A combined pig model to determine the net absorption of volatile fatty acids in the large intestine under different levels of crude fiber

Background:This study aimed to develop a combined model to quantify the net absorption of volatile fatty acids(VFA)in the large intestine(LI)of pigs.Methods:Fifteen female growing pigs(Duroc×Large White×Landrace)were ranked by body weight(30±2.1 kg)on day 0 and assigned to one of three treatments,namely the basal diet containing different crude fiber(CF)levels(LCF:3.0%CF,MCF:4.5%CF,and HCF:6.0%CF).The pigs were implanted with the terminal ileum fistula and the cannulation of the ileal mesenteric vein(IMV),portal vein(PV),and left femoral artery(LFA)from days 6 to 7.[13 C]-Labeled VFA and P-aminohippuric acid were constantly perfused into the terminal ileum fistula and the cannulation of the IMV(day 15),respectively.Blood samples were collected from the PV and the LFA during perfusion(5 h),and LI samples were collected.Results:The net flux of[12 C]-acetic acid in the PV was greater for LCF versus MCF(p=0.045),but no difference was observed in the net flux of[12 C]-propionic acid(p=0.505)and[12 C]-butyric acid(p=0.35)in the PV among treatments.The deposition of[12 C]-acetic acid in the LI was greater for LCF versus MCF(p=0.014),whereas the deposition of[12 C]-propionic acid(p=0.007)and[12 C]-butyric acid(p=0.037)in the LI was greater for LCF versus HCF.Conclusions:In conclusion,this pig model was found conducive to study the net absorption of VFAs in the LI,and LCF had more net absorption of VFAs in the LI than MCF and HCF.

IMMUNOCYTOCHEMICAL STUDY OF ENTEROCHROMAFFIN CELLS IN CARCINOMAS OF THE LARGE INTESTINE

In a series of 130 cases of adenocarcinomas of the large intestine, enterochromaffin (EC) cells were detected in 54 cases (41.3%) by limmunocytochemistry with anti-chromogranin monoclonal antibody. Among the 54 cases, 30 were found positive for serotonin, 14 for somatostatin, 11 for glucagon, 5 for pancreatic polypeptide, and only one for gastrin. The cases with EC cell (++) or polypeptide positive cells exhibited higher grade of differentiation, earlier stage of tumor extension and higher survival rate than those without EC cells. A significant difference of the EC cell population pattern among different histological grades of the tumors and non-neoplastic mucosa was found. The proportion of hormone, especially polypeptied positive cells was the highest in the mucosa and lowest in the moderately or poorly-differentiated carcinomas. The incidence, methodology and clinicopathological significance of EC cells found in the tumors are discussed.

Infrared Thermal Imaging-Based Research on the Intermediate Structures of the Lung and Large Intestine Exterior-Interior Relationship in Asthma Patients

Objective: By observing body surface temperature variation of the intermediate structures of the Lung(Fei) and Large Intestine(Dachang) exterior-interior relationship in asthmatic patients, to investigate the pathological response on the pathway of channels and to substantiate the objective existence of the intermediary structures. Methods: The study included 60 subjects meeting the bronchial asthma inclusion criteria(experimental group) and 60 healthy subjects(normal control group). ATIR-M301 infrared thermal imaging device was used for detecting body surface temperature of the subjects and collecting the infrared thermal images. The temperature values of the intermediate structures of Lung and Large Intestine exterior-interior relationship [throat, Quepen, elbow, nose, Lieque(LU 7), Pianli(LI 6)], control areas(0.2 cm lateral to the above structures) and Yintang(EX-HN 3) were measured on the infrared thermal image by infrared imaging system. Then, the above temperature values were compared and analyzed within and between two groups. Results: There were insignificant differences between the temperature on the left and right sides of the intermediate structures(Quepen, elbow, LU 7, LI 6) in normal control group(P>0.05). Except for that of Quepen, there were insignificant differences between the temperature of the intermediate structures and their corresponding control areas in normal control group(P>0.05). In the experimental group, the temperature on the left and right sides of the intermediate structures(Quepen, elbow, LU 7, LI 6) showed statistically significant differences(P<0.05 or P<0.01); the temperature difference between intermediate structure(throat, Quepen, elbow, nose, LI 6) and their respective control areas were also significant(P<0.05 or P<0.01). The temperature of the intermediate structures(throat, Quepen, elbow, LU7, LI 6) between the experimental group and normal control group showed significant differences(P<0.05 or P<0.01). Conclusions: This study is an initial step to validate the objective existence of Lung and Large Intestine exterior-interior relationship intermediate structures, as described in the Chinese classical medical literatures, through the functional imaging angle. The intermediate structures are the pathological reaction areas of the bronchial asthmatic patients.

Endoscopic miniprobe ultrasonography in diagnosis of carcinomas and submucosal tumors of large intestine

Objective To assess the value of endoscopic miniprobe ultrasonography in the diagnosis of carcinomas and submucosal tumors of the large intestine.Methods A total of 96 patients with carcinomas and submucosal tumors of the large intestine were given colonoscopic ultrasonography with a miniprobe (Olympus UM-2R, 12 MHz; UM-3R, 20 MHz) from December, 2000 to January, 2002. Results Carcinomas of the large intestine of 81 patients appeared as a hypoechoic mass under endoscopic ultrasonography, by which 67 patients (82.7%) were accurately diagnosed as having infiltrated colorectal carcinomas. The sensitivity of endoscopic ultrasonography in the diagnosis of lymph node metastasis was 55.4%, while the specificity was 68.8%. The positive predictive value and the negative predictive value were 0.88 and 0.28, respectively. All 15 cases with submucosal tumors were diagnosed correctly under endoscopic ultrasonography except for one leiomyoma, which was misdiagnosed as leiomyosarcoma. Conclusions Endoscopic miniprobe ultrasonography has a high accuracy in determining the invasion depth of carcinomas of the large intestine and the diagnosis of submucosal tumors. The pre-operative endoscopic ultrasonography may provide valuable information and influence the choice of therapy for carcinomas and submucosal tumors of the large intestine.

The Association between Pulmonary Function Impairment and Colon Inflammation in Ulcerative Colitis Patients： A Scientific Basis for Exterior-Interior Correlation between Lung and Large Intestine

Objective： To investigate the involvement of pulmonary function impairment in ulcerative colitis（UC）, and explore a scientific basis for the Chinese medicine（CM） theory of exterior-interior correlation between Lung（Fei） and Large intestine（Dachang）. Methods： Totally 120 patients with a diagnosis of UC were recruited and the demographics, clinical data, and blood samples were collected. C-reactive protein（CRP） and erythrocyte sedimentation rate（ESR） concentrations were measured. Every patient accepted pulmonary function test and took chest radiograph（CXR）. Results： Pulmonary function abnormalities were present in 72 of 120 patients. The median（interquartile range） vital capacity（VC）, forced vital capacity（FVC）, forced expiratory volume in 1 s（FEV_1）, carbon monoxide diffusion capacity（DL_∞） of lung, total lung capacity（TLC） and functional residual volume（FRV） were decreased in distal UC and pancolitis compared with ulcerative prochitis（P〈0.0005）. Male patients had increased VC, FEV_1/FVC, and residual volume（RV）/TLC compared with female（P〈0.0005）, but decreased DLCO and carbon monoxide iffusion capacity（KCO） of lung/alveolar ventilation（P〈0.0005）. Age was strongly correlated with RV（Spearman rank correlation coefficient（rs）=–0.57, P〈0.0001）, and RV/TLC（rs=0.48, P〈0.0001）. Age was also correlated with FEV_1/FVC（rs=–0.29, P=0.001）, forced expiratory flow in 75% vital capacity（FEF75%, rs=–0.20, P=0.03）, DLCO（rs=–0.21, P=0.02）, TLC（rs=–0.25, P=0.006）, and FRV（rs=–0.28, P=0.002）. The course of disease was correlated with FEF75%（rs=–0.18, P=0.049） and KCO（rs=–0.19, P=0.036）. Chest radiograph abnormalities were presented in 38 of 120. Pulmonary symptoms were presented in 10 of 120. Other extraintestinal complications were presented in 21 of 120. Conclusions： Pulmonary function impairment was more frequently than other extraintestinal complications in UC patients, which may be affected by sex, age, extent and course of disease. These results may be a scientific basis for the theory of exterior-interior correlation between Lung and Large intestine.

Fate of undigested proteins in the pig large intestine:What impact on the colon epithelium?

Apart from its obvious agronomic interest in feeding billions of people worldwide,the porcine species represents an irreplaceable experimental model for intestinal physiologists and nutritionists.In this review,we give an overview on the fate of proteins that are not fully digested in the pig small intestine,and thus are transferred into the large intestine.In the large intestine,dietary and endogenous proteins are converted to peptides and amino acids(AA)by the action of bacterial proteases and peptidases.AA,which cannot,except in the neonatal period,be absorbed to any significant level by the colonocytes,are used by the intestinal microbes for protein synthesis and for the production of numerous metabolites.Of note,the production of the AA-derived metabolites greatly depends on the amount of undigested polysaccharides in the pig's diet.The effects of these AA-derived bacterial metabolites on the pig colonic epithelium have not yet been largely studied.However,the available data,performed on colonic mucosa,isolated colonic crypts and colonocytes,indicate that some of them,like ammonia,butyrate,acetate,hydrogen sulfide(H_(2)S),and p-cresol are active either directly or indirectly on energy metabolism in colonic epithelial cells.Further studies in that area will certainly gain from the utilization of the pig colonic organoid model,which allows for disposal of functional epithelial unities.Such studies will contribute to a better understanding of the potential causal links between diet-induced changes in the luminal concentrations of these AA-derived bacterial metabolites and effects on the colon epithelial barrier function and water/electrolyte absorption.

Risk factors for small intestinal adenocarcinomas that are common in the proximal small intestine

The frequency of primary small intestinal adenocarcinoma is increasing but is still low.Its frequency is approximately 3%of that of colorectal adenocarcinoma.Considering that the small intestine occupies 90%of the surface area of the gastrointestinal tract,small intestinal adenocarcinoma is very rare.The main site of small intestinal adenocarcinoma is the proximal small intestine.Based on this characteristic,dietary animal proteins/lipids and bile concentrations are implicated and reported to be involved in carcinogenesis.Since most nutrients are absorbed in the proximal small intestine,the effect of absorbable intestinal content is a suitable explanation for why small intestinal adenocarcinoma is more common in the proximal small intestine.The proportion of aerobic bacteria is high in the proximal small intestine,but the absolute number of bacteria is low.In addition,the length and density of villi are greater in the proximal small intestine.However,the involvement of villi is considered to be low because the number of small intestinal adenocarcinomas is much smaller than that of colorectal adenocarcinomas.On the other hand,the reason for the low incidence of small intestinal adenocarcinoma in the distal small intestine may be that immune organs reside there.Genetic and disease factors increase the likelihood of small intestinal adenocarcinoma.In carcinogenesis experiments in which the positions of the small and large intestines were exchanged,tumors still occurred in the large intestinal mucosa more often.In other words,the influence of the intestinal contents is small,and there is a large difference in epithelial properties between the small intestine and the large intestine.In conclusion,small intestinal adenocarcinoma is rare compared to large intestinal adenocarcinoma due to the nature of the epithelium.It is reasonable to assume that diet is a trigger for small intestinal adenocarcinoma.

Clinicopathological features and expression of regulatory mechanism of the Wnt signaling pathway in colorectal sessile serrated adenomas/polyps with different syndrome types

BACKGROUND Colorectal cancer(CRC)is the third most common cancer worldwide,with the fourth highest mortality among all cancers.Reportedly,in addition to adenomas,serrated polyps,which account for 15%-30%of CRCs,can also develop into CRCs through the serrated pathway.Sessile serrated adenomas/polyps(SSAs/Ps),a type of serrated polyps,are easily misdiagnosed during endoscopy.AIM To observe the difference in the Wnt signaling pathway expression in SSAs/Ps patients with different syndrome types.METHODS From January 2021 to December 2021,patients with SSAs/Ps were recruited from the Endoscopy Room of Shanghai Traditional Chinese Medicine-Integrated Hospital,affiliated with Shanghai University of Traditional Chinese Medicine.Thirty cases each of large intestine damp-heat(Da-Chang-Shi-Re,DCSR)syndrome and spleen-stomach weakness(Pi-Wei-Xu-Ruo)syndrome were reported.Baseline comparison of the general data,typical tongue coating,colonoscopy findings,and hematoxylin and eosin findings was performed in each group.The expression of the Wnt pathway-related proteins,namelyβ-catenin,adenomatous polyposis coli,and mutated in colorectal cancer,were analyzed using immunohistochemistry.RESULTS Significant differences were observed with respect to the SSAs/Ps size between the two groups of patients with different syndrome types(P=0.001).The other aspects did not differ between the two groups.The Wnt signaling pathway was activated in patients with SSAs/Ps belonging to both groups,which was manifested asβ-catenin protein translocation into the nucleus.However,SSAs/Ps patients with DCSR syndrome had more nucleation,higherβ-catenin expression,and negative regulatory factor(adenomatous polyposis coli and mutated in colorectal cancer)expression(P<0.0001)than SSA/P patients with Pi-Wei-Xu-Ruo syndrome.In addition,the SSA/P size was linearly correlated with the related protein expression.CONCLUSION Patients with DCSR syndrome had a more obvious Wnt signaling pathway activation and a higher risk of carcinogenesis.A high-quality colonoscopic diagnosis was essential.The thorough assessment of clinical diseases can be improved by combining the diseases of Western medicine with the syndromes of traditional Chinese medicine.

Experimental Study on the Mechanism of Protective Effect of Free Fu on Gut-derived Endotoxin-Mediated Lung Damage

The effect of tumor necrosis factor-α (TNF-α) on endotoxin (ET)-mediated lung damage caused by incomplete ligation of large intestine and the influence of free Fu on the expression of TNF-α mRNA were explored. Forty SD rats were randomly divided into 4 groups: normal control group, model group, ligation group and treatment group (n=10 in each group). The models were made by the method of partly ligating the rectum outside the body. The plasma level of lipopolysaccaride was measured by dynamic nephelo metric method and the serum level of TNF-α was detected by the method of radioactive immunity. The expression of TNF-α mRNA in lung tissue was detected by RT-PCR method. The results were compared among the 4 groups. The results showed the plasma levels of ET and serum TNF-α in the model group and the expression of TNF-α mRNA in the lung tissues were remarkably higher than those in the normal control group (P<0.01). After the treatment of free Fu, all of the above indexes in the treatment group were all decreased as compared with model group (all P<0.01), and the damage to lung was alleviated. It was concluded that TNF-α might play a very important role in the ET-mediated lung damage caused by incomplete ligation of large intestine, free Fu could protect the lung from damage.

Expression of adipokine ghrelin and ghrelin receptor in human colorectal adenoma and correlation with the grade of dysplasia

BACKGROUNDGhrelin is an adipokine that plays an important role in energy balance. Expressionof ghrelin and ghrelin receptor has been investigated in different tissues andtumors. Studies regarding expression of ghrelin and ghrelin receptor in colorectaltumors are scarce and no data on expression of ghrelin and its receptor incolorectal adenomas has been published. Ghrelin and ghrelin receptor werehighly expressed in colon carcinoma cells while expression was decreased in lessdifferentiated tumors, presuming that ghrelin might be important in early phasesof tumorigenesis.AIMTo investigate the expression of ghrelin and ghrelin receptor in human colorectaladenomas and adjacent colorectal tissue.METHODSIn this prospective study (conducted from June 2015 until May 2019) we included92 patients (64 male and 28 female) who underwent polypectomy for colorectaladenomas in the Department of Gastroenterology and Hepatology, “Sestre milosrdnice” Clinical Hospital Center in Zagreb, Croatia. After endoscopicremoval of colorectal adenoma, an additional sample of colon mucosa in theproximity of the adenoma was collected for pathohistological analysis. Adenomaswere graded according to the stage of dysplasia, and ghrelin and ghrelin receptorexpression were determined immunohistochemically in both adenoma andadjacent colon tissue using the polyclonal antibody for ghrelin (ab150514,ABCAM Inc, Cambridge, United States) and ghrelin receptor (ab48285, ABCAMInc, Cambridge, United States). Categorical and nominal variables were describedthrough frequencies and proportions and the difference between specific groupswere analyzed with Fisher’s and Fisher-Freeman-Halton’s method respectively.Spearman's rank correlation coefficient was determined for correlation ofexpression of ghrelin and ghrelin receptor in adenoma and adjacent colon tissuewith the grade of adenoma dysplasia.RESULTSAmong 92 patients with colorectal adenoma 43 had adenomas with high-gradedysplasia (46.7%). High expression of ghrelin was 7 times more common in highgradeadenoma compared to low-grade adenomas (13.95% to 2.04%, P = 0.048),while the expression of ghrelin in adjacent colon tissue was low. We found nocorrelation between ghrelin receptor expression in adenoma and adjacent colontissue and the grade of colorectal adenoma dysplasia. The most significantcorrelation was found between ghrelin and ghrelin receptor expression inadenomas with high-grade dysplasia (rho = 0.519, P < 0.001).CONCLUSIONGhrelin and ghrelin receptor are expressed in colorectal adenoma and adjacenttissue with ghrelin expression being more pronounced in high grade dysplasia asa possible consequence of increased local synthesis.

Endogenous mucin conveyed to the mucosa with microbes can assure lumen fermentation and large intestinal security-swine versus fowl

Endogenous protein leaving the ileum largely consists of accrued mucins from the upper gastrointestinal tract(GIT)that had resisted digestion.The amounts released rely on their mucosal generation during enteral feeding which vary with age as well as diet.These digestion resistant proteins of endogenous origin continue to be unavailable in the large intestine,whereas those of dietary origin provide amino acids that largely support the existing microbial population while denying limited amounts for absorption.Other mucins pre-exist within the large intestine as two layers at the lumen surface.A loose layer harboring a diverse microbial population is superimposed on the unstirred water layer(USWL)which simultaneously acts as an obstacle to microbes at the loose layer while performing as a molecular sieve for nutrients.The USWL is formed through interplay between enterocyte and goblet cells;however,the basis for presence of the loose layer is elusive.Large intestinal fermentation predominates within the colon of swine,whereas fowl employ their ceca.Motility within the colon of swine segregates fine materials into haustrae out-pocketings that parallel their placement within the ceca of fowl.Viscous mucins from small intestinal endogenous losses may envelop microbes within the large intestinal lumen to present successive adherents on the USWL that assemble its loose layer.The loose layer continually functions as a microbial reservoir in support of lumen fermentation.Microbial catabolism of mucin within the loose layer is known to be slow,but its proximity to the enterocyte is of advantage to enterocyte absorption with by-product amino acids fostering the USWL.

Discussion on the clinical application of colorectal cancer based on the theory of "Tongqixiangqiu"

Objective:To explore the application of the theory of"Tongqixiangqiu"and its application in traditional Chinese medicine in order to find out the clinical application of colorectal cancer.Methods:Referring to the ancient medical works and modern literature on the theory of"Tongqixiangqiu",combined with the disease characteristics of colorectal cancer and the clinical experience of famous doctors in ancient and modern times,to explore its application in the clinical treatment of colorectal cancer.Results:The theory of"Tongqixiangqiu"has rich connotations,among which"anti-adjuvant therapy"and"lung and intestine combined treatment"are the representatives of the specific application of the theory.The methods of cold and heat counteraction,compatibility and external treatment as well as the idea of spleen deficiency and Qi stagnation type colorectal cancer pay attention to tonifying Fei qi,nourishing Fei yin,and promoting Sanjiao Qi mechanism play an important role in the differentiation and treatment of colorectal cancer in TCM.Conclusion:The theory of"Tongqixiangqiu"is widely used in the treatment of colorectal cancer,which has the advantages of significant curative effect,synergism and toxicity reduction,prolonging the survival period and improving the quality of life of patients.

CLINICAL SIGNIFICANCES OF THE EXPRESSION OF METALLO- THIONEIN IN FIVE TYPES EPITHELIUM CELL CANCER

Objective： To study the expressions of （CSC）, bladder transitional cell cancer metallothionein and the significances in cervical squamous cell cancer （BTC）, esophageal squamous cell cancer （ESC）, gastral tubular adenocarcinoma （GC） and large intestinal tubular adenocarcinoma （LIC）. Methods： lmmunohistochemical method was used to examine the expression rates of MT in five types of cancer tissue. Results： The expression rates of MT were 75.00% （24/32） in ESC, 52.27% （46/88） in GTC, 59.46% （44/74） in LIC, 64.86% （48/74） in BTC and 58.57% （41/70） in CSC respectively. The positive rates of MT expression were higher in low differentiation and deep muscular group than those in medium or high differentiation and superficial muscular invasion group （P〈0.05）. Conclusion： The expression of MT is related to differentiation degree and invasion degree.

A Comparative Study of The Regular Pattern of Syndrome and Treatment of Lung-intestine Related Diseases in Ancient and Modern Medical Cases Based on Data Mining

Objective: To analyze the similarities and differences of the applications of "the lung and large intestine being interior-exteriorly related"between the ancient and modern clinical practices, and to reveal the theory meaning.Method: Based on the ancient and modern medical cases database, 245 ancient medical records and 373 modern medical records were studied with the general statistical description and analysis of association rules, and the results were compared to summarize the similarities and differences of the regular pattern of syndrome and treatment on lung-large intestine related diseases in ancient and modern medical records.Results: In modern medical cases, intestinal diseases appeared with the main symptom of constipation due to deficiency of lung qi and qi stagnation of large intestine were always treated by purgation together with replenishing and restoring lung qi. In ancient medical cases, large intestine heat was always caused by lung heat and a variety of diarrhea symptoms appeared. They were always treated by clearing heat and moistening lungs. In addition, the symptom of bound stool caused by qi stagnation of large intestine due to lung qi stagnation was always treated by lowering lung qi to regulate and smooth large intestine qi. And Armeniae Amarum Semen was used by both as a core medicinal herb.Conclusion: Ascending-descending of qi movement is the core of the lung and large intestine relationship. In other words, the lung and the large intestine communicate through qi.

An increase in corn resistant starch decreases protein fermentation and modulates gut microbiota during in vitro cultivation of pig large intestinal inocula

High-protein diet could cause an increase in protein fermentation in the large intestine, leading to an increased production of potentially detrimental metabolites. We hypothesized that an increase in corn resistant starch content may attenuate the protein fermentation. The aim of this study was to evaluate the effect of resistant starch on protein fermentation by inocula from large intestine of pigs using in vitro cultivation. Fermentation patterns were analyzed during a 24-h incubation of cecal and colonic digesta with varying corn resistant starch contents, using casein protein as sole nitrogen source. The results showed that the concentration of short-chain fatty acids(SCFA) and cumulative gas production were significantly increased(P < 0.05), while ammonia-nitrogen(NH_3-N) and branched-chain fatty acids(BCFA), which indicated protein fermentation, decreased when the corn resistant starch levels increased(P < 0.05). The copies of total bacteria, Bifidobacterium and Lactobacillus were significantly increased with the increased corn resistant starch levels after incubation(P < 0.05). The copies of the Bifidobacterium and Lactobacillus in cecum were significantly higher than those in colon(P < 0.05). We conclude that the addition of corn resistant starch weakens the protein fermentation by influencing microbial population and reducing protein fermentation in the cecum and colon in vitro.

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.