DEVELOPING STRATEGIES TO CONTROL NECROTIC ENTERITIS IN BROILER CHICKENS

Necrotic enteritis (NE) caused by Clostridium perfringens (CP) remains a continuous challenge worldwide in the broiler chicken industry. Therefore, the objective of this thesis was to develop effective control strategies against NE. After the literature review of NE in Chapter 1, the development of subclinical and clinical NE disease models using predisposing factors such as an abrupt increase of feed protein content from 20% to 28% or by exposing birds to variant infectious bursal disease virus or combination of both were demonstrated. A total of 10-15% mortality and 55-68% birds showed classical NE lesions. A significant microbial shift in the jejunum was also demonstrated with increased Escherichia coli and Clostridium and decreased Lactobacillus with the severity of NE. Additionally, the number of toxin genes present in CP isolates were co-related to the pathology and severity of the microbial dysbiosis in NE infected chickens. In Chapter 3, a needle free, industry feasible vaccination strategy against NE utilizing the concept of gut-lung axis was described. Intrapulmonary delivery (IPL) of a live CP vaccine at hatch with or without administration of cytosine phosphorothioate guanine oligodeoxynucleotides (CpG-ODN) by the in ovo route at day 18 of incubation, and with or without administration of a booster vaccine was able to protect birds against homologous and heterologous CP associated NE in broiler chickens. Immunoprotection against NE in broiler chickens associated with homologous and heterologous isolates of CP by vaccinating broiler chickens orally with a live CP vaccine adjuvanted with cholera toxin (CT) at hatch with or without in ovo delivery of CpG-ODN and without a booster vaccine was demonstrated in Chapter 4. In addition, broiler breeders were vaccinated orally with a live CP-CT vaccine which protected their progeny against NE. In Chapter 5, metabolomic profiles and metabolic pathways in the jejunum of broiler chickens with NE were determined. Among 34 differentially expressed metabolites, butyric acid and histamine were significantly increased in NE infected birds. Therefore, butyric acid was identified as potential predictor metabolite of NE. In conclusion, knowledge from our work contributed a greater understanding of pathogenesis, prevention, and diagnosis of NE in broiler chickens.

Name thesis:degree_name

Doctor of Philosophy (Ph.D.)

Level thesis:degree_level

Doctoral

Discipline thesis:degree_discipline

Veterinary Pathology

Grantor

University of Saskatchewan

Year dc:date.issued

2024

Author dc:creator

• Gautam, Hemlata

Advisor dc:contributor.advisor

• Gomis, Susantha

Committee members dc:contributor.committeemember

• Ngeleka, Musangu
• Tikko, Suresh
• Griebel, Philip
• Boulianne, Martine
• Detmer, Susan

• Necrotic enteritis
• Broiler chickens
• Vaccination strategies

Language dc:language.iso

en

Handle dc:identifier.uri

https://hdl.handle.net/10388/16103

OAI identifier oai:identifier

oai:harvest.usask.ca:10388/16103