How to Prevent and Treat White Muscle Disease in Farmed Ostriches? A Detailed Guide to Practical Methods
White muscle disease, also known as myositis or muscular dystrophy, is a degenerative muscle disease; in essence, it is one of the syndromes of widespread tissue damage caused by nutritional and metabolic disorders (including muscular dystrophy, hepatic dystrophy and steatitis, etc.). This disease occurs in poultry, and can affect both domestic fowl and domesticated game birds, with a certain geographic distribution. In addition, among mammals, horses, cattle, sheep, deer and others can also develop the disease. Young birds and growing birds are most commonly affected, and young ostriches are even more susceptible. [Causes] The cause of white muscle disease is not yet fully understood, but it is certain that the occurrence of this disease is closely related to the deficiency or insufficiency of vitamin E and selenium and their mechanisms of action. Selenium deficiency: the selenium content of soils and plants varies markedly around the world; mountainous areas, hills and deserts mostly belong to low-selenium regions; in alkaline soils, water-soluble selenium is relatively high and easily absorbed by plants, whereas in acidic soils, complex selenium is abundant but difficult for plants to absorb. Selenium has a strong antioxidant effect in animals and can protect cells from oxidative damage; selenium is also a component of glutathione peroxidase, enabling the enzyme to become activated and perform its role in decomposing peroxides. If selenium is deficient, it can lead to cell degeneration, necrosis, destruction of vitamin E and accumulation of unsaturated fatty acids, ultimately causing inflammatory changes, degeneration and necrosis in the liver, muscles and adipose tissue. It is generally considered that the suitable selenium content in feed is 1×00.0000001, and if it is below 5×0.00000001, varying degrees of disease can be induced. In addition, excessive amounts of antagonistic elements such as copper, zinc, arsenic, mercury and cadmium in the feed can also affect the absorption of selenium and promote the onset of disease. Vitamin E deficiency: vitamin E is also an antioxidant, with the effect of protecting cell membranes from peroxide damage; its mechanism is to inhibit the production of peroxides. If the feed is rancid, the diet ratio is unreasonable, or feed and forage are improperly harvested, processed or stored (sun-drying, baking, moulding, soaking in water and poor ventilation, etc.), vitamin E deficiency can result.
[Diagnostic Points]
1) Epidemiological features This disease has relatively obvious epidemiological characteristics. First, it has a certain regional pattern, occurring mostly in low-selenium areas, such as the diagonal selenium-deficient belt in China extending from Heilongjiang to Yunnan. About 2/3 of the country's area is selenium-deficient; Heilongjiang, Jilin, Inner Mongolia, Qinghai, Shaanxi, Sichuan and Tibet and other regions all belong to selenium-deficient areas, and especially in the northern regions, where green feed is lacking during the long winter, the disease is extremely likely to occur. Second, it has a certain seasonality. The disease occurs mostly in winter and spring (from October to April), during which the climate is cold, vitamin-rich green feed is severely lacking, and this period also coincides with the peak season for poultry breeding and hatching, thus leading to a high incidence in young and juvenile birds. Third, the disease mostly occurs in groups, but it is not contagious. Fourth, it can occur in all poultry, with young turkeys, young ostriches and chicks being more commonly affected.
2) Clinical features The disease is characterized by inflammatory degeneration and necrosis of skeletal muscle and cardiac muscle, hepatitis and steatitis (fatty liver, yellow fat disease), resulting in symptoms such as weakness, movement disorders, yellow discoloration and digestive system dysfunction. In the end, most die of exhaustion. In cases of young and juvenile ostriches, there is general weakness and listlessness, drooping head, crooked neck, anaemia, atrophy of the leg and chest muscles, unsteady standing or even inability to rise from the ground, and some have a stiff gait, ruffled feathers and depression. Most develop loose stools or watery stools. It occasionally occurs in growing birds, and rarely in adult birds.
3) Necropsy features In cases of exudative diathesis, subcutaneous oedema of the chest and abdomen can be seen, and in some cases there is also oedema at the base of the legs and wings; the oedematous areas contain pale yellowish-green gelatinous exudate or pale yellowish-green fibrin material. There are congested spots on the inner sides of the neck, abdomen and loins. In cases of muscular dystrophy, the main lesions are in the skeletal muscle, cardiac muscle, liver and pancreas, followed by the kidneys and brain. The affected muscles are degenerated, pale in colour, resembling boiled meat, with loose muscle fibres, appearing as yellowish-white or greyish-yellow punctate, striated or patchy areas, brittle, softened or necrotic, and calcified. The cardiac muscle is dilated and thinned, with haemorrhagic spots on the endocardium of the papillary muscles, and greyish-white or greyish-yellow spots parallel to the muscle fibres can be seen under the endocardium and epicardium. The liver is enlarged, brittle and shows a betel-nut-like pattern. The kidneys are congested, swollen and have haemorrhagic spots. The pancreas is degenerated. Some have intestinal inflammatory lesions.
[Prevention and Control Measures]
1) For treatment, 0.005% sodium selenite solution can be injected subcutaneously or intramuscularly: 0.1-0.3 millilitres for young poultry, 1 millilitre for adult poultry, together with an injection of α-tocopherol 0.1-0.4 milligrams.
2) For prevention, 1×0.0000001-2×0.0000001 sodium selenite can be added to the diet of young poultry, and 20 milligrams of vitamin E added per kilogram of feed. It should be noted that selenium is toxic, and if used in excess or continuously over a long period it can easily cause cumulative poisoning; poisoning can also easily occur if there is a calculation error or uneven mixing. Generally, supplement once every 15-30 days. The effective nutritional dose of selenium is 0.03-0.04 milligrams per kilogram of body weight, which can exert its effects of promoting weight gain and preventing disease; the toxic dose is 3-4 milligrams per kilogram of body weight; the dietary requirement is 1×0.0000001.