Influence of calcium depletion on medullary bone of laying hens

Abstract

Medullary bone of birds maintained on a low-calcium diet represents a good model to study modifications of matrix composition in calcified tissue undergoing intense formation and resorption. The composition of the bone matrix during the low-calcium diet has been analyzed by both chemical and histological techniques. Sixty White Leghorn pullets 1 year old were used for the experiment. Fifteen birds served as controls and were killed on day zero; the remaining birds were placed on a calcium-deficient diet (0.13% calcium) and sacrificed after 4, 7, and 12 days of treatment in groups of 15. Serum levels of calcium, PTH, and estrogens were also measured. Chemical analysis of the samples were made for total nitrogen, hydroxyproline, hexosamine, hexoses, calcium, and phosphorus. Collagen and proteoglycans of the matrix of medullary bone of the egg-laying hens were found to be affected by the low-calcium diet. They either increased or decreased during the experiment but never in parallel. The increment of serum PTH is considered responsible for the variations in the amount of collagen. The effects of this hormone are magnified by the fall of serum estrogens as shown also by variations in the amounts of noncollagenous protein. In the late phase of the diet the matrix is represented by poorly calcified osteoid tissue rich in noncollagenous protein, i.e., proteoglycans and glycoproteins.

Dietary calcium deficiency in laying ducks impairs eggshell quality by suppressing the process of shell biomineralization

“…Unexpectedly, there were few shell-less eggs observed during the depletion period because the frequency of ovulation was reduced. This observation is in accordance with previous reports in laying hens that dietary calcium deficiency decreased egg production (Nevalainen, 1969;de Bernard et al, 1980;Abdallah , 1993). It probably indicates an adaptable biological physiology of laying birds in response to calcium deficiency.…”

A Histomorphometric, Structural, and Immunocytochemical Study of the Effects of Diet-induced Hypocalcemia on Bone in Growing Rats

“…Calcium deficiency in these animals produced severe bone alterations characterized by an increase in osteoid but no change in thickness of the growth plate. These data are consistent with some previous reports indicating that hypocalcemia induces calcification defects similar to those observed in rickets and osteomalacia (Bloom et al 1958;Stauffer et al 1973;de Bernard et al 1980;Pettifor et al 1984). Vitamin D is probably not a major contributor to the resulting alterations because there was only a partial change in osteoid parameters when doses were raised from 1000 to 2500 IU.…”

“…1958; Stauffer et al 1973), and (d) in young, growing animals, the presence of severe calcification defects similar to those observed in rickets and osteomalacia (Bloom et al 1958;Stauffer et al 1973;de Bernard et al 1980;Pettifor et al 1984).…”

Medullary bone in fossils: function, evolution and significance in growth curve reconstructions of extinct vertebrates

“…In fact, Ca‐deficient diet first increases the amount and mineralization of MB at the expense of structural cortical bone (Whitehead & Fleming, ; Beck & Hansen, ; Whitehead, ). After a longer period of Ca deficiency MB remains unmineralized but its amount does not change (de Bernard et al ., ; van De Velde et al ., ). Fleming et al .…”