The Lack of Response of 25-Hydroxy-Vitamin D3 on Egg Shell Quality or Other Criteria in Laying Hens

Three experiments were conducted in which old hens, young hens and old hens producing a high percentage of shell-less and ultra-thin-shelled eggs were used. Birds in each category were divided into two groups. They were fed either a layer diet containing 3.00% calcium, 0.75% phosphorus and 2200 I.C.U. of vitamin D3 per kg. of feed or the same diet plus 1.1 mg. 25-OH-D3 per kg. of feed. The results of these experiments indicated that 25-OH-D3 had no significant effect on egg production, serum calcium, feed consumption, egg weight or specific gravity of eggs.