Influence of Supplemental Microbial Phytase on First Cycle Laying Hens Fed Phosphorus-deficient Diets from Day One of Age

Pullets (19 wk of age) previously fed varying levels of aP (available P) with and without phytase (Natuphos) from Day 1 of age were used to determine the influence of 300 FTU phytase/kg diet on hen performance during Phase 1 (Week 21 to 36) and 2 (Week 37 to 48). At 19 wk of age, pullets were switched from developer diets to layer diets. The aP levels used in this portion of the study remained at 0.1, 0.2, 0.3, and 0.4% with and without phytase. These were the same levels fed in the starter and developer diets. Feed consumption, egg production, egg weight, egg specific gravity, and mortality were the criteria used. Reduction of aP from 0.4 to 0.2% had no effect on feed intake, egg production, egg weight, or eggshell quality (P > 0.05). However, hens fed 0.1% aP showed reduced feed intake, egg production, and bone mineral density (P < 0.001) and increased mortality (P < 0.001), but 300 FTU/kg phytase supplementation completely prevented these deficiencies. Eggs from hens fed 0.2, 0.3 and 0.4% aP diets were heavier than those fed 0.1% aP. Interactions between aP and phytase for feed consumption (P < 0.003), egg production (P < 0.001), and egg weight (P < 0.04) indicated that phytase corrected all deficiency symptoms in hens consuming 0.1% aP but showed no influence on hens fed aP levels > 0.2%. During Phase 2, aP by phytase interactions for feed consumption and egg production demonstrated that dietary phytase-corrected reductions related to P deficiency in hens consuming 0.2% aP. Results indicate that the addition of phytase in pullet diets from Day 1 of age through the first lay cycle can prevent reductions in performance of pullets fed low P diets.