INFLUENCE OF PROCESSING ON DIETARY ENZYME EFFECT AND NUTRITIVE-VALUE OF DIETS FOR LAYING HENS

Two experiments were carried out to examine the influence of a Trichod erma viride enzyme complex [cellulase, endo-beta-(1:3)(1:4)-glucanase, xylanase] on nutrient utilization and production parameters of laying hens. In exp. 1, the influence of extrusion (110 degrees C, 20 s) and dietary enzyme addition on the nutritive value of the diet was tested . Dietary treatments were as follows: M and MR, unprocessed feed, plus or minus enzyme; E, feed extruded without enzyme; ER(-1), feed extrud ed with enzyme; ER-2, enzyme added after extrusion. Diets were fed in mash form. Partial inactivation of the enzyme took place as indicated by a significant difference in energy use in groups ER-1 and ER-2 (73 vs. 75%). According to the enzyme-affected changes of the feed extract viscosity, 65% of the enzyme initial efficacy were lost as a result o f extrusion. Nevertheless, the addition of enzyme before extrusion (ER -1) was not without effect, as birds fed the ER-1 diet had improved en ergy (73 vs. 71%) and fat utilization (89 vs. 85%) as compared with th ose fed the extruded unsupplemented diet (E). Extrusion decreased feed AME content by 0.3 MJ kg(-1). A significant interaction between proce ssing and enzyme for energy and fat utilization indicated a greater be neficial effect of enzyme in extruded feed. Experiment 2 was arranged in a same way as exp. 1, with the exception that pelleting (70 degrees C) replaced the extrusion process. Feed extract viscosity measurement s revealed that pelleting reduced initial enzyme efficacy by 52%. Desp ite this, enzyme improved nutrient utilization in unprocessed and pell eted diet to the same extent, and no further improvements were observe d by supplementation of the feed after processing. Pelleting itself di d not affect nutritive value of the feed.