ADDIS ABABA UNIVERSITY COLLEGE OF VETERINARY MEDICINE AND

AGRICULTURE

INDIVIDUAL PRESENTATION ON VITAMIN “A” DEFICIENCY IN POULTRY

BY:

Akinaw Wagari

Instructor: Tilaye D. (DVM, MSc, Assistant Prof.)

June, 6/2015

Bishoftu, Ethiopia

Outlines

INTRODUCTIONIMPORTANCE TYPICAL CLINICAL FINDINGSTYPICAL GROSS FINDINGSTYPICAL LIGHT MICROSCOPIC FINDINGSPOST-MORTEM LESIONSDIAGNOSISTREATMENT PREVENTION

1. INTRODUCTION

Biochemistry starts by giving answer for innocent mankind question like:

What is life?

What is death?

What is growth?

Life is the organization of elements found on the earth. Whereas death is the disorganization

those of elements which form life.

Cont….

• Elements

• Molecules Macro-molecules Proteins, NA, CHO and Lipids

Micro-molecules Vitamins, hormones and minerals Biomolecules

• Fat soluble (ADEK) and water soluble

• Vitamin A is a generic term that refers to fat-soluble compounds found as preformed vitamin A (retinol) in

animal products and as provitamin A carotenoids in fruit and vegetables.

• The three active forms of vitamin A in the body are retinol, retinal and retinoic acid.

Cont…

• Vitamin A is involved in regulating the growth and specialization (differentiation) of virtually

all cells.

• It has important roles in normal immune functions; and eye development and vision. 

• Its deficiency is occasionally seen in chickens and turkeys (insufficient vitamin A during 1-7

weeks of age). As other nutritional deficiencies, classic signs of deficiency are very rare in

commercial poultry fed complete diets.

• Its deficiency is associated with an increased susceptibility to infections, as well as to thyroid

and skin disorders.

Cont…

• Deficiencies of vitamins may occur following inappropriate formulation, the use of impotent

commercial preparations or destruction of nutrients in feed by oxidation.

• Avitaminosis A in chicks will show poor growth and feathering and in advanced cases, ataxia

(inability to stand), xerophthalmia (“dry eye”) and chronic purulent conjunctivitis

(accumulation of yellow caseous material beneath the eyelids).

• Laying hens subjected to avitaminosis A will show a deterioration in internal egg quality and a

high prevalence of blood spots. Fertility and hatchability of breeders will be adversely affected.

Cont…

• Diagnosis of avitaminosis can be confirmed by microscopic examination of the trachea and oral

mucosa.

• The characteristic change comprises squamous metaplasia, in which normal columnar epithelial

cells regress to multiple layers of flattened cells.

• Both immature and adult flocks will show kidney degeneration and the accumulation of urate in

the ureters.

• In advanced cases urate deposit on the viscera (visceral gout) => postmortem examination.

2. IMPORTANCE OF VITAMIN A IN POULTRY

• Epithelial differentiation: Vit A deficiency -> impaired epithelial differentiation -> reduction

in mucus-secreting cells -> squamous metaplasia of respiratory and genitourinary epithelium -

> hyperkeratosis.

Vision

• Decreased synthesis of some glycoproteins and immunoglobulins by intestinal mucosa

> impaired local immunity.

• Vitamin A deficiency causes rapid depletion of retinal and rhodopsin, since it must be replaced

daily; results in “night blindness”.

• Corneal opacity

Growth

• Vit A deficiency -> retarded osteoclastic resorption of endosteal bone -> defective remodeling

of membranous bone -> asynchrony between developing CNS and bones of skull and spinal

column.

• Retarded growth

CNS

• Ostodystrophy/defective remodeling of skull bones -> increased intracranial pressure ->

cerebellum herniation into foramen magnum; cranial and spinal nerve degeneration;

hydrocephalus.

Reproduction

• Vit A deficiency -> arrest of spermatogenesis at the spermatid phase in all species, especially in

cattle, rats and chickens.

Typical clinical findings

• Signs and lesions usually develop in 2-5 months depending on amount stored in the liver and

other tissues

• Chicks and poultry’s: Cessation of growth, hunched-up posture, emaciation, lethargy, mild

ataxia, swollen eyelids with a mucoid oculo-nasal discharge.

Cont…

• Laying hens: Decreased egg production with increased incidence of blood spots, emaciation,

weakness, ruffled feathers.

• Azotemia: Chronic Vit A deficiency also damages renal tubules.

Typical gross findings

• Small white nodules (1-3 mm) often with a central depression in nasal passages, mouth,

esophagus, pharynx and often into the crop.

Cont…

• Seromucoid watery masses fill turbinates and may cause facial swelling.

• The paranasal sinuses, trachea and bronchi may be lined by a delicate

pseudomembrane.

• Other lesions: bone deformities,

keratinization of the tongue,

corneal opacity

Typical light microscopic findings

• Dilation of submucosal glands; replacement of glandular epithelium with squamous metaplasia

• Atrophy and de-ciliation of respiratory cells +/- necrosis

• Bone lesions: Decreased endosteal and periosteal osteoblasts -> impaired bone growth, bone

remodeling and thin cortex.

Post-mortem lesions

• Eyelids inflamed and adhered

• Pustules in mouth and pharynx

• Excessive urates in kidneys and ureters

Diagnosis

• Signs, lesions, feed formulation

• Differential diagnosis

• Oral lesions

• Fowl pox(avian poxvirus): Raised nodules with necrotic centers in oropharynx and

esophagus

• Trichomoniasis (Trichomonas gallinae): Caseous proliferative lesions in buccal cavity,

pharynx, esophagus, crop, especially in pigeons and raptors

• Thrush (Candida albicans): Crop mucosa is thickened with white circular, raised plaques

Cont…

• Mucoid oro-nasal discharge and facial swelling

• Infectious coryza (Hemophilus paragallinarum): Profuse nasal discharge (“wet beak”)

• Infectious bronchitis (coronavirus): Swollen sinuses, catarrhal nasal and ocular discharge,

caseous exudate in lower trachea and bronchi

Cont…

• Neurologic signs

• Ataxia in severe deficiency may resemble Vitamin E deficiency; differentiation is by

histologic examination of the brain (Vitamin E deficiency causes encephalomalacia).

Vitamin A deficiency prevention

• Free-range chickens get their vitamin A from leafy greens, but chickens in an enclosure require

it in their feed.

• Supplementation of diet with vitamin A, antioxidant, good quality raw materials.

Vitamin A deficiency treatment

• Treatment consists of changing the chicken’s feed and of supplementing feed with vitamin A at

two to four times the normal level for two week (vitamin A in drinking water).

• A water-soluble vitamin A supplement is available for ease of administration.

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