List of five major deficiency diseases of chicken:- 1. Vitamin B1 Deficiency 2. Vitamin B2 Deficiency 3. Vitamin E Deficiency 4. Fatty Liver Haemorrhagic Syndrome 5. Slipped Tendon.
Deficiency Disease # 1. Vitamin B1 Deficiency:
In birds, vitamin B1 (thiamine) deficiency is clinically and morphologically manifested with paralysis of limbs and muscle atrophy, beginning from the flexors of toes and ascending towards the extensors of legs, wings and the neck.
The chickens acquire a specific posture with flexed legs and the head drawn back (stargazing). As hypovitaminosis B1 causes a severe anorexia, thiamine supplementation to the drinking water is advised until the recovery of acute deficiency and thereafter, the vitamin could be added to the forage.
Deficiency Disease # 2. Vitamin B2 Deficiency:
The hypovitaminosis B2 (riboflavin deficiency) is characterized with impaired oxidation processes and dystrophic changes in the peripheral nerves. The typical clinical sign is curled toes due to paralysis. In the beginning, the toes are slightly flexed and chickens tend to stand on their hocks.
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In moderate cases, a marked leg weakness and toe flexion in a different extent are observed. In severe cases, the toes are completely curled downward and inward and complete weakness of legs is present. A considerable improvement and relief could be expected if the treatment is initiated in the initial stage of the disease. Water soluble vitamins, that are easily utilized, are recommended.
Deficiency Disease # 3. Vitamin E Deficiency:
The deficiency of vitamin E in poultry is manifested in three different forms: encephalomalacia, muscular dystrophy and exudative diathesis. Each of them is usually encountered independently, although sometimes they occur at a time. Encephalomalacia is a crazy chick disease — an abnormal softening of the brain tissues. The signs are associated to the central nervous system lesions.
They include ataxia, disequilibrium, falling on the back, frequent movements with the wings, strongly stretched legs (clonic spasms) and twisting of the head. Rarely, torticollis or opisthotonus could be observed.
Encephalomalacia is usually observed at the age of 15-30 days but could also be present as early as after the 7th day as well as after the 56th day of life. Pathoanatomically, oedema, haemorrhages and colliquativenecroses are detected in the cerebellum.
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In the majority of cases, the haemorrhages vary from hardly perceptible to petechial. Muscular dystrophy signs are usually unapparent, but locomotor problems could occur. The pectoral and thigh muscles are most commonly affected, and in them, white or yellowish muscle fibres are found, responsible for the striated appearance of skeletal muscles, due to Zenker’s necrosis.
Gelatinous subcutaneous oedemas are discovered in the ventral body parts: breast, abdomen, mandibular space. The skin of legs is often cyanotic. The diagnosis is based upon the typical clinical signs and the lesions. The results of the histological examination have a particular value for confirmation of the diagnosis, especially of encephalomalacia and muscular dystrophy.
Deficiency Disease # 4. Fatty Liver Haemorrhagic Syndrome:
The fatty liver haemorrhagic syndrome (FLHS) is a widely prevalent sporadic disease mainly among commercial layers. The FLHS outbreaks are often associated with hot weather and a period of extensive egg- laying. The hens in the flock are overweight (on the average by 20% or more) and a sudden drop in egg production is observed. The birds are discovered suddenly dead, with pale head skin.
In the abdomen, large blood clots are detected. Clinically healthy birds in the flock could also exhibit liver haematomas, dark red (fresh) or green to brown (old). Considerable amounts of fat are detected in the abdominal cavity.
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The only successful approach for prevention is the reduction of obesity in layers. The use of lipotropic agents such as vitamin E, vitamin B12 and choline chloride gives conflicting results. The avoidance of heat stress and moulded forages is helpful.
Deficiency Disease # 5. Slipped Tendon (Perosis):
Perosis or chondrodystrophy is encountered in young birds whose diet is deficient in manganese (Mn) or some of the following vitamins: choline, nicotic acid, pyridoxine, biotin or folic acid. This is an anatomic deformation of leg bones in young chickens, turkey poults, pheasant poults, etc.
It is characterized by retarded growth of long bones, widening of the tibiometatarsal joint, twisting or bending of the distal end of tibia and the proximal end of metatarsus and finally, slipping of the gastrocnemius muscle tendon from its condyles. Clinically, it is manifested by impaired locomotion.
The vitamin D3 deficiency or lack, or the impaired ratio of calcium and phosphorus result in rachitis in young birds. It is encountered more frequently in industrial poultry breeding where the forages are often inadequately balanced.
The deficiency of vitamin D3 and phosphorus are more common in growing birds whereas the calcium deficiency in young or adult layer hens. The newly hatched chickens have depleted calcium stores.
The calcium deficiency is rapidly manifested if they do not receive an adequate diet supplement. Clinically and morphologically, soft bones or various degree of bone deformation are determined. The birds usually lie down and their growth is retarded.
The diagnosis is based upon the complex evaluation of their age, signs and lesions. The supplementation of vitamin D3 with water or forage and the balancing of Ca/P ratio in the diet contribute to the favourable outcome of the disease.