Observations on the Voluntary Intake of Calcium Supplements by the Laying Hen

THE calcium needs of the laying hen can be met by furnishing the required calcium in the feed, by free-choice offering of a calcium supplement, or by a combination of both. The calcium requirement of a laying hen is largely determined by the fraction of dietary calcium retained and by the amount of egg shell secreted (Hurwitz and Griminger, 1962). Since the latter depends upon rate of egg production, size of eggs, and thickness of shell, considerable variability is to be expected among hens. When the calcium requirement is expressed as a percent of the ration, feed intake, and therefore caloric density of the ration, will constitute an additional factor (Griminger, 1961). In view of these variables adjustment of the calcium intake by a free-choice offering of calcium supplements appears to offer a logical solution to the problem of supplying the right amount of calcium for each hen, provided, of…