Four experiments were conducted to determine the effect of time of dietary calcium intake on shell quality. Hens in Experiments 1 to 3 were fed one or more diets containing the following calcium levels: 3.4% (daily); 6.4 and .4% (on consecutive days, in a 2-day feeding cycle); and 9.4, .4, .4% (on consecutive days, in a 3-day feeding cycle) such that each group received essentially 3.4% calcium over a 1-, 2-, or 3-day period, respectively. In Experiment 2, hens were also fed a 3.4 and .4% calcium diet on consecutive days in a 2-day feeding cycle. Three treatment groups were used in Experiment 4; the control group was fed a 3.4% calcium diet from 6 am to 8 pm; the other two groups were fed a .4% calcium diet over the same time period except that they were dosed with 3.0 g calcium at 8 am or 4 pm daily. Hens receiving diets containing an average of 3.4% calcium or approximately 3.4 g calcium per day over 2- or 3-day periods could not maintain shell weight, egg specific gravity, or serum calcium at levels comparable to that of control hens fed 3.4 g calcium daily. Hens fed the calcium-deficient diet also tended to overconsume feed when compared to controls. Hens dosed with 3.0 g calcium at 8 am consumed significantly less feed and had significantly lower shell weight and egg specific gravity than control hens, whereas dosing hens with 3.0 g calcium at 4 pm had no significant adverse effect on feed consumption or shell weight. It was concluded that time of dietary calcium intake had a significant effect on the ability of the hen to maintain shell quality.
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LENNARDS et al. (1981) studied this question.