The aim of this study was to determine the best level of crude protein in the diet of Japanese quails in the production phase. A total of 300 quails at 16 weeks of age in cages, in a completely randomized design with five treatments and six replicates of ten birds per experimental unit was used. The levels evaluated were 14, 17, 20, 23 and 26% crude protein and diets were formulated to be isoenergetic. A quadratic effect was observed for feed intake, egg weight, egg mass, energy intake, energy efficiency per dozen eggs, nitrogen digestibility, shell percentage, nitrogen retention, weight of yolk, albumen and shell. A linear effect was observed for egg production, protein intake, feed conversion by egg mass, energy efficiency per egg mass in kg, final weight and yolk percentage and specific gravity. There was no significant effect on feed conversion per dozen, percentage of albumen, shell thickness and serum uric acid. The recommendation is of a 20% crude protein level for Japanese quail during the laying phase.
uric acid digestibility; egg yolk; egg; nitrogen retention