Colonic Digesta Research Articles

Digesta retention patterns in geese (Anser anser) and turkeys (Meleagris gallopavo) and deduced function of avian caeca

Although it is well-known that retrograde transport of urine fills the caeca of birds with fluid and small particles, the function of avian caeca is still not fully understood. We measured mean retention times (MRT) of solute (cobalt-EDTA, Co), small particle (<2mm, chromium-mordanted fibre, Cr) and large particle (8mm, cerium-marked fibre, Ce) markers in geese (Anser anser) and turkeys (Meleagris gallopavo) fed alfalfa pellets ad libitum. Intake did not differ between species. Turkeys had longer MRT for all markers (Co: 10.4 vs. 3.2h; Cr 23.3 vs. 2.9h; Ce 9.5 vs. 2.1h), achieved a higher fibre digestibility, and had a higher calculated dry matter gut fill. Thus, geese and turkeys correspond to the typical dichotomy of good fliers vs. poor fliers/flightless species in avian herbivores. Because uric acid is fermented much faster by microbes than fibre, the ultimate cause of short-MRT digesta retention in avian caeca as in geese is possibly rather uric acid than fibre fermentation. The numerical differences between marker MRT in geese correspond to a colonic separation mechanism that delays the excretion of fluids more than small and again more than large particles. In contrast to geese, turkeys excreted solid and liquid (caecal) faeces. Liquid faeces contained less fibre and more crude protein than solid faeces and accounted for the excretion of 7, 25 and 34% of Ce, Co and Cr markers. Marker excretion patterns and MRT for liquid faeces (Co 15 vs. Cr 50h) suggest that small particles did not simply move in parallel to fluids, but were retained selectively by being trapped in colonic digesta upon expulsion from caeca, with subsequent repeated retrograde transport into caeca with the next batch of urine. Given the absence of coprophagy in birds (in contrast to small mammalian herbivores), such a delay of small (microbial) particle escape from the caeca appears reasonable.

Microbial Activity in the Large Intestine of Chicks Fed Diets with Different Types and Levels of Inulin

Abstract The aim of the study was to evaluate the effects of dietary level of two types of inulin differing in the degree of polymerization (DP) on microbial activity in the large intestine of chicks. The experiment was performed on 70 one-day-old Ross 308 male chicks divided into 7 groups fed starter-type diets without inulin addition or supplemented with 0.2%, 0.4% or 0.6% of inulin with DP≥10 (IN10), or DP≥23 (IN23). After 14 days of feeding birds were sacrificed to collect digesta samples from caeca and colon. Caecal digesta was examined for pH, concentrations of short-chain fatty acids (SCFA) and amines, activities of β-glucosidase and mucinase, and relative amount of selected bacterial populations, whereas in colonic digesta only pH, SCFA and amines were analysed. Regardless of DP, inulin level did not affect digesta pH, activity of bacterial enzymes and relative amounts of Clostridium spp., Lactobacillus spp., Bifidobacterium spp. and E. coli populations. Dietary level of IN10 significantly affected propionic acid concentration, which was greater in caecal digesta of birds fed diet supplemented with 0.2% of IN10 compared to other groups and feeding diets supplemented with all levels of IN10 significantly reduced histamine concentration compared to the control. There were no effects of inulin on microbial activity indices in the colon. The present study indicates that, regardless of DP, inulin does not modify considerably microbial activity in the large intestine of chicks.

Oat products modulate the gut microbiota and produce anti-obesity effects in obese rats

Three oat products were supplemented into high fat diets and fed to obese rats for 8 weeks. Each oat product decreased body weight, epididymal fat accumulation, and serum inflammatory factor levels and significantly regulated serum lipid levels. Oat bran significantly reduced mean adipocyte size and TNF-α mRNA expression levels. Principal components analysis showed that the oat products shifted the overall structure of gut microbiota in DIO rats. The relative abundances of Bacteroidetes and Firmicutes and the Bacteroidetes/Firmicutes ratio were altered towards that of normal rats. Spearman's correlation analysis showed that changes in the overall microbiota composition were significantly correlated with total cholesterol, triacylglycerol, endotoxin, and tumour cell necrosis factor-α levels in serum, and mRNA expression levels. Oat products significantly increased the total short-chain fatty acids (SCFA) concentration in colonic digesta. These results suggest that oat products attenuate obesity and related metabolic disorders while modifying the gut microbiota composition in high fat diet-induced obese rats.

Effects of chito-oligosaccharide on intestinal mucosal amino acid profiles and alkaline phosphatase activities, and serum biochemical variables in weaned piglets

The present experiment was conducted to determine the effects of chito-oligosaccharide (COS) on intestinal mucosal amino acid profiles and alkaline phosphatase (ALP) activities, and serum biochemical variables in weaned piglets. A total of 24 piglets (BW=7.82±0.21kg) were weaned at 25 d of age and were blocked by body weight, sex, and litter and randomly assigned to one of two treatments consisting of a basal diet (CON) or the basal diet supplemented with 30mg/kg COS for a 14-d period. Each treatment was assigned to 6 pens (2 piglets/pen) and 6 piglets (3 males and 3 females) were randomly selected from each treatment (1 pigs/pen) for blood and tissue sampling. Dietary supplementation with COS increased (P<0.05) serum IgG and urea nitrogen contents, and tended to increase (P<0.10) serum calcium. The ileal mucosal ALP activity in piglets fed with COS diet were greater (P<0.05) than that in CON piglets. Dietary supplementation with COS increased (P<0.05) the contents of Asn and Cys, and tended to increase (P<0.10) the contents of Asp and Orn in the small intestinal mucosa of weaned piglets. Moreover, the contents of short chain fatty acid (SCFA) in caecal and colonic digesta of weaned piglets were affected (P<0.05) by dietary COS supplementation. There were interactions (P<0.05) between dietary COS and intestinal section for mucosal AA contents and digesta SCFA contents in weaned piglets. In conclusion, the results of the present experiment suggest that dietary supplementation with COS affects intestine and immune functions of weaned piglets.

Molecular analysis of the gut microbiome of diabetic rats supplemented with prebiotic, probiotic, and synbiotic foods

Beneficial symbionts residing in our gut have positive therapeutic effects on several metabolic disorders including diabetes. Oral administration of probiotic and prebiotic foods strengthens the beneficial symbiont populations in the gut and may prevent immune-mediated destruction of pancreatic β-cells. The present study was designed to elucidate the gut microbiome of diabetic rats supplemented with a Lactobacillus probiotic and a Saccharomyces cerevisiae (SC) cell wall prebiotic. Diabetes mellitus was induced in male Wistar rats with allaxon monohydrate (150 mg/kg). The rats were fed chow maintenance diet (control and diabetic control groups) or the same diet supplemented with a SC prebiotic (1 %), probiotic (multispecies Lactobacillus @108 CFU), or synbiotic. On d30, DNA was extracted from colon digesta for 16S ribosomal RNA (rRNA) gene sequencing. Serum was obtained to estimate total oxidant and anti-oxidant concentrations. A distinct clustering pattern (Unifrac distances, analysis of similarities (ANOSIM) P = 0.0361) was observed for the different treatment groups, with the main distinction consisting of the separation between the control and the diabetic control groups. Distinct bacterial clades dominated different treatment groups, particularly for the control and the diabetic control groups, though several bacterial groups overlapped, demonstrating a core microbiota dominated mainly by Firmicutes and Bacteroides. A trend of dysbiosis, characterized by low species richness, was observed in the diabetic rats, albeit not statistically significant. Serum oxidant and anti-oxidant concentrations were not different (P > 0.05) among different treatment groups. No significant effects of supplementations of prebiotic, probiotic, and synbiotic were observed on species richness or clustering pattern of the microbiome.

Effects of intrauterine growth retardation and Bacillus subtilis PB6 supplementation on growth performance, intestinal development and immune function of piglets during the suckling period.

The aim of this study was to investigate the effects of intrauterine growth retardation (IUGR) and Bacillus subtilis PB6 supplementation in formula milk (FORM) on growth performance, intestinal development and immune function of neonates using a porcine model. Fourteen pairs of normal birth weight and IUGR piglets (7days old) were randomly assigned to receive FORM or FORM supplemented with B. subtilis PB6 (FORM-BsPB6) for a period of 21days. Blood samples, intestinal tissues and digesta were collected at necropsy and analysed for morphology, digestive enzyme activities, immune cell abundance, expression of genes associated with innate immunity and barrier function and microbial populations. Regardless of diet, IUGR significantly decreased average daily dry matter intake and average daily weight gain (P<0.05). Moreover, IUGR significantly decreased plasma concentrations of immunoglobulin A, interleukin 1β, count and percentage of blood lymphocytes (P<0.05). Meanwhile, IUGR markedly decreased villous height and maltase activity, as well as mRNA abundance of Toll-like receptor 9 and Toll-interacting protein in the ileum (P<0.05). Regardless of body weight, FORM-BsPB6 markedly decreased the feed conversion ratio (P<0.05), due to better intestinal development, as indicated by increased villous height (P<0.05), activities of maltase and sucrase in the intestine (P<0.10). Moreover, both mRNA and protein abundances of zonula occludens-1 and claudin-1 in the ileum as well as the copy number of Bacillus in colonic digesta were increased (P<0.05) in piglets fed FORM-BsPB6 relative to FORM. The results of this study indicate that IUGR delayed growth, intestinal development and immune function of piglets, while FORM-BsPB6 improved digestive capability and intestinal barrier function.

High‐Calorie Diet Induced Chronic Colonic inflammation: A Human‐Relevant Porcine Model to Assess Whole Food Approach to Reduce Colon Cancer Risk

Recent studies have shown a critical link between high‐calorie diet (HCD)‐induced chronic inflammation and colon cancer. A recent prospective study revealed a positive association between interleukin‐6 (IL‐6), a pro‐inflammatory cytokine, and colon cancer risk. Recently, we developed a human‐relevant pig model for diet‐induced chronic inflammation where clinical markers of inflammation, calprotectin and LCN‐2, were elevated in colonic digesta and mucosa. In the current study, we hypothesized that HCD will elevate the IL‐6 signaling pathway proteins and these proteins levels will correlate with colon cancer risk (Ki‐67 proliferative index and zone) markers. We further hypothesized that anthocyanin rich purple‐fleshed potatoes suppress IL‐6 pathway proteins and colon cancer risk factors. We observed elevated colonic mucosal IL‐6 expression in HCD‐consuming pigs (3 weeks post‐weaning consumed diets for 13 weeks, n = 8 / group) compared to standard diet (SD, qPCR, P = 0.04) and IL‐6 expression levels strongly correlated with Ki‐67 proliferative index and zone (r = 0.604, 0.743; P = 0.017, 0.002; respectively). LC/MS‐MS‐based proteomic analysis and Ingenuity Pathway Analysis showed that HCD consumption alters IL‐6 signaling pathway proteins (PI3KR4, IL‐1α, Mapk10, Akt3, PIK3CG, PIK3R5, Map2k2). Furthermore, these proteins strongly correlated (r = 0.811, P = 0.001) with Ki‐67 proliferative index/zone. We observed that supplementation of HCD with anthocyanin containing purple‐fleshed potatoes (10% w/w), even after baking, tended to suppress HCD‐elevated IL‐6 expression (P ≤ 0.1) and IL‐6 linked proteins, IL‐1α and Map2k1 (P ≤ 0.1). Our results highlight the importance of IL‐6 signaling in diet‐linked induction/prevention of chronic colonic inflammation/cancer and demonstrate the potential of whole foods as a dietary intervention to counteract chronic inflammation and carcinogenesis using a human‐relevant pig model.Support or Funding InformationNational Research Initiative Grant 2009‐55200‐05197 from the USDA National Institute for Food and Agriculture (2009–2012)

The effect of feed intake on digesta passage, digestive organ fill and mass, and digesta dry matter content in sheep (Ovis aries): Flexibility in digestion but not in water reabsorption

The ruminant gastrointestinal tract (GIT) adapts to changes in diet quality or feed intake level, but studies that investigate changes in organ fill, tissue mass, and function simultaneously are rare. We used 3 groups of 7 mature sheep each, fed at different DM intake levels (range 25–64gkg−0.85d−1) for 3 weeks preceding slaughter. We determined the mean retention times (MRT) of a solute and two different-sized particle markers (and their ratios indicating particle sorting and digesta washing) in the reticulorumen (RR) and the GIT, total tract digestibility, as well as digesta wet mass, wet organ tissue mass, and the dry matter (DM) concentration of digesta in the indvidual GIT sections. As DM intake increased, digesta wet mass in the RR and spiral colon increased by organ distension. Simultaneous increases in digesta wet mass in the omasum and small intestine were parallel to increases in organ tissue mass. DM digestiblity, MRT in the RR, measures of the RR sorting mechanism (MRTlargeparticleRR/MRTsmallparticleRR) and RR digesta washing (MRTparticleRR/MRTsoluteRR) all remained constant across intake levels. Whereas the DM concentration increased in the rumen with intake, it remained significantly lower in the reticulum than in rumen. DM concentration in the omasum and abomasum remained constant, but both MRT in the distal GIT and DM concentration in the spiral and distal colon digesta decreased with increasing intake, translating into higher fecal water losses. These results indicate that the flexibility of the mature sheep's GIT ensures constant digestive functions (such as digestibility, particle sorting, digesta washing) at different intake levels but does not compensate for greater fecal water losses at increasing intakes.

Retention of solute and particle markers in the digestive tract of chinchillas (Chinchilla laniger).

The chinchilla (Chinchilla laniger) is a herbivorous hystricomorph South American rodent for which no mean digesta retention times have been reported so far. Six animals (mean body mass ± standard deviation: 513±99g) on a diet of grass hay and lucerne-based pellets were given a pulse dose of a solute (cobalt-EDTA) and a particle (chromium-mordanted fibre, <2mm) marker with subsequent frequent faecal collection. Dry matter intake was 45.2±8.0g/kg(0.75) /day. Mean retention times were 22.2±5.3h for solutes and 25.4±5.2h for particles, with the difference being not significant within individuals. This indicates the presence of a 'mucus-trap' colonic separation mechanism, which is in accord with morphological descriptions of the typical colonic furrow in chinchillas. Corresponding to a strategy of colonic digesta separation and caecotroph formation, secondary marker excretion peaks indicated coprophagic events that were spaced approximately 12h apart. Given that these retention times appear longer than measures reported for rabbits (Oryctolagus cuniculus) or guinea pigs (Cavia procellus), it would be interesting to compare the digestive efficiency of chinchillas on high levels of dietary fibre to other species.

Grain-rich diets altered the colonic fermentation and mucosa-associated bacterial communities and induced mucosal injuries in goats.

Remarkably little information is available about the impact of high-grain (HG) feeding on colonic mucosa-associated bacteria and mucosal morphology. In the present study, 12 male goats were randomly assigned to either a hay diet (n = 6) or an HG diet (65% grain; n = 6) to characterise the changes in the composition of the bacterial community in colonic mucosa and the mucosal morphology of the colon. The results showed that HG feeding decreased the colonic pH and increased the concentrations of total short chain fatty acids and lipopolysaccharides in colonic digesta. The principal coordinate analysis results showed that the HG diet altered the colonic mucosal bacterial communities, with an increase in the abundance of genus Blautia and a decrease in the abundance of genera Bacillus, Enterococcus, and Lactococcus. The HG-fed goats showed sloughing of the surface layer epithelium, intercellular tight junction erosion, cell mitochondrial damage, and upregulation of the relative mRNA expression of IL-2 and IFN-γ in colonic mucosa. Collectively, our data indicate that HG feeding induced changes in colonic mucosal morphology and cytokines expression that might be caused by excessive fermentation and dramatic shifts in the bacterial populations in the colon.

In a Neonatal Piglet Model of Intestinal Failure, Administration of Antibiotics and Lack of Enteral Nutrition Have a Greater Impact on Intestinal Microflora Than Surgical Resection Alone

Data are limited on how short bowel syndrome (SBS) affects the healthy developing intestinal microbiome, with even less assessing different SBS anatomical surgical models. This study was conducted to describe the "ileal" and "colonic" microflora in 2 surgical models of SBS. Neonatal piglets (2-5 days old) underwent intestinal resection, leaving the ileum (JI anatomy, n = 6) or removing the ileum and ileocecal valve (JC anatomy, n = 5), or sham surgery (sham; n = 4). JI, JC, and sham piglets commenced parenteral nutrition on day 0 and received ampicillin and trimethoprim-sulfadoxine on days 0-4 for prevention of line sepsis. At day 7, ileal and colonic digesta were collected, and they were also collected from age-matched sow-fed piglets (n = 6). DNA extraction, sequencing, and annotation followed standard procedures. Colonic and ileal bacterial genus diversity and relative bacterial abundance were greater ( P < .05) in sow-fed compared with JI, JC, and sham piglets; however, minor differences were observed in either location between sham, JI, and JC piglets and within the surgical model. In the colon, sow-fed piglets had higher ( P < .05) abundance of Lactobacillus (26%) and tended to have lower ( P = .06) abundance of Enterococcus (<.1%) than JI, JC, or sham piglets, in which Lactobacillus and Enterococcus abundance averaged <.1% and 9%, respectively. Intestinal resection reduces bacterial diversity in the large bowel, and the difference is associated with the presence/absence of the ileum and ileocecal valve. The lack of enteral nutrition and antibiotic administration (ie, sow-fed vs surgery) had a greater influence on the observed shift in diversity and relative abundance than intestinal resection.

The effect of algal polysaccharides laminarin and fucoidan on colonic pathology, cytokine gene expression and Enterobacteriaceae in a dextran sodium sulfate-challenged porcine model.

The algal polysaccharides laminarin (LAM) and fucoidan (FUC) have potent anti-inflammatory activities in the gastrointestinal tract. Our objective was to examine the impact of prior consumption of LAM and/or FUC on pathology and inflammation following a dextran sodium sulfate (DSS) challenge in pigs. Pigs (n 7/group) were assigned to one of five experimental groups for 56 d. From 49-55 d, distilled water or DSS was administered intragastrically. The experimental groups were: (1) basal diet + distilled water (control); (2) basal diet + DSS (DSS); (3) basal diet + FUC + DSS (FUC + DSS); (4) basal diet + LAM + DSS (LAM + DSS); and (5) basal diet + LAM + FUC + DSS (LAMFUC + DSS). The DSS group had decreased body-weight gain (P < 0·05) and serum xylose (P < 0·05), and increased proximal colon pathology score (P < 0·05), diarrhoeal score (P < 0·001) and colonic Enterobacteriaceae (P < 0·05) relative to the control group. The FUC + DSS (P < 0·01), LAM + DSS (P < 0·05) and LAMFUC + DSS (P < 0·05) groups had improved diarrhoeal score, and the LAMFUC + DSS (P < 0·05) group had improved body weight relative to the DSS group. The FUC + DSS group (P < 0·001), LAM + DSS group (P < 0·05) and LAMFUC + DSS group (P < 0·001) had lower IL-6 mRNA abundance relative to the DSS group. The LAM + DSS group had reduced Enterobacteriaceae in proximal colon digesta relative to the DSS group (P < 0·05). In conclusion, FUC or a combination of FUC and LAM improved body-weight loss, diarrhoeal scores and clinical variables associated with a DSS challenge in pigs, in tandem with a reduction in colonic IL-6 mRNA abundance.

Pigs that are divergent in feed efficiency, differ in intestinal enzyme and nutrient transporter gene expression, nutrient digestibility and microbial activity

Feed efficiency is an important trait in the future sustainability of pig production, however, the mechanisms involved are not fully elucidated. The objective of this study was to examine nutrient digestibility, organ weights, select bacterial populations, volatile fatty acids (VFA’s), enzyme and intestinal nutrient transporter gene expression in a pig population divergent in feed efficiency. Male pigs (n=75; initial BW 22.4 kg SEM 2.03 kg) were fed a standard finishing diet for 43 days before slaughter to evaluate feed intake and growth for the purpose of calculating residual feed intake (RFI). Phenotypic RFI was calculated as the residuals from a regression model regressing average daily feed intake (ADFI) on average daily gain (ADG) and midtest BW0.60 (MBW). On day 115, 16 pigs (85 kg SEM 2.8 kg), designated as high RFI (HRFI) and low RFI (LRFI) were slaughtered and digesta was collected to calculate the coefficient of apparent ileal digestibility (CAID), total tract nutrient digestibility (CATTD), microbial populations and VFA’s. Intestinal tissue was collected to examine intestinal nutrient transporter and enzyme gene expression. The LRFI pigs had lower ADFI (P<0.001), improved feed conversion ratio (P<0.001) and an improved RFI value relative to HRFI pigs (0.19 v. −0.14 SEM 0.08; P<0.001). The LRFI pigs had an increased CAID of gross energy (GE), and an improved CATTD of GE, nitrogen and dry matter compared to HRFI pigs (P<0.05). The LRFI pigs had higher relative gene expression levels of fatty acid binding transporter 2 (FABP2) (P<0.01), the sodium/glucose co-transporter 1 (SGLT1) (P<0.05), the glucose transporter GLUT2 (P<0.10), and the enzyme sucrase–isomaltase (SI) (P<0.05) in the jejunum. The LRFI pigs had increased populations of lactobacillus spp. in the caecum compared with HRFI pigs. In colonic digesta HRFI pigs had increased acetic acid concentrations (P<0.05). Differences in nutrient digestibility, intestinal microbial populations and gene expression levels of intestinal nutrient transporters could contribute to the biological processes responsible for feed efficiency in pigs.

Interactive Effects of Indigestible Carbohydrates, Protein Type, and Protein Level on Biomarkers of Large Intestine Health in Rats.

The effects of indigestible carbohydrates, protein type, and protein level on large intestine health were examined in rats. For 21 days, 12 groups of six 12-week-old male Wistar rats were fed diets with casein (CAS), or potato protein concentrate (PPC), providing 14% (lower protein level; LP), or 20% (higher protein level; HP) protein, and containing cellulose, resistant potato starch, or pectin. Fermentation end-products, pH, and β-glucuronidase levels in cecal digesta, and ammonia levels in colonic digesta were determined. Cecal digesta, tissue weights, cecal and colon morphology, and colonocyte DNA damage were also analyzed. Digesta pH was lower, whereas relative mass of cecal tissue and digesta were higher in rats fed pectin diets than in those fed cellulose. Cecal parameters were greater in rats fed PPC and HP diets than in those fed CAS and LP diets, respectively. Short-chain fatty acid (SCFA) concentrations were unaffected by protein or carbohydrate type. Total SCFA, acetic acid, and propionic acid concentrations were greater in rats fed LP diets than in those fed HP. Cecal pool of isobutyric and isovaleric acids was greater in rats fed PPC than in those fed CAS diets. PPC diets decreased phenol concentration and increased ammonia concentration in cecal and colonic digesta, respectively. Cecal crypt depth was greater in rats fed PPC and HP diets, and was unaffected by carbohydrates; whereas colonic crypt depth was greater in rats fed cellulose. Myenteron thickness in the cecum was unaffected by nutrition, but was greater in the colon of rats fed cellulose. Colonocyte DNA damage was greater in rats fed LP diets than in those fed HP diets, and was unaffected by carbohydrate or protein type. It was found that nutritional factors decreasing cecal digesta weight contribute to greater phenol production, increased DNA damage, and reduced ammonia concentration in the colon.

Effects of high levels of dietary zinc oxide on ex vivo epithelial histamine response and investigations on histamine receptor action in the proximal colon of weaned piglets.

The aim of the study was to identify the effect of high dietary zinc oxide (ZnO) levels on the histamine-induced secretory-type response and histamine metabolism in the porcine proximal colon. After weaning at d 26, 3 diets with low (LZn), normal (NZn), and high (HZn) concentrations of zinc (57, 164, or 2,425 mg/kg) were fed to a total of 120 piglets. Digesta and tissue samples were taken from the ascending colon after 7 ± 1, 14 ± 1, 21 ± 1, and 28 ± 1 d. Partially stripped tissue was mounted in Ussing chambers, and histamine was applied either to the serosal or mucosal compartments. Tissue was pretreated with or without aminoguanidine and amodiaquine to block the histamine-degrading enzymes diamine oxidase (DAO) and histamine -methyltransferase (HMT), respectively. Gene expression and catalytic activity of DAO and HMT in the tissue were analyzed. The numbers of mast cells were determined in tissue samples, and histamine concentration was measured in the colon digesta. Colon tissue from another 12 piglets was used for functional studies on histamine H and H receptors by using the neuronal conduction blocker tetrodotoxin (TTX) and the H and H receptor blocker chloropyramine and famotidine, respectively. After serosal histamine application to colonic tissue in Ussing chambers, the change of short-circuit current (Δ) was not affected by pretreatment and was not different between Zn feeding groups. The Δ after mucosal histamine application was numerically lower ( = 0.168) in HZn compared to LZn and NZn pigs. Mast cell numbers increased from 32 to 46 d of life ( < 0.05). Further studies elucidated that the serosal histamine response was partly inhibited by chloropyramine or famotidine ( < 0.01). The response to mucosal histamine tended to be decreased when chloropyramine but not famotidine was applied from either the serosal or the mucosal side ( = 0.055). Tetrodotoxin alone or in combination with chloropyramine resulted in a similar reduction in the mucosal histamine response ( < 0.01). In conclusion, the present study could not identify marked changes in colonic histamine metabolism on dietary ZnO oversupplementation. For the first time, however, H receptors were functionally identified in the pig colon that are localized either on neurons or on cells that activate secretion via neurons. Luminal histamine can elicit a secretory-type response via these receptors.

Carotenoid and polyphenol bioaccessibility and cellular uptake from plum and cabbage varieties

Plum and cabbage are rich in carotenoids and polyphenols. However, their bioactivity depends on their release and intestinal uptake. Four varieties of Brassicaceae (Duchy, Scots Kale, Kale, Kalorama) and Prunus (Cherry Plum, Plum 620, Ersinger, Italian Plum) were studied; bioaccessibility following in vitro digestion, cellular uptake (Caco-2 vs. co-culture cell model: Caco-2:HT-29-MTX (90:10%) and colonic fermentation were determined for carotenoids/polyphenols; the influence of certain kitchen preparations was likewise studied. Carotenoids were non-significantly influenced by the latter, while for polyphenols, boiling and steaming significantly reduced total phenolics (p<0.05). Carotenoid bioaccessibility did not differ significantly between Prunus vs. Brassicaceae varieties, but xanthophyll was higher than carotene bioaccessibility (p<0.01). Polyphenol bioaccessibility was low (<10%), possibly compromised by the cream containing test meal. Total carotenoid cellular uptake varied between varieties (0.3–4.1%), being higher for carotenes (4.1%) than for xanthophylls (1.6%, p<0.01), and were higher for the co-culture cell model compared to Caco-2 cells (p<0.01). Total carotenoid recovery in the colonic fraction varied from 4% to 25%. Lower bioaccessibility of carotenes thus appeared to be somewhat counterbalanced by higher cellular uptake. The potential positive role of the mucus layer for cellular uptake and the fate of the colonic digesta deserve further attention in the future.

Short-chain fatty acid profiles from flaxseed dietary fibres after in vitro fermentation of pig colonic digesta: Structure–function relationship

Abstract Flaxseed (Linum usitatissimum L.) is rich in dietary fibres. There are four major soluble dietary fibre fractions, and their molecular structures have been characterised; however, the structure–function relationship on the short-chain fatty acid (SCFA) profiles is still unknown. SCFA profiles produced by in vitro fermentation of pig colonic digesta with soluble flaxseed dietary fibre fractions were determined by gas chromatography with psyllium arabinoxylans as the reference fibres. The results revealed that total SCFA production from all tested dietary fibres were significantly higher than negative control (NC) after 72 h fermentation. Acetic acid was the major SCFA produced, followed by propionic acid and butyric acid during 72 h fermentation. The acetic acid production from flaxseed kernel xyloglucans, and butyric acid production from flaxseed mucilage arabinoxylans were significantly higher than negative control (NC) after 48 h fermentation. Both psyllium and flaxseed mucilage arabinoxylans promoted butyric acid production more effectively than other tested dietary fibres during 48 h fermentation, while flaxseed kernel xyloglucans and flaxseed RG-I were more effective on promoting acetic acid production. The dietary fibre strucutre played major roles on promoting specific SCFAs, and the conformational characteristics might contribute to the difference of fermentability rates. Flaxseed dietary fibres were relatively slower fermentable dietary fibres as compared with psyllium fibres, and all flaxseed dietary fibres had higher level of total SCFA production than psyllium fibres after 72 h incubation. This research should further promotes the utilisation of flaxseed dietary fibres, and contributes to the optimisation of colonic health based on more balanced diets with both grain and oilseed.

Responses in colonic microbial community and gene expression of pigs to a long-term high resistant starch diet.

Intake of raw potato starch (RPS) has been associated with various intestinal health benefits, but knowledge of its mechanism in a long-term is limited. The aim of this study was to investigate the effects of long-term intake of RPS on microbial composition, genes expression profiles in the colon of pigs. Thirty-six Duroc × Landrace × Large White growing barrows were randomly allocated to corn starch (CS) and RPS groups with a randomized block design. Each group consisted of six replicates (pens), with three pigs per pen. Pigs in the CS group were offered a corn/soybean-based diet, while pigs in the RPS group were put on a diet in which 230 g/kg (growing period) or 280 g/kg (finishing period) purified CS was replaced with purified RPS during a 100-day trial. Real-time PCR assay showed that RPS significantly decreased the number of total bacteria in the colonic digesta. MiSeq sequencing of the V3-V4 region of the 16S rRNA genes showed that RPS significantly decreased the relative abundance of Clostridium, Treponema, Oscillospira, Phascolarctobacterium, RC9 gut group, and S24-7-related operational taxonomic units (OTUs), and increased the relative abundance of Turicibacter, Blautia, Ruminococcus, Coprococcus, Marvinbryantia, and Ruminococcus bromii-related OTUs in colonic digesta and mucosa. Analysis of the colonic transcriptome profiles revealed that the RPS diet changed the colonic expression profile of the host genes mainly involved in immune response pathways. RPS significantly increased proinflammartory cytokine IL-1β gene expression and suppressed genes involved in lysosome. Our findings suggest that long-term intake of high resistant starch (RS) diet may result in both positive and negative roles in gut health.

Feed Fermentation with Reuteran- and Levan-Producing Lactobacillus reuteri Reduces Colonization of Weanling Pigs by Enterotoxigenic Escherichia coli.

This study determined the effect of feed fermentation with Lactobacillus reuteri on growth performance and the abundance of enterotoxigenic Escherichia coli (ETEC) in weanling piglets. L. reuteri strains produce reuteran or levan, exopolysaccharides that inhibit ETEC adhesion to the mucosa, and feed fermentation was conducted under conditions supporting exopolysaccharide formation and under conditions not supporting exopolysaccharide formation. Diets were chosen to assess the impact of organic acids and the impact of viable L. reuteri bacteria. Fecal samples were taken throughout 3 weeks of feeding; at the end of the 21-day feeding period, animals were euthanized to sample the gut digesta. The feed intake was reduced in pigs fed diets containing exopolysaccharides; however, feed efficiencies did not differ among the diets. Quantification of L. reuteri by quantitative PCR (qPCR) detected the two strains used for feed fermentation throughout the intestinal tract. Quantification of E. coli and ETEC virulence factors by qPCR demonstrated that fermented diets containing reuteran significantly (P < 0.05) reduced the copy numbers of genes for E. coli and the heat-stable enterotoxin in feces compared to those achieved with the control diet. Any fermented feed significantly (P < 0.05) reduced the abundance of E. coli and the heat-stable enterotoxin in colonic digesta at 21 days; reuteran-containing diets reduced the copy numbers of the genes for E. coli and the heat-stable enterotoxin below the detection limit in samples from the ileum, the cecum, and the colon. In conclusion, feed fermentation with L. reuteri reduced the level of colonization of weaning piglets with ETEC, and feed fermentation supplied concentrations of reuteran that may specifically contribute to the effect on ETEC.

Addition of inulin, alfalfa and citrus pulp in diets for piglets: Influence on nutritional and faecal parameters, intestinal organs, and colonic fermentation and bacterial populations

The effects of the inclusion of inulin, fresh alfalfa and fresh citrus pulp in diets for piglets on intake, nutritional and faecal parameters, digestive tract size, fermentation kinetics and colonic microbial populations was evaluated. Twenty-four cross-breed piglets (initial BW: 9.75±1.63kg) in a randomized complete block design were housed in metabolic cages and assigned to one of 4 treatments: 100% corn and soybean meal control diet (CON), 97% CON+3% inulin (INU), 95.5% CON+4.5% fresh alfalfa (ALF) and 95.5% CON+4.5% fresh citrus pulp (CIT). The experiment consisted of a 12 d adaptation period followed by 12 d for samples collection. The last 2 days of the experiment all animals were euthanized, the digestive tract of each animal was removed and an individual sample of colonic digesta was collected. Feed intake tended to be lower in the fibre supplemented groups (P=0.098), and was lower in ALF than in CIT (P=0.026). Groups receiving fibres tended to excrete more faeces (P=0.088), evacuated softer faeces (P=0.041) and presented a lower digestibility of CP (P=0.003). Retention of N was higher in the CON group than in fibre containing diets (P=0.009), and lower for ALF than for CIT (P=0.034). Colonic pH was lower in CIT and ALF treatments than in INU (P=0.016), in vitro gas volume was higher in the fibre-supplemented groups than in CON (P=0.048), but no differences between colonic bacterial counts were noticed among treatments. From the data obtained we conclude that the addition of fresh alfalfa and citrus pulp produce some beneficial effects in terms of promoting an increase in the hindgut fermentation, but negative aspects related to poorer nutrients absorption and N utilization can limit the usage of these fibrous sources.