This research wasdeveloped to estimate the energy values (TDN) of feeds, concentrate and roughage,through equations proposed by NRC (2001) and validate from the comparison amongTDN values estimated by these equations and those observed in the total collectionfeces. Five concentrate feeds (wheat bran, soybean meal, corn ground, wholesoybean and whole cotton seed) an five roughage feeds (brachiaria hay, cornsilage, tifton haylage, elephant grass silage and elephantgrass) were evaluatedby using 20 crossbred Holstein x Zebu steers. The procedure to validate thevariables evaluated was done by adjusting models of simple linear regressionusing predicted and observed values. The observed and predicted value of TDNvalues for roughage and concentrate feeds were similar (P>0,05). It was concludedthat the equations proposed by NRC (2001) were efficient to estimate the TDNvalues of feeds under brazilian conditions.
