ESTIMATION OF THE LEVEL OF ENZYME PREPARA TION REQUIRED TO OBTAIN OPTIMUM NUTRIENT UTILIZATION AND GROWTH-PERFORMANCE IN YOUNG BROILER CHICKS FED IN BARLEY DIETS

Two experiments on broiler chicks were carried out to estimate the opt imum level of an enzyme preparation with predominant beta-glucanase an d xylanase activities added to barley-containing starter diets. In the balance experiment, nitrogen retention and nitrogen-corrected apparen t metabolizable energy (AMEn) were measured using diets containing 62. 15% barley. The diets used in the growth experiment contained 25% barl ey and the criteria of response were growth rate and feed efficiency. In both experiments, the enzyme preparation was included into the diet s at five levels ranging from 0 to 0.012%. Nutrient utilization and gr owth performance increased linearly as the enzyme level increased unti l the maximum was reached and then remained relatively unchanged. The levels of enzyme preparation required to obtain optimum nutrient utili zation and growth performance as estimated using the bent-stick model were 0.0072 and 0.0073% fur N-retention and AMEn and 0.0087 and 0.0081 % for weight gain and feed efficiency, respectively.