Calcium Metabolism in the Laying Hen

Abstract

Three experiments were conducted to determine the influence of time of oviposition on shell quality. One thousand and eighty DeKalb pullets (34 weeks of age) and 560 Kimber hens (52 weeks of age) were used in experiments 1 and 2, respectively. In both experiments eggs were collected at 8:30 a.m., 12 noon, 1:00, 2:00, 3:00, 4:00, and 5:00 p.m. on Wednesdays for three consecutive weeks. In experiment 3, eggs were collected from 1080 DeKalb pullets (40 weeks of age) at hourly intervals from 7:00 a.m. through 8:00 p.m. Egg cycles were determined using daily production records beginning 10 days before the initiation of the experiment. The results indicated that time of oviposition is related to shell quality. Eggs laid in the afternoon have an average specific gravity greater than eggs laid in the morning. In general, the later in the afternoon the egg was laid the greater the specific gravity. This was also true when only the terminal egg of sequences was used. Shell quality of the terminal egg appeared to improve as the cycle length increased. Possible causes and significance of this phenomenon were discussed.