental diet, with the exception of some intestinal sections of the F 1 and F 2 generations, in which desquamative cells in the lumen and eosinophils in the villi were seen, suggesting possible allergic reactions. The results show that earthworm meal is similar to casein as a protein source for rats and could be considered safe in diet formulations for livestock.