A 3 × 3 factorial experiment with three levels of fennel extract (FE) (0, 50, and 100 mg/kg of diet) and three levels of added vitamin D3 (Vit D3) (0, 3500 and 4200 IU/kg of diet), was carried out to evaluate reproduc-tive performance and immune response of post molted broiler breeders (76-84 weeks). Broiler breeders were weighed at 10 week after molting (74 weeks) then randomly distributed into 36 pens in order to have a similar mean pen body weight (BW). Each pen consisted of 10 hens and 1 rooster. The birds received ex-perimental diets at 74 weeks of age. Performance data were recorded daily, whereas egg quality traits were determined every 4 weeks. To determine the settable hatch, fertile hatch, embryonic mortality, real hatch, chick quality, chick sexing, chick weight and relative chick weight, eggs from each pen were collected three times a week, marked and incubated in a commercial hatchery for 21 days. Two blood samples were taken from two hens in each pen to assay Newcastle and Influenza antibody titers every two weeks. Dietary fen-nel extract supplementation significantly increased egg production, chick quality and improved Newcastle antibody titer over time (P<0.022). Furthermore, the addition of FE to diet significantly decreased double yolk and pewee eggs (P<0.001). Yolk color was affected by the addition of vitamin D3 in the whole ex-perimental period. Significant interactions between FE and vitamin D3 on embryonic mortality were ob-served. The results of this study showed that supplementation of diet with FE exhibits beneficial effects on egg production, double yolk eggs, peewee eggs, chick quality, and Newcastle antibody titer. Dietary sup-plementation of vitamin D3 improved yolk color with no adverse effect on productiveperformance.

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