Study on the stress effect of adding citric acid to broiler diet on production performance

270 Ross broiler chicks in a completely randomized design from 7-42 days old with 3 replication having 10 birds in each replicate, in a 3×3 factorial were used. The treatments included three levels of citric acids (0, 3 and %6) and three levels of phytase (0, 500 and 1000 enzyme unit). The results showed that addition of citric acid to diets having phytase significance effects (p<0.0001) on gaining weight and feed intake during the period of the experiment but had no significance effect on feed conversion ratio. Chicks having %6 citric acid in their diets had a significantly lower gaining weight and feed intake comparing to those having %3 citric acid in their diets (p<0.0001) but addition of %3 citric acid just numerically improved feed conversion ratio. Also interaction between citric acid and phytase was observed throughout the experimental period.