Ruminants are major contributors of methane (CH4) emission. Ruminants mainly emit CH4 as a result from digestion of feed and rumen microorganisms digest structural carbohydrate in the feed resulting in the production H2 and CO2. These compounds are used by methanogens to produce CH4.
One of the strategies to reduce CH4 emission from rumen is to add a compound that can be an alternative H2 sink agent and redirect H2 utilization from CH4 to SCFA production. Addition of the compound may create H2 starvation for methanogen and may lead to less CH4 production. Phloroglucinol is a natural product of rumen metabolism of tannin and several rumen bacteria reportedly can reduce phloroglucinol to acetate by using H2. This result showed that phloroglucinol may be able to be used as an alternative H2 sink agent. However, the effect of manipulation on rumen fermentation in vitro by using phloroglucinol is not known. Therefore, we aimed to study the effect of phloroglucinol in CH4 mitigation strategy.
In the first study, the experiment was designed to determine the effect of phloroglucinol alone on CH4 emission, rumen fermentation profiles, and rumen microbial population density. The incubation was conducted by using a substrate only as control and 5 different doses of phloroglucinol. The results showed that 10 mmol/L phloroglucinol reduced CH4 production by 15.0%. Total gas production, dry matter digestibility (DMD), CH4/total SCFA, and NH3-N were simultaneously reduced by phloroglucinol, but it had no effect on the total SCFA concentration. Acetate increased at the expense of propionate. This might indicate the redirection of H2 utilization from CH4 to acetate, and might be related to CH4 reduction. Phloroglucinol had no effect on methanogen, but it reduced the population density of R. albus.
In the second study, the effect of phloroglucinol and forage to concentrate (F:C) ratio on CH4 emission, rumen fermentation profiles, and microbial population density were investigated. The treatments were 0, 6, 10 mmol/L phloroglucinol, and two different F:C ratio, low and high F:C ratios. The results showed that phloroglucinol reduced CH4 significantly in both diets. However, there were no effect of F:C ratio and F:C + phloroglucinol on CH4 production. Acetate proportion in both diet increased by addition of phloroglucinol. DMD, NH3-N, and methanogen relative quantity were reduced by phloroglucinol. Phloroglucinol significantly affected total SCFA production in both diets. The reduction of CH4 by phloroglucinol was probably related to simultaneous reduction on methanogen relative quantity and DMD.
In conclusion, phloroglucinol is able to reduce CH4 production in the rumen in vitro. It might change the fermentation of the rumen by redirecting H2 utilization to SCFA production. However, the reduction of CH4 was followed by simultaneous reduction of digestibility.
内容記述
本文/GRADUATE SCHOOL OF BIORESOURCES MIE UNIVERSITY
103p
EFFECTS OF “PHLOROGLUCINOL”, AN ANTI-METHANOGENIC AGENT, ON IN VITRO RUMEN METHANOGENESIS
2019DB0704.pdf
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