Over the last few years, we have tested a number of feeds and feed rations using the in vivo balance method, designed to determine the actual digestibility of nutrients. At our workplace, rams of the Romanovská ovce breed are used for these determinations with the use of a two-week preparation period and a four-day trial period, during which feed consumption is measured, feces are collected and the composition of feed, residues and feces is subsequently determined. The digestibility of individual nutrients is subsequently determined from these results. In recent years, we have focused mainly on determining the digestibility of nutrients in silages from different types of legumes, feed rations with different types and contents of grain fodder, with a focus on assessing amaranth compared to other types of grain fodder. Furthermore, we also devoted ourselves to testing the digestibility of corn silage produced using different harvesting methods.