The Calcium Requirements of Laying Hens and Effects of Dietary Oyster Shell Upon Egg Shell Quality

Abstract

IN 1962 the Subcommittee on Poultry Nutrition of the National Research Council (N.A.S.-N.R.C, 1962) revised its recommended calcium requirement for laying hens. A level of 2.75% was adopted as the new recommendation, based on the many reports indicating the need for more calcium than the 2.25% previously recommended. The 2.75% level of calcium also was recommended in the fifth revised edition of The Nutrient Requirements of Poultry (N.A.S.-N.R.C, 1966). However, Peterson et al. (1960) reported that a level of at least 3.4% was necessary for maximum egg shell quality. They also noted that environmental temperature had an important influence upon the required calcium level. Numerous other reports have provided evidence for a dietary calcium requirement greater than 2.75% for maximum shell quality (Hurwitz and Griminger, 1962; Harms and Waldroup, 1961; Reddy and Sanford, 1963). A deficiency of calcium is generally recognized to cause a decline in egg production and a…