Vitamin A Deficiency In Poultry

Vtamin A is essential in poultry diets for growth, good vision, and integrity of mucous membranes. Mucous membranes are the inner linings of the digestive, respiratory, urinary, and genital systems in which changes of vitamin A deficiency are mostly observed. From a nutritional point of view, vitamin A is the most challenging, because it is most likely to be deficient in poultry.

Causes of Deficiency

I. Low levels of vitamin A in the feed

2. Oxidation of vitamin A in the feed

3. Errors in mixing

4. Intercurrent disease, for example, coccidiosis, worm infestation

Deficiency Symptoms

In chicks, symptoms include loss of appetite, poor growth, ruffled feathers, sleepiness, and weakness. Deficient chicks are very susceptible to infections, due to inadequate antibody production.

In adult chickens, changes of vitamin A deficiency first appear in the pharynx and oesophagus. These changes block the ducts of mucous glands (present in the mucous membranes). As a result, their contents lead to the development of small white pustules (raised spots). That is, the blocked ducts of the mucous glands cause distension of the glands with secretions and dead materials. Pustules are easily seen and are the characteristic lesions of vitamin A deficiency on postmortem examination . Egg production decreases sharply and hatchability is reduced.

Diagnosis

This is based on the characteristic postmortem findings in the oesophagus.

Postmortem Findings

I. Inner lining of the oesophagus shows tiny white raised granules (Fig. 107, 108). These are distended, impacted mucous glands.

2. Kidneys may present gout.

Treatment of Deficiency

Administer a stabilized vitamin A preparation at a level of about 10,000 IU vitamin A per kg of feed .

Prevention

I. Use stabilized vitamin A preparation in the feed.

2. Add adequate levels of antioxidants in the feed.

3. Provide adequate storage for feed and feed ingredients.