Effects of Alkaline Hydrogen Peroxide Treatment of Rice Straw Fiber on Ruminal Fermentation Characteristics and Microbial Diversity in Vitro
The aim of this experiment was to evaluate the rumen degradation rate of rice straw fiber treated with alkaline hydrogen peroxide and its effects on rumen fermentation parameters and microbial diversity in vitro.Taking the normal rice straw as control,the rice straw fiber treated with alkaline hydrogen peroxide was fer-mented for 72 h in vitro and the gas production was measured at 4,8,12,18,24,36,48 and 72 h,respec-tively.At 0.5,4,12,24,48 and 72 h,six fermentation bottles were collected from each group to determine the contents of volatile fatty acid(VFA),ammonia nitrogen(NH3-N)and microbial protein(MCP),and the remaining substrate was collected for the determination of fiber degradation rate.The fermentation substrate was collected at 72 h and stored at-80 ℃ for subsequent DNA extraction and high-throughput analysis.The results showed as follows:1)the dry matter degradation rate of rice straw fiber was 1.64 times that of rice straw at 72 h of fermentation(P＜0.05),and the degradation rates of neutral detergent fiber,acid detergent fiber,cel-lulose and hemicellulose were significantly higher than those of rice straw(P＜0.05).The dry matter degrada-tion time of rice straw fiber was shorter than that of rice straw.Rice straw fiber degradation occurred at 4 h and rice straw degradation occurred at 12 h.2)The scanning electron microscope results showed that compared with the rice straw,the fiber structure of rice straw was more loose,the number of microbial adhesion was more,and the digestion was more complete after 72 h of fermentation.3)The total gas production,total vola-tile fatty acid content and contents of propionate and isovalerate in rice straw fiber were extremely significantly higher than those in rice straw(P＜0.01),and the ratio of methane production to total gas production,the con-tents of butyrate,isobutyrate and valerate,and the ratio of acetate to propionate were significantly or extremely significantly lower than those in rice straw(P＜0.05 or P＜0.01).At 72 h of fermentation,the total bacteria number and MCP content in rice straw fiber were extremely significantly higher than those in rice straw(P＜0.01),and the NH3-N content was extremely significantly lower than that in rice straw(P＜0.01).4)The αdiversity results showed that the microflora diversity in rice straw fiber was significantly higher than that in rice straw(P＜0.05).At the phylum level,the results of microbial difference analysis showed that there was no significant difference in phyla with relative abundance greater than 1％between rice straw fiber and rice straw(P＞0.05).At the genus level,the relative abundances of Ruminococcus,Saccharofermentans and Prevotel-laceae_UCG-001 in rice straw fiber were significantly lower than those in rice stalk(P＜0.05),while the rela-tive abundances of unculured_Lachnospiraceae,Probable_genus_10,Bacteroidales_F082 and Lachnospiraceae_UCG-009 were significantly higher than those in rice straw(P＜0.05).In summary,the rice straw fiber is more easily degraded by microorganisms than rice straw and can generate more energy substances such as VFA,which can be used as a potential product in ruminant production.[Chinese Journal of Animal Nutrition,2024,36(7):4739-4750]
万方数据
维普
