Current study deals with the biological evaluation of locally characterized recombinant thermostable α-amylase in poultry broiler chicks. The enzyme was produced under pre-optimized conditions using E.coli BL21CodonPlus (DE3) cells transformed with pET21a containing α-amylase gene from Thermotoga naphthophila. The enzyme was utilized for the supplementation of poultry feed. Regarding poultry trials, 150 day-old broiler chicks were divided randomly into 5 groups with 30 birds in each group. Group A served as negative control and was fed on standard feed without supplementation. Group B, C and D were fed on feed supplemented with 200, 400 and 600 IU/kg of locally produced recombinant thermostable α-amylase while group E served as positive control and was fed on feed supplemented with commercially available α-amylase. The birds were housed under controlled conditions for a period of 7 weeks. Supplementation of poultry feed with 600 IU/kg recombinant α-amylase resulted in significant enhancement of weight gain from 596g (Group A) to 694g (Group D), and improved FCR value from 2.17 (Group A) to 1.95 (Group D) at the end of 7^th week. Group D showed promising weight gain and improved FCR value of 694g and 1.95 as compared to 666g and 2.09 for group E supplemented with commercially available α-amylase. Locally produced thermostable recombinant α-amylase showed committed results and proves its potential for its utilization in poultry feed industry. Its domestic production at large scale will save huge foreign exchange for the import of this enzyme.

Index terms- Recombinant α-amylase, Thermotoga naphthophila, Thermostable, Feed industry, Feed Conversion Ratio, Weight gain