Calcium metabolism in broiler breeder hens. 1. Calcium status of the digestive tract of broiler breeders throughout a 24-hour period.

Dry matter and calcium content of the digestive tract were determined on two groups of broiler breeders during a 24-hr period. The individually caged hens were fed either ad lib or restricted to 122 g of feed during a 4-hr feeding period each day from 0700 to 1100 hr. The hens received artificial light from 0700 to 2300 hr. On Day 14 of the feeding program a total of 100 hens, 10 from each group, were necropsied at selected intervals (0700, 1100, 1900, 2300, 0300 hr), and the contents of the various segments of the digestive tract and feces were collected and analyzed for dry matter and calcium. The calcium analysis also included any endogenous excretions and, therefore, absorption values are apparent. Hens restricted to 122 g feed per day had only 51.7% of the dry matter and 64.2% of the calcium consumed during the 4-hr feeding period remaining in the digestive tract at 1100 hr. By 2300 hr only 20.6% of the feed and 28.1% of the calcium remained. Hens had only approximately 14% (14.2 g) of their total dry matter intake and 16% (.70 g) of the calcium available for absorption from 0300 hr. The ad lib group, with an average intake of 171 g feed per day, had consumed only 26% of their daily feed intake by 1100 hr. Fifty-five percent of the dry matter consumed and 22% of the calcium remained in the digestive tract at 1100 hr. It was concluded that broiler hens restricted to morning feeding do not maintain a constant and equal metering of dry matter or calcium from the crop into the digestive tract throughout a 24-hr period.