The Effect of Increased Dietary Calcium on Hens Chosen for Their Ability to Produce Eggs with High and Low Specific Gravity

Two experiments were conducted in which two groups of hens, selected for the production of high specific gravity or low specific gravity eggs, were each subdivided into two groups. One group received a diet containing 3% calcium and the other group received a diet containing 5% calcium. Specific gravity of eggs from hens fed the diet containing 5% calcium was significantly higher than specific gravity of eggs from hens fed the diet containing 3% calcium. Hens selected for their ability to produce eggs with low specific gravity continued to lay eggs with lower specific gravity than did hens selected for eggs with high specific gravity. The interaction of hens selected for high and low specific gravity and dietary calcium level, was not statistically significant. This indicated that the difference in initial specific gravity of eggs which hens were laying did not influence their response to increase dietary calcium level. Rate of egg production, egg weights, feed consumption and body weight gains were not significantly influenced by selecting birds for high or low specific gravity or by feeding 3 or 5% dietary calcium.