Effects of dietary supplementation of citric acid and a high dose of phytase on growth performance, intestinal morphology, blood calcium and phosphorous concentration

A total of 500 one-day old broiler chicks (as hatched) were assigned to 4 treatments with 5 replicates and 25 chickens in each replicate. Experimental design was a completely randomized block design in a 2×2 factorial arrangements with 2 levels of citric acid (0 and 0.4 % of diet; A0 and A1, respectively) and 2 levels of phytase (0 and 2000 FTU/kg diet; P0 and P1, respectively) in three phases including starter (1-10d), grower (11-24d) and finisher (25-42d). During grower, finisher and overall period of experiment feed intake and body weight gain was increased by dietary citric acid addition. Dietary phytase supplementation increased feed intake at finisher and overall period of experiment (P>0.05) and increased body weight gain during grower and overall period of experiment (P>0.05). The interaction effect of phytase and citric acid was significant for feed intake and body weight gain through the experimental period (P<0.01). Serum phosphorous was increased by phytase supplementation and alkaline phosphatase decreased by inclusion of citric acid to the diet (P>0.05). The interaction effect of phytase and citric acid significantly increased serum calcium, alkalin phosphatase and phosphorous in A0P0, A1P0 and A1P1 treatments, respectively (P>0.05). Crypt depth and villi length were significantly higher in A1P1 and A1P0 treatments, respectively (P<0.05). it was concluded that dietary addition of phytase improves broiler performance and intestinal morphology and the effect was more pronounced by supplementation of citric acid.