Effects of defaunation on microbial activities in the rumen of rams consuming a mixed diet (fresh Digitaria decumbens grass and concentrate)

Eugène, Maguy; Archimède, Harry; Michalet-Doreau, B.; Fonty, Gérard

doi:10.1051/animres:2004008

Cited by 18 publications

(10 citation statements)

References 35 publications

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“…Simultaneously, defaunation also changed the VFA profile in the culture solution, resulting in a lower molar proportion of C2 and C4 but a higher proportion of C3 and consequently leading to lower C2 to C3 ratio than faunation. The current results were in agreement with earlier study (Eugène et al, 2004), where an increase in C3 was frequently accompanied by a decrease in C2 and C4. Molar proportions of C3 varied inversely with C4, and C2 maybe coherent with removal of protozoa which lead to changes in microbial groups and alteration of microbial fermentation, thus led to a shift in the balance of H2 metabolism between C3 and methane production in defaunation group.…”

Section: Discussionsupporting

confidence: 94%

Effect of Defaunation on In Vitro Fermentation Characteristics and Methane Emission When Incubated with Forages

Qin¹,

Choi²,

Lee³

et al. 2013

Journal of The Korean Society of Grassland and Forage Science

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An in vitro study was conducted to determine the effects of defaunation (removal of protozoa) and forage sources (rice straw, ryegrass and tall fescue) on ruminal fermentation characteristics, methane (CH4) production and degradation by rumen microbes. Sodium lauryl sulfate, as a defaunation reagent, was added into the mixed culture solution to remove ruminal protozoa at a concentration of 0.375 mg/ml. Pure cellulose (0.64 g, Sigma, C8002) and three forage sources were incubated in the bottle of culture solution of mixed rumen microbes (faunation) or defaunation for up to 24 h. The concentration of ammonia-N was high under condition of defaunation compared to that from faunation in all incubations (p<0.001). Total VFA concentration was increased at 3, 6 and 12 h (p<0.05~p<0.01) but was decreased at 24 h incubation (p<0.001) under condition of defaunation. Defaunation decreased acetate (p<0.001) and butyrate (p<0.001) proportions at 6, 12 and 24 h incubation times, but increased propionate (p<0.001) proportion at all incubation times for forages. Effective degradability of dry matter was decreased by defaunation (p<0.001). Defaunation not only decreased total gas (p<0.001) and CO2 (p<0.01~0.001) production at 12 and 24 h incubations, but reduced CH4 production (p<0.001) at all incubation times for all forages. The CH4 production, regardless of defaunation, in order of forage sources were rice straw > tall fescue > ryegrass > cellulose (p<0.001) up to 24 h incubation. (Key words : Defaunation, Forages, Effective degradability, Total gas, Methane emission). INTRODUCTIONThe forages make up a large proportion of the diet in ruminant production systems. The feeding of forages as energy sources to ruminants is highly depended on rumen fermentation of the fiber such as cellulose and hemicelluloses by rumen microbes (Wina et al., 2006). Rumen protozoa are metabolically active and serve a multifunctional role in metabolizing dietary nutrients through several ways (Morgavi et al., 2010). Protozoa are well known to secrete hydrolytic enzymes (Coleman, 1986) and positively contributed to 20% of fiber degradation (Dijkstra and Tamminga, 1995). In addition to their role in fiber degradation, rumen protozoa are positively related to methane (CH4) production in the rumen. Finlay et al. (1994) described a symbiotic relationship of ruminal ciliate protozoa with methanogens, which has been proved to allow an interspecies H2 transfer from ciliate protozoa to methanogens for CH4 synthesis, and the symbiotic methanogens associated with rumen ciliate protozoa may account for 37% of the total CH4 production. Some studies have shown that defuanation (removal of protozoa in the rumen) decreased CH4 production up to 10.8% (Kreuzer et al., 1986) or 24.1% (Morgavi et al., 2008) when the cattle were fed forage diets. Furthermore, it is well known that ruminants fed forage-based diets produce more CH4 than those fed high level of concentrate diets (Johnson et al, 2000).Since CH4 emission from ruminants has increasingly caused widesprea...

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Section: Discussionsupporting

confidence: 94%

Effect of Defaunation on In Vitro Fermentation Characteristics and Methane Emission When Incubated with Forages

Qin¹,

Choi²,

Lee³

et al. 2013

Journal of The Korean Society of Grassland and Forage Science

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“…As shown and discussed above, defaunation increases total bacterial numbers, and some authors have also reported shifts in numbers of functional bacterial groups, including cellulolytic bacteria (Williams and Withers, 1993). In addition, total polysaccharidase activities have been shown to be greater in the rumen of faunated animals compared with defaunated ones (Williams and Withers, 1991;Santra and Karim, 2002;Eugène et al, 2004a). Hence, another objective of this study was to examine if defaunation has an effect on the abundance of bacterial species that are considered the major rumen fibrolytic bacteria: F. succinogenes, R. albus, and R. flavefaciens (Morrison et al, 2009).…”

Section: Effect Of Long-and Short-term Defaunation On Cellulolytic Bamentioning

confidence: 80%

Long-term defaunation increases the abundance of cellulolytic ruminococci and methanogens but does not affect the bacterial and methanogen diversity in the rumen of sheep1

Mosoni

Martin

Forano

et al. 2011

Journal of Animal Science

107

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Protozoa are commensal eukaryotes in the rumen of herbivores. Protozoa are large producers of hydrogen, which is utilized by methanogenic archaea to produce methane, a greenhouse gas. The removal of protozoa from the rumen (defaunation) decreases methanogenesis, but also negatively affects fiber digestion, which is the main function of the rumen. The aim of this study was to examine the effect of long-term defaunation on the structure of the microbiota and particularly methanogenic archaea and fibrolytic bacteria to better understand the microbial mechanisms responsible for the decrease in methanogenesis and fibrolysis. The trial was conducted in 5 adult sheep subjected successively to long-term defaunation (2 yr), refaunation (12 wk), and short-term defaunation (10 wk). Methanogens were enumerated by quantitative PCR targeting the rrs (16S ribosomal RNA subunit) and mcrA (methyl coenzyme-M reductase) genes. The rrs gene was used to quantify the 3 major culturable rumen cellulolytic bacterial species (i.e., Fibrobacter succinogenes, Ruminococcus albus, and Ruminococcus flavefaciens) and total bacteria. Bacterial and methanogen diversity was also examined by PCR-DGGE (PCR-denaturing gradient gel electrophoresis) analysis targeting the rrs and mcrA genes, respectively. Total rumen bacterial density estimated as rrs copies per gram of DM of rumen content increased in response to long- and short-term defaunation (+1 log, P < 0.001), but without noticeable shifts in diversity. Defaunation increased the rrs copies per gram of DM of rumen content of R. albus and R. flavefaciens (+2 log, P < 0 0.001), but did not affect that of F. succinogenes. Despite a 20% reduction in methane emission in the 2 defaunated periods, the mcrA and rrs copies of methanogens per gram of DM of rumen content increased (+1 log, P < 0.001) in the absence of protozoa, whereas the diversity of the dominant methanogenic community was not modified. This study shows no major difference between long- and short-term defaunation in abundance and diversity of bacteria and archaea. It also provides evidence that monitoring the abundance and diversity of methanogens is not sufficient to comprehend the microbial mechanisms leading to a reduction in methane emissions by ruminants. This study also reports for the first time in sheep a selective effect of defaunation on the abundance of cellulolytic bacterial species.

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“…Santra and Karim (2002) observed that CMCase activity was lower in defaunated lambs while xylanase activity was similar in faunated and defaunated lambs. Eugène et al (2004) observed that both CMCase and xylanase activities were reduced in the absence of protozoa. Williams and Withers (1991) found that b-d-xylosidase activity was 4-8 times higher in the refaunated than defaunated sheep.…”

Section: Discussionmentioning

confidence: 95%

The dynamics of major fibrolytic microbes and enzyme activity in the rumen in response to short- and long-term feeding of Sapindus rarak saponins

2006

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Aims: To investigate the short‐ and long‐term effects of an extract of Sapindus rarak saponins (SE) on the rumen fibrolytic enzyme activity and the major fibrolytic micro‐organisms. Methods and Results: Two feeding trials were conducted. In the short‐term trial, four fistulated goats were fed a basal diet containing sugar cane tops and wheat pollard (65 : 35, w/w) and were supplemented for 7 days with SE at a level of 0·6 g kg−1 body weight. Rumen liquor was taken before, during and after SE feeding. In the long‐term trial, 28 sheep were fed the same basal diet as the goats and were supplemented for 105 days with 0·24, 0·48 and 0·72 g kg−1 body mass of the extract. Rumen liquor was taken on days 98 and 100. Protozoal numbers were counted under the microscope. Cell wall degradation was determined by enzyme assays and the major fibrolytic micro‐organisms were quantified by dot blot hybridization. Sapindus extract significantly depressed rumen xylanase activity in both trials and carboxymethylcellulase activity in the long‐term trial (P < 0·01). Fibrobacter sp. were not affected by the SE in both trials, while ruminococci and the anaerobic fungi showed a short‐term response to the application of saponins. Protozoal counts were decreased only in the long‐term trial with sheep. Conclusion: These data suggest that there is an adaptation of Ruminococcus albus, Ruminococcus flavefaciens and Chytridiomycetes (fungi) to saponin when fed over a long period. The fact that no correlation between the cell wall degrading enzyme activities and the cell wall degrading micro‐organisms was observed suggests that the organisms tracked in this experiment are not the only key players in ruminal cell wall degradation. Significance and Impact of the Study: Sapindus rarak saponins partially defaunate the rumen flora. Their negative effect on cell wall degradation, however, is not related to rumen organisms currently recognized as the major cell wall degrading species. The adaptation of microbes in the long‐term feeding experiment suggests that the results from short‐term trial on the ruminal microbial community have to be interpreted carefully.

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Effects of defaunation on microbial activities in the rumen of rams consuming a mixed diet (fresh Digitaria decumbens grass and concentrate)

Cited by 18 publications

References 35 publications

Effect of Defaunation on In Vitro Fermentation Characteristics and Methane Emission When Incubated with Forages

Effect of Defaunation on In Vitro Fermentation Characteristics and Methane Emission When Incubated with Forages

Long-term defaunation increases the abundance of cellulolytic ruminococci and methanogens but does not affect the bacterial and methanogen diversity in the rumen of sheep1

The dynamics of major fibrolytic microbes and enzyme activity in the rumen in response to short- and long-term feeding of Sapindus rarak saponins

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