Re-Evaluation of Calcium and Phosphorus Requirements of Laying Hens for Optimum Performance and Eggshell Quality

摘要: Abstract A long-term experiment was conducted to re-evaluate the Ca and available P (AP) requirements of laying hens for optimum performance eggshell quality. The lasted from 20 64 wk age divided into three phases: Phase 1, 36 age; 2, 54 3, 52 age. treatments (T) consisted diets with 3.5 5.5% in increments .5% a constant level AP (.4%) (T1 T5); step-up phase feeding regimen 3.5, 4.5, (T6); step-down .4, .3, .2% (3.5%) (T7); concurrent or without substitution 50% oyster shell pulverized limestone (T8 T9); similar T9 cholecalciferol 2,200, 4,400, 8,800 ICU/kg (T10). Increasing dietary did not have any beneficial effects on quality, indicating that National Research Council (1984) estimated requirement 3.75 g per hen day is adequate formation. regimen, their combination, were effect Also, increasing hen's presence had quality during Phases 2 3 even when contained generous levels Ca. Percentage retention reduced absolute remained an increase each experiment. Plasma bone influenced by Bone ash different among 1 In fed .4 .3 significantly lower than other treatments. Egg production