Which gland is stimulated when feeding close-up cows a calcium deficient diet?

The parathyroid gland plays a crucial role in maintaining calcium balance in the body, especially in dairy cattle. When cows are fed a calcium-deficient diet, the parathyroid gland is stimulated to secrete parathyroid hormone (PTH). This hormone helps to regulate calcium levels in the blood by promoting the release of calcium from bones, increasing the absorption of calcium from the intestines, and enhancing the reabsorption of calcium in the kidneys. This physiological response is critical for preventing conditions related to low calcium levels, such as milk fever, particularly in close-up cows that are just before calving when their calcium needs increase significantly.

The other glands listed, while important in other physiological processes, do not have the same direct role in regulating calcium levels in response to dietary deficiencies. The pituitary gland is involved in the regulation of various hormones that control growth and lactation but does not directly manage calcium metabolism. The thyroid gland primarily regulates metabolism and growth through hormones such as thyroxine, and does not directly influence calcium homeostasis. Similarly, the adrenal gland is responsible for producing hormones like cortisol and adrenaline that deal with stress responses and metabolism, rather than calcium regulation. Therefore, the parathyroid gland is the key player in responding to low