Effects of microbial phytase supplementation on egg production, eggshell quality, andmineral retention of laying hens fed different levels of phosphorus

ABSTRACT A 20-wk feeding trial (21 to 40 wk of age) was conducted to evaluate the effects of phytase supplementation on egg production, egg quality, nutrient retention, and P excretion of laying hens fed diets containing different levels of P. Nine hundred and sixty ISA Brownâ hens were randomly allocated to completely randomized block arrangement of four diets: corn-soybean diet (1.4 % tricalcium phosphate, TCP) without (T1, control) and with phytase (T2); 0.7 % TCP (T3) or 0 % TCP (T4) diet with phytase. Dietary microbial phytase was added at a level of 500 U/kg. Both hen-day and hen-housed egg production of T2 were significantly (P < 0.05) higher than other treatments, which were not different among themselves. Egg weights were also significantly (P < 0.05) different among treatments,wit