Effects Of Different Moderate Temperatures And Environmental Relative Humidity On Diversity Of The Intestinal Microbial Flora And Nitrogen Metabolism Of Broilers

Ambient temperature was one of the important factors that affected the poultry intestinal flora and nitrogen metabolism. As the ambient temperature changed, poultry normal intestinal flora and nitrogen metabolism would be affected. This study was carried out to investigate the effects of different moderate temperatures and environmental relative humidity on structural diversity of cecal bacteria and nitrogen metabolism in broilers, which would contributed to healthy breeding on broilers.In this study, we tested the effects of constant temperature and diurnal temperature cycling on broiler performance, nitrogen utilization and nitrogen emissions. The treatment of control group was 21℃ and 60% RH(relative humidity), and the experimental group was 26℃/31℃, 30% RH/85% RH. 16 S rDNA-based denaturing gradient gel electrophoresis(DGGE) was performed to detect the bacterial community and diversity in the ceacal digesta of broilers at test 7 days and 14 days, combined with common and specific bands tapping recovered DNA cloning and sequencing. The main results were showed as follows:1.(1) Broiler cecal DGGE bands at 26℃ and 31℃ were lower than 21℃, and31℃ was lower than 26℃. At 31℃, broiler cecal DGGE bands were significantly lower at test 14 d, compared with 7 d.(2) The bacterial community and diversity of 26℃ and31℃ groups were less than at 21℃. At 31℃ group, the bacterial community and diversity of 14 d were significantly lower than that at 7 d;(3) Alistipes timonensis and Barnesiella viscericola were predominant in 21℃, 26℃ and 31℃ treatment groups.The special bacteria in 21℃, 26℃ and 31℃ treatment groups were Ruminococcus faecis, Lutispora thermophila and Faecalibacterium prausnitzii respectively, 31℃group was Gemmiger formicilis.2.(1) Treated with 30% RH, the number of cecum DGGE strips in test 14 days was significantly lower than that in test 7 days. Test 7 days, the number of cecum DGGE strips in 30% RH group was higher than that in 60% RH group, and 85% RH was higher than 60% RH. Test 14 days, the number of cecum DGGE strips at 30% RH and85% RH were higher, compared with 60% RH;(2) Test 7 days, treatment with 85% RH had a significant impact on the intestinal microflora. Test 14 days, the impact on intestinal flora at 30% RH was obvious;(3) Within the 26℃ intermittent temperatureunder different humidy, the common cecal microbiota was Faecalibacterium prausnitzii.Test for 7 day, the specific cecal bacteria of 30% and 85% RH group was Stomatobaculum longum grow.3.(1) The number of denaturing gradient gel electrophoresis bands of 30% RH and85% RH group was lower than that of 60 % RH group. Treated with 30% RH, the number of denaturing gradient gel electrophoresis bands in test 14 days were significantly lower than that in test 7 days.(2) Test 7 days, treatment with 85% RH significantly impacted on the intestinal microflora. Test 14 days, treatment with 30%RH of the intestinal flora was obvious. Compared with test 14 days, treatment with 30%RH had a significant influence on cecal microflora on test 7 days;(3) Within the 31℃intermittent temperature under different humidity common cecal microbiota was Clostridium proteolyticum and Faecalibacterium prausnitzii. In the test for 7 days, the specific bacteria of 30% and 60% RH cecal group was Clostridium hungatei. In the test for 14 days, 60% and 85% cecal group of specific bacteria was Bacteroides vulgatus.4.(1) Test 7 days, compared with 21℃, growth performance with continuous heat treatment at 26℃ depressed. During the test period, growth performance reduced in31℃ treatment group, compared with 26℃ treatment group. While treatment with the diurnal cycle changing temperature at 21/31℃ had a significantly higher ADFI.(2)When compared to 21℃ treatment group, STP of birds in 31℃ treatment group was significantly decreased. Test 7 days, STP of diurnal cycle changing temperature was significantly decreased at 21/31℃, compared with 26 ℃.(3) Birds treated with 31℃had a significant decrease of SUN and a significant increase of NEDG and NEFI,compared with that of 21℃. SUN of birds in 26℃ treatment group had a significant decrease, while NEFI had a significant increase. SUN of birds treated with diurnal cycle changing temperature at 21/31℃ was significantly decreased, compared with 26℃.The results showed that: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 effect would change as the temperature varies.In conclusion, at the intermittent partial heat environment of 26℃ and 31℃,different broiler intestinal flora structure and diversity would changed at 85% and 30%RH, and the extent of effect varies with the different processing time.Compared with 21℃, treatment at 26℃ and 31℃ had significant effects on nitrogen metabolism and growth performance of birds. Compared with constanttemperature at 26℃, broilers treated with diurnal cycle changing temperature at 21/31℃had significantly decreased nitrogen utilizationand and increased nitrogen emission of birds.In summary, moderate environment could change broiler intestinal flora structure and diversity, which also effects on nitrogen metabolism and growth performance of birds.