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Effects of Oviposition Time, Hen Age, and Extra Dietary Calcium on Egg Characteristics and Hatchability

Instituto Superior de Agronomia, 1399 Lisboa Codex, Portugal; Phone: (01) 3638161; FAX: (01) 3635031

Correspondence: M. Chaveiro Soares

This study sought to determine the effect of extra dietary calcium, oviposition time, and hen age on eggs produced by a commercial broiler breeder flock at 46 and 65 wk of age. A breeder flock of approximately 15,400 birds (13,900 females) was divided into two groups: no extra calcium supplementation (NC), and extra calcium supplementation (CS). The CS group received a coarse limestone supplement (4g/hen/day) at 16:30 hr. Eggs were collected at 2 hr intervals between 08:00 and 18:00 hr.

For both ages, egg weight decreased and specific gravity increased as time of laying became later in the day. Egg specific gravity, fertility, embryo viability, and hatchability declined with hen age. At 46 wk of age specific gravity (SG) rose slightly but significantly when the calcium supplement was provided. Added calcium had no statistically significant effect on other variables studied. At 65 wk of age, SG and egg weight loss during incubation were the only variables not influenced by the calcium supplementation. Egg weight, fertility, embryo viability, and hatchability were significantly (P<. 01) improved.

Key Words: Broiler hatchability • calcium supplement • egg specific gravity • hen age • oviposition time