Prevention and Control Techniques for Selenium Deficiency in Chickens (Exudative Diathesis)

Selenium deficiency is one of the common trace element deficiencies in young chickens, and is more frequently seen in meat-type and dual-purpose chicks. It is mainly characterized by serous exudation in the loose subcutaneous areas of the chest, abdomen, thighs, submandibular region, and neck, which is why it is also called exudative diathesis.

1. Causes A lack of selenium in the feed is the main cause of this disease. The occurrence of this disease shows obvious breed differences; the incidence rate in fast-growing meat-type and dual-purpose breed chickens that develop quickly in early stages is much higher than in egg-type breed chickens. The most common age of onset is 14 to 70 days in young chickens, and it often occurs together with vitamin E deficiency, though there are also cases of it occurring alone.

2. Clinical symptoms In the early stage of the disease, the flock shows no obvious symptoms, and only careful poultry managers can notice bluish-purple discoloration on the chest of a few chickens. As time goes on, chickens with unsteady walking, fluffy feathers, poor spirits, lying down, and bluish-purple discoloration under the skin of the chest and abdomen begin to appear in the flock, and their number tends to increase rapidly. In many severely affected chickens, the above changes are not only present on the chest and abdomen but also extend to the thighs, lower jaw, and neck, with the lower jaw becoming swollen and enlarged. During this period, the chicken droppings contain purulent mucus, and there is indigestion. If not treated in time, the sick chickens will lie down motionless, stop eating and drinking, pass green droppings, and eventually die.

3. Anatomical and pathological changes The dead chickens show varying degrees of serous exudation under the skin of the chest, abdomen, thighs, lower jaw, and neck, and the exudate contains blood, with the subcutaneous area of the chest and abdomen being the most severely affected. The mucosa of the duodenum and jejunum is congested and hemorrhagic, the gallbladder is enlarged and filled with dark green bile, and other organs generally show no obvious changes.

4. Diagnosis and differentiation A preliminary diagnosis can be made based on the disease characteristics, clinical symptoms, and pathological changes found during necropsy. Attention should be paid to distinguishing it from staphylococcosis. Skin ulceration, feather loss, and skin exudation in chickens with staphylococcosis are important points of difference from this disease.

5. Prevention and treatment Meat-type and dual-purpose chicks must be fed a complete-price feed. If selenium deficiency is found in the flock, immediately add the following drugs to the feed for treatment: add 100 grams of sodium selenite vitamin E, 30 grams of diaveridine, and 50 grams of dried yeast to 50 kg of feed. Grind the three drugs into powder, mix them evenly into the feed, and feed continuously for 5 days. At the same time, add 15,000 units of penicillin and 10,000 units of streptomycin per chicken to the drinking water each time, twice a day, and continue providing this drinking water for 3 days.