Influence of Isoamylase Supplementation on Performance and α-Amylase Activities of Broilers Fed Maize-Soybean Meal Diets

An experiment was conducted to study the influence of isoamylase supplementation to maize-soybean diets on productive performance and amylase activities of broilers from 1 to 42 d of age.The results showed that different dose of isoamylase (300g/T,600 g/T,900 g/T, containing 3000113 of isoamylase/g) in the maize - soybean meal diet significantly affected the performance of broilers within 1-42 days. Within 1-21 days, the average daily gain(ADG) of experimental groups( experiment I (E I) experiment II (E II) experiment III (E III)) improved by 3.2% -10.32%(P>0.05) compared with the control groups(negative control(NC) and positive control(PC)), average daily feed intake(ADFI) improved by 0.63%-7.43%(P>0.05), while feed conversion-ratio decreased by 0.55%-4.43%(P>0.05); Within 21-42 days, the ADG of experimental groups decreased by 1.38%-4.84% and ADFI by 11.89%-15.58% (P<0.05), feed conversion ratio by 5.41%-7.54% compared with that in the NC group; Within 1-42 days, the ADG of experimental groups improved by 0.54%-4.06%(P>0.05), while ADFI decreased by 0.75%41.83% (P<0.05), and feed conversion ratio by 3.97%-7.52% (P>0.05) compared with those in the negative control. Isoamylase supplementation influenced amylase activity of various parts of the chyme in digestive tract and the tissues of small intestine and pancreas. 21 d, the amylase activity in experimental groups improved by 4.67%-79.29%(P<0.05) compared with PC, alpha-amylase activity in the majority experimental groups were lower than PC group, but the difference was not significant(P>0.05).