The objective ofthis work was to evaluate the equations adopted by the NRC and Detmann to estimatethe energy content of agricultural and agroindustrial byproducts. It was evaluatedbyproducts of pineapple, cocoa, palm oil, beans, sunflower, guava, cassava bark,cassava stem, raw cassava, papaya, mango, passion fruit, turnip and corn glutenmeal. All animals received corn silage and the mixture urea/ammonium sulfate(9:1) so rations with the two levels of each byproduct remained isonitrogenous.Among the models for digestible crude protein prediction (CPad), Detmann 2 modelpresented difference by the hypotheses test for joint null while estimates bythe NRC and Detmann 1 models were similar to those obtained by in vivoobservations. For digestible ether extract (EEad), digestible non-fibrous carbohydrates(NFCad) and digestible neutral detergent fiber (NDFd), the estimates obtainedby the model proposed by the NRC differed, by the test of significance of hypothesesof joint null, to in vitro observations and the best adjustment was obtainedby the model suggested by Detmann, having as a consequence, the value. However,among all the digestible fractions, NDFd presented the greatest dispersion ofpoints regarded to equality line. NRC and Detmann models can be considered asefficient in predicting total digestible nutrients (TDN) and digestible energy(DE) because the estimates do not differ from the observed values, however theyalso present great dispersion of the points regarded to equality line. It isrecommended to use the models proposed by Detmann for predicting digestiblefractions of crude protein, ether extract and non fibrous carbohydrates on agricultureand agroindustrial byproducts.
