Poultry vitamin D deficiency
Vitamin D (Vitamin D), also known as calciferol vitamin d, has many types, all of which are steroid derivatives, among which vitamins D2 and D3 are more important.
Vitamin D3 is a white needle-like substance, easily soluble in ethanol and chloroform, slightly soluble in oil, insoluble in water, with a melting point of 82-88 °C, and also changes due to light and oxygen, but vitamin D3 is more stable than vitamin D2.
Vitamin D is the most abundant in cod liver oil, and also more abundant in animal liver and eggs. Generally, plant-based feeds contain little or no vitamin D. There is a large amount of ergot alcohol in green feeds, which can form vitamin D2 under ultraviolet irradiation. Therefore, hay powder prepared by sunlight exposure contains some vitamin D. In addition, 7-dehydrocholesterol is synthesized in the skin and adipose tissue of animals, and can be converted into vitamin D3 under ultraviolet irradiation. Therefore, under normal circumstances, vitamin D supplementation is not particularly required in the feed, but if the poultry is completely housed, the feed needs to be supplemented with vitamin D3.
Vitamin D is converted into 25-hydroxyvitamin D3 in the liver, and under the action of parathyroid hormone, 25-hydroxyvitamin D3 is converted into 1,25-dihydroxyvitamin D3 in the kidney, and 1,25-dihydroxyvitamin D3 is in It plays its physiological role in the kidneys or transported to the intestines, bones and other tissues through the blood. Its main physiological functions are:
①Maintain the normal level of blood calcium and blood phosphorus together with parathyroid hormone to prevent tics.
②Activate the transport system of intestinal epithelial cells, so that calcium and phosphorus are actively transported through the intestinal epithelium to increase the absorption of calcium and phosphorus.
③ Act on the renal tubular epithelial cells, promote the renal tubular reabsorption of calcium and calcium phosphate, and reduce the loss of calcium from the urine.
④Promote the formation of calcium-binding protein, and play the role of active calcium transport, while promoting the absorption of phosphorus. Saturate calcium and phosphorus in the blood. To ensure the normal calcification process of bones.
①The ratio of calcium and phosphorus in the diet is inappropriate. The optimal ratio of calcium and phosphorus in the diet is 2:1. Above or below this optimal ratio will increase the need for vitamin D.
②The source of phosphorus in the diet. When the diet contains poorly available phosphorus, such as phytate phosphorus or other forms of phosphorus, the amount of vitamin D needs to be increased.
③ There is insufficient sunlight for house-raised chickens. 11-45 minutes of daily sun exposure for growing chickens is sufficient to prevent rickets. Inadequate sun exposure can lead to vitamin D deficiency.
④The requirement of vitamin D is greatly increased when the diet contains mycotoxins.
When the chicks are lacking, the appetite is good, but the growth is poor, or even stops growing, the legs are weak, the gait is unsteady, and the hocks land on the ground, and finally cannot stand. Bone becomes soft or swollen, beak and claws become soft and pliable, ribs also become soft, ribs and costal cartilages, where ribs and vertebrae swell, forming round nodules that are "beaded", vertebrae in the sacrum And the tail is bent downward, the long bones become brittle and easy to break, the sternum is scoliosis, the middle of the thorax is acutely invaginated, and the thoracic cavity becomes smaller.
When laying hens are deficient in vitamin D, they will initially produce thin-shelled eggs and soft-shelled eggs, and then the egg production will decline, resulting in a complete shutdown and a reduced hatching rate. The chicks are difficult to hatch, and the hatched chicks are weak. Severe deformity and curvature of the sternum, softening of the ribs and claws, invagination of the junction of the sternum and vertebrae, and swelling. Long bones become brittle due to demineralization and are easily fractured, and sick chickens limp, manifested in a squatting posture with the body sitting on the legs.
A characteristic change in chicks is the beading of the rib and spine junctions. The pathological changes of adult chickens are osteoporosis, which becomes brittle and brittle, and the joints of ribs and vertebrae are swollen and spherical.
①Ensure the content of vitamin D in the feed. For free-range chickens, sun-dried green hay and cod liver oil can be added to the feed, while receiving sunlight. Intensive cage chickens must add vitamin D to the feed, chicks and reserve chickens The additive dosage is 200 international units per kilogram of feed, and 500 international units per kilogram of feed for laying hens and commercial chickens.
② Ensure the content of calcium and phosphorus in the feed, and maintain an appropriate ratio.
③Maintain proper exercise to promote bone development and enhance bone function. It is not easy for laying hens to be caged too early, and it is advisable to cage them one month before the start of production.
④ When there is a deficiency, the dosage of vitamin D in the feed is 2-4 times the normal dosage. For chickens with severe symptoms, cod liver oil can be taken orally, 2-3 drops each time for chicks, 3 times a day, and 0.5 ml of vitriol calcium is injected into adult chickens, and the effect is better.