Tryptophan in the Japanese quails diets in the rearing and laying periods

The effects of feeding levels of tryptophan on performance and stress of Japanese quails (Coturnix coturnix japonica) in the rearing and laying periods were evaluated. In the rearing phase, from 30 to 44 days old, 192 Japanese quails were lodged to cages and allotted to completely randomized blocks design, with four nutrition plans [0.27% (control) 0.52; 0.77 and 1.02% of tryptophan] with six replicates and eight birds per cage. Performance (feed intake, body average weight gain, feed conversion ratio), mortality rate and physiological parameters (heterophil/lymphocyte ratio) and corticosterone blood plasma were evaluated. In the lay period, another 192 Japanese quails were allotted to a completely randomized design in a four nutrition plans [0.23% (control); 0.48; 0.73 and 0.98% of tryptophan] with six replicates and eight birds per cage. Performance (feed intake, egg production, feed conversion ratio/egg dozen), mortality rate and physiological parameters (heterophil/lymphocyte ratio) and corticosterone blood plasma was evaluated. The tested tryptophan levels did not affect performance and physiological parameters of Japanese quails in the rearing and laying phases.