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Yolk sac infections in broiler chicks: studies on Escherichia coli, chick acquired immunity, and barn microbiology Open Access


Other title
Maternal transfer of IgY
Barn sanitation
Broiler chick
Green fluorescent protein
Yolk sac infections
Avian pathogenic Escherichia coli
Type of item
Degree grantor
University of Alberta
Author or creator
Ulmer Franco, Ana M
Supervisor and department
McMullen, Lynn (Agricultural, Food, and Nutritional Science)
Examining committee member and department
Wu, Jianping (Agricultural, Food, and Nutritional Science)
Guan, Leluo (Agricultural, Food, and Nutritional Science)
Fasenko, Gaylene (Animal and Range Sciences, New Mexico State University, las Cruces, NM)
Magor, Katharine (Biological Sciences)
Allan, Brenda J. (Vaccine and Infectious Disease Organization, Saskatoon, SK)
Department of Agricultural, Food, and Nutritional Science

Date accepted
Graduation date
Doctor of Philosophy
Degree level
The avian yolk sac is a well vascularised membrane that surrounds the yolk of an embryonated egg and functions as a placenta-like structure transferring yolk nutrients including maternal antibodies, to the embryo. The absorption of the yolk sac content during the first days post-hatching is essential for chick growth and development. However, the infection of the yolk sac is the main cause of chick mortality accounting for large economic losses to the poultry industry. The overall goal of this thesis was to study the epidemiological triad of yolk sac infections: the pathogen: Escherichia coli, the susceptible host: the chick, and the environment: the chicken barn. In the first experiment a strain of avian pathogenic E. coli was transformed with a plasmid carrying a green fluorescent protein. Using fluorescence microscopy it was observed that E. coli entered the yolk sac via the chick navel. In the second experiment, the effects of breeder flock age on the total IgY content of egg yolk and yolk sac was determined. It was concluded that IgY increased with breeder flock age in eggs and yolk sacs. The consequences of these results on chick health are unknown. In the third experiment, the effects of cleaning and disinfection methods of the chicken barn on microbial counts were analyzed in barn swabs and in pooled organ and yolk sac samples. It was surprising to observe that 4 days after placing chicks in the barn, samples of chicks from “cleaner” pens had more bacteria than those of chicks from “dirtier” pens. In the fourth experiment, all E. coli isolated from barn and chick samples from the previous experiment were typified using the RAPD method. It was determined that “cleaner” pens had greater E. coli variability than “dirtier” pens. Also, more E. coli types were shared between chicks and the environment in “cleaner” pens suggesting that chicks that are placed in very clean environments acquired more environmental E. coli than chicks placed in environments with greater bacterial loads. The long term consequences of environmental sanitation on chick growth and development, disease susceptibility, and broiler performance should be studied.
License granted by Ana Ulmer Franco ( on 2011-09-29T21:57:17Z (GMT): Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of the above terms. The author reserves all other publication and other rights in association with the copyright in the thesis, and except as herein provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.
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