The present study was undertaken to investigate the effects of Flammulinavelutipes stem base (FVS) on growth performance, microbial flora and volatile fatty acids of growing layers under heat stress condition. A total of 72 ISA Brown hens were randomly divided into six treatments: thermoneutral temperature control group (CON), heat stress control group (HS), heat stress antibiotic group (ANT) as positive control and heat stress FVS groups (20, 40 or 60 g/kg FVS). The experimental period had a duration of 28 d (days 84-112). On day 98, daily gain average was significantly higher (p<0.05) in the FVS groups than in the HS group. The number of bands in the FVS groups were higher (p<0.05) than in the HS group on day 98. The microbial similarity between the 60 g/kg FVS group and the HS group were the lowest on day 98. FVS group's specific bacteria were mainly Coprococcus comes, [Clostridium] papyrosolvens, Butyricicoccuspullicaecorumon day 98. Whereas on day 112, the FVS groups specific bacteria were mainly Parabacteroides distasonis, Coprobacterfastidiosus, Elusimicrobiumminutum. The content of acetic acid and butyric acid were higher (p<0.05) in 20 g/kg FVS group than in the CON group on day 112. In conclusion, FVS can lighten the adverse effect of heat stress by increasing the diversity of intestinal flora in growing layers.
The microbial residues, due to their closely connection with humic substances (HS), aroused our considerable interest. The method of shake-flask in liquid culture was adopt to accumulate them, in which the cellulose served as the sole C source. The microbial suspensions including Trichoderma viride (Tv), Aspergillus niger (An), Penicillium (P) and mixed strains (Ms) were inoculated into the cellulose culture fluid respectively. The incubation was performed for 70 days at a constant temperature of 28 ºC. The results showed that different microbial treatments had different effects on the C turnover in the cellulose fluid, among which Ms performed the most effective role in accumulating microbial residue and consuming organic C of cell metabolic product, Tv followed. As compared to cellulose, large amounts of inorganic N in the fluid could be transferred into the organic N components of residue. In the mean time, the proportion of aromatic rings could be increased at the cost of losing O-containing groups. Specifically, the degrees of condensation were enhanced by Tv and An, however their degrees of oxidation were inhibited. On the contrary, the P and Ms treatments had a significant advantage in the oxydative degradation of cellulose. Although some intermediate products (polysaccharides, phenolic compounds, carboxylic groups and syringyl units etc.) of HS could be detected in the microbial residues treated by Tv and An, their organic molecules did not still achieve the polymerization degree of real HS.
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