Meta-analysis of the effects of available phosphorus levels and phytase on eggshell quality parameters in laying hens: influence of dose, enzyme origin, and nutritional reduction

This study aimed to evaluate, through a meta-analysis, the effects of phytase supplementation in diets for laying hens on eggshell quality parameters, including shell weight percentage (SWP), shell thickness (ST), shell breaking strength (SBS), and specific gravity (SG). The methodology consisted of a systematic review and quantitative integration of data from 16 scientific articles published between 2021 and 2025, analyzing statistical contrasts among diets with adequate phosphorus (P) levels (positive control), phosphorus-deficient diets (negative control), and diets supplemented with the enzyme phytase. The main results showed that dietary phosphorus reduction significantly impaired eggshell structural quality, reducing ST by an average of 3.50 µm and SBS by 0.23 kgf, whereas SWP and SG were not markedly affected. Phytase supplementation effectively mitigated these adverse effects, increasing ST by an average of 3.14 µm and SBS by 0.20 kgf compared to the deficient group, restoring these parameters to levels comparable to those observed in hens fed nutritionally adequate diets. Additionally, the enzyme's efficacy remained stable regardless of its origin (bacterial or fungal) or the evaluated dosage (up to 1,000 FTU/kg). It is concluded that phytase is a key nutritional tool for maintaining eggshell structural quality under conditions of phosphorus deficiency, optimizing mineral utilization and preserving the productive efficiency of laying hens.