Effect of adding Xylanase and Phytase Enzymes to Broiler Diets on the Performance and Carcass Yield and Quality

Abstract

Three experiments were run to study the effects of dietary microbial xylam 500 (xylanase + amylase) enzyme (Experiment 1), phytase (Nutrase P) enzyme (Experiment 2) and their combinations (Experiment 3) on performance and carcass characteristics of broiler chicks fed on diet containing 10% wheat bran. The experimental design used in each experiment was completed randomized design (CRD). Two control diets were formulated in each experiment, (A) negative control diet (without wheat bran or enzymes) and (B) positive control diet (with 10% wheat bran). In experiment one, two levels of microbial xylam, 500 and 750 g/ton were added to the positive control diet. In experiment two, two levels of microbial phytase, 1000 and 1500 g/ton were added to the positive control diet. In each experiment, 120 seven day-old unsexed Hubbard broiler chicks were used. The chicks in each experiment were allotted randomly in 4 treatment groups ×5 replicates, each of 6 chicks. In experiment three, 4 dietary combinations of xylam and phytase enzymes, (500 and 1000 g/ton); (750 and 1000 g/ton); (500 and 1500 g/ton) and (750 and 1000 g/ton) respectively were added to the positive control diet, using 180 seven day- old unsexed Hubbard broiler chicks, allotted randomly to 6 treatment groups× 5 replicates, each of 6 chicks. All chicks in each experiment were formulated to be isonitrogenous (22.8%) and isocaloric (3100 kcal/kg) according to the recommended dietary requirements for broilers (NRC, 1994). Experimental parameters covered performance, slaughter and carcass data and economic appraised. The results showed that the addition of microbial xylam and phytase enzymes, individually or in combinations to the diet containing wheat bran improved significantly (P<0.05) the body weight gain, feed intake and feed conversion ratio values of the broiler chicks at different stages of the growth. XIII No significant differences were observed between wheat bran diets supplemented with the two enzymes, separately or in combinations and the negative control diet in body weight gain, feed intake and feed conversion ratio values of broiler chicks. The mortality rate was not significantly influenced by the dietary treatments. The results indicated that there were no significant differences among all treatment groups in the percentages of carcass dressing, internal organs (liver, heart and gizzard) commercial cuts (thigh, drumstick and breast) and their percent of separable meat; meat chemical composition (moisture, protein, fat and ash) and subjective meat quality parameters (tenderness, juciness, flavour and colour) of the broiler chicks. Economically appraised values were profitability ratio (1.18) of group C. (500g xylam/ton) was the highest of the test groups. Profitability ratio (1.22) of the test group C (1000g phytase/ton) was the highest of the test groups. Profitability ratio (1.06) of the test group E (500 and 1500/g xylam and phytase combinations) respectively was the highest of the tests groups.