The effect of variation of calcium intake on production performance and shell quality.

Two experiments were conducted to determine the effects of moderate variation of calcium intake on production performance and shell quality. In Experiment 1, birds were fed diets containing 1.5 and 5.5% calcium, respectively, in the first and second 3-day period of 10 6-day cycles. In Experiment 2, calcium concentrations alternated between 2 and 5%. In both experiments, control groups were fed a diet containing 3.5% calcium for the duration of the experiment (60 days). Birds were 28 weeks old at the beginning of Experiment 1 and 50 weeks old at the beginning of Experiment 2. Overall egg production, egg weight, egg mass, feed consumption, feed conversion, and body weight gain were consistently lower for the birds of the alternating groups than the birds of the control groups in both experiments. Shell quality as measured by shell thickness, breaking strength, specific gravity, and percent shell in most cases was significantly reduced within 24 hr of feeding the low calcium diets and improved to normal within 24 hr of feeding the high calcium diets in both experiments. These experiments suggest that calcium variation of the extent used in these experiments reduces optimum performance; shell quality is reduced within 24 hr of feeding a low calcium diet.