V. Vranjes et al., TRICHODERMA-VIRIDE ENZYME COMPLEX AS AFFECTED BY EXTRUSION OF BARLEY-BASED BROILER DIETS - RESPONSE, Archiv fur Geflugelkunde, 60(2), 1996, pp. 81-87
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.