The relationship between reproductive activity and blood calcium in the calcium‐deficient hen

Abstract

1. The dependence of reproductive activity in the laying hen upon adequate calcium intake has been investigated.

2. The response of plasma luteinising hormone concentration in calcium‐deficient, as compared with calcium‐replete hens, to injections of luteinising hormone releasing hormone and progesterone suggested that the primary site of reproductive dysfunction is the hypothalamus rather than the pituitary gland.

3. Laying hens, when presented with a calcium‐deficient diet, ceased to lay as the plasma ionised calcium concentration decreased to less than 1.0 mm, supporting the view that there is a threshold of blood calcium activity below which reproductive activity ceases.

4. Supplementation of the diet with calcium produced an immediate restoration of plasma ionised calcium concentration to normal, despite an interval of a few days before the plasma total calcium returned to normal and egg laying resumed.

Notes

Present address: Department of Physiology and Pharmacology, University of Southampton, Bassett Crescent East, Southampton SO9 3TU, England.

Present address: Department of Physiology, Thompson Hall, Cook College, Rutgers University, New Jersey 08903, USA.