Influence of Dietary Calcium Deficiency on Yolk and Serum Calcium, Yolk and Organ Weights and Other Selected Production Criteria of the Pullet

Two experiments were conducted with pullets being fed either a 0.05% or a 3.0% calcium diet for 25 days. Egg production from birds fed the 0.05% calcium diet was reduced approximately 75% within nine days. During the last three days the pullets fed the calcium-deficient diet laid at the rate of 10.7% of which approximately one-half were hard-shelled eggs. The first soft-shelled eggs were observed on the third day and by the sixth day soft-shelled egg production had peaked at approximately 20%. Within six days serum calcium from birds fed the 0.05% calcium diet was reduced by approximately 50% and it remained at this level for the next 18 days. A gradual reduction in yolk calcium and yolk weight was observed for 15 days at which time they had reached their lowest value of 0.105% and 11.8 g. compared to the control values of 0.159% and 16.0 g., respectively. Shell weight, shell thickness and egg weight also gradually decreased for approximately two weeks. The birds fed the calcium-deficient diet had smaller ovaries, oviducts, pituitaries and combs and had larger parathyroids.