L-isoleucina contribuindo para a redução proteica de poedeiras comerciais de 80 a 100 semanas de idade

Abstract

The aim of this study was to evaluate the effects of low crude protein diets, supplemented or not with L-isoleucine, on the productive performance and eggs quality in commercial laying hens housed in conventional cage and cage-free systems from 80-to-100weeks-old, projecting alternatives for a more sustainable egg production. The laying hens were housed in conventional and cage-free systems. In total, 768 Isa Brown laying hens were distributed in two experiments: Experiment 1 – Cage-free (576 laying hens); and Experiment 2 - Conventional cages (192 laying hens). In each experiment, hens were randomly distributed in three dietary treatments: control (160 g/kg of CP), low crude protein (LCP; 135 g/kg of CP) and low crude protein + L-isoleucine (LCP + ILE; 135 g/kg of CP). The performance and egg quality parameters of the models were evaluated. Analysis of variance and the least squares method were performed based on Mixed procedure; means were compared through Tukey-test (P<0.05). Experiment 1, Hens subjected to the LCP + ILE treatment have shown intermediate feed intake and lower body weight, compared to animals subjected to other treatments (P<0.05). Experiment 2, no differences in body weight were observed between laying hens treated with LCP and LCP + ILE; however, hens treated with LCP +ILE recorded higher feed intake than those submitted to LCP diet. Egg quality (percentage and amount of albumen and eggshell) has increased in animals treated with diets supplemented with L-isoleucine (P<0.05), in both production systems. The inclusion of ILE in a balanced essential amino acids diet allowed the reduction of crude protein levels, maintaining the productive performance in old laying hens. In the current commercial scenario, where protein sources have a high cost, the use of diets with CP reduction and supplementation with crystalline amino acids becomes advantageous in relation to traditional high protein diets. In the present study, was observed that the inclusion of ILE improves feed conversion and egg shell quality, increases the albumen rate and reduces GHG emissions (climate change including land use change (GWP LUC) [kg CO2 eq.]) by 8% in comparison to control diet, reducing nutrient waste and making the system more ecologically sustainable.