Mild heat stress changes the microbiota diversity in the respiratory tract and the cecum of
layer-type pullets.
Poult Sci 2020;
99:7015-7026. [PMID:
33248618 PMCID:
PMC7704960 DOI:
10.1016/j.psj.2020.09.024]
[Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 08/28/2020] [Accepted: 09/04/2020] [Indexed: 12/21/2022] Open
Abstract
The present study aimed to research the effects of cyclic heat environment on the microbial diversity and structure of respiratory tract and cecum of chicken. A total of 360 layer-type pullets at 11 wk of age were subjected to different temperature treatments for 10 wk: constant 22°C; cyclic temperature 22°C to 24°C, 22°C to 26°C, 22°C to 28°C, 22°C to 30°C; the ambient temperature increased from 10:00, reached the set point within 1 h, and maintained until 18:00, thereafter the temperature was restored to 22°C; and the relative humidity was maintained at 60%. The result showed that feed intake of the chickens on ambient temperature 30°C group was significantly lower than that of the chickens on ambient temperature 24°C. The white blood cell, red blood cell, lymphocyte, hemoglobin, and pecked-cell volume content were highest at 24°C on 14, 16, and 18 wk. The ratio of CD3+CD4+/CD3+CD8+ T cells was lowest at 30°C. Meanwhile, the abundance of cecum bacteria in chickens at 30°C was lower than that at 24°C. Cyclic heat environment temperature treatment did not significantly affect the concentration of secretory immunoglobulin A in chicken bronchoalveolar lavage fluid (BALF) levels during 10 wk of trial. The diversity index analysis showed that the effect of 24°C on the cecum flora of chickens was optimal. Abundance of Firmicutes bacteria in the lung flora and cecum flora was lower at 30°C than at 24°C group. Similarly, the microorganism, Brevibacillus in the BALF was also significantly lower at 24°C. In conclusion, cyclic 24°C treatment was beneficial for the feed intake, blood routine indexes, microflora structure of the cecum, and respiratory tract in laying pullets.
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