Digesta transit in different segments of the gastrointestinal tract of pigs as affected by insoluble fibre supplied by wheat bran

Particle size of insoluble fibres and gelation of soluble fibres influence digesta passage rate throughout the gastrointestinal tract of finishing pigs

Fibres, as abundant in agricultural by-products, exhibit a large range of physicochemical properties that can influence digestive processes such as digesta mean retention time (MRT), thereby affecting nutrient digestion kinetics. In this study, we investigated the effects of particle size of insoluble fibres, and gelation of soluble fibres on MRT of liquids, fine solids, and fibrous particles in the different segments of the gastrointestinal tract (GIT) of pigs. Twenty-four boars (51.6 ± 4.90 kg) were allocated to four diets; two diets contained 15% wheat straw, either coarsely chopped or finely ground (1-mm screen), two diets contained 27% wheat bran without or with the addition of 10% low-methylated pectin. After 14 days of adaptation to the diet, a total collection of faeces was performed to determine the total tract digestibility of nutrients. Thereafter, pigs were fed diets supplemented with tracers for at least 5 days and dissected following a frequent feeding procedure to approach steady-state passage of digesta. The MRT of liquids (Co-EDTA), fine solids (TiO2), and fibrous particles (Chromium-mordanted fibres) in the different segments of the GIT were quantified. In the stomach, particle size reduction of straw decreased the MRT of fine solids by 02:39 h, and fibrous particles by 07:21 h (P < 0.10). Pectin addition to the wheat bran diet reduced the MRT of fine solids by 03:09 h, and fibrous particles by 07:10 h (P < 0.10), but not of liquids, resulting in less separation between digesta phases in the stomach compared with the bran diet (P < 0.05). In the mid-small intestine (SI), pectin addition reduced the MRT of fibrous particles and the separation between fibrous particles and fine solids. No further effects of particle size reduction of straw nor pectin addition on MRT and digestibility of starch, nitrogen, or fat were observed in the SI. In the large intestine (LI), particle size reduction of straw reduced separation between fibrous particles and fine solids (P < 0.10), while pectin addition had no effects. Total tract, non-starch polysaccharide degradation of straw was poor (∼31%), and unaffected by particle size reduction (P > 0.10). The complete fermentation of pectin did not influence the degradation of wheat bran fibres (∼51%). In conclusion, the effects of particle size of insoluble fibres and gelling properties of soluble fibres on the passage of digesta phases were most pronounced in the stomach, but less prominent in distal segments of the GIT.

Investigation of the nutritional and functional roles of a combinational use of xylanase and β-glucanase on intestinal health and growth of nursery pigs

BACKGROUND

Xylanase and β-glucanase combination (XG) hydrolyzes soluble non-starch polysaccharides that are anti-nutritional compounds. This study aimed to evaluate the effects of increasing levels of XG on intestinal health and growth performance of nursery pigs.

METHODS

Forty pigs (6.5 ± 0.4 kg) were assigned to 5 dietary treatments and fed for 35 d in 3 phases (11, 9, and 15 d, respectively). Basal diets mainly included corn, soybean meal, and corn distiller's dried grains with solubles, contained phytase (750 FTU/kg), and were supplemented with 5 levels of XG at (1) 0, (2) 280 TXU/kg xylanase and 125 TGU/kg β-glucanase, (3) 560 and 250, (4) 840 and 375, or (5) 1,120 and 500, respectively. Growth performance was measured. On d 35, all pigs were euthanized and jejunal mucosa, jejunal digesta, jejunal tissues, and ileal digesta were collected to determine the effects of increasing XG levels and XG intake on intestinal health.

RESULTS

Increasing XG intake tended to quadratically decrease (P = 0.059) viscosity of jejunal digesta (min: 1.74 mPa·s at 751/335 (TXU/TGU)/kg). Increasing levels of XG quadratically decreased (P < 0.05) Prevotellaceae (min: 0.6% at 630/281 (TXU/TGU)/kg) in the jejunal mucosa. Increasing XG intake quadratically increased (P < 0.05) Lactobacillaceae (max: 40.3% at 608/271 (TXU/TGU)/kg) in the jejunal mucosa. Increasing XG intake quadratically decreased (P < 0.05) Helicobacteraceae (min: 1.6% at 560/250 (TXU/TGU)/kg) in the jejunal mucosa. Increasing levels of XG tended to linearly decrease (P = 0.073) jejunal IgG and tended to quadratically increase (P = 0.085) jejunal villus height to crypt depth ratio (max: 2.62 at 560/250 (TXU/TGU)/kg). Increasing XG intake tended to linearly increase the apparent ileal digestibility of dry matter (P = 0.087) and ether extract (P = 0.065). Increasing XG intake linearly increased (P < 0.05) average daily gain.

CONCLUSIONS

A combinational use of xylanase and β-glucanase would hydrolyze the non-starch polysaccharides fractions, positively modulating the jejunal mucosa-associated microbiota. Increased intake of these enzyme combination possibly reduced digesta viscosity and humoral immune response in the jejunum resulting in improved intestinal structure, and ileal digestibility of nutrients, and finally improving growth of nursery pigs. The beneficial effects were maximized at a combination of 550 to 800 TXU/kg xylanase and 250 to 360 TGU/kg β-glucanase.

Effect of a probiotic and an antibiotic on the mobilome of the porcine microbiota

Introduction: To consider the growing health issues caused by antibiotic resistance from a "one health" perspective, the contribution of meat production needs to be addressed. While antibiotic resistance is naturally present in microbial communities, the treatment of farm animals with antibiotics causes an increase in antibiotic resistance genes (ARG) in the gut microbiome. Pigs are among the most prevalent animals in agriculture; therefore, reducing the prevalence of antibiotic-resistant bacteria in the pig gut microbiome could reduce the spread of antibiotic resistance. Probiotics are often studied as a way to modulate the microbiome and are, therefore, an interesting way to potentially decrease antibiotic resistance. Methods: To assess the efficacy of a probiotic to reduce the prevalence of ARGs in the pig microbiome, six pigs received either treatment with antibiotics (tylvalosin), probiotics (Pediococcus acidilactici MA18/5M; Biopower® PA), or a combination of both. Their faeces and ileal digesta were collected and DNA was extracted for whole genome shotgun sequencing. The reads were compared with taxonomy and ARG databases to identify the taxa and resistance genes in the samples. Results: The results showed that the ARG profiles in the faeces of the antibiotic and combination treatments were similar, and both were different from the profiles of the probiotic treatment (p < 0.05). The effects of the treatments were different in the digesta and faeces. Many macrolide resistance genes were detected in a higher proportion in the microbiome of the pigs treated with antibiotics or the combination of probiotics and antibiotics. Resistance-carrying conjugative plasmids and horizontal transfer genes were also amplified in faeces samples for the antibiotic and combined treatments. There was no effect of treatment on the short chain fatty acid content in the digesta or the faeces. Conclusion: There is no positive effect of adding probiotics to an antibiotic treatment when these treatments are administered simultaneously.

Effects of dietary xylanase supplementation on growth performance, intestinal health, and immune response of nursery pigs fed diets with reduced metabolizable energy

This study aimed to investigate the effects of xylanase on growth performance and intestinal health of nursery pigs fed diets with reduced metabolizable energy (ME). One hundred ninety-two pigs at 8.7 kg ± 0.7 body weight (BW) after 7 d of weaning were allotted in a randomized complete block design with initial BW and sex as blocks. Eight dietary treatments consisted of 5 ME levels (3,400, 3,375, 3,350, 3,325, and 3,300 kcal ME/kg) below the NRC (2012) requirement and 4 levels of xylanase (0, 1,200, 2,400, and 3,600 XU/kg) to a diet with 3,300 kcal ME/kg. All pigs received their respective treatments for 35 d in 2 phases, pre-starter (14 d) and starter (21 d). On day 35, eight pigs in 3,400 kcal/kg (CON), 3,300 kcal/kg (LE), and 3,300 kcal/kg + 3,600 XU xylanase/kg (LEX) were euthanized to collect jejunal tissues and digesta for the evaluation of mucosa-associated microbiota, intestinal immune response, oxidative stress status, intestinal morphology, crypt cell proliferation, and digesta viscosity as well as ileal digesta to measure apparent ileal digestibility. Data were analyzed using the MIXED procedure on SAS 9.4. The LE increased (P < 0.05) jejunal digesta viscosity, tended to have decreased (P = 0.053) relative abundance of Prevotella, and tended to increase (P = 0.055) Lactobacillus. The LE also increased (P < 0.05) the concentration of protein carbonyl whereas malondialdehyde, villus height (VH), villus height to crypt depth ratio (VH:CD), apparent ileal digestibility (AID) of nutrients, and finally average daily feed intake were decreased (P < 0.05). The LE did not affect average daily gain (ADG). The LEX decreased (P < 0.05) digesta viscosity, increased (P < 0.05) the relative abundance of Prevotella, decreased (P < 0.05) Helicobacter, decreased (P < 0.05) the concentration of protein carbonyl, tended to increase (P = 0.065) VH, and decreased (P < 0.05) VH:CD and crypt cell proliferation. Moreover, LEX increased (P < 0.05) the AID of dry matter and gross energy and tended to increase (P = 0.099; P = 0.076) AID of crude protein, and ether extract. The LEX did not affect ADG but did tend to decrease (P = 0.070) fecal score during the starter phase. Overall, reducing ME negatively affected intestinal health parameters and nutrient digestibility without affecting growth. Supplementation of xylanase mitigated some of the negative effects observed by ME reduction on intestinal health and digestibility of nutrients without affecting growth.

SNAPIG: a model to study nutrient digestion and absorption kinetics in growing pigs based on diet and ingredient properties

Current feed formulation and evaluation practices rely on static values for the nutritional value of feed ingredients and assume additivity. Hereby, the complex interplay among nutrients in the diet and the highly dynamic digestive processes are ignored. Nutrient digestion kinetics and diet × animal interactions should be acknowledged to improve future predictions of the nutritional value of complex diets. Therefore, an in silico nutrient-based mechanistic digestion model for growing pigs was developed: "SNAPIG" (Simulating Nutrient digestion and Absorption kinetics in PIGs). Aiming to predict the rate and extent of nutrient absorption from diets varying in ingredient composition and physicochemical properties, the model represents digestion kinetics of ingested protein, starch, fat, and non-starch polysaccharides, through passage, hydrolysis, absorption, and endogenous secretions of nutrients along the stomach, proximal small intestine, distal small intestine, and caecum + colon. Input variables are nutrient intake and the physicochemical properties (i.e. solubility, and rate and extent of degradability). Data on the rate and extent of starch and protein hydrolysis of different ingredients per digestive segment were derived from in vitro assays. Passage of digesta from the stomach was modelled as a function of feed intake level, dietary nutrient solubility and diet viscosity. Model evaluation included testing against independent data from in vivo studies on nutrient appearance in (portal) blood of growing pigs. When simulating diets varying in physicochemical properties and nutrient source, SNAPIG can explain variation in glucose absorption kinetics (postprandial time of peak, TOP: 20-100 min observed vs 25-98 min predicted), and predict variation in the extent of ileal protein and fat digestion (root mean square prediction errors (RMSPE) = 12 and 16%, disturbance error = 12 and 86%, and concordance correlation coefficient = 0.34 and 0.27). For amino acid absorption, the observed variation in postprandial TOP (61 ± 11 min) was poorly predicted despite accurate mean predictions (58 ± 34 min). Recalibrating protein digestion and amino acid absorption kinetics require data on net-portal nutrient appearance, combined with observations on digestion kinetics, in pigs fed diets varying in ingredient composition. Currently, SNAPIG can be used to forecast the time and extent of nutrient digestion and absorption when simulating diets varying in ingredient and nutrient composition. It enhances our quantitative understanding of nutrient digestion kinetics and identifies knowledge gaps in this field of research. Already useful as research tool, SNAPIG can be coupled with a postabsorptive metabolism model to predict the effects of dietary and feeding-strategies on the pig's growth response.

Fluorescence imaging around the abdomen allows evaluation of gastrointestinal retention of various forms of diet in mice

OBJECTIVES

The aims of this study were to evaluate gastrointestinal (GI) retention of an ingested meal by fluorescence imaging and compare how retention is affected by differences in the physical characteristics of meals.

METHODS

Mice were given an oral fluorescent indocyanine green (ICG) probe enclosed in a liposome. We evaluated the correlation between abdominal and GI fluorescence signals. ICG was administered to mice treated with atropine, and abdominal fluorescence was observed repeatedly. Mice were continuously given a regular chow or a liquid diet containing a low or high methoxyl (LM or HM)-pectin through a catheter placed in the stomach for 2 d, after which the mice were given ICG. In all studies, the mice's abdominal and GI fluorescence signals were observed with in vivo imaging equipment.

RESULTS

The fluorescence intensities (FIs) of the abdomen and the excised GI tract correlated strongly. Attenuation of the abdominal FI was delayed in the atropine-treatment group compared with the non-treated group. The attenuation of abdominal FI 8 to 24 h after ICG administration was significantly weakened in the HM group compared with the regular chow and LM groups.

CONCLUSIONS

Observing FI attenuation around the abdomen allows for the evaluation of GI tract retention of an ingested meal. Compared with a solid meal, a liquid meal stays longer in the digestive tract, whereas a liquid meal in which the viscosity increases in the stomach is retained like a solid meal.

Wheat bran inclusion level impacts its net energy by shaping gut microbiota and regulating heat production in gestating sows

An accurate estimation of net energy (NE) of wheat bran is essential for precision feeding of sows. However, the effects of inclusion level on NE of wheat bran have not been reported. Inclusion level was hypothesized to impact NE of wheat bran by regulating gut microbiota and partitioning of heat production. Therefore, twelve multiparous sows (Yorkshire × Landrace; 2 to 4 parity) were assigned to a replicated 3 × 6 Youden square with 3 successive periods and 6 diets in each square. The experiment included a corn-soybean meal diet (WB0) and five diets including 9.8% (WB10), 19.5% (WB20), 29.2% (WB30), 39.0% (WB40) and 48.7% wheat bran (WB50), respectively. Each period included 6 d of adaptation to diets followed by 6 d for heat production measurement using open-circuit respiration chambers. Compared with other groups, WB30, WB40, and WB50 enriched different fiber-degrading bacteria genera (P < 0.05). Apparent total tract digestibility of neutral detergent fiber and acid detergent fiber of wheat bran were greater in WB30 and WB40 (P < 0.05). Physical activity (standing and sitting) decreased as inclusion level increased (P = 0.04), which tended to decrease related heat production (P = 0.07). Thermic effect of feeding (TEF) was higher in WB50 than other treatments (P < 0.01). Metabolizable energy of wheat bran was similar among treatment groups (except for WB10). NE of wheat bran conformed to a quadratic regression equation with inclusion level (R2 = 0.99, P < 0.01) and peaked at an inclusion level of 35.3%. In conclusion, increasing inclusion level decreased energy expenditure of sows on physical activity and promoted growth of fiber-degrading bacteria, which improved energy utilization of fiber. Fermentation of wheat bran fiber by Prevotellaceae_UCG-003 and norank_f__Paludibacteraceae might increase TEF. Consequently, sows utilized energy in wheat bran most efficiently at an inclusion level of 35.3%.

Effects of pretreating wheat middlings and sunflower meal with fiber degrading enzymes on components solubilization and utilization in broiler chickens

Pretreating fibrous feedstuffs with exogenous enzymes may improve their utilization in broiler chickens. Pretreatment of wheat middlings (WM) and sunflower meal (SM) with fiber degrading enzymes (FDE) was investigated for 1) in vitro solubilization of crude protein (CP) and fiber-degrading (experiment 1), and 2) apparent retention (AR) of CP, neutral detergent fiber (NDF), nitrogen corrected apparent metabolizable energy (AMEn), as well as the concentration of ceca digesta metabolites in broiler chickens (experiment 2). In experiment 1, WM was pretreated with FDE and SM with FDE ± protease and incubated in a shaker for 24 or 48 h at 40°C and 200 rpm. Samples were centrifuged, and the supernatant used for assay of sugars and organic acids and pellet processed for determination of apparent disappearance (AD) of dry matter (DM), fiber, and CP solubilization. In experiment 2, WM and SM were pretreated with FDE for 24 h, oven-dried, and incorporated in iso-caloric and iso-nitrogenous experimental diets. Diets were: 1) a corn-soybean meal positive control (PC); 2) PC plus untreated WM and SM (negative control, NC), and diets 3, 4, 5, and 6 test diets, in which the untreated WM and SM in NC were replaced with pretreated WM and SM at 25% (N25), 50% (N50), 75% (N75), and 100% (N100), respectively. Diets were prepared in mash form in two phases (starter, days 0 to 21 and finisher, days 22 to 42) and had TiO2 (0.3%) as an indigestible marker. A total of 288 Ross708 d-old male broiler chicks were placed in cages based on body weights (6 birds/cage) and allocated diets (n = 8). Birds had free access to feed and water. Samples of excreta for AR and AMEn, and of ceca digesta for the concentration of short-chain fatty acids (SCFA) were collected at the end of each phase. Pretreatment with FDE increased (P < 0.001) solubilization of CP, AD of NDF, and release of sugars and organic acids in the supernatant. The mixture of FDE and protease further increased (P < 0.001) CP solubilization in SM. Feeding pretreated WM and SM had a linear response (P ≤ 0.038) on AMEn, and gross energy (GE) (day 21) and a quadratic response (P < 0.05) on AR of components and AMEn (day 42) and concentration of total SCFA on day 42. On day 42, N25 and N50 had higher AR of DM, CP, NDF, and GE than N75 and N100. In conclusion, pretreatment of WM and SM with enzymes increased CP and fiber degradation. Incorporating moderate amounts (N25 and N50) of pretreated WM and SM in a corn-soybean meal diet fed to broiler chickens improved nutrient and energy utilization.

Review: Methods and biomarkers to investigate intestinal function and health in pigs

Society is becoming increasingly critical of animal husbandry due to its environmental impact and issues involving animal health and welfare including scientific experiments conducted on farm animals. This opens up two new fields of scientific research, the development of non- or minimally invasive (1) methods and techniques using faeces, urine, breath or saliva sampling to replace existing invasive models, and (2) biomarkers reflecting a disease or malfunction of an organ that may predict the future outcome of a pig's health, performance or sustainability. To date, there is a paucity of non- or minimally invasive methods and biomarkers investigating gastrointestinal function and health in pigs. This review describes recent literature pertaining to parameters that assess gastrointestinal functionality and health, tools currently used to investigate them, and the development or the potential to develop new non- and minimally invasive methods and/or biomarkers in pigs. Methods described within this review are those that characterise gastrointestinal mass such as the citrulline generation test, intestinal protein synthesis rate, first pass splanchnic nutrient uptake and techniques describing intestinal proliferation, barrier function and transit rate, and microbial composition and metabolism. An important consideration is gut health, and several molecules with the potential to act as biomarkers of compromised gut health in pigs are reported. Many of these methods to investigate gut functionality and health are considered 'gold standards' but are invasive. Thus, in pigs, there is a need to develop and validate non-invasive methods and biomarkers that meet the principles of the 3 R guidelines, which aim to reduce and refine animal experimentation and replace animals where possible.

Effect of Particle Size of Wheat and Barley Grain on the Digestibility and Fermentation of Carbohydrates in the Small and Large Intestines of Growing Pigs

The objective of this investigation was to study the effects of different cereal types, barley and wheat, with different particle sizes (PS) on the recovery of ileal digesta and fecal excretion, digestion of nutrients and fiber components, mean transit time (MTT), and short-chain fatty acid content and composition in growing pigs studied in two experiments. Five barrows with ileal cannulas (initial BW 35.9 ± 1.5 kg) in Experiment 1 and thirty-two castrated pigs (30.8 ± 1.3 kg) in Experiment 2 were fed four different diets: barley fine, barley coarse, wheat fine and wheat coarse diets. The cereal type and PS did not influence the relative weight of the small and large intestines and pH of digesta, whereas MTT in the large intestine of pigs fed the coarse barley diet was lower compared to pigs fed other diets (p < 0.05). Pigs fed the coarse barley diet had lower apparent ileal digestibility (AID) and apparent total tract digestibility (ATTD) of nutrients and fiber (p < 0.05), whereas pigs fed the fine barley diet had similar AID and ATTD to pigs fed wheat fine and coarse diets (p < 0.05). In conclusion, the barley diet was more influenced by PS in comparison to wheat, thereby inducing lower AID and ATTD of nutrient.

PBPK Model To Predict Marbofloxacin Distribution in Edible Tissues and Intestinal Exposure in Pigs

Marbofloxacin (MAR) is a fluoroquinolone antibiotic used in food-producing animals in European Union, especially in pigs. In this study, MAR concentrations in plasma, comestible tissues, and intestinal segments were determined in pigs injected with MAR. Based on these data and the literature, a flow-limited PBPK model was developed to predict the tissue distribution of MAR and estimate the withdrawal period after label-use in Europe. A submodel describing the different segments of the intestinal lumen was also developed to assess the intestinal exposure of MAR for the commensal bacteria. During model calibration, only four parameters were estimated. Then, Monte Carlo simulations were performed to generate a virtual population of pigs. The simulation results were compared with the observations from an independent data set during the validation step. A global sensitivity analysis was also carried out to identify the most influential parameters. Overall, the PBPK model was able to adequately predict the MAR kinetics in plasma and edible tissues, as well as in small intestines. However, the simulated concentrations in the large intestine were mostly underestimated, highlighting the need for improvements in the field of PBPK modeling to assess the intestinal exposure of antimicrobials in food animals.

Insoluble fibers affect digesta transit behavior in the upper gastrointestinal tract of growing pigs, regardless of particle size

Physicochemical characteristics of dietary fibers may modulate digesta transit behavior. The present study was conducted to clarify the effect of level and particle size (PS) of insoluble fibers on digesta mean retention time (MRT) in the proximal gastrointestinal tract (mouth-ileocecal junction). Six ileal-cannulated pigs (26.8 ± 2.08 kg) were assigned to 3 dietary treatments in a 3 × 3 replicated Latin-square design. Finely ground (1 mm screen) or coarse (intact) oat husks (OH) and soybean hulls (SBH) were added (50:50, w/w) to a maize-whey protein-wheat-based diet at 50 (low) or 250 g/kg (high) inclusion levels to obtain a low-fine fiber (LF), high-fine fiber (HF), and high-coarse fiber (HC) diet. Markers to follow liquids (Co-EDTA), fine solids (Y3O2), or fibrous particles (Yb-mordanted OH and Cr-mordanted SBH) were given as a single pulse dose and marker concentrations were subsequently measured hourly in digesta for 13 h after administration. Mean retention time values were obtained from the concentration of markers in digesta observed over time by fitting a generalized Michaelis-Menten equation and calculating the time of peak. Fiber addition and fiber particle size neither affected the MRT of liquid nor solid digesta phases (P = 0.903). Segregation between solid and liquid digesta phases was observed for all diets (P < 0.0001), although the extent of segregation was greater for LF compared with HF and HC (P = 0.0220). The MRT of SBH particles, but not of OH-particles was longer for coarse vs fine PS (96 min, P < 0.05). In conclusion, digesta MRT was influenced by the dietary concentration but not by PS of insoluble fibers. The addition of insoluble fibers reduces digesta phase segregation from mouth to distal ileum in growing pigs.

Large intestinal dynamics differ between fowl and swine: Anatomical modifications, microbial collaboration, and digestive advantages from fibrolytic enzymes

The large intestinal systems of fowl and swine recover nutrients from ileal indigesta by a strategically different manner. Indigesta with fowl enter a short colon where retro-peristalsis using urine from the urodeum carries small particulates and solutes into both ceca while coarse materials collect in the cloaca. Fowl repetitively add fine and soluble materials into both ceca to continue fermentation until complexity of the remainder exceeds microbial action, then contents apart from faeces are entirely evacuated. Indigesta with swine initially enter a short cecum followed by a lengthy progression through to the rectal ampulla. Wall out-pocketings of circular muscle or haustrae occur throughout the length of the pig's cecum and helicoidal colon. Each pocket carries contents acquired earlier in the cecum. Motility collects fines and solutes into haustrae during their progression through the colon whereas coarse particulates assemble in the core. Haustrae contents continually ferment during movement to the distal colon with resulting volatile fatty acids (VFA) and electrolytes being absorbed. Mucin loosely covers the lumen surface in caeca as well as helicoidal colon that may capture microbes from active intestinal contents as well as release others to sustain fermentation. The microbial community continually modifies to accommodate fibre complexity as encountered. Resistant starches (RS) and simple oligosaccharides rapidly ferment to yield VFA while encouraging butyric acid in the cecum and anterior colon, whereas non-starch polysaccharides (NSP) complexity requires extended durations through the remaining colon that enhance acetic acid. Residual fibre eventually results in undue complexity for fermentation and consolidates at termination of the colon. These compact pellets are placed on core contents to form faeces having a nodular surface. Acetic, propionic, and butyric acids represent the bulk of VFA and are derived from non-digestible carbohydrates. Fibrolytic enzymes, when supplemented to feed, may increase the proportion of oligosaccharides and simpler NSP to further the rate as well as extent of fermentation. Active absorption of VFA by mucosal enterocytes employs its ionized form together with Na⁺, whereas direct membrane passage occurs when non-dissociated. Most absorbed VFA favour use by the host with a portion of butyric acid together with by-products from protein digestion being retained to reform mucin and sustain mucosal integrity.

Dietary fibers with low hydration properties exacerbate diarrhea and impair intestinal health and nutrient digestibility in weaned piglets

Background

This study aimed to investigate the hydration properties of different-source fibrous materials by comparing their water-binding capacity (WBC), water swelling capacity (WSC), viscosity, and in vivo effects of selected samples on growth performance, nutrient digestibility, diarrhea, and intestinal health in weaned piglets.

Methods

A total of 13 commercially available fibrous materials were first compared in chemical composition and in vitro hydration property. Subsequently, 40 weaned piglets were randomized to five experimental dietary groups (8 piglets per group): control diet (a basal diet without dietary fiber, CON), basal diet supplemented with 5% microcrystalline cellulose (MCC), 5% wheat bran (WB), 5% Moringaoleifera leaf powder (MOLP), or 5% sugar beet pulp (SBP), followed by analyzing their growth performance and diarrhea rate in a 28-d experiment. After the feeding experiment, anaesthetized piglets were killed, and their intestinal and colon content or plasma samples were analyzed in nutrient digestibility, intestinal morphology, intestinal barrier, short-chain fatty acids (SCFAs), and bacterial population.

Results

In vitro studies showed low hydration properties for WB and MCC, while medium hydration properties for MOLP and SBP. In vivo studies indicated that compared with medium hydration property groups, low hydration property groups showed (1) exacerbated diarrhea, impaired intestinal health, and reduced apparent fecal digestibility of dry matter, gross energy, acid detergent fiber, and neutral detergent fiber; (2) decreased SCFAs concentration and relative levels of Lactobacillus and Bifidobacterium, but increased levels of Escherichia coli and Brachyspira hyodysenteriae in colon contents. Additionally, SBP showed optimal performance in reducing diarrhea and increasing SCFAs production. Correlation analysis revealed a positive correlation of fiber hydration properties with in vitro SCFAs production, and diarrhea index and nutrient digestibility were negatively and positively correlated with SCFAs levels in the colon contents of weaned piglets, respectively.

Conclusions

Different-source dietary fibers varied in their hydration properties and impacts on diarrhea, microbial composition and SCFAs production in weaned piglets. WB and MCC could exacerbate diarrhea and impair nutrient digestibility, probably because their low hydration properties were detrimental to gut microbial homeostasis and fermentation. Our findings provide new ideas for rational use of fiber resources in weaned piglets.

Characteristics of recombinant xylanase from camel rumen metagenome and its effects on wheat bran hydrolysis

In the present study, we explored the effects of a novel xylanase from camel rumen metagenome (CrXyn) on wheat bran hydrolysis. CrXyn was heterologously expressed in Escherichia coli and showed maximum activity at 40 °C and pH 7.0. Furthermore, CrXyn exhibited preferential hydrolysis of xylan, but no obvious activity toward other substrates, including carboxymethylcellulose and Avicel. Using wheat straw xylan as a substrate, the Km and Vmax values for CrXyn were 5.98 g/L and 179.9 μmol xylose/min/mg protein, respectively. Mn²⁺ was a strong accelerator and significantly enhanced CrXyn activity. However, CrXyn activity was inhibited (~50 %) by 1 mM and 5 mM ethylenediaminetetraacetic acid (EDTA) and completely inactivated by 5 mM Cu²⁺. CrXyn tolerated 5 mM sodium dodecyl sulphate (SDS) and 15 % methanol, ethanol, and dimethyl sulfoxide (DMSO), with >50 % residual activity. CrXyn effectively hydrolyzed wheat bran, with xylobiose and xylotetraose accounting for 79.1 % of total sugars produced. A remarkable synergistic effect was found between CrXyn and protease, leading to an obvious increase in amino acids released from wheat bran compared with the control. CrXyn also enhanced the in vitro hydrolysis of wheat bran. Thus, CrXyn exhibits great potential as a feed additive to improve the utilization of wheat bran in monogastric animal production.

Antagonistic Effects of Lipids Against the Anti-Escherichia coli and Anti-Salmonella Activity of Thymol and Thymol-β-d-Glucopyranoside in Porcine Gut and Fecal Cultures In Vitro

Strategies are sought to reduce the carriage and dissemination of zoonotic pathogens and antimicrobial-resistant microbes within food-producing animals and their production environment. Thymol (an essential oil) is a potent bactericide in vitro but in vivo efficacy has been inconsistent, largely due to its lipophilicity and absorption, which limits its passage and subsequent availability in the distal gastrointestinal tract. Conjugation of thymol to glucose to form thymol-β-d-glucopyranoside can decrease its absorption, but in vivo passage of effective concentrations to the lower gut remains suboptimal. Considering that contemporary swine diets often contain 5% or more added fat (to increase caloric density and reduce dustiness), we hypothesized that there may be sufficient residual fat in the distal intestinal tract to sequester free or conjugated thymol, thereby limiting the availability and subsequent effectiveness of this biocide. In support of this hypothesis, the anti-Salmonella Typhimurium effects of 6 mM free or conjugated thymol, expressed as log₁₀-fold reductions of colony-forming units (CFU) ml^-1, were diminished 90 and 58%, respectively, following 24-h in vitro anaerobic fecal incubation (at 39°C) with 3% added vegetable oil compared to reductions achieved during culture without added oil (6.1 log₁₀ CFU ml^-1). The antagonistic effect of vegetable oil and the bactericidal effect of free and conjugated thymol against Escherichia coli K88 tested similarly were diminished 86 and 84%, respectively, compared to reductions achieved in cultures incubated without added vegetable oil (5.7 log₁₀ CFU ml^-1). Inclusion of taurine (8 mg/ml), bile acids (0.6 mg/ml), or emulsifiers such as polyoxyethylene-40 stearate (0.2%), Tween 20, or Tween 80 (each at 1%) in the in vitro incubations had little effect on vegetable oil-caused inhibition of free or conjugated thymol. Based on these results, it seems reasonable to suspect that undigested lipid in the distal gut may limit the effectiveness of free or conjugated thymol. Accordingly, additional research is warranted to learn how to overcome obstacles diminishing bactericidal activity of free and conjugated thymol in the lower gastrointestinal tract of food-producing animals.

Toward Precise Nutrient Value of Feed in Growing Pigs: Effect of Meal Size, Frequency and Dietary Fibre on Nutrient Utilisation

Simple Summary

Feed costs are the most important in swine production. Precise determination of nutritional values of pig diets can help reducing feed costs by reducing security margins for nutrients and therefore provide a more sustainable swine production. In commercial farms, pigs have free access to feed and eat with no limitation according to their natural behaviour. In contrast, during digestibility trials, pigs are restricted in their daily intake of feed, which is distributed in a limited number of meals. The number of meals per day and the amount of feed consumed daily can affect the digestibility of the nutrients, the transit time and the metabolism. To reduce feed costs, by-products are frequently added to diets. Most by-products are rich in dietary fibre, which are known to have negative effects on digestibility. Enzymes can be supplemented in the diet to counteract the negative aspects of dietary fibre, but their efficiency can vary depending on the number of meals per day and the amount of feed consumed daily.

Abstract

Nutritional values of ingredients have been and still are the subject of many studies to reduce security margins of nutrients when formulating diets to reduce feed cost. In most studies, pigs are fed a limited amount of feed in a limited number of meals that do not represent how pigs are fed in commercial farm conditions. With free access to feed, pigs follow their intrinsic feeding behaviour. Feed intake is regulated by satiety and satiation signals. Reducing the feed intake level or feeding frequency can affect digestibility and transit time and induce metabolic changes. To reduce feed costs, alternative ingredients that are frequently rich in dietary fibre are added to diets. Fibre acts on the digestion process and transit time by decreasing energy density and causing viscosity. Various analyses of fibre can be realised, and the measured fibre fraction can vary. Exogenous enzymes can be added to counteract the effect of fibre, but digestive tract conditions, influenced by meal size and frequency, can affect the efficiency of supplemented enzymes. In conclusion, the frequency and size of the meals can affect the digestibility of nutrients by modulating gastrointestinal tract conditions (pH and transit time), metabolites (glucose and short-chain fatty acids) and hormones (glucagon-like peptide 1 and peptide tyrosine tyrosine).

Effects of cereal and protein source on performance, apparent ileal protein digestibility and intestinal characteristics in weaner piglets

Rye and rapeseed meal (RSM) are alternatives to wheat and soybean meal (SBM) in pig nutrition. The inclusion of rye and RSM instead of wheat and SBM may increase dietary fibre content in the feed, which may affect digestive physiology and intestinal function. However, research on the combined feeding of rye and RSM in piglets is still scarce. The aim of this study was to investigate the effects of rye and RSM containing feed on growth performance, protein and amino acid digestibility, physical characteristics of the digesta and the intestinal morphology in weaner piglets. A total of 88 piglets aged 28 d were randomly allotted to four different feeding groups at weaning: wheat/SBM, wheat/RSM, rye/SBM, rye/RSM. Cereals were included at 48%, SBM at 25% and RSM at 30%. Body weight gain and feed intake were recorded weekly. After 33 d, piglets were euthanised for assessment of digesta and intestinal morphology. Rye did not affect performance, whilst RSM resulted in reduced weight gain (p = 0.024) and feed intake (p = 0.037). Apparent ileal digestibility of crude protein and amino acids was decreased by rye and RSM (p < 0.05). Rye caused an acidification (p = 0.045) and increased viscosity (p = 0.013) of small intestinal digesta, a lower dry matter content of jejunal and colonic digesta (p < 0.05) and an increased relative weight of the colon tissue (p < 0.001). In conclusion, performance was not reduced when rye was used as an alternative to wheat in diets for weaner piglets. The inclusion of RSM instead of SBM to piglets' diet lowered animal performance under our conditions. Further investigations are warranted to characterise the quality of rapeseed meal and the optimum inclusion level in the diet for young pigs.

Closely related Lak megaphages replicate in the microbiomes of diverse animals

Lak phages with alternatively coded ∼540 kbp genomes were recently reported to replicate in Prevotella in microbiomes of humans that consume a non-Western diet, baboons, and pigs. Here, we explore Lak phage diversity and broader distribution using diagnostic polymerase chain reaction and genome-resolved metagenomics. Lak phages were detected in 13 animal types, including reptiles, and are particularly prevalent in pigs. Tracking Lak through the pig gastrointestinal tract revealed significant enrichment in the hindgut compared to the foregut. We reconstructed 34 new Lak genomes, including six curated complete genomes, all of which are alternatively coded. An anomalously large (∼660 kbp) complete genome reconstructed for the most deeply branched Lak from a horse microbiome is also alternatively coded. From the Lak genomes, we identified proteins associated with specific animal species; notably, most have no functional predictions. The presence of closely related Lak phages in diverse animals indicates facile distribution coupled to host-specific adaptation.

Etiology of Colitis-Complex Diarrhea in Growing Pigs: A Review

Simple Summary

Diarrhea in growing pigs is a challenge for the pig industry since it is associated with reduced animal welfare, retarded growth, increased feed conversion ratio, and is often treated with antibiotics. One of the major causes of diarrhea in the growing period is large intestinal inflammation, often referred to as colitis. The exact causes of colitis-complex diarrhea are still to be understood, but dietary factors and/or pathogens have been recognized as the major factors in developing colitis-complex diarrhea. In this review, a thorough picture of pathogens, dietary factors, and a number of possible biomarkers related to colitis-complex diarrhea is presented.

Abstract

Colitis-complex diarrhea (CCD) in pigs can be defined as a type of diarrhea, which is associated with colonic inflammation and disrupted colonic gut barrier functionality in growing pigs (4–16 weeks post-weaning). It is a challenge for the pig industry as it is associated with the high use of antibiotics, reduced animal welfare, and depressed growth rate. The exact etiology of CCD is still unclear; however, pathogens including Brachyspira (B.) hyodysenteriae, B. pilosicoli, and swine whipworms such as Trichuris (T.) suis have been involved in specific colitis (SC). In the absence of specific pathogens, dietary factors, such as high levels of protein, pelleted feedstuffs, and lack of sufficient antioxidants, can result in non-specific colitis (NSC). On the other hand, supplement of polyunsaturated fatty acids (PUFA) and polyphenols, sufficient supply of essential amino acids (e.g., threonine, cysteine, and proline), short-chain fatty acids (SCFA; especially butyrate), and resistant starch have shown to confer preventing/ameliorating effects on CCD. Different putative biomarkers associated with CCD have been presented. It is anticipated that a comprehensive picture of the possible causes of CCD and potential dietary interventions could cast light on the direction of future studies aimed at developing preventive and curative strategies against CCD in growing pigs.

Kiwifruit (Actinidia deliciosa), compared with cellulose and psyllium, influences the histology and mucus layer of the gastrointestinal tract in the growing pig

Kiwifruit (KF) fiber, a mixture of soluble and insoluble fibers, elicits mucosal changes in the gastrointestinal tract (GIT). This study aimed to define the nature of these changes in mucosal features throughout the GIT of the growing pig in response to semi-synthetic iso-fiber diets containing cellulose (CEL, low GIT luminal functionality) as the sole fiber source (4.5%), or diets where half of the CEL was replaced by either PSY fiber (PSY husk, high GIT luminal functionality) or KF fiber (consumed as intact fruit). Entire male growing pigs (n = 24, 21 kg bodyweight) received the three diets (n = 8) for 42 d. GIT tissues, digesta, and feces were sampled. The partial replacement of CEL increased (P≤ 0.05) the ileal (KF 22% and PSY 33%) and colonic (PSY 86%) mucus layer thickness, whereas it decreased the rectal crypt depth (KF -26%), and small intestinal (duodenum to ileum) villus length (PSY -17%). The number of duodenal goblet cells was 77% higher (P≤ 0.05) for KF than CEL. Pigs fed the KF-containing diet had greater (P≤ 0.05) apparent ileal organic matter digestibility and apparent total tract organic matter digestibility compared with CEL, but the lowest amount of fermented organic matter in the large intestine. In conclusion, partial substitution of CEL with PSY or KF at a constant, practically-relevant dietary fiber intake, affected several measures of GIT functionality with effects being specific to the added fiber.

Interplay between grain digestion and fibre in relation to gastro-small-intestinal passage rate and feed intake in pigs

PURPOSE

The combined effects of grain digestibility and dietary fibre on digesta passage rate and satiety in humans are poorly understood. Satiety can be increased through gastric distention, reduced gastric emptying rate and when partially digested nutrients reach the terminal ileum to stimulate peptide release through the ileal/colonic brakes to slow the rate of digesta passage. This study determined the effects of grain digestibility and insoluble fibre on mean retention time (MRT) of digesta from mouth-to-ileum, feed intake (FI), starch digestion to the terminal ileum and faecal short chain fatty acids (SCFA) in a pig model.

METHOD

Twelve grain-based [milled sorghum (MS), steam-flaked-sorghum, milled wheat, and steam-flaked-wheat (SFW)] diets with different intrinsic rates of starch digestion, assessed by apparent amylase diffusion coefficient (ADC), and fibre from oat hulls (OH) at 0, 5 and 20% of the diet were fed to ileal-cannulated pigs.

RESULT

MRT was affected by grain-type/processing (P < 0.05) and fibre amount (P < 0.05). An approximate tenfold increase in ADC showed a limited decline in MRT (P = 0.18). OH at 20% increased MRT (P < 0.05) and reduced FI (P < 0.05). Ileal digestibility of starch increased and faecal SCFA concentration decreased with ADC; values for MS being lower (P < 0.001) and higher (P < 0.05), respectively, than for SFW.

CONCLUSIONS

Lower ileal digestibility of starch, higher faecal SCFA concentration and longer MRT of MS than SFW, suggest the ileal/colonic brakes may be operating. FI appeared to decrease with increasing MRT. MRT increased and intake decreased with grain-based foods/feeds that have low starch digestibility and substantial amounts of insoluble fibre.

Screening of probiotic candidates in a simulated piglet small intestine in vitro model

The CoMiniGut in vitro model mimicking the small intestine of piglets was used to evaluate four probiotic strains for their potential as a preventive measure against development of diarrhea in weaned pigs. In the in vitro system, piglet digesta was inoculated with pathogenic enterotoxigenic Escherichia coli F4 (ETEC F4), and the short-chain fatty acid profile and the gut microbiota composition were assessed. A total of four probiotic strains were evaluated: Enterococcus faecium (CHCC 10669), Lactobacillus rhamnosus (CHCC 11994), Bifidobacterium breve (CHCC 15268) and Faecalibacterium prausnitzii (CHCC 28556). The significant differences observed in metabolite concetration and bacterial enumeration were attributed to variation in inoculating material or pathogen challenge rather than probiotic treatment. Probiotic administration influenced the microbiota composition to a small extend. Learnings from the present study indicate that the experimental setup, including incubation time and choice of inoculating material, should be chosen with care.

Evaluation of Thymol-β-d-Glucopyranoside as a Potential Prebiotic Intervention to Reduce Carriage of Zoonotic Pathogens in Weaned and Feeder Pigs

The gut of food-producing animals is a reservoir for foodborne pathogens. Thymol is bactericidal against foodborne pathogens but rapid absorption of thymol from the proximal gut precludes the delivery of effective concentrations to the lower gut where pathogens mainly colonize. Thymol-β-d-glucopyranoside is reported to be more resistant to absorption than thymol in everted jejunal segments and could potentially function as a prebiotic by resisting degradation and absorption in the proximal gut but being hydrolysable by microbial β-glycosidase in the distal gut. Previous in vitro studies showed bactericidal effects of thymol-β-d-glucopyranoside against Campylobacter, Escherichia coli, and Salmonella enterica serovar Typhimurium in the presence but not absence of intestinal microbes expressing β-glycosidase activity, indicating that hydrolysis was required to obtain antimicrobial activity. Presently, the oral administration of thymol-β-d-glucopyranoside was studied to examine the effects on intestinal carriage of Campylobacter, E. coli, and S. Typhimurium in swine. The effects of thymol-β-d-glucopyranoside or thymol on antimicrobial sensitivity of representative E. coli isolates and characterized Salmonella strains were also explored. Results from two in vivo studies revealed little antimicrobial effects of thymol-β-d-glucopyranoside on Campylobacter, E. coli, or S. Typhimurium in swine gut. These findings add credence to current thinking that hydrolysis and absorption of thymol-β-d-glucopyranoside and thymol may be sufficiently rapid within the proximal gut to preclude delivery to the distal gut. Antibiotic susceptibilities of selected bacterial isolates and strains were mainly unaffected by thymol. Further research is warranted to overcome obstacles, preventing the delivery of efficacious amounts of thymol-β-d-glucopyranoside to the lower gut.

Effects of corn particle size on energy and nutrient digestibility in diets fed to young pigs and adult sows

Objective

This research was carried out to investigate the effects of corn particle size on the apparent total tract digestibility (ATTD) of energy and nutrients fed to pigs at four different growth stages and therefore to provide basis for better application of corn in pig feeds.

Methods

Eighteen weanling piglets, 18 growing barrows, 24 gestating sows and 24 lactating sows were used in this study. Within each stage, pigs were allotted to 1 of 3 or 4 corn-soybean meal diets which were formulated with different corn particle size in a completely randomized design with 6 replicate pigs per diet. Each stage lasted for 19 days, including 7 days for cages adaptation, 7 days for adaptation to diets and followed by 5 days for total collection of feces and urine.

Results

For nursery and growing stages, the results showed that digestible energy content and ATTD of gross energy (GE), dry matter (DM), neutral detergent fiber (NDF), and acid detergent fiber (ADF) was increased (p<0.05) as the corn particle size reduced. Meanwhile, the metabolizable energy content and ATTD of crude protein (CP) tended to increase. For gestating sows, no differences were found in the ATTD of nutrients among dietary treatments. As for lactating sows, there were linear and quadratic increases (p<0.05) in the ATTD of DM, GE, NDF as the corn being finer milled. Quadratic response in ATTD of ADF and CP (p<0.05) were observed as sows fed with four different diets.

Conclusion

Reducing corn particle size can increase digestibility of nutrients fed to young pigs and lactating sows. No effects were observed in present experiment when gestating sows were fed with different particle sized corn.

Effects of Dietary Fiber on Nutrients Utilization and Gut Health of Poultry: A Review of Challenges and Opportunities

Simple Summary

The inclusion of agricultural co-products has been increased to utilize the nutrients in these products available at low cost, but inherently, it adds a high dietary fiber content in the poultry diets. The use of exogenous feed enzymes along with advancements in feed milling, feed formulation, and processing of these non-conventional ingredients to improve their digestibility and utilization have played an emphatic role in boosting their use globally. Despite such developments, the presence of a high level of dietary fibers (DF) acting in an anti-nutritive manner still poses challenges in poultry feeding. Various isolated forms of fiber or feed enzymes to break DF into fermentable substrates are being used extensively to provide potential prebiotics to support beneficial gut microbiota or probiotics to improve the gut health of poultry raised without antibiotic growth promoters (AGP). This review reports and discusses the existing challenges in feeding high-DF feed ingredients to poultry and the opportunities that are available to improve the nutritive value of such non-conventional feed ingredients by adopting various technologies.

Abstract

Many fibrous ingredients incorporated in poultry feed to reduce production costs have low digestibility and cause poor growth in poultry. However, all plant-based fibers are not equal, and thus exert variable physiological effects on the birds, including but not limited to, digestibility, growth performance, and microbial fermentation. Several types of fibers, especially oligosaccharides, when supplemented in poultry diets in isolated form, exhibit prebiotic effects by enhancing beneficial gut microbiota, modulating gut immunity, boosting intestinal mucosal health, and increasing the production of short-chain fatty acids (SCFA) in the gut. Recently, poultry producers are also facing the challenge of limiting the use of antibiotic growth promoters (AGP) in poultry feed. In addition to other alternatives in use, exogenous non-starch polysaccharides digesting enzymes (NSPase) and prebiotics are being used to provide substrates to support the gut microbiome. We also conducted a meta-analysis of different studies conducted in similar experimental conditions to evaluate the variability and conclusiveness in effects of NSPase on growth performance of broilers fed fibrous ingredients. This review presents a holistic approach in discussing the existing challenges of incorporating high-fiber ingredients in poultry feed, as well as strategies to fully utilize the potential of such ingredients in improving feed efficiency and gut health of poultry.

Trends in feed evaluation for poultry with emphasis on in vitro techniques

Accurate knowledge of the actual nutritional value of individual feed ingredients and complete diets is critical for efficient and sustainable animal production. For this reason, feed evaluation has always been in the forefront of nutritional research. Feed evaluation for poultry involves several approaches that include chemical analysis, table values, prediction equations, near-infrared reflectance spectroscopy, in vivo data and in vitro digestion techniques. Among these, the use of animals (in vivo) is the most valuable to gain information on nutrient utilization and is more predictive of bird performance. However, in vivo methods are expensive, laborious and time-consuming. It is therefore important to establish in vitro methods that are reliable, rapid and practical to assess the nutritional quality of feed ingredients or complete diets. Accuracy of the technique is crucial, as poor prediction will have a negative impact on bird performance and, increase feed cost and environmental issues. In this review, the relevance and importance of feed evaluation in poultry nutrition will be highlighted and the various approaches to evaluate the feed value of feed ingredients or complete diets will be discussed. Trends in and practical limitations encountered in feed evaluation science, with emphasis on in vitro digestion techniques, will be discussed.

The glyphosate formulation Roundup® LB plus influences the global metabolome of pig gut microbiota in vitro

Glyphosate is the world's most widely used herbicide, and its potential side effects on the intestinal microbiota of various animals, from honeybees to livestock and humans, are currently under discussion. Pigs are among the most abundant livestock animals worldwide and an impact of glyphosate on their intestinal microbiota function can have serious consequences on their health, not to mention the economic effects. Recent studies that addressed microbiota-disrupting effects focused on microbial taxonomy but lacked functional information. Therefore, we chose an experimental design with a short incubation time in which effects on the community structure are not expected, but functional effects can be detected. We cultivated intestinal microbiota derived from pig colon in chemostats and investigated the acute effect of 228 mg/d glyphosate acid equivalents from Roundup® LB plus, a frequently applied glyphosate formulation. The applied glyphosate concentration resembles a worst-case scenario for an 8-9 week-old pig and relates to the maximum residue levels of glyphosate on animal fodder. The effects were determined on the functional level by metaproteomics, targeted and untargeted meta-metabolomics, while variations in community structure were analyzed by 16S rRNA gene profiling and on the single cell level by microbiota flow cytometry. Roundup® LB plus did not affect the community taxonomy or the enzymatic repertoire of the cultivated microbiota in general or on the expression of the glyphosate target enzyme 5-enolpyruvylshikimate-3-phosphate synthase in detail. On the functional level, targeted metabolite analysis of short chain fatty acids (SCFAs), free amino acids and bile acids did not reveal significant changes, whereas untargeted meta-metabolomics did identify some effects on the functional level. This multi-omics approach provides evidence for subtle metabolic effects of Roundup® LB plus under the conditions applied.

Effects of Optimal Carbohydrase Mixtures on Nutrient Digestibility and Digestible Energy of Corn- and Wheat-Based Diets in Growing Pigs

This study aimed to evaluate the effects of optimal carbohydrase mixture (OCM) on macronutrients and amino acid digestibility and the digestible energy (DE) in growing pigs fed the corn-soybean meal-based diet (CSM) and the wheat-soybean meal-based diet (WSM). A total of 36 ileal-cannulated pigs (50.9 ± 4.9 kg initial body weight) were allotted to four dietary treatments randomly, which included CSM and WSM diets, and two diets supplied with corresponding OCM. These OCMs were screened using an in vitro method from our previous study. After the five day adaptation period, fecal samples were collected from d six to seven, and ileal digesta samples were collected on d 8 and 10. Chromic oxide was added as an indigestible marker. The results show that the addition of OCM improved the apparent ileal digestibility (AID) of dry matter (DM), ash, carbohydrate (CHO), neutral detergent fiber, and gross energy (GE) and the apparent total tract digestibility (ATTD) of DM, CHO, and GE in CSM diet (p < 0.05), but reduced the apparent hindgut disappearance (AHD) of DM in CSM diet (p < 0.05). The ATTD of DM, crude protein (CP), ether extract (EE), ash, and GE and the AHD of DM, CP, EE, ash, CHO, and GE in WSM diet were improved by the OCM addition (p < 0.05), whereas the AID of DM, CP, ash, CHO, and GE were decreased (p < 0.05). The respective DE contents in CSM and WSM diets were increased from 15.45 to 15.74 MJ/kg and 15.03 to 15.49 MJ/kg under the effects of OCM (p < 0.05). Similar to the trend of AID of CP, the OCM addition increased the AID and standardized ileal digestibility (SID) of Ile, Thr, and Cys in CSM diet, but decreased the AID and SID of Ile, Phe, Thr, Val, Ala, Pro, Ser, and Tyr in WSM diet. In conclusion, the OCMs screened by an in vitro method could improve the total tract nutrient digestibility and DE for pigs fed corn-based diet or wheat-based diet but had inconsistent effects on the ileal digestibility of nutrients and energy.

The dietary protein content slightly affects the body temperature of growing pigs exposed to heat stress

Heat stress (HS) increases body temperature (BT) and reduces feed intake in pigs. Increasing the dietary protein content may correct the reduced amino acid intake provoked by HS, but it may further increase BT. The effect of dietary protein level on BT of HS pigs was analyzed with nine ileal cannulated pigs (61.7 ± 2.5 kg body weight). A thermometer set to register BT at 5-min intervals was implanted into the ileum. There were two treatments: low-protein (10.8%) wheat-free-amino acid diet (LP); high-protein (21.6%), wheat-soybean-meal diet (HP). The study was conducted in two 10-d periods; in each period, d1 to d6 was for diet adaptation, d7 to d9 was for data analysis, and d10 for ileal sample collection. Pigs were fed at 0600 h (morning), 1400 h (midday), and 2200 h (evening), same amount each time. Following, the separate contribution of ambient temperature and thermal effect of feeding on the postprandial BT increment was analyzed in fed and fasted pigs. Ambient temperature ranged from 30.1 to 35.4 °C and relative humidity from 50% to 84%. Both ambient temperature and BT followed similar patterns. The BT of HP pigs after the morning and midday meals was higher (P < 0.05) but size of the BT increments did not differ between HP and LP pigs. Midday and evening postprandial BT were higher than postprandial morning BT (P < 0.05). The BT increment was larger and longer after the midday than after the morning and evening meals (P < 0.05). The capacity of pigs to dissipate postprandial body heat depends on the accumulated thermal load received before their meals, because the thermal load before the morning meal was smaller than that before the evening meal. The estimated contribution of thermal effect of feeding (0.42 to 0.87 °C) on the total postprandial BT increment (0.69 to 1.53 °C) was larger (P < 0.05) than that of ambient temperature (0.27 to 0.66 °C). In conclusion, these data indicate that the dietary protein level has a small effect on the BT of HS pigs regardless of feeding time. Also both the thermal effect of feeding and ambient temperature impact the BT of HS pigs, although the former had a stronger effect. This information may be useful to design better feeding strategies for pigs exposed to HS conditions.

Reformulation and food combination as strategies to modulate glycaemia: the case of apple pomace containing biscuits administered with apple juice to healthy rats

Conventional (CB) and apple-pomace-reformulated (RB) biscuits were administered to healthy rats. Although the areas under curve (AUC) of glucose concentration were comparable between samples, differences in the glycaemic profile of CB and RB were observed. RB caused an initial steeper increase in glycaemia but a shift in the glycaemic peak from 45 to 60 min, as compared to CB. When CB or RB was ingested with apple juice (AJ) no differences were observed as compared to their ingestion with a soft drink (SD) simulating AJ sugar content, indicating that reformulation, more than the presence of AJ, was crucial in affecting the glycaemic response. Consumer acceptability towards reformulation was assessed through conjoint analysis, by simulating labels reporting information on reformulation. Consumers preferred information generally referring to the health-promoting effect (i.e. "low sugar" and "high fibre" contents), despite directly relating to a specific disease (i.e. "suitable for diabetics" and "low glycaemic index").

Dietary Soluble and Insoluble Fiber With or Without Enzymes Altered the Intestinal Microbiota in Weaned Pigs Challenged With Enterotoxigenic E. coli F18

Post-weaning diarrhea caused by enterotoxigenic E. coli (ETEC) causes significant economic losses for pig producers. This study was to test the hypotheses that an ETEC challenge disrupts intestinal microbial homeostasis and the inclusion of dietary soluble (10% sugar beet pulp) or insoluble fiber (15% corn distillers dried grains with solubles) with or without exogenous carbohydrases will protect or restore the gut microbial homeostasis in weaned pigs. Sixty crossbred piglets (6.9 ± 0.1 kg) were blocked by body weight and randomly assigned to one of six treatments (n = 10), including a non-challenged control (NC), ETEC F18-challenged positive control (PC), ETEC-challenged soluble fiber without (SF-) or with carbohydrases (SF+), and ETEC-challenged insoluble fiber without (IF-) or with carbohydrases (IF+). Pigs were housed individually and orally received either ETEC inoculum or PBS-sham inoculum on day 7 post-weaning. Intestinal contents were collected on day 14 or 15. The V4 region of the bacterial 16S rRNA was amplified and sequenced. High-quality reads (total 6,671,739) were selected and clustered into 3,330 OTUs. No differences were observed in α-diversity among treatments. The ileal microbiota in NC and PC had modest separation in the weighted PCoA plot; the microbial structures were slightly altered by SF+ and IF- compared with PC. The PC increased ileal Escherichia-Shigella (P < 0.01) and numerically decreased Lactobacillus compared to NC. Predicted functional pathways enriched in the ileal microbiota of PC pigs indicated enhanced activity of Gram-negative bacteria, in agreement with increased Escherichia-Shigella. The SF+ tended to decrease (P < 0.10) ileal Escherichia-Shigella compared to PC. Greater abundance of ileal Streptococcus, Turicibacter, and Roseburia and colonic Prevotella were observed in SF- and SF+ than PC (P < 0.05). Pigs fed IF + had greater Lactobacillus and Roseburia than PC pigs (P < 0.05). The ETEC challenge reduced total volatile fatty acid (VFA) compared with NC (P < 0.05). The SF+ tended to increase (P < 0.10) and SF- significantly increased (P < 0.05) colonic total VFA compared with PC. Collectively, ETEC challenge disrupted gut microbial homeostasis and impaired microbial fermentation capacity. Soluble fiber improved VFA production. Dietary fiber and carbohydrases altered microbiota composition to maintain or restore microbial homeostasis.

The Activation of Mucosal-Associated Invariant T (MAIT) Cells Is Affected by Microbial Diversity and Riboflavin Utilization in vitro

Recent research has demonstrated that MAIT cells are activated by individual bacterial or yeasts species that possess the riboflavin biosynthesis pathway. However, little is known about the MAIT cell activating potential of microbial communities and the contribution of individual community members. Here, we analyze the MAIT cell activating potential of a human intestinal model community (SIHUMIx) as well as intestinal microbiota after bioreactor cultivation. We determined the contribution of individual SIHUMIx community members to the MAIT cell activating potential and investigated whether microbial stress can influence their MAIT cell activating potential. The MAIT cell activating potential of SIHUMIx was directly related to the relative species abundances in the community. We therefore suggest an additive relationship between the species abundances and their MAIT cell activating potential. In diverse microbial communities, we found that a low MAIT cell activating potential was associated with high microbial diversity and a high level of riboflavin demand and vice versa. We suggest that microbial diversity might affect MAIT cell activation via riboflavin utilization within the community. Microbial acid stress significantly reduced the MAIT cell activating potential of SIHUMIx by impairing riboflavin availability through increasing the riboflavin demand. We show that MAIT cells can perceive microbial stress due to changes in riboflavin utilization and that riboflavin availability might also play a central role for the MAIT cell activating potential of diverse microbiota.

Wheat bran and oat hulls have dose-dependent effects on ad-libitum feed intake in pigs related to digesta hydration and colonic fermentation

Undigested nutrients and fermentable fibre in the distal ileum and colon stimulate intestinal brakes, which reduce gastric-emptying and digesta-passage-rate, and subsequently limit feed/food-intake. Fibre can also stimulate passage rate potentially increasing feed intake (FI). In order to experimentally determine the relationships between these two hypothesised actions of fibre, five levels of wheat-bran (WB) or oat-hulls (OH) were added to a highly digestible starch-based diet fed to pigs ad-libitum for three weeks. Average-daily-feed-intake (ADFI), faecal short-chain-fatty-acids (SCFA) and related parameters were determined at 7, 14 and 21d. A linear mixed model was fitted to FI and fermentation parameters. Overall, WB diets showed 8-11% lower ADFI (7-14d: p < 0.05; 7-21 & 0-21d: p = 0.053) than OH diets. WB diets produced over 20% more (21d: p < 0.01) SCFA than OH or Control diets. WB at 25% produced 22% more (7d: p < 0.05) SCFA than any other diet. Diets with WB at 25 and 35%, showed higher hydration capacity than any other diet (p < 0.001). OH at 10% had an unusually low FI and a markedly higher hydration capacity. With increasing levels of OH, intake of base diet was 7% more than control at 5% OH, but 8% less than control at 20% OH. With increasing WB content, intake of base diet decreased. From these results, we propose that three mechanisms control the effects of fibre on FI: initial increase in passage rate and feed intake at low concentrations of non-swelling fibres; a depression in FI from high fibre bulk; and reduced feed intake from stimulation of ileal and colonic brakes.

Polymeric Films for the Encapsulation, Storage, and Tunable Release of Therapeutic Microbes

Microbe-based therapeutics (MBTs) are an emerging therapeutic modality for treating gastrointestinal infections and inflammatory bowel diseases. Current formulations for oral delivery of MBTs use capsules to achieve safe gastric transit, but oral formulations that control the spatiotemporal concentration of MBTs are yet to be developed, despite well-established connections between all therapeutics and their location, concentration, and distribution at sites of action. The development of a multi-functional polymer-based encapsulation system to formulate MBTs for enhanced storage and delivery through formulation of a model MBT, Lactobacillus casei ATCC393, is reported here. This approach enables the additive inclusion of excipients and polymers to grant specific functions, toward the development of a modular MBT platform. Through addition of established excipients, the formulation provides long-term storage of the encapsulated MBT. By adding higher molecular weight polymers, the release kinetics of the encapsulated MBTs can be modified. The inclusion of a mucoadhesive polymer significantly increases the adhesion force between the formulation and the intestinal tissue. Together, mucoadhesive and sustained release properties can be used to modulate the spatiotemporal concentration of MBTs. The formulation is compatible with standard oral capsules, thus maintaining existing clinical advantages of oral capsules while providing new functions from film encapsulation.

Effects of different sources and levels of dietary iron and selenium on the postprandial net portal appearance of these minerals in growing pigs

The present study compares the net portal appearance of dietary iron (Fe) and selenium (Se) after meals containing different sources and levels of these minerals. Twelve pigs (55.1 ± 3.7 kg) were used in a cross-over design to assess the 11-h net portal-drained viscera (PDV) flux of serum Fe and Se after ingestion of boluses containing inorganic (I) or organic (O) dietary Fe and Se at industry average (A; 200 and 0.6 mg, respectively) or high (H; 400 and 1.2 mg, respectively) levels. Arterial serum Fe concentrations increased by an average of 158% within 6 h post-meal and gradually decreased thereafter (P < 0.001). Values were greater (P < 0.001) for I than for O until 6 h post-meal and greater (P ≤ 0.001) for A than for H from 4 to 8 h post-meal. For the whole post-prandial period (11 h), arterial serum Fe concentrations tended (P = 0.06) to be greater for I than for O and were lowest for HO (P ≤ 0.03). Net PDV flux of Fe tended to be greater for AI than for AO (P ≥ 0.07). Cumulative appearance of Fe in PDV serum (% of dietary intake) was greater for I than for O (2.43 vs. -0.76%; P = 0.02) and A tended to be greater than H (1.96 vs. -0.29 %; P = 0.09) until 3 h post-meal, but these effects further faded out (P ≥ 0.43). Arterial serum Se concentration decreased for all treatments (average of 7%) from premeal values (P < 0.001), and this was more pronounced for O than for I (P = 0.03). Irrespective of treatment, net PDV flux of Se was positive (different from 0, P ≤ 0.03) during the first 90 min post-meal, decreased to negative minimum values (different from 0, P = 0.03) at 5 h post-meal, and was not different from 0 thereafter (P ≥ 0.11). Cumulative appearance of Se in PDV serum (% of dietary intake) was greater for I than for O (20.0 vs. -3.8%; P = 0.04) only at 45 min post-meal. In conclusion, both dietary Fe and Se absorption are limited to the early post-meal period. Whereas for Fe, the level effect is in accordance with the known negative correlation between its dietary concentration and percentage of intestinal absorption, this was not the case for dietary Se. The postabsorptive availability of dietary I was greater than O for both minerals and, particularly for Fe, at low levels.

In vitro prebiotic potential of agricultural by-products on intestinal fermentation, gut barrier and inflammatory status of piglets

The inclusion of fibre-rich ingredients in diets is one possible strategy to enhance intestinal fermentation and positively impact gut ecology, barrier and immunity. Nowadays, inulin-type fructans are used as prebiotics in the feed of piglets to manipulate gut ecology for health purposes. Likewise, some by-products could be considered as sustainable and inexpensive ingredients to reduce gut disorders at weaning. In the present study, chicory root and pulp, citrus pulp, rye bran and soya hulls were tested in a three-step in vitro model of the piglet's gastro-intestinal tract combining a pepsin-pancreatin hydrolysis (digestion), a dialysis step using cellulose membranes (absorption) and a colonic batch fermentation (fermentation). The fermentation kinetics, SCFA and microbiota profiles in the fermentation broth were assessed as indicators of prebiotic activity and compared with the ones of inulin. The immunomodulatory effects of fermentation supernatant (FS) were investigated in cultured intestinal porcine epithelial cells (IPEC-J2) by high-throughput quantitative PCR. Chicory root displayed a rapid and extensive fermentation and induced the second highest butyrate ratio after inulin. Citrus pulp demonstrated high acetate ratios and induced elevated Clostridium clusters IV and XIVa levels. Chicory root and pulp FS promoted the intestinal barrier integrity with up-regulated tight and adherens junction gene expressions in comparison with inulin FS. Chicory pulp FS exerted anti-inflammatory effects in cultured IPEC-J2. The novel approach combining an in vitro fermentation model with IPEC-J2 cells highlighted that both chicory root and pulp appear to be promising ingredients and should be considered to promote intestinal health at weaning.

Feed intake patterns nor growth rates of pigs are affected by dietary resistant starch, despite marked differences in digestion

Current feed evaluation systems often assume that fermented starch (i.e. resistant starch (RS)) yields less energy than digested starch. However, growth rates of pigs fed low and high RS diets are often the same when feed is available ad libitum. This may be explained by its effect on digestive processes changing feeding behavior, and consequently energy utilization. This study aims to investigate the effect of RS on nutrient digestion and digesta passage rate in pigs, in combination with its effect on feeding behavior and growth performance under ad libitum conditions. In experiment 1, 20 male pigs (40 ± 2.82 kg) were fed diets containing either 50% waxy maize starch (low in RS (LRS)) or high-amylose maize starch (high in RS (HRS)), and soluble and insoluble indigestible markers. After 14 days of adaptation to the diets, pigs were fed hourly to reach steady state (6 h), dissected, and digesta were collected from eight segments. From the collected samples, nutrient digestion and passage rate of the solid and liquid digesta fraction were determined. In experiment 2, 288 pigs (80 ± 0.48 kg; sex ratio per pen 1 : 1; boar : gilt) were housed in groups of 6. Pigs were ad libitum-fed one of the experimental diets, and slaughtered at approximately 115 kg. Feed intake, growth and carcass parameters were measured. Ileal starch digestibility was greater for LRS-fed than for HRS-fed pigs (98.0% v. 74.0%; P < 0.001), where the additional undigested starch in HRS-fed pigs was fermented in the large intestine. No effects of RS on digesta passage rate of the solid or liquid digesta fraction and on feeding behavior were observed. Growth rate and feed intake did not differ between diets, whereas feed efficiency of HRS-fed pigs was 1%-unit higher than that of LRS-fed pigs (P = 0.041). The efficiency of feed used for carcass gain did not differ between diets indicating that the difference in feed efficiency was determined by the non-carcass fraction. Despite a 30% greater RS intake (of total starch) with HRS than with LRS, carcass gain and feed efficiency used for carcass gain were unaffected. RS did not affect digesta passage rate nor feeding behavior suggesting that the difference in energy intake between fermented and digested starch is compensated for post-absorptively. Our results indicate that the net energy value of fermented starch currently used in pig feed evaluation systems is underestimated and should be reconsidered.

Impact of dietary zinc:copper ratio on the postprandial net portal appearance of these minerals in pigs1

The present study compared the net intestinal absorption of zinc (Zn) and copper (Cu) after meals containing different dietary ratios among these trace elements. Ten 46-kg pigs were used in a cross-over design to assess the 10-h net portal-drained viscera (PDV) flux of serum Cu and Zn after ingestion of boluses containing ZnSO4 and CuSO4 in different Zn:Cu ratios (mg:mg): 120:20; 200:20; 120:8; and 200:8. Arterial Zn concentrations peaked within the first hour post-meal and responses were greater with 200 (0.9 to 1.8 mg/L) than with 120 mg (0.9 to 1.6 mg/L) of dietary Zn (dietary Zn × time, P = 0.05). Net PDV flux of Zn was greater (P = 0.02) with 200 than with 120 mg of dietary Zn and tended to be greater (P = 0.10) with 20 than with 8 mg of dietary Cu. The cumulative PDV appearance of Zn (% of dietary intake) was greater with 120 than 200 mg of dietary Zn from 8 h post-meal (P ≤ 0.04) and with 20 than 8 mg of dietary Cu from 7 h post-meal (P ≤ 0.05). At the end of the postprandial period (10 h), estimated PDV appearance of Zn was 16.0%, 18.4%, 12.0%, and 15.3% of Zn intake for 120:8, 120:20, 200:8, and 200:20 ratios, respectively. For Cu, irrespective of treatment, arterial values varied (P < 0.01) by less than 5% across postmeal times. Net PDV flux was not affected by treatments (P ≥ 0.12), but the value for ratio 120:20 was different from zero (P = 0.03). There was an interaction dietary Zn × dietary Cu on cumulative PDV appearance of Cu (% of dietary intake) at 30 min post-meal (P = 0.04) and thereafter at 3 h post-meal (P = 0.04). For the whole postprandial period (10 h), estimated PDV appearance of Cu was 61.9%, 42.1%, -17.1%, and 23.6% of Cu intake for 120:8, 120:20, 200:8, and 200:20 ratios, respectively. In conclusion, the present dietary amounts and ratios of Zn and Cu can affect the metabolic availability of both trace minerals for pigs. Ratios with 120 mg of dietary Zn maximized the postintestinal availability of both Zn and Cu.

Review: Effects of fibre, grain starch digestion rate and the ileal brake on voluntary feed intake in pigs

Grains rich in starch constitute the primary source of energy for both pigs and humans, but there is incomplete understanding of physiological mechanisms that determine the extent of digestion of grain starch in monogastric animals including pigs and humans. Slow digestion of starch to produce glucose in the small intestine (SI) leads to undigested starch escaping to the large intestine where it is fermented to produce short-chain fatty acids. Glucose generated from starch provides more energy than short-chain fatty acids for normal metabolism and growth in monogastrics. While incomplete digestion of starch leads to underutilised feed in pigs and economic losses, it is desirable in human nutrition to maintain consistent body weight in adults. Undigested nutrients reaching the ileum may trigger the ileal brake, and fermentation of undigested nutrients or fibre in the large intestine triggers the colonic brake. These intestinal brakes reduce the passage rate in an attempt to maximise nutrient utilisation, and lead to increased satiety that may reduce feed intake. The three physiological mechanisms that control grain digestion and feed intake are: (1) gastric emptying rate; (2) interplay of grain digestion and passage rate in the SI controlling the activation of the ileal brake; and (3) fermentation of undigested nutrients or fibre in the large intestine activating the colonic brake. Fibre plays an important role in influencing these mechanisms and the extent of their effects. In this review, an account of the physiological mechanisms controlling the passage rate, feed intake and enzymatic digestion of grains is presented: (1) to evaluate the merits of recently developed methods of grain/starch digestion for application purposes; and (2) to identify opportunities for future research to advance our understanding of how the combination of controlled grain digestion and fibre content can be manipulated to physiologically influence satiety and food intake.