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| Author(s): |
Wanderley Moreno Quinteiro Filho
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Faculdade de Medicina Veterinária e Zootecnia (FMVZ/SBD) |
| Defense date: | 2009-01-30 |
| Examining board members: |
João Palermo Neto;
Paulo César Maiorka;
Irenilza de Alencar Naas
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| Advisor: | João Palermo Neto |
| Abstract | |
The concept of animal welfare is a reality in the world poultry industry. Stressed chickens present a decrease in growth performance and feed conversion, physiological and hormonal changes as well as an increased susceptibility to diseases. Recurrent changes induced by in stress in human and animals immune functions were also reported after stress in poultry. Besides that, stressed events were reported to be related to intestinal microbiota integrity disturbances. In this sense, we evaluated the effects of heat stress (26±1ºC, 31±1ºC and 36±1ºC) on broiler chickens performance parameters, intestinal morphology and innate immunity, correlating and discussing the observed data under a neuroimmune perspective. Ours results showed the heat stress (31±1ºC and 36±1ºC) in broiler chickens (1) decreased body weight gain and feed consumption, however feed conversion and mortality decreased only in chickens submitted to 36±1ºC, (2) decreased the bursa of Fabricius relative weight in 31±1ºC and 36±1ºC, but thymus relative weight decreased only in the 36±1ºC stressed chickens, (3) decreased macrophage basal oxidative burst, however only the 31±1ºC heat stress decreased S. aureus induced oxidative burst, (4) increased corticosterona serum levels, and (5) induced an enteritis characterized by increased presence of lymphocytes and plasmocytes within the lamina propria of jejunum. These obtained results suggested that heat stress-induced changes in broiler chickens were a consequence of a neuroimune activity disturbance, most probably, on animals HPA axis activity. Thus, a possible increase in corticosterona serum levels induced by the heat stress underlay the effects of this stressor on birds\' performance and immune function, leading to the appearance of intestinal histophatological signs of inflammation. (AU) | |