Effects of phytase superdoses on peaking Hy-Line W-36 laying hen egg production and egg quality

This study evaluated the impact of superdosing a new generation phytase, HiPhorius™ (HP), on egg production (EP), egg quality, and bone mineralization in laying hens from 22 to 34 weeks-of-age. Four dietary treatments were studied: a Positive Control (PC), a Negative Control (NC) with 0.16% non-phytate phosphorus (nPP), NC + 1,100 FYT/kg HP, and NC + 1,500 FYT/kg HP. Weekly performance was analyzed using the GLM procedure in SAS, while four-week period data (Pd1: 23-26 wk, Pd2: 27-30 wk, Pd3: 31-34 wk) were analyzed using repeated measures ANOVA. Preplanned contrasts compared PC vs. NC, NC vs. phytase-supplemented diets, and PC vs. phytase-supplemented diets. Superdosed HP improved EP and FCR compared to the NC, with performance comparable to the PC, particularly in Pd1 and Pd3. Egg quality responses to HP were inconsistent, with some improvements in albumen height (AH) and Haugh unit (HU) in specific wks, but no sustained differences across the laying cycle. Bone mineralization was largely unaffected, although contrast analysis indicated that phytase supplementation to NC diets increased tibia ash weight (mg/kg BW) compared with NC alone. These findings suggest that superdosing HiPhorius™ can maintain production efficiency in reduced nPP diets, but its effects on egg quality and bone mineralization may be variable.