Abnormal Bone Changes Associated with Hormonal Treatment in Chicken

Abstract

Poultry may be subjected during their breeding to many stressors such as poor management; inadequate ventilation, high stocking density, and poor litter condition, beside diseases of many causes resulting in stimulation of adrenal cortex with increased steroids. Increased plasma gluco.corticoids in association with stress is an important component in the pathogenesis of many changes in ;the body that may occur under the condition of stress.

The effect of glucocorticoid in the form of exogenous dexamethasone, a

ynthetic analogue of glucocorticoids, on bone growth and structure was studied I in. the present work. A number of 90 two- weeks old chickens of native breed

tvere obtained from a commercial private farm and injected intramuscular with hexamethasone. A number of 30 which were used in a pilot experiment in thich the .chickens were given dose of 0.4,.1 or 5 mg dexamethasone, moreover 6I0 chickens were used as the main exper.iment using a dose of 5 mg for 7 days or lmg for 7,14, and 30 days. .

The results showed that there was loss of condition and unthriftiness of treated birds with drop of feathers, retardation of bone growth manifested by a I decrease in the volume and length when compared with their controls. Six of I 0

Jhickens treated with high dose of dexamethasone died before the end of the I first week.

Microscopical examination of the tibia showed retardation of endochondr•al

bone formation. I

Tibia of chickens treated for two to four weeks with

dexamethasone showed more advanced changes in the form of reduction in the I thickness of metaphysial trabeculea, increased porosity of the shaft due to

Jidening of vascular and Haversian canals.