In order to determine nutritional requirement of digestible threonine for white-egg laying hens in the second production cycle (from 79 to 95 weeks of age), it was carried out an experiment with 180 commercial Lohmann LSL laying hens, distributed in five diets (0.380; 0.413; 0.446; 0.479 and 0.512% digestible threonine), six replicates and six birds per experiment unit. Levels of threonine in the ration quadratically affected feed intake, feed conversion per mass and per dozen of eggs, laying rate, weight and mass of eggs. It was not observed significant effect of the levels of threonine in the ration on weight gain, Haugh unity, index of yolk and albumen and percentage of yolk and albumen, except for shell percentage, which was quadratically affected. Through statistic analyzes and biological interpretation and using feed conversion per dozen of eggs as a decision parameter, the requirement of digestible threonine in the period from 79 to 95 weeks of age is 0.469%, corresponding to a threonine consumption of 459 mg/bird/day.
amino acids; egg production; egg quality
