The Comparative Value of Five Calcium Sources for Laying Hens

Abstract

Supplemental calcium sources for Red × Rock sex-linked females were studied. Each of six treatments involved seven replicates of 24 birds or a total of 168 birds per treatment. Beginning at 33 weeks of age, the supplemental calcium in the diets was supplied by 1) granular limestone, 2) aragonite, 3) oyster shell, 4) clam shell, 5) egg shell and 6) egg shell with ration modification to utilize the protein in the egg shell meal. There were statistically significant supplemental calcium source differences among treatment means in overall hen-day but not in overall hen-housed egg production or in feed efficiency, livability, body weight, egg weight, or egg shell thickness at any age sampled. Haugh unit values for the group receiving aragonite as the supplemental calcium source were significantly greater than for the groups receiving clam shells or limestone at 56 weeks of age but at the other ages sampled, no significant treatment differences existed.