Fine Structural Evaluation of Parathyroid Glands From Cows Fed Low and High Calcium Diets

Abstract

The calcium (CA) content of the prepartal diet has been shown to significantly influence the development of profound hypocalcemia with paresis in dairy cows near parturition. The mechanisms by which these provocative and preventative diets influence endocrine function and skeletal metabolism are uncertain. The objective of this investigation was to evaluate the effects of feeding high and low CA diets on the ultrastructure and function of parathyroid chief cells in adult cows.The effects of feeding a low CA diet (4.9 gm/day for 30 days) was investigated in 3 non-1actating Jersey cows. The serum CA decreased from 10.7 to 8.8 mg/100 ml after 30 days.