Efeito de zeólita (Clinoptilolita) em dietas com dois níveis de proteína sobre o coeficiente de metabolizabilidade dos nutrientes e energia em frango de corte

Abstract

The literature indicates that the use of performance-enhancing additives in the utilization of dietary nutrients makes it possible to achieve better production rates. The aim of this study was to evaluate the effect of adding zeolite to diets with two levels of crude protein (3% below and at requirement) on the metabolizability of dry matter (DM), crude protein (CP) and crude energy, as well as determining the apparent metabolizable energy (AME) and apparent metabolizable energy corrected for nitrogen (AMEn) of the experimental rations in the different phases of broiler chickens (1 to 7, 8 to 21, 22 to 35 and 36 to 42 days). 720 1-day-old male Ross broiler chicks were housed in a completely randomized design in a 4x2 factorial scheme, with four levels of Celpec zeolite (0; 1.0; 2.0 and 3.0%) and 2 levels of CP in the diet (at the requirement and another with a 3% reduction), with 8 treatments with 6 replications and 15 birds per plot. The 3% lower CP level was adopted in order to challenge the use of zeolite in the diets. There was a significant interaction for all the variables studied and in all the broiler phases. In the 1 to 7 day phase, diets containing reduced protein and the inclusion of 2% zeolite significantly increased the values of MME (3617+-84 kcal/kg) and MNE (3418+-77 kcal/kg), being higher than diets without zeolite supplementation (2804+- 76 kcal/kg), with the opposite effect occurring when supplementing this additive in diets with adequate protein levels. For the other phases (8 to 21, 22 to 35 and 36 to 42 days), there was a different effect to that of the pre-initial phase, i.e. the positive effect of zeolite at the 2% level in relation to better nutritional and energy use of the feed occurred when supplemented with diets containing adequate levels of protein. This research shows that supplementing with up to 2% zeolite increased the utilization of nutrients and energy from diets with adequate levels of CP in all stages of the birds' lives. However, in the 1-7 day stage, this same level of zeolite (2%) improved this utilization when added to diets with a 3% reduction in CP.