A comparison between buffalo (Bubalus bubalis) and cow (Bos taurus) rumen fluids in terms of the in vitro fermentation characteristics of three fibrous feedstuffs

Rumen fluids from fistulated buffalos (Italy‐BRF) and cows (Netherlands‐CRF) were used as inocula to determine the fermentation kinetics of three forages. These were corn silage (CS), grass silage (GS) and wheat straw (WS) which had originated from both regions, giving six substrates in total. Fermentation kinetics was assessed by the measurement of cumulative gas production. Organic matter (OM) loss and volatile fatty acid (VFA) concentration at the end of the fermentation period were also determined. Both BRF and CRF ranked the substrates in the same order for total VFA, total gas production and the maximum rate of substrate degradation (CS > GS > WS). However, while the ranking of substrates was the same for both species, the absolute values differed significantly between the two inocula. Gas production, expressed as cumulative volume per unit mass of incubated (OMCV, ml g^?1) and as cumulative volume per unit mass of OM degraded (OM ml g^?1) for CRF was consistently higher than that for BRF for all substrates (p < 0.0001). VFA production, particularly of acetic and butyric acids, was significantly (p < 0.0001) lower for BRF than for CRF, though the digestibility of OM was the same for both inocula. VFA production predicted by the use of stoichiometric equations was generally higher than the observed gas production. These equations also predicted that the calculated amount of OM utilised for microbial growth was higher for BRF than for CRF. This may explain why diets having the same energy content but less protein can be fed to buffalo since they seem to have a lower requirement for protein compared with cattle. This possibility will need to be investigated in vivo. Given the similar ranking of feedstuffs between the two sources of inocula, these results suggest that either inoculum would be suitable for use in the cumulative gas production test as a measure of feedstuff evaluation. However, given the differences in absolute values, it is recommended that inocula from the species which will receive the feedstuff should be used. Copyright © 2004 Society of Chemical Industry     

In vitro degradability of three forages: fermentation kinetics and gas production of NDF and neutral detergent‐soluble fraction of forages

The fermentation of the neutral detergent‐soluble (NDS) fraction of three forages (alfalfa hay, Italian ryegrass + oats hay and corn silage) was measured using a curve subtraction technique with in vitro gas production data from the whole forage (WF) and the isolated neutral detergent fibre (NDF). NDF disappearance and volatile fatty acid (VFA) production were determined. There was no significant difference between the VFA patterns from the whole forage and the isolated NDF. There were significant (P < 0.001) linear correlations between the volume of gas and moles of VFA produced and the mass of fibre digested in the NDF samples. Using the monophasic curve model, maximum gas production rates (R_M) for the whole forages and the isolated NDF and NDS fractions can be calculated. For all three forages we obtained R_M‐NDS > R_M‐WF > R_M‐NDF. Trends in the rates of gas and VFA production were similar in the whole forages. The NDF showed a high superimposition between substrate degradability and VFA production. Our experiment confirmed the curve subtraction technique as a simple method to obtain information on the size and digestion kinetics of the NDS fraction, which helps in understanding the nutritional significance of this important fraction of the forages studied. © 2001 Society of Chemical Industry     

Repeated measurements of in vitro fermentation of fibre‐rich substrates using large intestinal microbiota of sows

BACKGROUND: Fibrous ingredients for pig diets can be characterized by in vitro fermentation. In vitro fermentation methods often use a one‐time measurement of gas production during the incubation of test substrates with one faecal inoculum. The representativeness of this approach can be questioned as measuring time and number of animals from which inoculum originates may influence fermentation results. An in vitro fermentation trial was conducted incubating three fibrous substrates with three inocula in five replicates (different fermentation runs) to test the influence of run and origin of inocula. RESULTS: Total gas production and maximal rate of gas production differed (P < 0.05) between fermentation runs, but less than substrates (P < 0.01). The ranking order between substrates remained similar for each run. Fermentation of cellulose led to higher coefficients of variation between inocula compared to the fast fermentable substrates oligofructose and soy pectin. Differences ranged from 2% for total gas production up to 25% for maximal rate of gas production. CONCLUSION: One fermentation run can provide representative results for substrate ranking. Using multiple inocula mixed from four faecal samples each leads to high coefficients of variation for slow fermentable substrates like cellulose. Future studies should examine the optimal number of animals for inocula preparation to decrease variation. © 2012 Society of Chemical Industry     

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. Copyright © 2011 Society of Chemical Industry     

Uncooked Taiwanese yam (Dioscorea alata L. cv. Tainung No. 2) beneficially modulated the large bowel function and faecal microflora in BALB/c mice

This study investigated the effects of an uncooked Taiwanese yam, Dioscorea alata L. cv. Tainung No. 2, on faecal characteristics, faecal microflora, short‐chain fatty acid (SCFA) levels in the caecal content and faeces, and morphological and proliferation indices of the caecal and colonic crypts in BALB/c mice. Mice were randomly allocated to consume a control diet or a 25 or 50% (w/w) yam diet for 21 days. Faecal wet and dry masses increased with increasing proportions of dietary yam. Both yam diets similarly increased faecal moisture content and decreased faecal pH as compared with the control diet. The yam diets increased total bacteria and bifidobacteria counts and decreased Clostridium perfringens counts in faeces. The 50% yam diet, but not the 25% yam diet, increased total SCFA concentration in the caecal content. However, both yam diets increased total SCFA output in faeces. Both yam diets also promoted crypt depth, width and proliferation indices in the caecum; in contrast, they only promoted crypt width in the distal colon. In conclusion, the 25 and 50% yam diets increased the faecal mass and SCFA output, modulated the faecal microflora and thickened the mucosa lining of the caecum in BALB/c mice. Copyright © 2007 Society of Chemical Industry     

In vitro fermentation of rye carbohydrates including arabinoxylans of different structure

Freeze‐dried ileal effluent from cannulated pigs fed rye bread diets based on either whole rye or one of three rye milling fractions enriched in pericarp/testa, aleurone and endosperm was incubated in an in vitro fermentation system with faecal inocula from pigs fed a whole grain rye diet. Three and 48 hours of in vitro degradation of arabinoxylans were comparable to the caecal and faecal degradation respectively. The productions of short‐chain fatty acids were highest from the ileum samples of the diets high in fermentable carbohydrates (whole rye, aleurone and endosperm). However, fermentation of the pericarp/testa ileum sample produced half the amount of short‐chain fatty acids resulting from the other ileum samples despite the fact that the pericarp/testa carbohydrates (CHO) were not fermented at all. Treating the pericarp/testa with alkali prior to the incubation increased fermentability considerably (from 0 to 49% of total arabinoxylans) and suggested that, at least in lignified tissue, alkali‐labile cross‐links were more important determinants of arabinoxylan (AX) degradability than AX structure itself. Oxidative delignification of the pericarp/testa ileal effluent increased fermentability too, but to a much lower degree, which indicates that the type and extent of links between polymers and lignin rather than the amount of lignin are important in determining degradability. © 2000 Society of Chemical Industry     

Evaluation of gastrointestinal transit in rats fed dietary fibres differing in their susceptibility to large intestine fermentation

The rate and extent of in situ digesta transit after ingestion of diets containing dietary fibres differing in their susceptibility to large intestine fermentation were investigated. One hundred and twenty rats were fed diets containing 7.5% cellulose, inulin, potato fibre or maize starch for 3 days, then the same diets with titanium dioxide (TiO₂) for 3 days, followed by diets without TiO₂ for 2 days. In all diets, TiO₂ ratios rapidly increased within 24 h and reached a maximum level in duodenum, caecum and colon within 2–3 days. Inulin, potato fibre and maize starch-fed rats showed higher levels of caecal short-chain fatty acids, lower faecal polysaccharide concentrations, and reduced faecal output than the rats fed cellulose. Inulin was highly susceptible to caecal microbial fermentation compared to the other dietary fibres. Transit of these dietary fibres through the GI tract was rapid, and the rate of digesta transit was not affected by dietary fibre fermentability in the large intestine.     

Assessment of the effect of condensed (acacia and quebracho) and hydrolysable (chestnut and valonea) tannins on rumen fermentation and methane production in vitro

BACKGROUND: Tannins added to animal diets may have a positive effect on energy and protein utilisation in the rumen. The objective of this study was to examine the impact of different sources and concentrations (20, 50, 100, 150 and 200 g kg^?1 dry matter (DM)) of condensed (acacia and quebracho) and hydrolysable (chestnut and valonea) tannins on rumen microbial fermentation in vitro. The experiment also included a negative control with no tannins (control) and a positive control with monensin (10 mg L^?1). RESULTS: In vitro gas production and total volatile fatty acid (VFA) concentration decreased as tannin concentration increased. Addition of acacia, chestnut or valonea tannins at ≥ 50 g kg^?1 or quebracho tannins at ≥ 100 g kg^?1 resulted in a decrease (up to 40%) in methane (CH₄) production compared with the control. Valonea tannins were the only tannin source that reduced (?11%) CH₄ production at 50 g kg^?1 without affecting VFA concentration. Tannin treatments reduced ammonia (NH₃) and branched‐chain VFA concentrations, indicating a reduction in ruminal protein degradation. Monensin reduced CH₄ production (?37%) and NH₃ concentration (?20%) without affecting total VFA concentration. CONCLUSION: Supplying acacia, chestnut or valonea tannins at 50 g kg^?1 has the potential to reduce CH₄ production and ruminal protein degradation with minimum detrimental effects on efficiency of ruminal fermentation. Copyright © 2012 Crown in the right of Canada. Published by John Wiley & Sons, Ltd     

Difference in in vitro fermentability of four carbohydrates and two diets,using ileal and faecal inocula from unweaned piglets

An experiment was conducted to examine differences in the in vitro fermentability of four carbohydrate‐rich feed ingredients and two weaning piglet diets with and without these ingredients, using both the ileal contents and the faeces of unweaned piglets as inocula. In the first part of the experiment, cumulative gas production was measured over time, using faecal inocula mixed from nine specially raised crossbred piglets (no creep feed or antibiotics) at 3 weeks of age. Inulin, lactulose, unmolassed sugar beet pulp, wheat starch and the two diets were used as substrates and fermented in vitro for 72 h. Gas production was measured as an indicator of the kinetics of fermentation. Fermentation end‐products, including volatile fatty acids and ammonia, and organic matter loss, were also measured. For the fermentations of feed ingredients, samples were also collected for polymerase chain reaction/denaturing gradient gel electrophoresis analyses initially and after the fermentation process, to study changes in the composition of the bacterial community. This procedure was repeated 1 week later, using ileal contents from the same piglets as inoculum. There were significant differences between the inocula, in terms of both overall fermentation characteristics and composition and between the substrates. There was also a significant interaction between inocula and substrates, which suggests that there were potentially important differences in the microbial activity occurring in these two areas of the gastrointestinal tract (GIT). For the two diets, one with and one without addition of these fermentable ingredients, there were significant differences in terms of the kinetics, but less so in terms of the end‐products of fermentation. It was concluded that inocula from both the small and large intestine should be used to obtain a more accurate assessment of potential feed ingredients which will stimulate fermentation in the piglet GIT. Copyright © 2005 Society of Chemical Industry     

Fermentation characteristics of corn‐, triticale‐, and wheat‐based dried distillers' grains with solubles in barley‐based diets determined using continuous and batch culture systems

BACKGROUND: Dried distillers' grains with solubles (DDGS) are becoming increasingly available and popular as an alternative livestock feed. This study used continuous and batch culture techniques to compare the in vitro fermentation characteristics of diets containing corn‐, triticale‐ or wheat‐based DDGS at 200 g kg^?1 diet dry matter (DM) against a barley grain‐based control diet. RESULTS: In continuous fermentation of wheat DDGS diet, total volatile fatty acid (VFA) concentration was decreased by 15.7% across sampling times and NH₃ concentration was quadrupled compared with control, whereas fermentations of corn‐ and triticale‐DDGS diets were similar to the barley‐based control. In batch cultures, corn DDGS differed from control only in increased culture pH. Compared with control diet, triticale DDGS yielded lower total gas production (140.94 versus 148.78 mL g^?1 DM) and in vitro DM digestibility (IVDMD; 0.509 versus 0.535). Wheat DDGS diet yielded decreased total gas production (123.49 mL g^?1 DM) and IVDMD (0.468), as well as total VFA production (105.84 versus 134.20 mmol L^?1) and substantially increased ammonia concentration (151.61 versus 58.34 mg L^?1) and acetate:propionate ratio (2.94 versus 1.11). CONCLUSION: Corn‐ and triticale‐ DDGS diets exhibited fermentation characteristics similar to the barley based control diet, consistent with in vivo findings that these diets yielded no adverse effects on production. In vitro ruminal fermentation of wheat DDGS diet differed significantly from control in several aspects including 2.6 to 6X higher ammonia concentrations. Copyright © 2010 Crown in the right of Canada. Published by John Wiley & Sons, Ltd     

Spatial variation of intestinal skatole production and microbial community in Jinhua and Landrace pigs

BACKGROUND: An excessive accumulation of skatole in pigs is a major contributor to boar taint. Intestinal skatole concentrations may vary among different pig segments and breeds. The objective of this study was to evaluate the spatial variation of intestinal skatole production and the microbial community in local Jinhua and exotic Landrace pigs. RESULTS: For both breeds, skatole concentration increased towards the rectum and segment had a significant effect on skatole (P < 0.001). The caecal skatole concentration in Landrace was significantly lower than proximal, distal colonic and rectal skatole levels (P < 0.05). Compared with Jinhua pigs, the rectal skatole and proximal and distal colonic indole levels were significantly higher in Landrace pigs (P < 0.05). Volatile fatty acids were significantly affected by breed except for isobutyrate and isovalerate (P < 0.05), with higher butyrate level and lower pH in Landrace pigs (P < 0.05). There were no significant differences in mitosis and apoptosis for the two breeds. The denaturing gradient gel electrophoresis profile showed differences between breeds and segments within one breed, though some bands were common to all samples. CONCLUSION: The higher skatole levels in Landrace pigs may be not associated with higher intestinal apoptosis. The results suggested that pig genotype plays a role in the establishment of the host‐specific microbiota and that the variations in fermentation patterns are more likely to explain differences in intestinal skatole production. Copyright © 2009 Society of Chemical Industry     

Long‐term effects on the digestive tract of feeding large amounts of resistant starch: A study in pigs

The present study aimed to assess the digestive consequences of the long‐term intake of two starches providing different amounts of resistant starch. Growing pigs were used as the animal model and meal‐fed for 14 weeks on a diet containing a high amount of either raw potato starch (RPS) or corn starch (CS). Digestive adaptation was chronologically evaluated by measuring organic matter (OM), crude protein (CP), neutral detergent fibre (NDF) and starch digestibility. After 97 days, whole‐tract digestibility of OM, CP and NDF was lower for RPS‐ compared to CS‐fed pigs, whereas no differences were observed in faecal starch digestibility. In contrast, starch digestibility was reduced in the proximal compartments (ileum, caecum and proximal colon) of animals fed the RPS diet. The concentration of short‐chain fatty acids (SCFAs; P < 0.05), and purine bases (PBs; P < 0.01) was also higher in distal colon and rectum of animals fed the RPS diet. Changes in bacterial community structure (dendogram analyses) were seen in the rectum. Biodiversity tends to increase more in RPS compared to CS fed animals (34.1 vs. 28.8; P = 0.07). Among SCFAs, the proportion of butyrate was two‐fold higher in proximal colon digesta of RPS compared to CS fed pigs (0.20 vs. 0.11; P < 0.05). Increased butyrate formation in the colon reduced the number of apoptosis per crypt in the proximal colonic mucosa (0.38 vs. 0.62; P < 0.05). RPS fermentation reduced indices associated with damage to intestinal epithelial cells, such as crypt cell hyperproliferation and magnesium excretion. Long‐term ingestion of RPS induces pronounced changes of the digestive tract and their microflora, modifying mineral absorption and colonic morphology for which health benefits are likely to be associated. Copyright © 2007 Society of Chemical Industry     

Effects of ingestion of a green seaweed,Ulva lactuca,upon caecal and colonic mucosas in the germ‐free rat and in the heteroxenic rat harbouring a human bacterial flora

Effect of ingestion of green seaweed, Ulva lactuca, (70 g kg⁻¹) during a 6‐week period on caecal and colonic mucosas was studied in germ‐free (GF) rats and in heteroxenic (HE) rats harbouring a human bacterial flora (GF rats associated with a human flora). The pH and sulphide concentration of the caecal contents, crypt morphometry, mitotic index and mucin types in the caecal and distal colonic mucosas were determined. In the GF caecum, Ulva strongly increased crypt depth and mucin‐containing cells irrespective of the mucin type studied (neutral, acidic or sulphated) compared to the control diet but had no significant effect on mitotic index. The crypt depth and mucin‐containing cells in the caecum were higher in HE than in GF control rats. They were slightly but significantly increased by Ulva. In the distal colon mucosa of GF rats, Ulva decreased crypt depth and cell number as well as sulphomucin‐containing cells. Conversely, in the HE rats, it increased crypt depth and reduced the number of neutral mucin‐containing cells. These results show that Ulva lactuca exerts an intrinsic effect on mucosal morphometry and on mucin biosynthesis in GF rats. No pathological alteration was observed in the mucosas and no significant modification of the mitotic index or sulphide production was observed in HE rats. © 1999 Society of Chemical Industry     

Effect of substrate adaptation on the microbial fermentation and microbial composition of faecal microbiota of weaning piglets studied in vitro

The in vitro cumulative gas production technique can be used to assess microbial activity of a complex community, in relation to fermentation of a particular energy source. Therefore, in combination with an in vivo study to examine the effects of two different diets for weaning piglets, microbial activities of faeces were compared from animals on the two different diets. The two diets were: CHO diet [containing added fermentable carbohydrates, including sugarbeet pulp (SBP) and wheat starch (WST)], and control diet without any added fermentable carbohydrates. Neither diet contained antibiotics or extra added copper. Twenty‐four piglets were selected from 12 litters (two per litter), weaned at 4 weeks of age (neither creep feeding nor any antibiotic treatment before and during the study), and introduced to one of the two diets. After 9 days on the diet, faecal samples were collected from selected animals, and tested for their activity in terms of gas production kinetics, and end‐products such as volatile fatty acids, ammonia and dry matter disappearance of the two test substrates SBP and WST. The bacterial diversity was also analysed before and after in vitro fermentation using denaturing gradient gel electrophoresis analysis of amplified 16S rRNA genes. There were differences both in kinetics and end‐products of the substrates. More interestingly, significant differences were detected between inocula, although mainly in terms of fermentation kinetics of the two substrates. With the CHO inoculum, SBP was fermented faster than with the control, while this effect was reversed for WST. Significantly higher diversity, as measured by DGGE fingerprint analysis, was detected in the microbial community enrichment on SBP as compared with WST at the end of fermentation. The difference between the kinetics of SBP compared with WST fermentation by faecal microbiota from the CHO diet fed piglets suggests better adaptation to SBP fermentation than to WST fermentation. The WST fermentation was more unexpected, given that a significant amount of starch is known to be fermentable by the small intestinal microbiota. It was concluded that the microbial community composition and activity in the GIT may be changed in response to diet, and that this change can be detected in vitro. Copyright © 2005 Society of Chemical Industry     

In vitro fermentation kinetics of carbohydrate fractions of fresh forage,silage and hay of Avena sativa

The objective of this experiment was to evaluate the influence of preservation methods on the fermentation kinetics of carbohydrate fractions of fresh forage, hay and silage of oats, which have been harvested at the milky stage of grain ripening. Samples of unfractionated forage (WF), residue insoluble in 90% ethanol (EIR) and isolated neutral detergent fibre (NDF) were fermented in vitro and the gas production was monitored. To obtain the gas production and fermentation kinetics of the ethanol‐soluble fraction (A fraction) the gas produced from the EIR fermentation was subtracted from the WF gas at each time point. The same approach was used to obtain the gas production and fermentation kinetics of the fraction insoluble in 90% ethanol but soluble in neutral detergent solution (B₁ fraction), by subtracting the isolated NDF gas curve from the corresponding EIR curve. The fractional maximum rate of gas production (R_M) was lower for both preserved forages (p < 0.01 for silage; p < 0.05 for hay) than for fresh forage. Ensiling did not change the size of the A fraction but reduced by 40% its R_M (p < 0.01) compared with fresh forage. The potential gas production from the B₁ fraction and its R_M were reduced by 19% (p < 0.01) and 44% (p < 0.05), respectively. R_M of both A and B₁ fractions was the same for hay and fresh forage. The curve subtraction technique may be used to obtain an estimation of the rate for neutral detergent‐soluble fractions and to determine changes due to ensiling and haymaking on the rate of gas produced. Copyright © 2005 Society of Chemical Industry     

Effects of California chaparral plants on in vitro ruminal fermentation of forage and concentrate diet

BACKGROUND: The combustible nature of chaparral plants has been attributed to the presence of secondary compounds such as phenolic acids, flavonoids and essential oils, among others. However, the implication of the antimicrobial properties of secondary compounds of chaparral in modulating rumen microbial metabolism has not been determined. The effects of 11 chaparral plants on rumen microbial fermentation were assessed in an in vitro batch culture fermentation fed a barley silage:barley grain‐based low concentrate (LC) and high concentrate (HC) diets. RESULTS: With LC, gas production [g dry matter (DM) incubated] and DM disappearance (DMD) were unaffected by Adenostoma fasciculatum, Ceanothus cuneatus, Baccharis pilularis or Eriodictyon californicum, but all plants except C. cuneatus decreased (P < 0.05) CH₄ production. With HC diet, all species except A. fasciculatum decreased (P < 0.01) total gas produced. Total volatile fatty acids (VFA) produced, molar proportions of acetate, propionate and butyrate, and the acetate:propionate (A:P) ratio were unaffected by chaparral addition to both HC and LC diets. Increased concentrations of A. fasciculatum and E. californicum decreased (linear; P < 0.05) fermentability and productions of CH₄ and NH₃‐N. CONCLUSION: Among all chaparral species investigated A. fasciculatum and E. californicum added as 10% of LC diet showed some potential to exert beneficial effects on rumen microbial fermentation. © Her Majesty the Queen in Right of Canada 2012     

Different concentrations of grape seed extract affect in vitro starch fermentation by porcine small and large intestinal inocula

BACKGROUND: Grape seed extract (GSE) phenolics have potential health‐promoting properties, either from compounds present within the extract, or metabolites resulting from gastrointestinal tract (GIT) fermentation of these compounds. This study describes how GSE affected the kinetics and end‐products of starch fermentation in vitro using pig intestinal and fecal inocula. Six GSE concentrations (0, 60, 125, 250, 500, and 750 µg ml^?1 were fermented in vitro by porcine ileal and fecal microbiota using starch as the energy source. Cumulative gas production, and end‐point short chain fatty acids and ammonia were measured. RESULTS: GSE phenolics altered the pattern (gas kinetics, and end‐products such as SCFA and NH ) of starch fermentation by both inocula, at concentrations above 250 µg ml^?1. Below this level, neither inoculum showed any significant (P > 0.05) effect of the GSE. CONCLUSION: The results show that GSE phenolics at a concentration over 250 µg ml^?1 can have measurable effects on microbial activity in an in vitro fermentation system, as evidenced by the changes in kinetics and end‐products from starch fermentation. This suggests that fermentation patterns could be conceivably shifted in the actual GIT, though further evidence will be required from in vivo studies. Copyright © 2012 Society of Chemical Industry     

Assessing fibre‐rich feedstuffs in pig nutrition: comparison of methods and their potential implications

BACKGROUND: In organic farming, roughage has to be added to pigs' daily rations for animal welfare reasons. Since little is known about how roughage affects pigs, seven carbohydrate‐rich feedstuffs (corn silage, ryegrass, turnip leaf, turnip tuber, Jerusalem artichoke and two types of clover–ryegrass silage) were tested using two different in vitro methods—total tract digestibility and the gas production technique—to determine apparent digestibility by observing organic matter loss. The aim was to determine whether the results of different methods and treatments lead to similar results or rankings. RESULTS: The in vitro enzymatic incubation method showed 3–20% lower fermentabilities than the in vitro fermentation process. The pretreatment of substrates with enzymes before fermentation led to similar fermentabilities but different gas production kinetics compared to the fermentation of untreated substrates. Using two different inocula generated no significant differences. When the feedstuffs were ranked by their fermentability, the rank order was relatively similar for both methods. CONCLUSIONS: Different methods and pretreatments lead to different fermentabilities while a ranking of the results gives a similar order. Both methods seem to be appropriate tools for assessing feedstuffs. In order to determine which feedstuff is best utilised by the animal, further investigations of both digestibility and gas production kinetics are required. Copyright © 2009 Society of Chemical Industry     

Effects of probiotic,prebiotic and synbiotic follow‐up infant formulas on large intestine morphology and bone mineralisation in rats

The effects of powder functional follow‐up infant formulas on the morphology of the large intestine and the bone mineral content in rats were investigated. Infant formulas were supplemented with probiotics (Bifidobacterium bifidum and Bifidobacterium longum), prebiotics (galacto‐oligosaccharides (4′‐GOS) at 12, 50 and 100 g kg^?1) or synbiotics (bifidobacteria and 4′‐GOS) and administered to seven groups of weanling rats over 30 days. After sacrificing the animals, the caecum and colon were removed and the luminal content pH and the crypt depth and cell density within the epithelial layer were measured. Results showed that groups fed synbiotic diets had significantly (P < 0.05) lower caecal and colonic content pH values compared with the control group. However, no test diet significantly modified the crypt depth or cell density in the caecum. In contrast, all seven test diets significantly increased (P < 0.05) the crypt depth in both the proximal and distal portions of the colon. There was a high correlation (Pearson correlation coefficient 0.870) between caecal and colonic content pH values. On the other hand, colonic content pH was negatively correlated with crypt depth in both the proximal and distal colon and with cell density in the distal colon. The authors previously reported increases in calcium, magnesium and phosphorus absorption using the same infant formulas. In the present study it was concluded that the increase in calcium absorption took place in the distal colon whereas magnesium absorption increased in both the proximal and distal colon, and their contents (especially that of calcium) increased in both the femur and tibia. Copyright © 2007 Society of Chemical Industry     

The fermentation of lactulose in rats inoculated with Clostridium paraputrificum influences the activities of liver and intestinal xenobiotic‐metabolising enzymes

One of the most recent hypotheses concerning the protective effect of some dietary fibres against colon cancer implicates butyrate. Very few publications have addressed its possible influence on the phase II enzymes and on the bacterial enzymes involved in the enterohepatic recirculation of toxic compounds. We used an original model of monoxenic rats oriented towards the preferential production of butyrate. Fischer male germ‐free rats were mono‐associated with a strain of Clostridium paraputrificum. They were fed either a control diet or a lactulose‐enriched diet for 6 weeks. In the caeco‐colon the specific activities (SAs) of the microsomal enzymes (glutathione‐S‐transferase and UDP‐glucuronosyl‐transferase) were 1.7‐fold those of the control rats. In the intestine and liver the SAs of the phase II enzymes were not altered, nor was the hepatic cytochrome P450. In the caecum of the lactulose‐fed rats the SA of β‐glucuronidase decreased by 27% and that of β‐glucosidase doubled. The chronic consumption of lactulose doubled the total caecal short‐chain fatty acids, and the production of butyrate was enhanced. Since the germ‐free rats behaved differently when fed the same diets, we concluded that the fermentation products of lactulose (and not the lactulose itself) were involved in the effects we describe. The involvement of butyrate in this phenomenon is discussed. © 2001 Society of Chemical Industry