Effects of Phytase and Protease Supplementation on Growth Performance and Carcass Characteristics of Broiler Chickens Fed Sub-Optimal Levels of Crude Protein

Abstract

The experiment was carried out to evaluate the effect of phytase and protease supplementation on performance of broiler chickens fed diets with sub-optimal levels of crude protein (CP). One day old unsexed Acre Arbor broiler chicks (n=270) were randomly divided into 27 replicates of 10 chicks each. Birds were fed enzyme-supplemented diets with phytase (PHY) or protease (PRO) and their combination at different crude protein levels. Nine experimental diets were fed during the starting phase which was; the control (23% CP) without enzyme (T₁), 21% CP without enzyme (T₂), 21% CP plus PHY (T₃), 21% CP plus PRO (T4), 21% CP plus PHY and PRO (T₅); and 19% CP without enzyme (T₆), 19% CP plus PHY (T₇), 19% CP plus PRO (T₈), 19% CP plus PHY and PRO (T₉). Phytase and protease supplementation followed the same pattern in all phases, but the crude protein was 23, 21 and 18% CP (in T₁); 21, 18 and 16% CP (in T₂,T₃, T₄ and T₅) and 19, 16 and 14% CP (in T₆, T₇, T₈ and T₉) during starting, growing and finishing phase. Each of the diets was offered to three replicates of 10 birds each. Feed and water were given ad libitum and the birds were weighed weekly. At the starter phase, there was a synergistic effect of the combination of the two enzymes in birds on T5 which significantly (p<0.05) improved final body weight and daily weight gain compared to the control (T₁) and other treatments. From 0 -56 days, PHY supplementation significantly (p<0.05) improved final body weight and daily weight gain in suboptimal CP diets (T₃) compared to the non-supplemented normal protein diets (T₁), but performance was similar to birds on PRO and PRO plus PHY supplementation. There was no significant effect of treatments on carcass parameters except for drumstick and T₁ had the least value (p<0.05) compared to other treatments. It could be concluded that phytase, protease and the combination improved the performance of broiler chickens fed suboptimal crude protein diets and there was a synergistic effect of protease and phytase at the starter phase.