Effects of crude protein levels on egg quality traits of brown layers raised in two production systems

<div><p>ABSTRACT The objective of this study was the evaluation of egg quality of 30 to 45-week-old brown layers, raised in cages or on floor, supplemented with amino acids, using the ideal protein concept with levels of 14, 15, 16, and 18% crude protein. A total of 400 birds (Hy-sex Brown) were used, distributed into two breeding systems (conventional cage or floor). The evaluated variables were the yolk relative weight, yolk height, albumen relative weight, albumen height, specific gravity, eggshell thickness, and eggshell weight. Treatments consisted of reduced levels of crude protein and were provided to both groups equally. We adopted a completely randomized design, in a factorial scheme, composed of two breeding systems and four levels of crude protein, totaling eight treatments. Five replicates per treatment and 10 birds per experimental unit were used. The breeding system on floor was configured as an option in the breeding of brown layers, of Hy-sex Brown commercial lineage, in the period between the 30th and the 45th week of age, since it presents results equivalent to the ones obtained in the breeding system in cages, having the egg quality as parameter. The system of production on floor is configured as an option in the farming of brown layers, of the commercial lineage Hy-sex Brown.</p></div>