the effects of different levels of β-mannanase (hemicell®) on the performance and blood parameters of broiler

in order to study the effect of different levels of β-mannanase enzyme on the performance, blood parameters and carcass characteristics of broiler chicks (arbor acres), an experiment was conducted with 240 checks (44.6 grams average weight) under a completely randomized design with 4 treatments and 5 replications and 12 checks per each replicate. β-mannanase enzyme with the levels of zero (t1 control), 0.035 (t2), 0.05 (t3) and 0.075 (t4) percent were added to 4 experimental diets on the basis of maize-soybean meal for the periods of starter (7-21 days), grower (21-42 days) and total period of feeding system. daily feed intake (g/check/day), daily live weight gain (g/check/day), feed conversion ratio (fcr), blood parameters including glucose, calcium and phosphorous (mg/dl) during all periods of feeding system, percent body weight uniformity and carcass characteristics (%) at the end of feeding period, were measured. the results showed that addition of β-mannanase enzyme to experimental diets have increased daily live weight gain and improved fcr of all treatments containing  β-mannanase significantly (p<0.05) with respect to control during grower and total period of feeding system. but daily feed intake, blood parameters (glucose, calcium and phosphorous), body weight uniformity, and carcass characteristics as dressing percentage, % thigh, % breast, % liver, % gizzard, and % of total luminal tract of broilers did not affect by different levels of enzymes (p> 0.05). therefore, use of minimum of 0.035 % of β-mannanase would increase daily live weight gain and improves fcr of broilers in grower and total period of feeding system.