What Is a Selenium Deficiency?

Mainly due to the lack and deficiency of selenium in the feed. It is generally believed that the appropriate selenium content in the feed is 1 × 10-7, and if it is lower than 5 × 10-8, it can cause different degrees of disease. The selenium content in feed is related to the level of available selenium in the soil. The soil selenium content is affected by many factors, the decisive factor is the soil pH value. Selenium in alkaline soil is a water-soluble compound and is easily absorbed by plants; although the selenium content in acidic soil is high, compounds such as selenium and iron are not easily absorbed by plants. Sulfur content in the soil can greatly inhibit selenium absorption by plants; selenium in rivers and marshes is easily lost, and selenium content in the soil is also low; air temperature and precipitation are also factors affecting selenium content in feed plants; plants in cold and rainy years have low selenium content , Plants in dry years have high selenium content. In addition, too much antagonistic elements such as copper, zinc, arsenic, mercury, cadmium in the feed can affect the absorption of selenium and promote disease.

Chicken selenium deficiency

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Selenium Deficiency Selenium Deficiency Selenium is an essential trace element for poultry. It is an indispensable element for certain enzymes, vitamins and certain tissue components in the body. It is necessary for poultry growth, reproduction and prevention of many diseases. It can cause poultry when it is lacking Nutritional muscular dystrophy, exudative quality, pancreatic degeneration, selenium and vitamin E have complementary effects on preventing chicken brain softening and turkey muscle and stomach degeneration

Mainly due to the lack and deficiency of selenium in the feed. It is generally believed that the appropriate selenium content in the feed is 1 × 10-7, and if it is lower than 5 × 10-8, it can cause different degrees of disease. The selenium content in feed is related to the level of available selenium in the soil. The soil selenium content is affected by many factors, the decisive factor is the soil pH value. Selenium in alkaline soil is a water-soluble compound and is easily absorbed by plants; although the selenium content in acidic soil is high, compounds such as selenium and iron are not easily absorbed by plants. Sulfur content in the soil can greatly inhibit selenium absorption by plants; selenium in rivers and marshes is easily lost, and selenium content in the soil is also low; air temperature and precipitation are also factors affecting selenium content in feed plants; plants in cold and rainy years have low selenium content , Plants in dry years have high selenium content. In addition, too much antagonistic elements such as copper, zinc, arsenic, mercury, cadmium in the feed can affect the absorption of selenium and promote disease.

More common in production practice is the selenium caused by the common deficiency of trace elements selenium and vitamin E ---

The pathogenesis is not very clear, but most scholars believe that selenium and vitamin E have antioxidant effects, which can protect tissues from the damage of peroxides in the body and protect the normal function of cells. Selenium is an important component of glutathione peroxidase. It consists of 4 subunits, and each subunit binds to a selenium atom. Because the body produces some peroxides that can damage the lipid membranes of cells and subcellular (mitochondria, lysosomes, etc.) during metabolism, it can cause cell degeneration and necrosis. Glutathione peroxidase can destroy peroxide (H202) and reduce it to non-toxic hydroxyl (-OH) compounds, thereby preventing cell oxidation, myoglobin, and hemoglobin oxidation and maintaining oxygen transport capacity.

Selenium participates in the mixed function oxidase system of microsomes and plays the role of electron transfer. Therefore, selenium is closely related to the synthesis and inactivation of many important active substances and the biological transformation of exogenous drugs and toxicants (including carcinogenic diseases).

Selenium also participates in the synthesis of coenzyme A and coenzyme Q, and is also a cytochrome component related to electron transfer. They play an important role in the tricarboxylic acid cycle and electron transfer of the body's metabolism. Selenium also promotes protein synthesis in the body. When selenium cooperates with vitamin E, it can maintain normal fertility of animals. However, in the absence of selenium and vitamin E, the cell membrane of the body is damaged by the toxic damage of peroxides, and the integrity of the cells is lost, resulting in muscle cells (skeletal muscle, heart muscle), liver cells, pancreas and capillary cells, and nerve cells. Degeneration and necrosis occurred. Therefore, symptoms and pathological changes such as muscular dystrophy, muscular degeneration, pancreatic atrophy, exudative quality, and brain softening in poultry can be seen at the clinic.

The selenium deficiency disease has obvious epidemiological characteristics, and the main manifestations are as follows.

The disease can occur in chicks, ducklings, and turkeys. Clinical features are exudative quality, muscular dystrophy, pancreatic degeneration, and brain softening. Exudative quality often begins in chickens at the age of 2 to 3 weeks, and the incidence is as high as 80% to 90% at the age of 3 to 6 weeks. Most of them are acute, and the severely sick chicks can die within 3 to 4 days, and the longest course can be 1 to 2 weeks. The main symptom of the chick is a pale blue-green edema-like change under the skin of the sagging chest and abdomen. Some leg and wing roots can also develop edema, which can extend to the whole body in severe cases. Sick chickens with exudative qualities are highly depressed, their growth and development are stopped, their crowns are pale, their bodies are lying flat, their standing is difficult, their legs are spread apart when they are standing, and their walking obstacles. Defecation or watery stool, and eventually died of failure. Pathological changes of the necropsy showed edema-like exudate or yellowish-green fibrin coagulum in the edema. There are blood stasis spots on the neck, abdomen and inner thigh.

Some sick birds show significant muscular dystrophy, which is usually prone to occur at 4 weeks of age. It is characterized by general weakness, anemia, atrophy of the pectoral and leg muscles, unstable standing, and even paralysis of the legs and lying on the ground, loose and drooping wings, contamination around the anus, and finally died of failure.

The pathological changes of necropsy were mainly skeletal muscle, heart muscle, liver and pancreas, followed by kidney and brain. The lesions have muscle degeneration, pale color, meat-like appearance, grayish yellow, yellowish white dots, stripes, and flakes; the cross section has grayish white, yellowish stripes, and the texture becomes brittle, soft, and calcified. Myocardial dilatation and thinning is obvious in the left ventricle. Most of the papillary muscles have bleeding spots on the intima of the papillary muscles. There are yellow-white or off-white streaks parallel to the direction of muscle fibers in the endocardium and epicardium. The liver is swollen, hard and brittle, with a rough surface and a betel-like pattern on the section; some livers change from dark red to grayish yellow or khaki. The kidneys are congested and swollen, and the kidney parenchyma has bleeding spots and gray patches. Pancreatic degeneration, glandular atrophy, volume reduction has a solid sense, light color, mostly light red or pink, and severe acinar necrosis and fibrosis.

Some young chicks mainly show imbalances, dyskinesias and neurological disorders. This is due to softening of the cerebellum caused by vitamin E deficiency. Secondly, sick turkey chicks or chicks develop muscle degeneration.

Diagnosis

Make a diagnosis based on the local history of selenium deficiency, epidemiology, feed analysis, characteristic clinical symptoms and pathological changes, and good results with selenium preparations.

In the intensive poultry industry, research is being conducted on indicators to quickly monitor the state of selenium in the body, providing a strong scientific basis for early diagnosis, prediction, prevention and treatment. The following indicators are currently available.

1. Determination of selenium and vitamin E levels in body tissues and blood. The amount fluctuates with the amount of feed. It is generally believed that selenium content in whole blood is less than 0.05 & micro; g / ml is selenium deficiency, 0.05 ~ 0.1 & micro; g / ml is the edge of selenium deficiency, and more than 0.1 & micro; g / ml is suitable; ; g / g (wet) is the lack, in the range of 0.1 to 0.2 & micro; g / g (wet) is the critical value of selenium deficiency, more than 0.2 & micro; g / g is appropriate. The content of vitamin E in the liver of cerebral softening disease is 16.0mg, while that of healthy young is 72.15mg.

2. Determination of glutathione peroxidase (GSH-Px) activity in blood. Its value has a significant positive correlation with blood selenium level, and the determination of blood GSH-Px activity can be used as an index to quickly evaluate the state of selenium in animals. It is now necessary to establish a normal reference value for the early position of GSH-Px activity.

3 Determination of creatine phosphokinase (CPK). This enzyme is highly specific for myocardium and skeletal muscle, and its continuously increasing value indicates that muscle degeneration is progressive. When muscular dystrophy is caused by selenium-tocopherol deficiency. Plasma (clear) CPK is elevated, so the study of poultry CPK zymogram is needed.

The disease is mainly for prevention. Add 1 × 10-7 2 × 10-7 sodium selenite to the diet of chicks and add 20mg of vitamin E per kg of feed. Take care to add the correct amount and stir well to prevent poisoning. During the treatment, a 0.005% sodium selenite solution is injected subcutaneously or intramuscularly, and the chicks are 0.1 to 0.3 m1 and the adult birds are 1.0 ml. Or use drinking water to prepare a solution containing 0.1 to 1 mg of sodium selenite per liter of water, which can be given to young birds for 5 to 7 days as a course of treatment. In the case of chicken brain softening, vitamin E must be the main prevention and treatment; for selenium deficiency such as exudative quality and muscular dystrophy, the selenium preparation must be the main prevention and treatment, which is effective and economical.

In some selenium-deficient areas, corn leaf was sprayed with sodium selenite, and the selenium content of corn and straw after spraying was significantly increased, and animal feed tests were performed to obtain good preventive effects.