The objective of this study was to evaluate the effects of microbial phytase on egg production and egg quality in older hens. A total of 216, 63-week-old Hy-line brown laying hens were distributed in a randomized complete design 10-week feeding trial of 3 dietary treatments with 12 replications per treatment and 6 hens per replication. The 3 dietary treatments were corn-soybean meal-based diets supplemented with 0 % (CON), 0.06 % (TRT1), and 0.12 % (TRT2) microbial phytase. Significantly higher

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... hen-day egg production was observed in the TRT1 treatment compared to CON (P < 0.05), except during the first two weeks of the experiment. During weeks 3, 4, and 9, TRT2 had a greater hen-day egg production percentage than CON (P < 0.05). The damaged egg ratio was not affected. The egg quality parameters (e.g., eggshell color, eggshell strength, albumen height, egg weight, and the Haugh unit) were affected by microbial phytase supplementation (P < 0.05). However, there were no significant effects on the eggshell thickness and yolk color. In conclusion, microbial phytase supplementation to the diets of older hens could improve production performance, extend the peak laying period, and alter the egg quality parameters.