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Abstract
1. Seventeen 32‐week‐old White Leghorn laying hens were induced to become deficient in calciferol or in calcium (laying thin or soft shelled eggs) by withdrawing either cholecalciferol (27.5 μg/kg diet) or calcium (31 g/kg diet) supplements from the control diet.
2. The metabolic fate and metabolic clearance rate (MCR) of intravenously injected 3H‐oestradiol‐17ß were then monitored for 40 min.
3. In both the calciferol and calcium‐deficient groups a major oestrogen sulphate pathway was particularly affected, resulting in a decreased conversion of oestradiol‐17ß‐3‐sulphate to oestradiol‐17α‐3‐sulphate, with a concomitant reduced MCR of oestradiol‐17ß from plasma.
4. The metabolic defect was corrected by feeding the control diet.
5. Because the metabolic defect observed in calciferol deficiency occurred in Ca deficiency in a more severe form, we conclude that the more immediate cause was calcium rather than calciferol deficiency. To our knowledge, this is the first observation of a calcium‐deficient effect on oestrogen sulphate metabolism in vivo.