Yolk Mottling Associated With Dietary Calcium Deficiency

This study describes a previously unreported nutritional factor which may play an important role in mechanisms involved in yolk mottling. Seventy-five Kimber K-137 hens were divided into two groups. A corn-soy diet containing 3.0 percent calcium (Ca) was fed to group 1, which was composed of 15 birds. Group 2 (60 birds) was fed the same diet except that limestone was removed and replaced with sand resulting in a level of 0.05 percent calcium. Yolk calcium determinations and examinations for abnormal yolks were made at regular intervals throughout the 24-day experiment. Severe yolk mottling and decreased yolk calcium were observed in eggs from hens fed the calcium-deficient diet within 12 days. The mottling appeared as reddish-brown splotches. Some yolks were so severely mottled that they resembled an ovum which had regressed for two or three days.