Efficacy of bacterial phytase, citric acid and their combination in broiler fed inorganic phosphorus free diet

Present study was conducted to assess the efficacy of Escherichia Coli derived phytase alone or with citric acid (CA) given inorganic phosphorus (P) free broiler diet.  Ninety six one-day old COBB-500 male broilers were divided into four groups and fed one of the following diets for a period of 35 days: positive control (PC) diet formulated based on the NRC (1994) recommendations, negative control (NC) diet (inorganic P free diet; containing 0.20% lower P than that in the PC diet), and two other diets were formulated by adding only phytase (500 FTU/kg of feed) or phytase with CA (500 FTU/kg of feed with 2 % CA) in the NC diet. Growth performance, serum minerals concentration, tibia and shank characteristics, and nutrient retention were measured. Impaired growth performance (final BW, BW gain, and FCR) in broilers (NC group) fed inorganic P free diet was restored with the addition of phytase in NC diet. Best FCR (1.83) was recorded in phytase added group and worst in NC group (2.03), however, further addition of CA with phytase did not show any significant variation. Lowest concentration of serum P (mg/dl), tibia P (%) and shank P (%) were ameliorated (P<0.05) by the addition of phytase, and the restoration magnitude was non-significantly greater in phytase with CA group. Retention of total P (%) in broilers given phytase added diet was comparable with broilers given PC diet, although the former diet contained lower level of available P in diet than the later one. Addition of CA further increased this retention (%) numerically. Broilers fed inorganic P free diet deficient in available P, with Escherichia Coli derived phytase showed the growth performance (P<0.05) and relative retention of P comparable with broilers fed NRC (1994) recommended one. Therefore, relying on Escherichia Coli derived phytase alone in available P deficient diet may be viable to ensure sufficient supply of P in broilers diets. Bangladesh Journal of Animal Science 51 (3): 107-114, 2022