Effects of phytase supplementation on broilers fed with calcium and phosphorus-reduced diets, challenged with Eimeria maxima and Eimeria acervulina: influence on growth performance, body composition, bone health, and intestinal integrity

Abstract

An experiment was conducted to evaluate the effects of phytase in calcium (Ca) and available phosphorous ( avP)-reduced diet on growth performance, body composition, bone health, and intestinal integrity of broilers challenged with Eimeria maxima and Eimeria acervulina. A total of 672 14-day-old male broilers were allocated to a 2 × 4 factorial arrangement with 6 replicates per treatment and 14 birds per replicate. Two factors were Eimeria challenge and 4 dietary treatments: 1) a positive control ( PC; 0.84% Ca and 0.42% avP); 2) a negative control ( NC; 0.74% Ca and 0.27% avP); 3) NC + 500 FTU/Kg of phytase ( NC + 500PHY); and 4) NC + 1,500 FTU/Kg of phytase ( NC + 1500PHY). On d 14, birds in the Eimeria-challenged groups received a solution containing 15,000 sporulated oocysts of E. maxima and 75,000 sporulated oocysts of E. acervulina via oral gavage. At 5 d postinoculation ( DPI), the challenged birds showed a higher ( P < 0.01) FITC-d level than the unchallenged birds. While the permeability of the NC group did not differ from the PC group, the phytase supplementation groups (NC + 500PHY and NC + 1500PHY) showed lower ( P < 0.05) serum FITC-d levels compared to the NC group. Interaction effects ( P < 0.05) of Eimeria challenge and dietary treatments on feed intake ( FI), mucin-2 ( MUC2) gene expression, bone ash concentration, and mineral apposition rate ( MAR) were observed. On 0 to 6 and 0 to 9 DPI, Eimeria challenge decreased ( P < 0.01) body weight ( BW), body weight gain ( BWG), FI, bone mineral density ( BMD), bone mineral content ( BMC), bone area, fat free bone weight ( FFBW), bone ash weight, bone ash percentage and bone ash concentration; and it showed a higher FCR ( P < 0.01) compared to the unchallenged group. The reduction Ca and avP in the diet (NC) did not exert adverse effects on all parameters in birds, and supplementing phytase at levels of 500 or 1,500 FTU/Kg improved body composition, bone mineralization, and intestinal permeability, with the higher dose of 1,500 FTU/Kg showing more pronounced enhancements. There was an observed increase in FI ( P < 0.01) when phytase was supplemented at 1,500 FTU/Kg during 0 to 6 DPI. In conclusion, results from the current study suggest that dietary nutrients, such as Ca and avP, can be moderately reduced with the supplementation of phytase, particularly in birds infected with Eimeria spp., which has the potential to save feed cost without compromising growth performance, bone health, and intestinal integrity of broilers.