Der Einfluß der Verfütterung von Silage aus frischem bzw. angewelktem Gras oder Heu auf die Futteraufnahme,Verdaulichkeit, Milchleistung und Blutzusammensetzung der Milchkühe

A survey is given of research results on ruminant lipid digestion obtained at the authors’ laboratory. Results are presented in terms of lipid changes occurring in the rumen and in terms of effects on nature, extent and site of digestion.

The rumen can be adapted to an extremely high capacity for triglyceride lipolysis, preferentially releasing polyunsaturated fatty acids that are then further hydrogenated with accumulation of oleic acid isomers in vitro only. Evidence was obtained for both microbial incorporation and synthesis of polyunsaturated acids. In vitro lipolysis is inhibited by pH values below 6.3 and by ionophores. Free fatty acids inhibit methanogenesis with associated increases in propionate production and decreases in acetate and butyrate productions; the latter being related to their defaunating effect. Both in the faunated and defaunated rumen, free fatty acids decrease fibre digestion, which is shifted to the hindgut, at least in sheep. Defaunation increases rumen microbial growth efficiency and may result in a higher duodenal flow of both feed and microbial protein, provided these increases are not overcome by a decreased apparent rumen OM digestibility. Considerable between animal variability exists for these effects, associated with variable effects on rumen particle and liquid volumes and outflow rates.     

The effect of pectin, corn and wheat starch, inulin and pH on in vitro production of methane, short chain fatty acids and on the microbial community composition in rumen fluid

Methane emission from livestock, ruminants in particular, contributes to the build up of greenhouse gases in the atmosphere. Therefore the focus on methane emission from ruminants has increased. The objective of this study was to investigate mechanisms for methanogenesis in a rumen fluid-based in vitro fermentation system as a consequence of carbohydrate source (pectin, wheat and corn starch and inulin) and pH (ranging from 5.5 to 7.0). Effects were evaluated with respect to methane and short chain fatty acid (SCFA) production, and changes in the microbial community in the ruminal fluid as assessed by terminal-restriction fragment length polymorphism (T-RFLP) analysis. Fermentation of pectin resulted in significantly lower methane production rates during the first 10 h of fermentation compared to the other substrates (P = 0.001), although total methane production was unaffected by carbohydrate source (P = 0.531). Total acetic acid production was highest for pectin and lowest for inulin (P < 0.001) and vice versa for butyric acid production from pectin and inulin (P < 0.001). Total propionic acid production was unaffected by the carbohydrate source (P = 0.791). Methane production rates were significantly lower for fermentations at pH 5.5 and 7.0 (P = 0.005), sustained as a trend after 48 h (P = 0.059), indicating that there was a general optimum for methanogenic activity in the pH range from 6.0 to 6.5. Decreasing pH from 7.0 to 5.5 significantly favored total butyric acid production (P < 0.001). Principle component analysis of T-RFLP patterns revealed that both pectin and pH 5.5 resulted in pronounced changes in the microbial community composition. This study demonstrates that both carbohydrate source and pH affect methane and SCFA production patterns, and the microbial community composition in rumen fluid.     

Stoichiometry of carbohydrate fermentation and microbial growth efficiency in a continous culture of mixed rumen bacteria

Summary A population of mixed rumen bacteria was maintained in a chemostat at four different dilution rates, with glocose as the growth limiting carbon and energy substrate. Increasing the dilution rate shifted the proportions of end products: methane decreased and propionate increased. Fermentation and hydrogen balances were calculated from the fermentation end products. Values were similar to earlier ones from batch incubations of rumen contents. This suggests that theoretical overall reaction schemes for carbohydrate fermentation in the rumen, proposed earlier, are also valid in continuous culture.A positive correlation between dilution rate and microbial growth efficiency (gN_inc./kg OM_f was observed, confirming earlier work.Apparently conflicting results of chemostat work and recent in vivo experiments are discussed.     

Changes in microbial community structure, methanogenesis and rumen fermentation in response to saponin-rich fractions from different plant materials

Aims:  Investigation of the effects of saponin-rich fractions on rumen fermentation, methane production and the microbial community.
Methods and Results:  Saponins were extracted from Carduus , Sesbania and Knautia leaves and fenugreek seeds. Two levels of saponin-rich fractions with a substrate were incubated using the Hohenheim gas method. Methane was measured using an infrared-based methane analyser and microbial communities using quantitative PCR. On addition of saponin-rich fractions, methane and short-chain fatty acid production was not affected. The protozoal counts decreased by 10–39%. Sesbania saponins decreased methanogen population by 78%. Decrease in ruminal fungal population (20–60%) and increase in Fibrobacter succinogenes (21–45%) and Ruminococcus flavefaciens (23–40%) were observed.
Conclusions:  The saponins evaluated possessed anti-protozoal activity; however, this activity did not lead to methane reduction. Fenugreek saponins seemed to have potential for increasing rumen efficiency. The saponins altered the microbial community towards proliferation of fibre-degrading bacteria and inhibition of fungal population.
Significance and Impact of the Study:  The uni-directional relationship between protozoal numbers and methanogenesis, as affected by saponins, is not obligatory. All saponins might not hold promise for decreasing methane production from ruminants.     

Increases in microbial nitrogen production and efficiency in vitro with three inhibitors of ruminal methanogenesis

It was hypothesized that the addition of crotonic acid or 3-butenoic acid would relieve constraints in digestibility observed when methane formation is inhibited by lumazine, propynoic acid, or ethyl 2-butynoate. In six incubations, one of the three methanogenesis inhibitors, at three different concentrations, was combined with either crotonic acid or 3-butenoic acid at two different concentrations. A mixture of buffer and ruminal fluid (4:1) was incubated with grass hay in Erlenmeyer flasks for 72 h. Initial concentrations were 0, 0.6, and 1.2 mmol/L for lumazine; 0, 2, and 4 mmol/L for propynoic acid; and 0, 4, and 8 mmol/L for ethyl 2-butynoate. 15Nitrogen (N) incorporation was used as a microbial marker. All three methanogenesis inhibitors decreased proteolysis. Propynoic acid and ethyl 2-butynoate at 8 mmol/L also decreased the digestibility of organic matter and neutral detergent fibre. However, all three inhibitors of methanogenesis increased the production of microbial N through an improvement of synthetic efficiency. Crotonic acid and 3-butenoic acid were generally ineffective in compensating digestibility decreases caused by the inhibitors of methanogenesis. It is of interest to elucidate the mechanisms by which these compounds increased the efficiency of microbial N production. Lumazine and the addition of low levels of ethyl 2-butynoate could potentially benefit animal production by lowering methane emissions, decreasing ruminal proteolysis, and increasing microbial N production without affecting organic matter digestibility.     

An rRNA approach for assessing the role of obligate amino acid-fermenting bacteria in ruminal amino acid deamination.

Ruminal amino acid degradation is a nutritionally wasteful process that produces excess ruminal ammonia. Monensin inhibited the growth of monensin-sensitive, obligate amino acid-fermenting bacteria and decreased the ruminal ammonia concentrations of cattle. 16S rRNA probes indicated that monensin inhibited the growth of Peptostreptococcus anaerobius and Clostridium sticklandii in the rumen. Clostridium aminophilum was monensin sensitive in vitro, but C. aminophilum persisted in the rumen after monensin was added to the diet. An in vitro culture system was developed to assess the competition of C. aminophilum, P. anaerobius, and C. sticklandii with predominant ruminal bacteria (PRB). PRB were isolated from a 10(8) dilution of ruminal fluid and maintained as a mixed population with a mixture of carbohydrates. PRB did not hybridize with the probes to C. aminophilum, P. anaerobius, or C. sticklandii. PRB deaminated Trypticase in continuous culture, but the addition of C. aminophilum, P. anaerobius, and C. sticklandii caused a more-than-twofold increase in the steady-state concentration of ammonia. C. aminophilum, P. anaerobius, and C. sticklandii accounted for less than 5% of the total 16S rRNA and microbial protein. Monensin eliminated P. anaerobius and C. sticklandii from continuous cultures, but it could not inhibit C. aminophilum. The monensin resistance of C. aminophilum was a growth rate-dependent, inoculum size-independent phenomenon that could not be maintained in batch culture. On the basis of these results, we concluded that the feed additive monensin cannot entirely counteract the wasteful amino acid deamination of obligate amino acid-fermenting ruminal bacteria.     

Dietary phytochemicals as rumen modifiers: a review of the effects on microbial populations

In the recent years, the exploration of bioactive phytochemicals as natural feed additives has been of great interest among nutritionists and rumen microbiologists to modify the rumen fermentation favorably such as defaunation, inhibition of methanogenesis, improvement in protein metabolism, and increasing conjugated linoleic acid content in ruminant derived foods. Many phytochemicals such as saponins, essential oils, tannins and flavonoids from a wide range of plants have been identified, which have potential values for rumen manipulation and enhancing animal productivity as alternatives to chemical feed additives. However, their effectiveness in ruminant production has not been proved to be consistent and conclusive. This review discusses the effects of phytochemicals such as saponins, tannins and essential oils on the rumen microbial populations, i.e., bacteria, protozoa, fungi and archaea with highlighting molecular diversity of microbial community in the rumen. There are contrasting reports of the effects of these phytoadditives on the rumen fermentation and rumen microbes probably depending upon the interactions among the chemical structures and levels of phytochemicals used, nutrient composition of diets and microbial components in the rumen. The study of chemical structure–activity relationships is required to exploit the phytochemicals for obtaining target responses without adversely affecting beneficial microbial populations. A greater understanding of the modulatory effects of phytochemicals on the rumen microbial populations together with fermentation will allow a better management of the rumen ecosystem and a practical application of this feed additive technology in livestock production.     

Methane production and substrate degradation by rumen microbial communities containing single protozoal species in vitro

AIMS: To assess the effect of protozoal species on rumen fermentation characteristics in vitro. METHODS AND RESULTS: Entodinium caudatum, Isotricha intestinalis, Metadinium medium, and Eudiplodinium maggii from monofaunated wethers and mixed protozoa from conventional wethers were obtained by centrifugation, re-suspended at their normal densities in rumen fluid supernatants from defaunated or conventional wethers and incubated in vitro. The presence of protozoa increased the concentration of ammonia and altered the volatile fatty acids balance with more acetate and butyrate produced at the expense of propionate. Differences among species were observed, notably in the production of methane, which increased with E. caudatum as compared to other ciliates and to defaunated and mixed protozoa treatments (P < 0.05). The increased methanogenesis was not correlated to protozoal biomass indicating that the metabolism of this protozoan and/or its influence on the microbial ecosystem was responsible for this effect. CONCLUSIONS: Entodinium caudatum stimulated the production of methane, a negative effect that was reinforced by a concomitant increase in protein degradation. SIGNIFICANCE AND IMPACT OF THE STUDY: Comparison of individual species of protozoa highlighted the particular influence of E. caudatum on rumen fermentation. Its elimination (targeted defaunation) from the rumen could reduce methane production without affecting feed degradation.     

Degradation of methionine by rumen contents in vitro and efficiency of its protection

Degradation of methionine (M), soya isolate (S) and casein hydrolysate (C) has been evaluated by incubation of these substrates (100 mg) with sheep rumen contents in vitro, in the presence of starch (250 mg). Five incubations were performed using one adult rumen fistulated sheep fed 300 g of hay and 300 g of concentrate daily. Total NH₃ production at different sampling times (after 2, 4, 6, 8 and 24 h of incubation) was calculated by subtracting the net NH₃-N production observed in the incubation containing starch only from that produced in the incubation containing the substrate. Protected M preparations, Smartamine (Sm) and Mepron (Mp), were also used. During two incubations of M, using four sheep on permanent pasture or fed four different hays, it was shown that the net disappearance of free M matches net NH₃ production at both low (2 mM) and high (20 mM) M concentration. The results indicate that the initial M degradation rate (3 h of incubation) was 12–14% that of C and never exceeded 1.5 mmol h⁻¹ l⁻¹ of rumen contents. Adaptation of the sheep rumen by daily introduction of 5 or 20 g of DL-methionine for 21 and 8 days, respectively, did not change this result (three to four incubations with rumen contents of three sheep fed 300 g of hay and 300 g of two different concentrates). The results also indicate that protection against rumen degradation was effective for Sm but not for Mp. The ‘effective degradation rate’ of M was estimated as 0.30 that of protein. Considering the high price of protected M (four to five fold the price of non protected M), and the low degradation rate of M, it is suggested that the latter be used at 1.43 of the amount normally added as rumen protected M, to obtain the same result.     

Monensin and dichloroacetamide influences on methane and volatile Fatty Acid production by rumen bacteria in vitro

The effect of monensin (0 or 33 mug/g of diet) upon rumen fermentation in the presence and absence of methanogenesis was determined in vitro by using mixed rumen organisms continuously cultured for 17 days. Methane was inhibited by dichloroacetamide (DCA; 32 mg/day) or by a pH of 5.1. Monensin effected a significant decrease in the ratio of acetic to propionic acid in the presence or absence of methanogenesis. In the absence of methanogenesis, the decrease in the ratio of acetic to propionic acid was entirely the result of increased propionic acid, whereas in the presence of methanogenesis the decrease in the ratio was the result of a combination of decreased acetic acid and increased propionic acid. There was a complementary interaction between monensin and DCA on volatile fatty acid production (expressed as millimoles of carbon per day). Addition of monensin to DCA-treated cultures resulted in the production of more acid; however, monensin and DCA had no beneficial effect on total carbon formed as acid and gases as compared with nonsupplemented control cultures. The monensin and DCA also resulted in greater digestion of neutral detergent fiber and less accumulation of formic acid and hydrogen as end products than did DCA alone. l-Lactic acid was produced in small but significantly greater amounts by the low-pH cultures, which also had less volatile fatty acid carbon formed from the fiber fraction of the forage supplied.     

A new perspective on the use of plant secondary metabolites to inhibit methanogenesis in the rumen

Recently, greenhouse gas emissions have been of great concern globally. Ruminant livestock due to production of methane during normal fermentation in the rumen contributes substantially to the greenhouse effects. During the recent decade, a paradigm shift has been initiated whether plant secondary metabolites (PSM) could be exploited as natural safe feed additives alternative to chemical additives to inhibit enteric methanogenesis. More than 200,000 defined structures of PSM have been known. Some plants or their extracts with high concentrations of bioactive PSM such as saponins, tannins, essential oils, organosulphur compounds, flavonoids and many other metabolites appear to have potential to inhibit methane production in the rumen. The possible mechanisms and effects of many PSM on rumen methanogenesis are not clearly understood. Saponins may decrease methanogenesis through the inhibition of rumen protozoa and in turn may suppress the numbers and activity of methanogens. Although the direct effect of saponins on methanogens has not been demonstrated, saponins might inhibit methanogens at high doses. Tannins may inhibit the methanogenesis directly and also via inhibition of protozoal growth. Essential oils, organosulphur compounds and flavonoids appear to have direct effects against methanogens, and a reduction of protozoa associated methanogenesis probably plays a minor role for these metabolites. The chemical structure and molecular weight of the PSM and chemical composition of diets dependent upon the different feeding regimes may influence the effects of PSM on methane production. Although PSM may negatively affect nutrient utilization, there is evidence that methanogenesis could be suppressed without adversely affecting rumen fermentation, which could be exploited to mitigate methane emission in ruminants.     

A shift towards succinate-producing Prevotella in the ruminal microbiome challenged with monensin

The time-resolved impact of monensin on the active rumen microbiome was studied in a rumen-simulating technique (Rusitec) with metaproteomic and metabolomic approaches. Monensin treatment caused a decreased fibre degradation potential that was observed by the reduced abundance of proteins assigned to fibrolytic bacteria and glycoside hydrolases, sugar transporters and carbohydrate metabolism. Decreased proteolytic activities resulted in reduced amounts of ammonium as well as branched-chain fatty acids. The family Prevotellaceae exhibited increased resilience in the presence of monensin, with a switch of the metabolism from acetate to succinate production. Prevotella species harbour a membrane-bound electron transfer complex, which drives the reduction of fumarate to succinate, which is the substrate for propionate production in the rumen habitat. Besides the increased succinate production, a concomitant depletion of methane concentration was observed upon monensin exposure. Our study demonstrates that Prevotella sp. shifts its metabolism successfully in response to monensin exposure and Prevotellaceae represents the key bacterial family stabilizing the rumen microbiota during exposure to monensin.     

Formate as an Intermediate in the Bovine Rumen Fermentation

An average of 11 (range, 2 to 47) mumoles of formate per g per hr was produced and used in whole bovine rumen contents incubated in vitro, as calculated from the product of the specific turnover rate constant, k, times the concentration of intercellular formate. The latter varied between 5 and 26 (average, 12) nmoles/g. The concentration of formate in the total rumen contents was as much as 1,000 times greater, presumably owing to formate within the microbial cells. The concentration of formate in rumen contents minus most of the plant solids was varied, and from the rates of methanogenesis the Michaelis constant, K(m), for formate conversion to CH(4) was estimated at 30 nmoles/g. Also, the dissolved H(2) was measured in relation to methane production, and a K(m) of 1 nmole/g was obtained. A pure culture of Methanobacterium ruminantium showed a K(m) of 1 nmole of H(2)/g, but the K(m) for formate was much higher than the 30 nmoles for the rumen contents. It is concluded that nonmethanogenic microbes metabolize intercellular formate in the rumen. CO(2) and H(2) are the principal substrates for rumen methanogenesis. Eighteen per cent of the rumen methane is derived from formate, as calculated from the intercellular concentration of hydrogen and formate in the rumen, the Michaelis constants for conversion of these substrates by rumen liquid, and the relative capacities of whole rumen contents to ferment these substrates.     

Effect of tamarind (Tamarindus indica) seed husk tannins on in vitro rumen fermentation

This study was conducted to determine the effect of tamarind seed husk (TSH) as a source of tannin on various parameters of rumen fermentation in vitro. The TSH contained 14% tannin (DM basis). The biological interference of TSH tannin on rumen fermentation was assessed using polyethylene glycol (PEG) 6000 as an indicator. Three compound feed mixtures (CFM) were prepared either without TSH (CFM-I), with 2.5% TSH (CFM-II) and with 7.5% TSH (CFM-III). Parameters studied were in vitro gas production with PEG, rate of substrate degradation, and microbial protein synthesis. Addition of PEG to TSH resulted in an increase in gas production from 5.5 to 16.5 ml per 200 mg DM. Presence of TSH tannin depressed cumulative gas production by 16.8% in CFM-II, and by 29.2% in CFM-III during initial stages of fermentation (i.e. at 8 h). Rate of substrate disappearance (T^1/2) was 14.4, 17.6 and 20.5 h in CFM-I, CFM-II and CFM-III, respectively. Irrespective of the carbohydrate source, presence of TSH tannin improved the efficiency of microbial protein synthesis in vitro. Thus, TSH is a natural source of tannin that can be used to beneficially manipulate rumen fermentation.     

瘤胃甲烷调控方法评述

反刍动物释放的甲烷不仅消耗6％～10％的能量摄入,而且是重要的温室效应气体。过去20多年以来,研究人员围绕瘤胃甲烷生成及其调控展开了大量的研究,目前采取的主要措施包括：（1）提供电子释放新途径;（2）利用疫苗、生物控制剂（噬菌体和细菌素）以及化学抑制剂等抑制产甲烷菌,以及（3）去原虫、添加植物提取物或有机酸等促进产乙酸菌增加,降低产甲烷菌可利用的氢。瘤胃生态系统是一个复杂的生态系统,能够将复杂碳水化合物转化成为挥发性脂肪酸,这个过程部分依赖于甲烷的生成和氢的消耗。因此,虽然各种调控措施能够在短期内抑制甲烷生成,但瘤胃微生态系统能够恢复原有的甲烷生成水平,这表明我们对瘤胃中氢代谢仍然认识不足。进一步提高对瘤胃内氢和甲烷生成的微生物生化机制的了解,有助于我们找到有效的甲烷调控措施。     

Characteristics of anaerobic oxalate-degrading enrichment cultures from the rumen.

Enrichment cultures of rumen bacteria degraded oxalate within 3 to 7 days in a medium containing 10% rumen fluid and an initial level of 45 mM sodium oxalate. This capability was maintained in serially transferred cultures. One mole of methane was produced per 3.8 mol of oxalate degraded. Molecular hydrogen and formate inhibited oxalate degradation but not methanogenesis; benzyl viologen and chloroform inhibited both oxalate degradation and methanogenesis. Attempts to isolate oxalate-degrading bacteria from these cultures were not successful. Oxalate degradation was uncoupled from methane production when enrichments were grown in continuous culture at dilution rates greater than or equal to 0.078 h-1. Growth of the uncoupled population (lacking methanogens) in batch culture was accompanied by degradation of 45 mM oxalate within 24 h and production of 0.93 mol of formate per mol of oxalate degraded. Oxalate degradation by the uncoupled population was not inhibited by molecular hydrogen or formate. Cell yields (grams [dry weight]) per mole of oxalate degraded by the primary enrichment and the uncoupled populations were 1.7 and 1.0, respectively.     

Influence of 1-[(E)-2-(2-methyl-4-nitrophenyl)diaz-1-enyl]pyrrolidine-2-carboxylic acid and diphenyliodonium chloride on ruminal protein metabolism and ruminal microorganisms.

The effects of 1-[(E)-2-(2-methyl-4-nitrophenyl)diaz-1-enyl]pyrrolidine-2-carboxy lic acid (LY29) and diphenyliodonium chloride (DIC) on the degradation of protein to ammonia were determined in a mixed rumen microbial population taken from sheep on a grass hay-concentrate diet. Both compounds decreased NH3 production by inhibiting deamination of amino acids. LY29, but not DIC, inhibited growth of the high-activity ammonia-producing species, Clostridium aminophilum and Clostridium sticklandii.     

Contribution of quinone-reducing microorganisms to the anaerobic biodegradation of organic compounds under different redox conditions

The capacity of two anaerobic consortia to oxidize different organic compounds, including acetate, propionate, lactate, phenol and p-cresol, in the presence of nitrate, sulfate and the humic model compound, anthraquinone-2,6-disulfonate (AQDS) as terminal electron acceptors, was evaluated. Denitrification showed the highest respiratory rates in both consortia studied and occurred exclusively during the first hours of incubation for most organic substrates degraded. Reduction of AQDS and sulfate generally started after complete denitrification, or even occurred at the same time during the biodegradation of p-cresol, in anaerobic sludge incubations; whereas methanogenesis did not significantly occur during the reduction of nitrate, sulfate, and AQDS. AQDS reduction was the preferred respiratory pathway over sulfate reduction and methanogenesis during the anaerobic oxidation of most organic substrates by the anaerobic sludge studied. In contrast, sulfate reduction out-competed AQDS reduction during incubations performed with anaerobic wetland sediment, which did not achieve any methanogenic activity. Propionate was a poor electron donor to achieve AQDS reduction; however, denitrifying and sulfate-reducing activities carried out by both consortia promoted the reduction of AQDS via acetate accumulated from propionate oxidation. Our results suggest that microbial reduction of humic substances (HS) may play an important role during the anaerobic oxidation of organic pollutants in anaerobic environments despite the presence of alternative electron acceptors, such as sulfate and nitrate. Methane inhibition, imposed by the inclusion of AQDS as terminal electron acceptor, suggests that microbial reduction of HS may also have important implications on the global climate preservation, considering the green-house effects of methane.     

In vitro study of the effect of different ionophore antibiotics and of certain derivatives on rumen fermentation and on protein nitrogen degradation

An in vitro study was carried out to evaluate the effect of different ionophore antibiotics and some of their derivatives on rumen fermentation and on the degradation of peanut meal nitrogen. The increase in the production of propionic acid at the expense of acetic acid, observed with lonomycin, nigericin, cationomycin and lysocellin, was identical to that noted with monensin. The decrease in methanogenesis observed in the presence of monensin was also found with cationomycin and lysocellin. With the exception of lysocellin, which greatly reduced protein degradation of peanut meal, and of nigericin, which had no effect on this parameter, the 2 other molecules presented the same action as monensin. The negative effect of monensin on microbial ammonia uptake was demonstrated with the same intensity in the presence of cationomycin; it was slightly higher with nigericin and particularly accentuated with lonomycin and lysocellin. Three ester derivatives of monensin (monensin acetate, monensin propionate and monensin butyrate) had a similar action to that of monensin on the orientation of rumen fermentations. The monensin isobutyrate derivative appeared to be more active than monensin and only weakly altered microbial ammonia uptake. The oxolonomycin and hydroxolonomycin derivatives behaved identically to lonomycin with respect to microbial metabolism and protein nitrogen degradation. Unlike the molecules from which they derive, the deacylated cationomycin and nigericic acid had no effect on the orientation of rumen fermentations. Of the compounds tested and presenting a potential 'growth-promoting action' at least comparable to that of monensin, and which demonstrated lower toxicity on mice, three molecules (oxolonomycin, lysocellin and cationomycin) appeared to present a zootechnical interest as feed additives for growing cattle.     

Immunization against Rumen Methanogenesis by Vaccination with a New Recombinant Protein

Vaccination through recombinant proteins against rumen methanogenesis provides a mitigation approach to reduce enteric methane (CH₄) emissions in ruminants. The objective of present study was to evaluate the in vivo efficacy of a new vaccine candidate protein (EhaF) on methanogenesis and microbial population in the rumen of goats. We amplified the gene mru 1407 encoding protein EhaF using fresh rumen fluid samples of mature goats and successfully expressed recombinant protein (EhaF) in Escherichia coli Rosetta. This product was evaluated using 12 mature goats with half for control and other half injected with 400ug/goat the purified recombinant protein in day 1 and two subsequent booster immunizations in day 35 and 49. All measurements were undertaken from 63 to 68 days after the initial vaccination, with CH₄ emissions determined using respiration calorimeter chambers. The results showed that the vaccination caused intensive immune responses in serum and saliva, although it had no significant effect on total enteric CH₄ emissions and methanogen population in the rumen, when compared with the control goats. However, the vaccination altered the composition of rumen bacteria, especially the abundance of main phylum Firmicutes and genus Prevotella. The results indicate that protein EhaF might not be an effective vaccine to reduce enteric CH4 emissions but our vaccine have potential to influence the rumen ecosystem of goats.