Efficacy of phytase on growth performance, nutrient utilization and bone mineralization in broiler chicken

A study was conducted to evaluate the efficacy of phytase produced by fungal immobilization in broiler chicken fed with maize–soy based diet. Three fungal isolates, one Aspergillus awamori (NCIM 885) and two species of Aspergillus foetidus sourced from soil samples showing good phytase activity were selected for bulk production employing immobilization technique. A feeding trial of 5-wk duration was conducted involving 192 chicks which were divided into four dietary treatments with six replicates having eight chicks in each following a completely randomized design. The dietary treatments consisted of one positive control (PC) group without any phytase enzyme (4.5g/kg available/non-phytin phosphorus (P) during starter and 4.0g/kg during finisher phase), one negative control (NC) group (3.2g/kg available/non-phytin P during starter and 2.8g/kg during finisher phase). In the third (lab phytase) and fourth (com phytase) treatment groups, the negative control diet was supplemented with two different enzymes sources, laboratory produced phytase @500 phytase unit FTU/kg and commercial phytase @500FTU/kg, respectively to meet the P requirements. The results indicated growth performance as well as calcium (Ca) and P utilization of broiler chicken was poor in low P (1.2g/kg non-phytin P less) fed birds. Supplementation of commercial phytase enzyme @500FTU/kg diet could replace 1.2g/kg of available or non-phytin P in broiler diet. However, supplementation of laboratory produced phytase enzyme @500FTU/kg in diet reduced feed intake with lower body weight gain and similar feed conversion ratio, Ca and P utilization in comparison to commercial phytase. Lower P in diet coupled with high environmental temperature increased the susceptibility to secondary infections. Laboratory phytase and commercial phytase supplementation reduced P excretion by 30%. It could be concluded that the efficacy of the laboratory phytase was inferior to that of commercial phytase.