Enhancing nutrient utilization in maize for broiler chickens by superdosing phytase

Abstract

Objective was to determine the effects of increasing level of phytase in maize-based diet for broilers from 1000 FTU/kg (the industry recommended level) to 2500 FTU/kg (super dose level) on coefficient of apparent ileal digestibility (CAID) of nutrients, and dietary apparent metabolizable energy corrected for nitrogen balance (AMEn) value. One hundred and eighty male broiler chicks were divided into 30 groups and fed 3 diets in a completely randomized design (10 groups/diet) from day 15 to day 21 of age. The diets were positive control (PC) diet, and negative control (NC) diet with phytase at 1000 or 2500 FTU/kg. The PC diet was formulated to meet or exceed the NRC (1994) recommended Ca and non-phytate requirements for broiler chickens. The NC diet was same as the PC diet except for Ca and non-phytate P contents, which were reduced 1.80 and 1.50 g/kg, respectively. Birds fed the PC diet had greater (P < 0.05) CAID of gross energy and crude protein than birds fed NC diet. The CAID of starch, Ca and P for PC diet did not differ from those for NC diet. However, the AMEn for PC diet was lower (P < 0.05) than that for NC diet (13.34 vs. 14.46 MJ/kg). An increase in level of phytase in the NC diet from 1,000–2,500 FTU/kg resulted in an increase (P < 0.05) in CAID of gross energy and crude protein by 2.5 and 7.1%, respectively, and tended to increase (P = 0.082) the CAID of P by 10.4%. An increase in level of phytase in the NC diet from 1,000–2,500 FTU/kg did not affect the CAID of starch and dietary AMEn value. In conclusion, an increase in level of phytase in a low Ca and non-phytate P maize-based diet improved ileal digestibility of gross energy, crude protein and P. This indicate that supplementation of phytase at super dose levels (≥2500 FTU/kg) is more beneficial with regard to improving ileal digestibility of energy, protein, and P in maize for poultry than supplementation of phytase at the industry recommended level.