One-hundred and fifty male chickens were used to evaluate the effects of different activities (0, 250, 500, 12 500 FTU/kg) of
phytase on their performance and
antioxidant concentration in the liver. The chicks were housed in 30 cages and were allocated to six replicates of five dietary treatments. All diets were formulated to be adequate in energy and
protein (12.90 MJ/kg metabolizable energy, 214 g/kg crude
protein), however, the negative control (NC) was lower in available P compared with the positive control (PC) (2.5 vs. 4.5 g/kg diet). The other three diets were the NC supplemented with
phytase at 250, 500 and 12 500 FTU/kg (NC + 250, NC + 500 and NC + 12 500 FTU respectively). The concentration of
antioxidants in the liver of the birds was determined using HPLC at 21 days of age. Low P diets (NC) reduced
weight gain, however, supplementation with
phytase improved
weight gain to the extent that it was better than the PC at the 12 500 FTU treatment (p < 0.05). Feed conversion ratio was also improved by the high level of
phytase supplement more than other treatments (p < 0.05). Feed consumption was not affected either by
dietary phosphorus concentration or by different
phytase supplementation. The
antioxidant data showed that the unsupplemented diet with low
phosphorus (NC) decreased the concentration of
coenzyme Q(10) and
retinol-linoleate in the liver compared with that of birds on the adequate
phosphorus treatment (PC).
Phytase supplementation, especially at the higher doses (500 and 12 500 FTU) increased the level of
coenzyme Q(10) to the same level as the PC treatment. In addition, the highest dose (12 500 FTU) of
phytase increased
retinol concentration in the liver of chickens compared with those on the NC treatment. The highest inclusion level of
phytase increased the
alpha-tocopherol level in the liver compared with the lower levels of
phytase (NC + 250 and NC + 500 FTU).