Calcium metabolism in laying hens. 4. Relations between eggshell formation and calcium retention rate by the chromic oxide indicator method.

Numerous studies for determining the availability and digestibility of nutrients with fowl have been developed by the chromic oxide (CraO3) indicator method3, 4, 6, 12-14, 16). The difference in chromic oxide contents were found between day and night excreta or feces in cockerel and cock12, 16). Less informations, however, were available on changes in levels of chromic oxide in day and night excreta of laying hen. In previous reports by ITOH and HATANO10, 11), the daily excretion and eggshell deposition of radiocalcium, and variations in the level of Ca45 contents in excreta at intervals of 4 hours were investigated in the laying hens received radioactivity at 10am or 4pm for consecutive 10 days. In this report, the chromic oxide content of excreta in laying hens were determined at intervals of 4 hours and the calcium retention rate calculated by the chromic oxide indicator method was compared between the days with and without eggshell formation.