TRICHODERMA-VIRIDE ENZYME COMPLEX AS AFFECTED BY EXTRUSION OF BARLEY-BASED BROILER DIETS - RESPONSE

In a growth and metabolism experiment with broiler chicken the influen ce of feed extrusion (105 - 110 degrees C) applied before pelleting (7 0 degrees C) on enzyme effect was studied. Dietary treatments were as follows: P and PC: pelleted feed, -/+ enzyme; E and EC-1: extruded and subsequently pelleted feed, -/+ enzyme; EC-2: enzyme added after extr usion and before pelleting. T. viride enzyme preparation at the level of 200 ppm was supplemented to the basal diet containing 40% winter ba rley. Cellulase and beta-glucanase activity in vitro was determined by radial enzyme diffusion method into a substrate containing gel. Deter mination of xylanase and amylase activity was not possible because of too high endogeneous activity and interference with the analysis. Each of the five experimental diets was tested on four replicates (cages) of eight male birds. Pelleting decreased cellulase activity by 20%, wh ile beta-glucanase was not affected. Extensive inactivation due to ext rusion occurred: in the EC-1 diet cellulase recovery was only 25%, whi le beta-glucanase activity was completely abolished. The feed extract viscosity measurements confirmed enzyme inactivation by extrusion: add ition of enzyme before and after processing (EC-1 and EC-2) lowered fe ed viscosity by 3.5% und 23%, respectively. Improved performance was r ecorded due to enzyme in both treatment groups on extruded supplemente d diets. Despite extensive enzyme inactivation due to extrusion, as de termined in vitro, significant improvements in FCR (1.845 vs. 1.766) a nd energy utilisation (0.732 vs. 0.744) in comparison to the extruded diet without enzyme were found. At the end of the experimental feeding (day 42) no clear benefits from adding enzyme after processing in res pect to growth performance parameters could be established. Neverthele ss, energy, fat and nitrogen utilisation, as well as FCR until day 21 were improved by subsequent enzyme addition indicating that enzyme eff ect was still diminished. The inconsistency between in vitro analysis and in vivo effect may be a consequence of eventually higher xylanase and/or amylase thermostability, being not determined in this experimen t. Some changes in the feed due to enzyme addition already during proc essing should not be excluded. Additionally, modifications in the feed most probably interfered with rest-enzyme activity, reinforcing its e ffect in the bird.