Development of an in vitro incubation technique for the estimation of the utilizable crude protein (uCP) in feeds for cattle

An in vitro incubation technique based on the first stage of the in vitro d igestion technique published by Tilley and Terry (1963) was developed to es timate the utilizable crude protein (uCP) of single feeds and feed mixtures as non ammonia-N after 24 h of incubation. The results of 25 Feed samples showed that there was a significant relationship between the uCP values cal culated by regression based on in vivo data sets (Y, CP [g.kg(-1) DM]) and those measured by the in vitro incubation technique (X, CP [g kg-' DM], 24 h incubation): y = 0.85 x + 18.0, r(2) = 0.84, P less than or equal to 0.001. It was concluded that it can be possible to determine the uCP value of sing le Feeds or feed mixtures by this in vitro incubation technique and to esti mate the uCP value of feeds by this regression equation.