Ascites In Poultry

Ascites is an accumulation of fluid in the abdominal cavity of chickens. It is not an infection, but is

caused by a series of complex events that affect the supply of oxygen for the tissues. Ascites has

emerged as a major source of economic loss in the broiler industry. In extreme situations, up to

25% mortality is seen. Ascites is confined to broilers. The modern broiler chicken is susceptible to ascites because of its rapid growth rate, high feed efficiency, and a large breast muscle mass, which require a high demand for oxygen. The metabolic rate of fast-growing broiler chicken is very high. Thus, an imbalance between oxygen supply and the oxygen required to sustain rapid growth rates and high food efficiencies, causes ascites in broiler chickens.

Causes

I • Rapid growth rate

2. Poor ventilation

3. Cold. It causes an increased demand for oxygen.

4. High energy diets

5. Overcrowding

6. Faulty brooding

7. Ammonia formation and dust

8. Sodium toxicity

9. Vitamin E/selenium deficiency

10. Mycotoxicosis

11. Stress

Symptoms

I. Sudden death.

2. Mortality is greatest after 28 days. The peak incidence of ascites occurs between 35 and 42 days of the growing period. H.owever, cases can occur from as early as 15 days and onward.

3. Affected birds are smaller than normal and depressed, with ruffled feathers. This is because the growth stops.

4. They have a pale head and a shrunken comb. Birds may be reluctant to move, show difficult breathing, even panting.

5. Severely affected birds show abdominal distension.

Diagnosis

Diagnosis can be easily made from the typical postmortem finding of abnormally distended abdomen,

containing fluid.

Postmortem Findings

I. The abdomen is markedly distended with fluid (Fig. 122, 123, 124, 125, 126, 127).

2. On opening, the abdominal cavity shows the presence of a large amount of clear yellow fluid. More than 300 ml of fluid, with or without fibrin clots, may be present.

3. The heart is greatly enlarged.

4. There may be accumulation of fluid under the covering of the heart (pericardium).

5. The liver may be swollen and congested, or firm and shrunken.

6. The lungs are extremely congested and oedematous. The intestines are severely congested.

Note: Some birds may die before ascites develops. That is, not all birds that die from ascites show

accumulation of fluid in the abdominal cavity.

Treatment

I. There is no effective treatment. Once birds show symptoms, death occurs fairly quickly.

2. Frusemide, a drug that increases the flow of urine, reduces mortality in ascites.

3. Vitamin C, vitamin E and organic selenium are effective in reducing mortality from ascites.

Control

I. Ascites can be prevented through feed restriction, or through the use of very low energy feed.

2. Ensure adequate ventilation.

3. In winter, prevent chilling, that is, sudden and severe exposure to cold.

4. Avoid dust and ammonia.

5. Minimize toxin contamination of the feed.

6. Increased vitamin E and organic selenium in the diet reduce mortality in ascites.