Comparison of two in vitro fermentation gas production methods using both rumen fluid and faecal inoculum from sheep

Efficacy of zinc nanoparticle supplementation on ruminal environment in lambs

BACKGROUND

Zinc nanoparticles (NPs) are characterized by high bioavailability, small size, and high absorbability. The purpose of this experiment was to determine the effect of Zn-NP feed supplementation on ruminal fermentation, microbiota, and histopathology in lambs. In vitro (24 h), short-term (STE, 28 d), and long-term (LTE, 70 d) experiments were performed. The lambs in STE were fed a basal diet (BD) composed of 350 g/d ground barley and 700 g/d meadow hay (Control), BD enriched with ZnO-NPs (80 mg Zn/kg of diet, ZnO-NPs), and BD enriched with Zn phosphate-based NPs (80 mg Zn/kg of diet, ZnP-NP). The in vitro gas production technique was used in incubated rumen fluid from STE. The lambs in LTE were fed BD (Control), BD enriched with ZnO-NPs (40 mg Zn/kg of diet, ZnO-NP40), BD enriched with ZnO-NPs (80 mg Zn/kg of diet, ZnO-NP80) and BD enriched with ZnO (80 mg Zn/kg of diet, ZnO-80).

RESULTS

After 24 h of incubation, dry matter digestibility was higher for ZnO-NP and ZnP-NP substrates than the control in an in vitro experiment (P < 0.001). The total bacterial population in the STE was lower (P < 0.001) in the ZnP-NP group than in the control and ZnO-NP groups, but the protozoan populations were not significantly different. The ammonia-N concentration in LTE was lowest in the ZnO-NP80 group (P = 0.002), but the activities of carboxymethyl cellulase (P < 0.001) and xylanase (P = 0.002) were higher in the ZnO-NP40, ZnO-NP80, and ZnO-80 groups than in the control group. Morphological observation after STE and LTE revealed histological changes (e.g. inflammation of the epithelium or edema of the connective tissue) in the rumen of lambs.

CONCLUSION

Zn-NP supplementation up to 70 d improved feed-use efficiency and influenced ammonia-N concentration and activities of hydrolases in the rumen. The active ruminal fermentation affected the health of the ruminal papillae and epithelium in the lambs, regardless of the application's form, dose, or duration. However, by affecting rumen microbial fermentation, Zn-NPs could alter fermentation patterns, thereby increasing the capacity of host rumen epithelial cells to transport short-chain fatty acids.

A systematic study of sheep faeces to be used as an alternative inoculum source in the Hohenheim gas test

In vitro studies of gas production (GP) using rumen fluid obtained from rumen-cannulated animals are common in feed evaluation for ruminants. The objective was to compare sheep faeces with rumen fluid from dairy cows as inocula in the Hohenheim gas test (HGT) using a large number of different-quality feeds. It then was evaluated whether GP obtained by using rumen inoculum (RI-GP) can be estimated from GP using faecal inoculum (FI-GP). Ninety feeds for ruminants including roughages (n = 27), total mixed rations (n = 6), commercial compound feeds for dairy cows (n = 18), cereal grains (n = 10), energy-rich by-products (n = 5), legume grains (n = 6), oilseed meals (n = 6), and other protein-rich feeds (n = 12) were incubated with either rumen inoculum (RI) or faecal inoculum (FI), and GP was recorded at 2, 4, 8, 12, 24, 48, and 72 h. Nonlinear equations were fitted to the GP data to determine GP kinetic parameters. Correlations between RI-GP and FI-GP were calculated for different time points. Linear regressions were calculated to estimate RI-GP from FI-GP using the entire data set or subsets of roughages and concentrates. GP kinetic parameters were lower for all feed categories when incubated with FI instead of RI. On average of all feed samples, the potential GP was 9 mL/200 mg dry matter (DM) lower and the rate of GP was 3.1%/h lower with FI than RI. The estimation of kinetic data for FI included a lag phase of 1.51 h on average, whereas no lag phase was estimated for RI. Estimated parameters indicated an overall lower fermentation activity of FI than RI. However, there was a very similar progression of GP curves of RI-GP and FI-GP. RI-GP after 24 h was significantly correlated with FI-GP in the time period of 24 to 60 h (r = 0.973 - 0.982, including all feed samples). Linear regression analysis showed that RI-GP after 24 h can be estimated from FI-GP after 24 h (Slope = 1.02, R2 = 0.97) and 48 h (Slope = 1.1, R2 = 0.97) including the complete data set. Splitting the data set into roughages and concentrate feeds did not lead to distinctly higher estimation accuracy. In conclusion, sheep faeces can be used as an alternative inoculum for studying a wide range of different-quality feedstuffs. The standard gas test may be modified without the need for rumen-cannulated animals.

Modulation of Rumen Microbes Through Extracellular Vesicle Released by the Rumen Fluke Calicophoron daubneyi

Parasite derived extracellular vesicles (EVs) have been proposed to play key roles in the establishment and maintenance of infection. Calicophoron daubneyi is a newly emerging parasite of livestock with many aspects of its underpinning biology yet to be resolved. This research is the first in-depth investigation of EVs released by adult C. daubneyi. EVs were successfully isolated using both differential centrifugation and size exclusion chromatography (SEC), and morphologically characterized though transmission electron microscopy (TEM). EV protein components were characterized using a GeLC approach allowing the elucidation of comprehensive proteomic profiles for both their soluble protein cargo and surface membrane bound proteins yielding a total of 378 soluble proteins identified. Notably, EVs contained Sigma-class GST and cathepsin L and B proteases, which have previously been described in immune modulation and successful establishment of parasitic flatworm infections. SEC purified C. daubneyi EVs were observed to modulate rumen bacterial populations by likely increasing microbial species diversity via antimicrobial activity. This data indicates EVs released from adult C. daubneyi have a role in establishment within the rumen through the regulation of microbial populations offering new routes to control rumen fluke infection and to develop molecular strategies to improve rumen efficiency.

Effect of dry medicinal plants (wormwood, chamomile, fumitory and mallow) on in vitro ruminal antioxidant capacity and fermentation patterns of sheep

The objective of this study was to determine the effect of dry medicinal plants (wormwood, chamomile, fumitory and mallow) and dietary substrates containing a mix of the plants on the end products of in vitro ruminal and intestinal fermentation, rumen protozoan population and ruminal antioxidant capacity of sheep. The experiment consisted of fermentations with the four plants used individually as the sole substrate and fermentation of a mix of medicinal plants (Plants): meadow hay:barley grain (MH:B), 700/300 w/w and Plants:MH:B, 100/600/300 w/w/w. The experiment was conducted using the in vitro gas production technique (IVGPT) with 35 ml of buffered inocula and approximately 250 mg (DM basis) of substrate incubated for 24 hr at 39°C in anaerobic conditions. Quantitative analyses of the bioactive compounds by ultra-high-resolution mass spectrometry in Plants identified three main groups: flavonoids (22 mg/g DM), phenolic acids (15 mg/g DM) and alkaloids (3 mg/g DM). The total antioxidant capacity (TAC) of the plant extracts and rumen fluid was analysed using a ferric reducing antioxidant power assay. The values of total and individual short-chain fatty acids, acetate:propionate ratio, pH and total gas production were significantly affected by the single plant substrates and inocula (p < .001). Apart from these parameters, the values of ammonia N, methane production and total gas produced were decreased in Plants:MH:B in comparison with MH:B (p < .001). A positive correlation was recorded between total polyphenols content and TAC of plant extracts (R2  = .778, p < .001). The counts of the total ciliate protozoan population in rumen fluid after 24 hr of fermentation were not significantly different (p > .05). Results suggest that the dietary substrate containing the medicinal plant mix possessed strong ruminal antioxidant capacity, had the potential to reduce methane emission and ammonia concentration and caused desirable changes in the gastrointestinal ecosystem.

In Vitro Techniques Using the DaisyII Incubator for the Assessment of Digestibility: A Review

Simple Summary

The Ankom Daisy^II incubator (AD^II; Ankom Technology Corporation Fairport, NY, USA) has gained acceptance as an alternative to traditional in vitro procedures. It reduces the labour requirement and increases the number of determinations that can be completed by a single operator. The apparatus allows for the simultaneous incubation of several feedstuffs in sealed polyester bags in the same incubation vessel, which is rotated continuously at 39.5 °C. With this method, the material that disappears from the bag during incubation is considered digestible. The method, which was first developed to predict the digestibility of feedstuffs for ruminants, has been modified and adapted to improve its accuracy and prediction capacity. Modifications used by various researchers include the use of different inocula, buffer solutions, and sample weights. Recently, attempts have been made to adapt the method to determine nutrient digestibility of feedstuff in non-ruminant animals, including pets.

Abstract

This review summarises the use of the Ankom Daisy^II incubator (AD^II; Ankom Technology Corporation Fairport, NY, USA), as presented in studies on digestibility, and its extension to other species apart from ruminants, from its introduction until today. This technique has been modified and adapted to allow for different types of investigations to be conducted. Researchers have studied and tested different procedures, and the main sources of variation have been found to be: the inoculum source, sample size, sample preparation, and bag type. In vitro digestibility methods, applied to the AD^II incubator, have been reviewed, the precision and accuracy of the method using the AD^II incubator have been dealt with, and comparisons with other methods have been made. Moreover, some hypotheses on the possible evolutions of this technology in non-ruminants, including pets, have been described. To date, there are no standardised protocols for the collection, storage, and transportation of rumen fluid or faeces. There is also still a need to standardise the procedures for washing the bags after digestion. Moreover, some performance metrics of the instrument (such as the reliability of the rotation mechanism of the jars) still require improvement.

Fermentation of fibre rich ingredients exposed in vitro to the faecal inoculums of swine and turkeys

This study was focused on in vitro fermentation and in vitro dry matter (DM) digestibility of different fibre rich ingredients that can be used in diets of pigs and turkeys. In vitro DM digestibility was determined by Daisy system via using faecal or excreta fluid of swine/turkeys as a source of inoculum. The ingredients used as substrates were commercial swine or turkey diet, dried beet pulp, wheat bran, hay, straw and two types of lignocelluloses (A and B). Marked differences between the ingredients were found and the values were: dried beet pulp (80%), swine/turkey diet (75%), wheat bran (60%), hay (40%) and straw (10%–20%). Of special interest are the data on the two lignocellulose products, the in vitro DM digestibility of product A was in the range of 20% (in turkeys) up to 30% (in pigs), whereas the product B had values of <5%. Moreover, the inoculums were incubated with the same substrates for 24h using gas measuring technique. Consecutively, commercial swine or turkey diet, dried beet pulp, wheat bran and hay produced high amounts of gas and volatile fatty acids. Lignocellulose A and straw provided lower and equal amounts of gases and fatty acids. However, lignocellulose B showed very little fermentation compared to the product A. In conclusions, faecal or excreta can be used as a source of microbial activity to determine the in vitro DM digestibility or fermentation of feeds. Comparing lignocellulose products with traditional fibre sources, the DM digestibility of lignocellulose A was greater than straw but its fermentation rate seems to be equal to straw. Thus, lignocellulose A can be used as a new source of fibre in diets of monogastric animals to optimize the gut health and improving the faeces or excreta quality.

Exogenous enzyme on in vitro gas production and ruminal fermentation of diet containing high level of concentrate

SUMMARY Exogenous enzyme preparations (fibrolytic activity (FIB), 0, 0.6, 1.2, 1.8, and 2.4 mg/ml liquid volume incubated; amylolytic activity (AMZ), 0, 0.05, 0.10, 0.15, and 0.20 mg/ml liquid volume incubated; proteolytic activity (PRO), 0, 0.05, 0.10, 0.15, and 0.20 mg/ml liquid volume incubated) were incubated in vitro. Their fermentation effects were assessed based on accumulated gas production, kinetic parameters, and fermentation profile using the technique of gas fermentation. Ruminal liquid was obtained from two rumen cannulated Santa Inês sheep, fed a diet with roughage-to-concentrate ratio of 20:80. Accumulated gas production was during 96 h of incubation, measured at 18 different times. After incubation, pH, dry matter degradability (DMD), organic matter in vitro digestibility (OMD), metabolisable energy (ME), partitioning factor (PF96), gas yield (GY24), short chain fatty acids (SCFA), and microbial protein production (MCP) were evaluated. Increasing FIB dose linearly decreased (P<0.05) lag time without affecting others kinetic parameters. However, FIB increased the accumulated gas production, resulting in improved DMD, OMD, ME, GY24 and SCFA. The addition of AMZ decreased linearly (P<0.05) lag time and increased (P<0.05) gas production on initial times of incubation without altering the fermentation profile. The inclusion of PRO did not affect (P>0.05) the evaluated parameters. The addition of these exogenous enzyme preparations with fibrolytic activity altered ruminal fermentation in vitro of diets containing high levels of concentrates.

Modulation of ruminal and intestinal fermentation by medicinal plants and zinc from different sources

Two experiments were conducted on sheep to determine the effect of dietary supplementation with zinc and a medicinal plant mixture on haematological parameters and microbial activity in the rumen and large intestine. In Experiment 1, 24 male lambs were randomly divided into four groups: One group was fed an unsupplemented basal diet (control), and three groups were fed a diet supplemented with 70 mg Zn/kg diet in the form of Zn sulphate (ZnSO₄ ), a Zn-chelate of glycine hydrate (Zn-Gly) or a Zn-proteinate (Zn-Pro), for five months. The ruminal content was collected separately from each lamb, and batch cultures of ruminal fluid were incubated in vitro with mixture of medicinal plants (Mix) with different roughage:concentrate ratios (800:200 and 400:600, w/w). Bioactive compounds in Mix were quantified by UPLC/MS/MS. In Experiment 2, four sheep were fed a diet consisting of meadow hay and barley grain (400:600, w/w), with Zn-Gly (70 mg Zn/kg diet), Mix (10% replacement of meadow hay) or Zn-Gly and Mix (Zn-Gly-Mix) as supplements in a Latin square design. Mix decreased total gas (p < 0.001) and methane (p < 0.01) production in vitro. In Experiment 1, caecal isobutyrate and isovalerate concentrations varied among the dietary treatments (p < 0.01). The isovalerate concentration of the zinc-supplemented groups in the distal colon was higher (p < 0.001) compared with the control. In Experiment 2, the molar proportion of isobutyrate was the highest in the faeces of the sheep fed the diet with Zn-Gly-Mix (p < 0.01). The plasma zinc concentration was higher in the groups fed a diet supplemented with zinc (p < 0.001). The haematological profile and antioxidant status did not differ between the dietary groups (p > 0.05). The diets containing medicinal plants and organic zinc thus helped to modulate the characteristics of fermentation in ruminants.

In vitro analysis of the effect of supplementation with activated charcoal on the equine hindgut

The present study uses in vitro analytical techniques to investigate the effect of activated charcoal on the microbial community of the equine hindgut and the metabolites they produce. Incubations were performed in Wheaton bottles using a 50 ml incubation of a high-energy feed or a low-energy feed, plus bottles with no added food source, together with five levels of activated charcoal (0, 10, 25, 50 or 100 mg per bottle) and fecal samples as a bacterial inoculum. Using this method the rate of gas production, volatile fatty acid and ammonia concentrations, and pH values were analyzed and found to vary depending on the addition of feed, but the activated charcoal had no effect (P>0.05) on any of these. It is already believed that the effect of activated charcoal as a control for toxic substances is at its highest in the foregut or midgut of animals, and therefore should have little impact on the hindgut. The data presented here suggest that if any of the activated charcoal does reach the hindgut, then it has no significant impact on the microbial community present, nor on the major metabolites produced, and so should not have a detrimental effect on the principal site of fermentation in the horse.

Quantification of organic acids in ruminal in vitro batch culture fermentation supplemented with fumarate using a herb mix as a substrate

Two 24 h in vitro batch culture experiments were conducted to investigate the effects of fumarate addition (10 mmol L−1) on the ruminal fermentation parameters of selected medicinal herbs, and the effects of different doses of fumarate (0, 10, or 30 mmol L−1) on ruminal metabolism of organic acids when a high-concentrate diet (meadow hay and barley grain, 400/600, w/w) was supplemented with a mix of medicinal herbs (Artemisia absinthium L., Melissa officinalis L., Malva sylvestris L., Matricaria chamomilla L., Plantago lanceolata L., Foeniculum vulgare Mill., and Althaea officinalis L.). Depending on the concentration, fumarate treatment decreased methane production (by 10–11%) and increased propionate proportions (by 5–13%) with high-concentrate diets. The organic acid (fumaric, succinic, malic, and lactic acid) concentrations in the batch culture were measured at intervals of 0, 4, 6, 12, and 24 h. The time and organic acid concentrations with 10 mmol L−1 fumarate were well correlated (R 2 = 0.846). The amount of succinate was accumulated and metabolized more slowly than that of fumarate (>24 h). The addition of fumarate and a herb mix could positively influence in vitro ruminal fermentation parameters of high-concentrate diets by increasing the levels of propionate and succinate as well as the pH, and by decreasing of methane emissions.

Substrates enriched by the fungus Cunninghamella echinulata: an in vitro study of nutrient composition, sheep rumen fermentation and lipid metabolism

AIMS

Enrichment of wheat bran (WB), corn meal (CM) and barley flakes (BF) with the oleaginous fungus Cunninghamella echinulata (CE) might lead to effective use of these by-products in ruminant nutrition. We examined their effects on rumen fermentation and lipid metabolism.

METHODS AND RESULTS

WB, CM and BF substrates without or with brewer's grains (WBG, CMG, BFG) and enriched with CE were incubated with meadow hay (MH, 500 : 500, w/w) in rumen fluid in vitro for 24 h. The dry matter of the CE-enriched substrates increased (by 2-4%); however, digestibility decreased (P < 0·01). Adverse effects of CE-enriched substrates on the rumen ciliate population were observed. Little effect on the rumen eubacterial population was detected by the 16S-polymerase chain reaction/denaturizing gradient gel electrophoresis method. The increase in γ-linolenic acid output in the MH + BFGCE diet (800 : 200, w/w) was accompanied by an increase in rumen biohydrogenation of polyunsaturated fatty acids.

CONCLUSION

The diet substrates enriched with the fungus CE were less digestible than the untreated cereal substrates; no appreciable positive effect was observed on rumen fermentation patterns or the eubacterial and ciliate populations.

SIGNIFICANCE AND IMPACT OF THE STUDY

The in vitro study showed that adding CE-enriched substrates to ruminant diets is not effective for improving rumen fermentation.

In vitro fermentation characteristics of diets with different forage/concentrate ratios: comparison of rumen and faecal inocula

BACKGROUND

The aim of this trial was to evaluate the replacement of rumen fluid with faeces as inoculum in studying the in vitro fermentation characteristics of diets for ruminants using the in vitro gas production technique. Six iso-protein diets with different forage/concentrate ratios were incubated with rumen fluid (RI) or faeces (FI) collected from sheep.

RESULTS

Most of the fermentation parameters were influenced by diet and inoculum (P < 0.01). With both inocula, organic matter degradability (dOM), cumulative gas production (OMCV) and maximum fermentation rate (R(max) ) increased as the amount of concentrate in the diet increased. R(max) was lower with FI vs RI (P < 0.01); dOM was higher with FI vs RI and the diet × inoculum interaction was significant. As expected, with both inocula, R(max) increased as the neutral detergent fibre content of the diet decreased. Significant correlations were obtained using both inocula between OMCV/dOM and gas/volatile fatty acid (VFA), while the correlation VFA/dOM was significant only with FI. The microbial biomass yield calculated by stoichiometric analysis for all diets was higher with FI vs RI. With FI the organic matter used for microbial growth showed an overall decreasing trend as the amount of concentrate in the diet increased.

CONCLUSION

The results indicate that both faeces and rumen fluid from sheep have the potential to be used as inoculum for the in vitro gas production technique.

Effects of high- and low-fiber diets on fecal fermentation and fecal microbial populations of captive chimpanzees

We examined fiber fermentation capacity of captive chimpanzee fecal microflora from animals (n = 2) eating low-fiber diets (LFDs; 14% neutral detergent fiber (NDF) and 5% of cellulose) and high-fiber diets (HFDs; 26% NDF and 15% of cellulose), using barley grain, meadow hay, wheat straw, and amorphous cellulose as substrates for in vitro gas production of feces. We also examined the effects of LFD or HFD on populations of eubacteria and archaea in chimpanzee feces. Fecal inoculum fermentation from the LFD animals resulted in a higher in vitro dry matter digestibility (IVDMD) and gas production than from the HFD animals. However, there was an interaction between different inocula and substrates on IVDMD, gas and methane production, and hydrogen recovery (P <0.001). On the other hand, HFD inoculum increased the production of total short-chain fatty acids (SCFAs), acetate, and propionate with all tested substrates. The effect of the interaction between the inoculum and substrate on total SCFAs was not observed. Changes in fermentation activities were associated with changes in bacterial populations. DGGE of bacterial DNA revealed shift in population of both archaeal and eubacterial communities. However, a much more complex eubacterial population structure represented by many bands was observed compared with the less variable archaeal population in both diets. Some archaeal bands were related to the uncultured archaea from gastrointestinal tracts of homeothermic animals. Genomic DNA in the dominant eubacterial band in the HFD inoculum was confirmed to be closely related to DNA from Eubacterium biforme. Interestingly, the predominant band in the LFD inoculum represented DNA of probably new or yet-to-be-sequenced species belonging to mycoplasms. Collectively, our results indicated that fecal microbial populations of the captive chimpanzees are not capable of extensive fiber fermentation; however, there was a positive effect of fiber content on SCFA production.