Repositori URV

Identificador: TDX:435

Handle: https://hdl.handle.net/20.500.11797/TDX435

Autors:
Juanpere Dominguez, Jordi

Resum:
The main objective of the present study is to evaluate the effects on nutritive value and birdperformance of microbial phytase supplementation in different types of poultry diets, and its impact in the environment.The aim of trial 1 was to evaluate and compare the effects of addition of microbial phytase on the improvement of performance, energy of diet and mineral retention in wheat- and corn-based diets. An additional objective was to define the optimum level of enzyme to be used in wheat-based diets.Treatments were based on two different cereals (corn or wheat), two concentrations of NPP (4.5 and 2.7 g NPP/kg of diet), and different levels of phytase on phosphorus deficient diets. In phosphorus deficient corn-based diets, inclusion of phytase increased final body weight, average daily feed consumption, and toe ash concentration, and also increased total phosphorus and calcium retention. In wheat diets, phytase supplementation to P-deficient diets increased toe ash concentration, and coefficient of apparent total phosphorus retention increased from 0.53 in P normal diets to 0.69-0.73 in P deficient diets, but not calcium retention. Phytase supplementation did not vary mineral excretion in any studied diet. Based on the higher R2 values, final body weight and toe ash value were the most sensitive indicators to assess P availability. Linear equations were used to calculate P equivalency values of phytase for non-phytate P. Using the average function of released P by microbial phytase derived at NPP level of 2.7 g/kg, 605 U of phytase could be equivalent to 1 g ofP. In trial 2, broilers were used to evaluate the effects of a microbial phytase on the improvement of performance, dietary energy and mineral retention, in barley diets with or without endogenous phytase. Treat