1. Four diets were offered to broiler @entity1573 from 7 to 17 d of age; these included a @entity3151 -adequate positive control (PC) (4  7 g/kg available P), a sub-optimal P negative control (NC, 2  5 g/kg available P) with (500 and 12500 FTU/kg) and without phytase. Dietary apparent metabolisable energy (AME), dietary net energy for production (NEp), the efficiency of AME retention (Kre), heat production and total tract @entity535 digestibility coefficients were determined. The determination of NEp involved a comparative slaughter technique in which growing @entity1573 were fed the experimental diets ad libitum. 2. Feed intake, weight gain and feed conversion efficiency increased significantly in a dose dependent manner in response to dietary phytase activity. Overall, the NEp of the phytase supplemented diets significantly improved by approximately 15  6% compared with the negative control, while dietary AME was unaffected. Although phytase did not affect AME, the large increase in the NEp demonstrated that dietary phytases improves energy utilisation, i.e. diverting more energy, not accounted for in the AME procedure, for production. This is largely a result of the stimulatory effect that phytase has on feed intake rather than on digestibility of the diet. 3. Overall, the diet supplemented with 12500 FTU had 6  4% significant improvement in total tract digestibility coefficients of the total @entity1522 compared with the negative control. With regard to individual @entity1522 , the impact of phytase was far more pronounced for @entity1889 , an important component of the gastrointestinal mucin, than for other @entity1522 . 4. Dietary NEp was more highly correlated with performance criteria than dietary AME and seems to be a more sensitive way to evaluate broiler response to phytase supplementation.

The effects of supplementary bacterial phytase on dietary energy and total tract XXXX digestibility when fed to young @entity1573 .

@entity1522 :: ('CHEBI:33709', 'Chemical') :: ['amino acids'] @entity535 :: ('CHEBI:33704', 'Chemical') :: ['amino acid'] @entity1573 :: ('9031', 'Species') :: ['chickens'] @entity3151 :: ('MESH:D010758', 'Chemical') :: ['phosphorus'] @entity1889 :: ('CHEBI:26986', 'Chemical') :: ['threonine']
@entity535 :: (CHEBI:33704,Chemical) :: ['amino acid']
