Climate Change Metagenomic Record Index

    Effect and mode of action of chitosan and ivy fruit saponins on the microbiota, fermentation and methanogenesis in the rumen simulation technique

    MGnify Record MGYS00000567

    Description
    Manipulation of the rumen microbial ecosystem to increase the efficiency of nutrient use by the animal, or to decrease its environmental impact, has long been a goal for nutritionists and gut microbiologist. This paper investigates the effect and mode of action of chitosan (CHI) and ivy fruit saponins (IVY) when used as novel feed additives for ruminants. These compounds were supplemented at 5% inclusion rate into a control diet (CON) in a rumen simulation technique. Both, CHI and IVY had a strong and similar ability to decrease methane emissions in comparison to CON (-42% and -40%, respectively). The mode of action of these feed avidities was however remarkably different: CHI promoted a shift in the fermentation pattern towards more energetically favourable pathways (propionate) which explained about two thirds of the decrease in rumen methanogenesis. This shift was achieved by a simplification and modification of the structure in the bacterial community consisting on an increment of Bacteroidetes and Proteobacteria in detriment of Firmicutes and Fibrobacteres. This substitution of fibrolytic bacteria by amylolitic bacteria induced by CHI resulted on a 2.5-fold increase in the amylase enzymatic activity, lactate concentration (+53%) and microbial protein yield (+14%) with no detrimental effect on feed digestibility. Additionally, CHI decreased the relative abundance of methanogens respect to total bacteria which could also contribute to lower rumen methanogenesis. On the contrary, IVY promoted only minor changes on the fermentation pattern and on the structure of the bacterial community which explained only one third of the observed decrease in rumen methanogenesis. Instead, IVY had a specific effect on the methanogens population. This effect consisted on a change in the structure of the methanogens community and a decrease in its diversity. This specific effect, together with the anti-protozoal activity, can be thus considered the main anti-methanogenic property for IVY. Moreover IVY showed to have some beneficial effect to buffer the post-prandial drop in rumen pH and to decrease rumen ammonia levels (-61%), but its anti-microbial properties had a negative impact on microbial protein synthesis (-10%). Therefore, both CHI and IVY should be further investigated in vivo in order to determine the optimum doses which maintain low rumen methanogenesis but prevent negative effects on the rumen microbial ecosystem.

    Related Publications

    Pubmed Record 27014222

    Abstract Text
    There is an increasing need to identify alternative feeds for livestock that do not compete with foods for humans. Seaweed might provide such a resource, but there is limited information available on its value as an animal feed. Here we use a multi-omics approach to investigate the value of two brown seaweeds, Ascophyllum nodosum (ASC) and Laminaria digitata (LAM), as alternative feeds for ruminants. These seaweeds were supplemented at 5% inclusion rate into a control diet (CON) in a rumen simulation fermenter. The seaweeds had no substantial effect on rumen fermentation, feed degradability or methane emissions. Concentrations of total bacteria, anaerobic fungi, biodiversity indices and abundances of the main bacterial and methanogen genera were also unaffected. However, species-specific effects of brown seaweed on the rumen function were noted: ASC promoted a substantial decrease in N degradability (-24%) due to its high phlorotannins content. Canonical correspondence analysis of the bacterial community revealed that low N availability led to a change in the structure of the bacterial community. ASC also decreased the concentration of Escherichia coli O157:H7 post-inoculation. In contrast, LAM which has a much lower phlorotannin content did not cause detrimental effects on N degradability nor modified the structure of the bacterial community in comparison to CON. This adaptation of the microbial community to LAM diets led to a greater microbial ability to digest xylan (+70%) and carboxy-methyl-cellulose (+41%). These differences among brown seaweeds resulted in greater microbial protein synthesis (+15%) and non-ammonia N flow (+11%) in LAM than in ASC diets and thus should led to a greater amino acid supply to the intestine of the animal. In conclusion, it was demonstrated that incorporation of brown seaweed into the diet can be considered as a suitable nutritional strategy for ruminants; however, special care must be taken with those seaweeds with high phlorotannin concentrations to prevent detrimental effects on N metabolism. This study highlights the value of combining fermentation and enzyme activity data with molecular characterization of the rumen microbiome in evaluating novel feeds for ruminants. Further experiments are required to determine the maximum seaweed inclusion rate tolerated by rumen microbes.

    Pubmed Record 26676056

    Abstract Text
    This study investigates the effects of supplementing a control diet (CON) with chitosan (CHI) or ivy fruit saponins (IVY) as natural feed additives. Both additives had similar abilities to decrease rumen methanogenesis (-42% and -40%, respectively) using different mechanisms: due to its antimicrobial and nutritional properties CHI promoted a shift in the fermentation pattern towards propionate production which explained about two thirds of the decrease in methanogenesis. This shift was achieved by a simplification of the structure in the bacterial community and a substitution of fibrolytic (Firmicutes and Fibrobacteres) by amylolytic bacteria (Bacteroidetes and Proteobacteria) which led to greater amylase activity, lactate and microbial protein yield with no detrimental effect on feed digestibility. Contrarily, IVY had negligible nutritional properties promoting minor changes in the fermentation pattern and on the bacterial community. Instead, IVY modified the structure of the methanogen community and decreased its diversity. This specific antimicrobial effect of IVY against methanogens was considered its main antimethanogenic mechanism. IVY had however a negative impact on microbial protein synthesis. Therefore, CHI and IVY should be further investigated in vivo to determine the optimum doses which maintain low methanogenesis but prevent negative effects on the rumen fermentation and animal metabolism.