Abstract: 【Objective】The objective of this study is to provide useful information for healthy breeding on broilers. Ambient temperature is one of the important factors affecting the poultry intestinal flora; as the ambient temperature changes, poultry normal intestinal flora will be affected. This study was carried out to investigate the effects of constant moderate temperatures on structural diversity of cecal bacteria in broilers. 【Method】One hundred and forty four 22-day-old Arbor Acres (AA) broilers were assigned to three environment chambers, each chamber contained six cages with eight birds per cage (four males and four females), with each cage used as a replicate. The pre-test period lasted for 7 days and broilers were kept at 21℃ and 60% relative humidity. When broilers were 29-day-old, the temperatures of each environmental chamber were gradually regulated to 21, 26 and 31℃, respectively, while maintaining the relative humidity at 60% and both kept constant until the end of the experiment. The trial period lasted for 14 days. On day 21 and 42, one birds from each replicate were randomly selected and killed, cecal contents were aseptically collected, placed in a centrifugal tube, rapidly frozen in liquid nitrogen, and stored at -80℃. The bacterial community and diversity in the ceacal digesta of broilers at the 7 and 14 days of constant moderate temperatures was studied by using 16S rDNA-based denaturing gradient gel electrophoresis (DGGE). 【Result】 (1) The number of PCR-denaturing gradient gel electrophoresis bands of 26 and 31℃ group was lower than 21℃ group, and 31℃ group was lower than 26℃, at 31℃, broiler cecal DGGE bands at the 14 days are significantly lower than at the 7 days. (2) The dendrograms and Shannon-Weaver indices revealed that diversity of the intestinal microbial flora at 26 and 31℃ group was less than at 21℃; at 31℃,14 days are significantly lower than at the 7 days; (3) DGGE profiles stripe sequence analysis showed that Alistipes timonensis and Barnesiella viscericola were predominant in the 21, 26 and 31℃ groups, The special bacteria in 21℃, 26 and 31℃ groups were Ruminococus faecis, Lutispora thermophila and Faecalibacterium prausnitzii respectively, 31℃ group were Gemmiger formicilis.【Conclusion】Compared with 21℃, continuous treatment with constant moderate temperature (26℃ and 31℃) can significantly impact the community structure and diversity of intestinal flora in broilers, and the extent of effect varies with the different temperatures.

Key words: moderate temperatures, broiler, microbiota, denaturing gradient gel electrophoresis, diversity