Nutritional Diseases of Poultry: Symptoms, Control, and Treatments

The modern poultry industry has evolved from decades of systematic growth and scientific innovations. Hence, today you can see a standard commercial egg-laying bird laying almost ten times the number and twice the size of eggs laid by her ancestor decades ago.

This and other improvements associated with the modern poultry bird are the outcome of genetic selection, which is in turn dependent on management and husbandry inputs such as nutrition, housing, and health.

An important feature of modern poultry birds is movement restriction because they are housed. Therefore the birds are entirely dependent on the operator to provide an adequate diet to meet their nutritional requirements for good health and efficiency in product formation.

For a diet to be adequate it must supply these elements not only in sufficient quantities but also in the right proportions. Proper nutrition, therefore, is a prerequisite to a profitable poultry operation.

Essential nutrients are required not only for normal growth and performance, their absence results in deficiency diseases.

Causes of Dietary Inadequacies

Nutritional problems in poultry can be a result of one or more of the following factors:

1. Absence of specific nutritional element(s) in feeds and feedstuff
2. Insufficiency of nutritional element(s) in feeds and feedstuffs
3. Excess nutritional element(s) in feeds and feedstuffs
4. Denaturation of nutrient(s) in feeds and feedstuffs in the cause of processing
5. Imbalance of nutrient(s) is formulated and compounded feed(s)
6. Bio-unavailability of nutritional element(s) in compounded feeds
7. Starvation in experimental situations or inadequate feed intake
8. Dysfunction of the digestive system and associated organs as a result of the disease.

Nutrient Constituents of Poultry Feed and Disorders and Diseases

The poultry diet contains six nutrients namely: carbohydrates, proteins, fats, minerals, vitamins, and water. However, the bulk of the feed is a carbohydrate, protein, and some fats.

The minerals and vitamins are present in minute quantities while the moisture content depends on the kind of processing feedstuffs are subjected to.

1. Carbohydrate

Carbohydrates supply most of the energy in the poultry diet required for all its metabolic activities like growth, egg production, and movements. Maize is one of the richest sources of energy and normally, only marginal deficiencies of carbohydrates can be noticed under field conditions.

Symptoms – Problems that can be fully or partly associated with carbohydrate deficiency are:

1. Impairment of all metabolic functions.
2. Reduced growth rate
3. Poor feathering
4. Reduction in number and size of eggs laid
5. Reduced liveability.
6. Mortalities.

Feeds with high energy content along with other nutritional deficiencies and environmental factors have been implicated in the causation of fatty liver syndrome (FLS) in layers.

Furthermore, FLS and fatty liver and hemorrhagic kidney syndrome in broilers and growers should not be ignored when other energy feedstuffs are substituted for maize as a source of energy.

Control – The metabolizable energy requirements of poultry at each physiological state must be used in diet formulation. In addition, correct measurements of each of the feeding stuffs must be made when diets are being compounded.

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2. Fats

Fats are good sources of energy and essential fatty acids like linoleic, linolenic, and arachidonic acids in the poultry diet. A lack or deficiency of these fatty acids will result in:

1. Suboptimal growth.
2. Fatty liver problems.
3. Susceptibility to respiratory diseases.

When a feed goes rancid because of the oxidation of its unsaturated fatty acids, many vitamins are destroyed and the free amino groups or proteins are bound thereby reducing their availability.

Control– Add antioxidants to feed and feeds should not be kept for more than 3 weeks in the store unfed to poultry.

3. Proteins

Proteins are sources of dietary amino acids needed by poultry for growth and productivity. There are about 20 amino acids, eleven of which are classified as essential amino acids (EAA).

Deficiency symptoms caused by EAA are:

1. Reduced growth
2. Poor feathering
3. Lowered egg production
4. Reduction in egg size
5. Frizzled feathers (specific for arginine deficiency
6. Poor skin ad feather pigmentation (specific for lysine deficiency)
7. Stunted growth (specific for glycine)
8. Poor liveability
9. Higher mortality rates.

Control – In feed compounding, determined appropriate inclusion rates of protein feedstuffs like fish meal, blood meal, soya bean meal, groundnut cake meal, etc according to feeding standards have to be adhered to.

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4. Minerals and Vitamins

In performing their physiological functions, inter-relationships exist among many minerals and vitamins. Thus the nutritional problems they cause will be considered in this light.

5. Vitamin A Deficiency

Affected chicks have ruffled feathers, unthrifty, lack coordination, retarded growth, staggering gait, and eye disorders. In adult birds, there is a decline in egg production and hatchability. Prevention is by giving synthetic vitamin A preparation.

6. Rickets

This is a nutritional disorder due to a deficiency or the balance of calcium, vitamin D, or phosphorus. Rickets is mostly seen in young birds.

Symptoms – This is characterized by abnormal skeletal development. Symptoms are soft bones and beaks, retarded growth, thin-shelled eggs, poor egg production and hatchability, abnormal gait, reduced appetite, reduced activity and sensitivity, and increased mortality.

Control – Rations containing adequate calcium, phosphorus, and vitamin D should be given. Sun-dried feds are useful.

6. Encephalomalacia (Crazy Chick Disease)

This is a disease of young chicks due to a deficiency of vitamin E in the feed. Vitamin E is an unstable compound that is easily destroyed by unsaturated fatty acid. Also, this disease may arise due to storing feed for an excessively long period resulting in loss of vitamin E.

Symptoms – The symptoms of the disease include coordinated gait, head retraction, paralysis, prostration, somersaulting, sterility and reproductive failure, and poor egg hatchability.

Control – compounded diets should not be kept (stored) for too long to prevent loss of vitamin E. Addition of selenium and antioxidants to diets is effective.

Treatment – There is no cure for affected chicks but the rectification of dietary deficiency will prevent new cases.

7. Curled-Toe Paralysis

This is a nutritional disease of chicks and poults caused by the deficiency of vitamin B₂ (riboflavin).

Symptoms – Curling of toes of affected chicks and poults, retarded growth diarrhea, and high mortality. In adult birds, there is poor egg hatchability.

Control– Compounded diets should have vitamin B₂ supplements.

Treatment – Water soluble multivitamins should be administered in the drinking water.

8. Chick Dermatitis

This is a disease caused by the deficiency of biotin and pantothenic acid. Calcium pantothenate is usually added to rations for young stock and breeding stock.

Biotin is usually sufficient in practical rations but the occurrence of perosis in turkeys under commercial conditions suggests the need for extra supplementation.

Symptoms – Cracks appear on the soles of the feet and toes of chicks usually at 3 to 4 weeks. The crust is seen at the corners of the mouth and on the eyelids causing the eyelids to stick together. Apart from these symptoms, deficiencies of biotin acid pantothenic acid also result in retarded growth, and reduced egg hatchability.

9. Slipped Tendon (Perosis)

This nutritional disease can be due to the deficiency of choline, folic acid, calcium, phosphorus, and manganese.

Choline requirements are usually met in feedstuffs but may be supplemented in a starter ration. Folic acid likewise is sufficient in common feedstuffs but may be supplemented for breeding chickens and turkeys.

Symptoms – There is a grass enlargement of the hock joint, birds are crippled and hock infection occurs.

Control – The addition of vitamin-mineral premixes to compounded diets is essential.

Treatment – Recovery is impossible, especially after the manifestation of symptoms.

10. Water

Water is described as a universal solvent. An interrelationship exists between feed and water in the performance of poultry.

Symptoms– In poultry, partial or total water deprivation will cause:

• Lowered growth rate
• Reduced egg production
• Death as a result of dehydration.

Control – Drinking water should be provided ad libitum. Such water should be clean cool, and low in salts. Water from direct natural sources, it should be free from germs, agrochemicals, and industrial wastes in developed economies where graded eggs attract a premium.

In addition, some of the diseases associated with egg production problems also have the potential of causing other losses such as mortalities and stress.

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