Evaluation of heat stress on Clostridium perfringens infection in broiler chickens

Author(s)

Atilio Sersun Calefi

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Faculdade de Medicina Veterinária e Zootecnia (FMVZ/SBD)
• Defense date: 2013-07-01

Examining board members

João Palermo Neto; Raphael Lucio Andreatti Filho; Antônio José Piantino Ferreira

• Advisor: João Palermo Neto

Abstract

The poultry sector presented the highest growth in the volume of production among all meat sectors in Brazil. The great participation of poultry products on human diet together with the risk of food and environmental contamination by resistant bacteria led the European Union (EU) countries to abolish the use of antibiotics as feed additives in animal production. This fact associated with the intensive farming system are being reported as responsible for the re-emergence of some already controlled diseases. The avian necrotic enteritis (NE) exemplify such an effect. Generally, stressful conditions are predisponent factors for disease development; heat stress is one of the most common stressor in poultry farms. This study focuses on the effects of heat stress (35 ± 1 º C) on the development of NE in broilers. For this purpose, 60 male broilers were divided into 6 groups: 1 - control group, 2 - stressed control group (C/HS35) 3 - thioglycolate group (T) 4 - thioglycolate stressed group (T/HS35); 5 - infected group (I) 6 - infected stressed group (I/HS35). Experimental infection with Clostridium perfringens, grown in thioglycollate broth medium, was given through the feed to the birds of groups I and I/HS35 from the 15th to 21st days of life. The heat stress (35 ± 1 °C) was induced continuously from the 14th to the 21st day of life in birds of the stressed groups. Throughout the experimental period the animals were kept in isolators. Compared to non-stressed animals, broilers subjected to heat stress showed: lower gross and microscopic score lesions in the small intestine; increased concentrations of IgA in duodenal lavage and decreased IgA concentrations in the jejunum; smaller concentrations of serum IgA and IgY; increased concentration of serum IgM; reduction in gut number of heterophils in the thioglycolate treated and in the infected groups. Therefore, this experimental model showed that heat stress presented a significant immunomodulatory role on the induced NE, most probably because it reduced intestinal inflammation via decrease in heterophils migration to the intestinal mucosa, which in turn might had reduced tissue damage during infamation, hence preventing the development of a more severe form of NE. (AU)

• FAPESP's process: 12/03103-2 - Evaluation of heat stress on the development of necrotic enteritis due to Clostridium perfringens in broilers
• Grantee: Atilio Sersun Calefi
• Support Opportunities: Scholarships in Brazil - Master