In the years 2019 – 2022, in the Insitute of Animal Science carried out several experiments as part of the activity of the research plan (DKRVO MZeRO0718), in which we compared the content of nutrients and the digestibility of traditionally fed cereals (wheat, barley, corn, fluffy, naked, black and triticale) and amaranth in in vitro tests to help pepsin-cellulase solubility for 24 hours, in sacco (ruminal degradability) and in vivo on Romanov sheep breed sheep. Part of the samples was exposed to microwave radiation with a value of 750 W for 5 minutes (or 3 minutes for amaranth seeds) and then the effect of this heat treatment on changes in nutrient composition and digestibility of dry matter and organic matter was compared. Amaranth seeds showed digestibility comparable to wheat, rye and naked oats; maize, barley and rolled oats had numerically lower digestibility.