Nutritional levels of calcium and available phosphorus for white-egg pullets and brown-egg pullets from 7 to 12 weeks of age

Four experiments were carried out using white-egg pullets and brown-egg pullets in two different phases, growth phase (7 to 12 age weeks) and production phase (20 to 28 age weeks), with objective to determine requirements of calcium and available phosphorus and the effects of levels calcium a available phosphorus in production. Chickens from 13 to 19 weeks age were identified for treatment and fed only commercial diet. For each experiment, the chickens were allotted in a completely randomized design with five calcium levels (0.60, 0.70, 0.80, 0.90, and 1.00%) or five level available phosphorus (0.25, 0.30, 0.35, 0.40, and 0.45%), four replicates and 16 pullets/EU for the growth phase and 8 chickens/EU for the production phase. The characteristics evaluated for the growth phase were weight gain, feed intake, feed: gain ratio, bone resistance, ash and bone calcium (calcium experiments) or bone phosphorus (experiments phosphorus), while for the egg production phase were evaluated ration consumption, eggs production, egg weight, egg mass and feed conversion (g ration/g egg and kg of ration/dozen of egg). Calcium requirements of 0.834% or 406 mg/pullets/day for white egg pullets and 0.815% or 440 mg/pullets/day for brown eggs pullets were estimated and for available phosphorus, requirements of 0.411% or 200 mg/pullets/day for white egg pullets and 0.361% or 184 mg/pullets/day for brown eggs pullets were estimated.