An experiment was carried out to determine the nutritional threonine requirement for white-egg and brown-egg laying hens, during a period from 21 to 36 weeks. Five hundred and seventy six laying hens, 288 from white-egg and 288 from brown-egg, were used during four experimental periods of 28 days each. A complete randomized blocks design in a fatorial arangement (level x trademarks), with six replicates (eight birds/replicate), was used. The treatments consisted on a basal diet with 14.2% crude protein supplemented with 0.025, 0.050, 0.075, 0.100, and 0.125% of L-threonine providing a total of 0.510, 0.535, 0.560, 0.585, 0.610, and 0.635% of threonine. The productive performance and internal egg quality were evaluated. Feed intake, egg production, egg mass and weight gain were superior for the brown-egg laying hens. Egg production and internal egg quality, feed: gain ratio, body weight gain were not influenced by the used threonine levels. The level of 0,510% of threonine, that correspond to 515 mg/hen·day (0,423% of digestible threonine) and 535 mg/hen·day (0,440% of digestible threonine), was sufficient to meet the performance and to the internal egg quality for the studied characteristics of both white-egg and brown-egg laying hens, respectively.
internal egg quality; light-weight hens; requirement; semi-heavy hens; threonine
