Excess dietary Ca forms insoluble complexes with phosphorus, resulting in decreased P absorption. The ratio of calcium to phosphorus is also important. Parathyroid hormones and active-form vitamin D are the most important regulators of blood calcium homeostasis.Ĭalcium and phosphorus also have an important relationship to each other within the diet. Calcitonin reverses PTH functions to lower blood Ca level to normal by decreasing calcium mobilization from bones. When blood Ca is high (hypercalcemia), another hormone called calcitonin is released by the parafollicular cells of the thyroid gland. Overall, the net result is an increase in blood Ca level to normal levels. In conjunction with PTH, vitamin D also enhances the mobilization of Ca from bone by increasing the activity of osteoclasts. ↓ Bone mineralization, g ut Ca absorption ↑ Bone Ca Mobilization, kidney resorption, gut Ca absorption When blood Ca is low (hypocalcemia), PTH is released from the parathyroid gland, which leads to increased Ca and P resorption from bone, increased P excretion into urine, and increased synthesis of active forms of vitamin D in the kidneys this in turn is due to an increase in absorption of dietary Ca from the gastrointestinal (GI) tract. This is brought about by the action of parathyroid hormone (PTH), calcitonin, and active forms of vitamin D as shown below. Regulation of Blood Calcium Levels: The body has a strictly controlled physiological regulation called homeostasis-that is, maintenance of a steady state of circulating blood plasma calcium. Ruminant animals produce microbial phytase enzyme that can split and liberate P. Monogastric animals lack the enzyme phytase to release them from the bound form and the term available P is commonly used to designate unbound forms of P in the diet of monogastric animals. The availability of P from such bound sources varies (20%–60%). However, P in cereal grains are present in the bound form as phytate or phytic acid. Thus calcium and phosphorus are crucial to different metabolic processes that sustain animal life. Phosphorus is also part of cell membrane phospholipids that are involved in maintaining cellular fluidity and transport of nutrients into cells. Similarly, deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) contains phosphorylated pentose sugars. For example, phosphorus is a component of the central compound in energy metabolism, adenosine triphosphate (ATP), which is a phosphorylated compound. The phosphorus that is found in the soft tissues of the body is involved in important phosphorylation reactions that are part of cellular oxidative pathways for energy metabolism.

The other 1% of Ca is distributed in cellular fluids, where they are involved in different metabolic and physiologic activities such as blood coagulation, nerve impulse and cell permeability maintenance, activation of certain enzymes, muscle contraction, or serving as activators of ion channels. Approximately 99% of the Ca and 80% of the P in the animal body occur in bones and teeth as a compound called hydroxyapatite. Calcium and Phosphorus Functionsīoth calcium (Ca) and phosphorus (P) function as structural components in the animal body. Minerals are classified into macro and micro minerals based on their presence and need in the animal diet. The functions and deficiencies of macrominerals and electrolytes (Na, K, Cl) discussed in this section are shown in table 15.1. Macrominerals include calcium, phosphorus, magnesium, sulfur, and electrolytes (sodium, potassium, chloride). Macrominerals are those minerals that occur in appreciable amounts in the animal body and are required in large quantities in the diet (> 0.01%). Minerals are classified into two groups-macro and micro (trace) minerals-based on the amounts needed in diet and not based on their importance for physiological functions. The current chapter will discuss only those definitely implicated in different animal nutrition problems in practical situations. Scientific literature lists 21 essential minerals. The functions include expression and regulation of genes and enzyme systems that regulate cellular function, activity and functionality of vitamins, osmotic balance, detoxification, immunity, cell membrane function, acid-base balance and regulation, and structural support and growth (i.e., bone). Minerals are more integrally a part of all biological functions in the body than any other single class of nutrient. The mineral matter constitutes about 4% of the animal body’s weight, and their presence is essential for maintaining life and animal health. Minerals are inorganic elements that are essential for the animal body’s physiological functions and metabolic processes. To introduce and discuss different inorganic elements of importance in animal health, welfare, and nutrition.

Chromium micro and macro minerals