Vitamin D exists in two main forms: ergocalciferol, which is derived from plants called vitamin D2 and cholecalciferol, and is derived from animal body as vitamin D3. Vitamin D precursors are found in plants (ergosterol) and animal (7-dehydrocholecalciferol) feeds, but they must be converted to vitamin D2 and vitamin D3 by ultraviolet radiation. Although vitamin D2 and vitamin D3 have long been considered to have the same biological activity in pigs, vitamin D3 is more active than vitamin D2.
Commercially available vitamin D3 is a spray-dried product or coated small particles. One International Unit (IU) is equivalent to 0.025 μg of cholecalciferol and has strong stability at room temperature. Vitamin D activity will be lost by 10% and 30% when stored at full price for 4 or 6 months.
Most of the vitamin D supplied in the diet is absorbed in the distal end of the small intestine. The absorbed vitamin D is sent to the liver through the lymphatic capillary system and then converted to 25-OH-D3 and returned to the blood. The synthesis of 25-OH-D3 occurs almost entirely in liver tissue, and the carboxylation reaction is carried out by a microsome accompanied by dehydrogenation of coenzyme II (NADPH), and oxygen molecules are inserted. 25-OH-D3 in serum is a good indicator of vitamin D levels in animals. This form of vitamin D3 is classified as a steroid hormone because it is produced by a single tissue (kidney) and converts 25-OH-D3 in tissue (small intestine and bone) to 1,25-(OH)2-D3 . This 1,25-(OH)2-D3 is more active than 25-OH-D3. Parathyroid hormone regulates the carboxylation process of 1,25-(OH)2-D3 and the rate of transport to bone, thereby regulating the deposition of calcium and phosphorus in bone.
Luminous Pressure Gauge
Luminous pressure gauge uses energy storage noctilucent powder as dial material which will glimmer for a long time after a few minutes of lighting so that the pressure gauge can be clearly read in the darkness. It is applicable for the support of diving gears and firefighting, live-saving equipment.
Luminous pressure gauge
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