الفهرس 
REVIEW OF LITERATUREOnly 14 pages are availabe for public view
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Abstract
Over the years, poultry hatchery operations have increased in size. This change has prompted increased expectations of improved hatchability, lower chick mortality, and better bird performance.
Until recently, the knowledge on incubation was not as developed as on other areas of the chicken production chain. The knowledge built during last years in poultry nutrition, health, management and environment was not followed by the field of incubation. Factors surrounding incubation were only recently recognized as important influences on chicken performance.
The environment of a poultry hatchery typically is highly contaminated with a variety of microorganisms that can affect the embryonic development. Eggs microbial populations are easily spread through the hatcher and then cycled into setters and hatchers by the ventilation system. Newly hatched chicks may become infected with microorganism from other hatching eggs. An effective hatchery sanitation is the corner stone to maximize hatchability, chick quality and performance. There are sound financial reasons for maintaining consistent chick quality and a good sanitation and monitoring new egg disinfectants which proves this.
Effective hatchery sanitation program is critical to achieve a high level of hatchability and to ensure the production of high quality chicks. The importance of an effective sanitation program in the hatchery to achieve a high level of hatchability and to ensure the production of high quality chicks has been firmly established. A common management tool in the handling of hatching eggs is treatment of the eggs with a fumigant or other types of disinfectants to reduce the number of microorganisms on the shell surface. The most effective sanitation system involves treating the eggs as soon as they are collected from the nest and before microorganisms penetrate the shell. Several recent research studies have examined the effectiveness, safety and ease of use of common disinfectants currently available for use in hatcheries and on eggs. It is important when selecting the best disinfectant to consider it is effect upon the developing embryo and the hatchery environment. The lethal action of disinfectants for various pathogens (Viruses, bacteria, fungi and protozoa) depends on the chemical composition of the disinfectant and the make-up of the organism.
Naturally, occurring biologically active compounds from plants are generally assumed to be more acceptable and less hazardous than synthetic compounds and represent a rich source of potential disease-control agents. Understanding of plant biochemistry, physiology and chemistry of natural products have shown that the secondary metabolites may be used to control infectious organisms to overcome the problems associated with synthetic chemicals. One such method involves the use of plant-derived-products, such as plant essential oils, having antimicrobial effect. Keeping all these points in consideration, an attempt has been made in the present thesis work to find out the practical applicability of natural essential oils to control microbial activity on eggshell and to determine its effects on hatchability of fertile egg, embryonic growth, development of chicks after hatch and birds performance.
The present study was carried out to investigate the effect of egg disinfection on embryonic development, hatchability characteristics and post-hatch productive performance in Bandarah local strain.