Phosphorus availability in broilers given phosphorus deficient diets containing phytase with and without citric acid

In the present study, the effects of phytase supplementation with and without citric acid (CA) on growth performance, carcass characteristics and serum minerals concentration, tibia and shank characteristics, and phosphorus (P) retention were determined in broilers fed non-phytate P deficient diets. Ninety six one day old male broilers (COBB-500) were divided into four groups (twenty four birds each, and were fed one of the following diets until they were 35 days old: positive control (PC) diet formulated based on the NRC (1994) recommendations, negative control (NC) diet containing 0.20 % lower non-phytate 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). At the age of 36 day, birds were sacrificed, samples were collected, processed, and then analyzed. Compared with the PC group, NC group showed impaired growth performance (final BW, BW gain, and FCR), serum P concentration, tibia and shank characteristics (dry weight, contents of ash and P). However, in most cases, these impairments 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 increased (P<0.05) in phytase added groups compared with NC group, and was comparable with PC group, although non-phytate P level was lower in those groups. In conclusion, broilers fed phytase added non-phytate P deficient diets (without any dietary synthetic source of P) showed the growth performance, mineral (P) concentration in blood and bone, and relative retention of P comparable with broilers fed recommended one. Addition of CA along with phytase in diet was a costlier affair without any significant beneficial effects.