Poultry Nutritional Deficiencies & Vitamin Disorders Guide
Clinical diagnostic manual for identifying calcium, phosphorus, and vitamin deficiencies in commercial broilers and layer flocks.
Scientific Overview
Nutritional and metabolic deficiencies in chickens are caused by feed mixing errors, toxic rancid fats, or poor absorption triggered by subclinical enteritis. Prompt diagnosis of early skeletal and shell symptoms prevents permanent flock unevenness.
1. Calcium & Vitamin D3 Deficiency (Rickets)
Etiology & Pathology: Calcium, Phosphorus, or Vitamin D3 deficiency. Without Vitamin D3, the bird cannot absorb calcium from the gut, forcing it to resorb calcium from bones.
Clinical Signs: Soft, rubbery bones and beaks that bend easily. Young chicks display a wobbly gait, enlarged hock joints, and reside in a resting position. In laying hens, it triggers **Cage Layer Fatigue** (osteomalacia), causing paralysis due to vertebral fractures.
Lesions: Beading of the ribs at the costochondral junction (rachitic rosary) and thickened growth plates in the tibiotarsus.
2. Vitamin E Deficiency (Encephalomalacia)
Etiology & Pathology: Deficiency of alpha-tocopherol, often caused by formulating feeds with rancid fats or oils that oxidize Vitamin E.
Clinical Signs: Also known as **Crazy Chick Disease**. Chicks display ataxia, head tremors, backward head twisting (opisthotonos), and lateral recumbency with pedaling leg movements.
Lesions: Swelling, congestion, and petechial hemorrhages on the cerebellum, with softening of cerebellar tissue (malacia).
3. Vitamin B-Complex Deficiencies (Paralysis)
Riboflavin (Vitamin B2) Deficiency: Triggers **Curled-Toe Paralysis**. Chicks sit on their hocks with their toes curled inward. Histopathology reveals severe myelin degeneration of the sciatic nerves.
Thiamine (Vitamin B1) Deficiency: Causes **Polyneuritis**. Sudden onset of stargazing posture (opisthotonos) where the head is retracted back over the spine due to motor nerve paralysis.
Poultry Nutritional Deficiencies & Vitamin Disorders Guide — Frequently Asked Questions
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