Nutritional Deficiencies in Poultry

Birds that are fed an adequate diet made up from a good commercial feed are unlikely to suffer from nutritional problems unless there are additional factors involved, such as diseases that result in diarrhoea or otherwise interfering with the digestive system. On the other hand, village, backyard or scavenging poultry are subject to the availability of food in their normal environment, which may occasionally be seasonally deficient in vitamins, minerals or other important dietary components.

Vitamins Minerals Protein and Amino Acid Deficiencies References and Further Reading   See Also: Minerals and Mineral Deficiencies Vitamins and Vitamin Deficiencies

The formulation and mixing of poultry feeds requires knowledge and experience in purchasing ingredients, testing of formulas, and quality control. Improper formulation and mixing of commercial poultry feeds can result in vitamin and mineral deficiencies, lack of protection against disease, and even toxicity.

The 13 vitamins required by poultry are usually classified as fat-soluble or water-soluble. The fat-soluble group includes vitamins A, D, E and K. The water-soluble vitamins are thiamin, riboflavin, nicotinic acid, folic acid, biotin, pantothenic acid, pyridoxine, vitamin B12 and choline. All these vitamins are essential for life and they must be provided in proper amounts for chickens to grow and reproduce. The egg normally contains sufficient vitamins to supply the needs of the developing embryo. For this reason, eggs are a good animal source of vitamins for the human diet.

Vitamin A is needed for the health and proper functioning of the skin and lining of the digestive, reproductive and respiratory tracts, and for normal development of bones. Inadequate vitamin A also reduces the immune system's response to challenge and further contributes to disease susceptibility. Vitamin A and its chemical precursors are relatively unstable. Feeds stored for a long time, or under poor conditions, may lose a large portion of their vitamin A. In chicks, a deficiency of vitamin A results in poor growth, along with droopiness, ataxia, and ruffled feathers, and in inflamation of the eyes. In mature birds, signs develop more slowly than in young birds, but the inflammation of the nose and eyes is much more pronounced. It is unlikely that a deficiency will be encountered when using properly prepared and stored commercial feeds. Green forage is a good source of vitamin A, so scavenging chickens are most likely to obtain sufficient vitamin A from their normal diet. However the concentration of the provitamin declines rapidly in dried feeds, and during periods when fresh feed is not available it may be necessary to provide vitamin supplements.

Vitamin D has an important role in bone formation and the metabolism of calcium and phosphorus. Sunlight is important for the produciton of Vitamin D. Vitamin D is involved with increasing the absorption of calcium and phosphorus from the gut. It also mobilizes stores of calcium and phosphorus from the kidney and bone so as to provide the animal with enough calcium and phosphorus when required (for example, for producing the egg shell in laying hens). In poultry, the effects of vitamin D deficiency include bones and beak that become soft and rubbery as well as reduced growth and egg production.

Vitamin B: The B complex of vitamins are involved in energy metabolism and the metabolism of many other nutrients. They are water soluble and not stored to any significant extent in the body. The particular symptoms will depend on the actual B vitamin that is deficient, but common deficiency symptoms to all the vitamins include:

• Loss of appetite
• Emaciation
• Weakness
• Dermatitis
• Feathering abnormalities

Sources of the vitamin B complex include leafy green material and oil seeds.

Vitamin E is fat soluble and if the feed is not stored well, or has gone rancid, the fat soluble viatimsn are most likely to have been destroyed. Vitamin E deficiency is associated with several diseases including:

	Avian Encephalomalacia	A disease of young chickens due to vitamin E deficiency, in which there is ataxia, incoordination, paralysis, and severe softening of the brain, especially in the cerebellum.
	Exudative Diathesis	Exudative diathesis is a severe edema (the presence of abnormally large amounts of fluid in the intercellular tissue spaces of the body) resulting from an increase in capillary permeability.
	Muscular Dystrophy	Muscular dystrophy in chicks is characterized by degeneration of the muscle fibers, especially of the breast, but also of the leg.

Vitamin K is an essential factor in the blood clotting process. A number of forms are known to exist, which animals are unable to make for themselves but which plants and bacteria can. Vitamin K made by bacteria in the bird’s gut cannot be absorbed because it is made too far down the gut and so can only be used if the animal subsequently pecks at faecal material. Deficiency of vitamin K results in poor blood clotting and birds that are easily injured and which may bleed to death. Most green, leafy materials are sources of vitamin K.

Calcium and Phosphorous: A deficiency of either calcium or phosphorus in the diet of young growing birds results in abnormal bone development even though the diet contains adequate vitamin D. The newly hatched chick requires an immediate supply of dietary calcium. A deficiency of either calcium or phosphorus results in lack of normal skeletal calcification. Diets must provide adequate quantities of calcium and phosphorus to prevent deficiencies. In laying hens, the provision of Oyster Shells, other broken or coarse ground shells, and/or Limestone grit provides a good source of calcium.

Manganese: A deficiency of manganese in the diet of young growing chickens is one of the causes of perosis (bone deformities) and of thin-shelled eggs and poor hatchability. Commercial poultry feeds should be supplemented with a source of available manganese. Most green feeds contain adequate amounts of manganese, so scavenging poultry should not suffer from a deficiency. However, problems are likely to be encountered in caged birds if the feed does not contain sufficient available manganese.

 

The optimal level of balanced protein intake for young growing chicks is about 18-23% of the diet; for young growing poults and gallinaceous upland game birds, about 26-30%; and for young growing ducklings and goslings, about 20-22% (Merck). If the protein content of the diet is below these levels, the birds tend to grow more slowly. Even when a diet contains the recommended quantities of protein, satisfactory growth also requires sufficient quantities and proper balance of all the essential amino acids. Deficiencies of essential amino acids result in retarded growth or reduced egg size or egg production.