The Relationship of Age on Ability of Hens to Maintain Egg Shell Calcification When Stressed with Inadequate Dietary Calcium

Abstract

Two experiments were conducted comparing the ability of young and old hens to maintain egg shell calcification when stressed with inadequate dietary calcium. In Experiment 1, 90 young hens and 90 old hens were divided into three equal groups and fed a diet containing 3.00%, 1.75%, or 1.00% calcium. Egg weight, specific gravity, and shell weight were determined on all eggs laid during the 4-day experiment. Feed consumption and serum calcium were determined by treatment. Experiment 2 was conducted similar to Experiment 1, except eggs were collected for 5 days. Samples of feces and bone were obtained on the fifth day and analyzed for minerals.The results of both experiments demonstrated that the old hens were able to maintain egg specific gravity, egg shell weight, egg weight, egg production, and serum calcium as well or better than young hens when both were stressed for short periods with diets that contained inadequate dietary calcium. Feed consumption was not significantly reduced by dietary calcium deficiency during this brief experimental period. Percent calcium, sodium, magnesium, and manganese in the feces were significantly reduced in hens (young and old) when fed diets containing 1.75 or 1.00% calcium. Tibia weight and ash were significantly reduced in young and old hens by decreasing the dietary calcium. It was concluded that the decline in shell quality with hen age is not due to a decline in the hen’s ability to absorb calcium or utilize skeletal calcium.