Nutrients central to maintaining intestinal absorptive efficiency and barrier integrity with fowl

Changes of intestinal barrier in the process of intestinal inflammation induced by Aeromonas hydrophila in snakehead (Channa argus)

Bacterial intestinal inflammation frequently occurs in cultured fish. Nevertheless, research on intestinal barrier dysfunction in the process of intestinal inflammation is deficient. In this study, we explored the changes of intestinal inflammation induced by Aeromonas hydrophila (A. hydrophila) in snakehead and the relationship between intestinal barrier and inflammation. Snakehead [(13.05 ± 2.39) g] were infected via anus with A. hydrophila. Specimens were collected for analysis at 0, 1, 3, 7 and 21 d post-injection. The results showed that with the increase of exposure time, the hindgut underwent stages of normal function, damage, damage deterioration, repair and recovery. Relative to 0 d, the levels of IL-1β and TNF-α in serum, and the expression of nod1, tlr1, tlr5, nf-κb, tnf-α and il-1β in intestine were significantly increased, and showed an upward then downward pattern over time. However, the expression of tlr2 and il-10 were markedly decreased, and showed the opposite trend. In addition, with the development of intestinal inflammation, the diversity and richness of species, and the levels of phylum and genus in intestine were obviously altered. The levels of trypsin, LPS, AMS, T-SOD, CAT, GPx, AKP, LZM and C3 in intestine were markedly reduced, and displayed a trend of first decreasing and then rebounding. The ultrastructure observation showed that the microvilli and tight junction structure of intestinal epithelial cells experienced normal function initially, then damage, and finally recovery over time. The expression of claudin-3 and zo-1 in intestine were significantly decreased, and showed a trend of first decreasing and then rebounding. Conversely, the expression of mhc-i, igm, igt and pigr in intestine were markedly increased, and displayed a trend of increasing first and then decreasing. The above results revealed the changes in intestinal barrier during the occurrence and development of intestinal inflammation, which provided a theoretical basis for explaining the relationship between the two.

Dynamic responses of blood metabolites to nutrient depletion and repletion in broiler chicken nutrition

A total of 720 male Cobb 500 broiler chicks were used in a 5 treatment and 8 replicate experiment to explore dynamic changes in blood metabolites in response to short-term nutrient depletion and repletion. Day old chicks were offered a corn and soybean meal-based common starter diet from d1 to 14 that was formulated to meet all nutrient requirements of the birds. From d15 to 17, the experimental diets were offered, before returning all groups to a common diet from d18 to 20, at which point the experiment was terminated. A total of 5 experimental diets were designed. A standard grower diet served as a control and was offered to 1 of the 5 groups of chicks. The additional 4 experimental groups comprised diets that were low in digestible phosphorus (P), total calcium (Ca), crude protein and digestible amino acids (AA) or apparent metabolizable energy (AME). The common grower diet that was offered from d18-20 was designed to be nutritionally complete and was intended to explore dynamic response to nutrient repletion. Blood was drawn from 8 chicks per treatment at time 0 (immediately prior to introduction of the experimental diets) and then again 3, 6, 12, 24, and 48h after introduction of the nutrient depleted diets. Additionally, blood was drawn 3, 6, 12, 24, and 48h after the introduction of the nutritionally complete common grower diet. Chicks were not sampled more than once. Feed intake, body weight and feed conversion ratio (FCR) were assessed on d14, 17, and 20. Blood metabolites were analyzed using the iSTAT Alinity V handheld blood analyzer, the Vetscan VS2 Chemistry Analyzer and the iCheck Carotene Photometer. Live performance metrics were not affected by the short-term nutrient depletion and all chicks grew normally throughout the experiment. The diet with low digestible P generated a rapid temporary decrease in plasma P and an increase in plasma Ca, that were returned to baseline following the re-introduction of the common grower feed. Introduction of the diet with low total Ca resulted in a significant increase in plasma P, effects which were also mitigated during the nutrient repletion phase. Total plasma protein, albumin and uric acid (UA) were decreased, and plasma glucose increased, in the chicks that received the diet with low crude protein and digestible AA. There was a delayed increase in aspartate amino transaminase (AST) associated with the diets with low digestible P and low AME. These results demonstrate the capacity of blood biochemistry to adapt to quantitative and qualitative changes in nutrient intake. Point-of-care analysis of blood biomarkers offers nutritionists a valuable opportunity to calibrate nutritional matrices for common dietary ingredients, zootechnical feed additives and to optimize diet phase changes. It can be concluded that many blood biomarkers are plastic to changes in diet nutrient density and offer an objective index for optimization of nutritional programs for commercial broiler production.

Screening of reliable reference genes for the normalization of RT-qPCR in chicken gastrointestinal tract

The application of reverse transcription quantitative real-time PCR technology for the production of gene tissue expression profiles is a widely employed approach in molecular biology research. It is imperative to ascertain internal reference genes that exhibit stable expression across diverse tissues to ensure the precision of tissue gene expression profiles. While there have been studies documenting the most suitable reference genes for various tissues in chickens, there is a dearth of research on the identification of reference genes in the gastrointestinal (GI) tract of chickens. This study utilized 4 different algorithms (Delta CT, BestKeeper, NormFinder, and Genorm) to assess the stability of 19 internal reference genes in various GI tract tissues, including individual GI tract tissues, the anterior and posterior GI tract, and the entire GI tissue. The RefFinder software was employed to comprehensively rank these genes. The research findings successfully identified the most appropriate internal reference genes for each type of GI tissue. Furthermore, TBP, DNAJC24, Polr2b, RPL13, andAp2m exhibited stable expression in the entire and posterior GI tract, whereas HMBS, TBP, Ap2m, GUSB, DNAJC24, and RPL13 demonstrated stable expression in the anterior GI tract. However, the internal reference genes commonly utilized, namely β-Actin, 18s RNA, and ALB, exhibit poor stability and are not advised for future investigations concerning gene expression in the GI region. Consequently, MUC2 and CDX1, 2 genes that specifically express in the gut, were chosen for examination to ascertain the stability of the aforementioned internal reference genes in this particular study. In summary, this study presents a relatively stable set of internal reference genes that can be employed to enhance the precision of quantifying mRNA expression levels in functional genes within the chicken GI tract.

Challenges and Opportunities in the Oral Delivery of Recombinant Biologics

Recombinant biological molecules are at the cutting-edge of biomedical research thanks to the significant progress made in biotechnology and a better understanding of subcellular processes implicated in several diseases. Given their ability to induce a potent response, these molecules are becoming the drugs of choice for multiple pathologies. However, unlike conventional drugs which are mostly ingested, the majority of biologics are currently administered parenterally. Therefore, to improve their limited bioavailability when delivered orally, the scientific community has devoted tremendous efforts to develop accurate cell- and tissue-based models that allow for the determination of their capacity to cross the intestinal mucosa. Furthermore, several promising approaches have been imagined to enhance the intestinal permeability and stability of recombinant biological molecules. This review summarizes the main physiological barriers to the oral delivery of biologics. Several preclinical in vitro and ex vivo models currently used to assess permeability are also presented. Finally, the multiple strategies explored to address the challenges of administering biotherapeutics orally are described.

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.

Comparison of zinc bioavailability in zinc-glycine and zinc-methionine chelates for broilers fed with a corn-soybean meal diet

The objective of this study was to compare the bioavailability of zinc (Zn) from zinc-glycine (Zn-Gly) and zinc-methionine (Zn-Met) as compared with zinc sulfate (ZnSO4) used as a standard in broilers. A total of 1,200 one-day-old male broilers (Cobb 500) were randomly allotted to one of 10 treatments with eight replicate cages of 15 birds each. The broilers were fed a corn-soybean meal basal diet (containing 26.46 mg Zn/kg; control) or the basal diet added with 40, 80, and 120 mg Zn/kg as Zn-Gly, Zn-Met, or ZnSO4 for 14 days. The relative bioavailability value (RBV) was calculated based on multiple linear regression slope ratios of Zn concentrations in tibia and pancreas, pancreas metallothionein (MT) concentration, and pancreas MT mRNA abundance on added Zn intake. When comparing the control with all Zn-supplemented treatments, Zn addition did not significantly affect average feed intake and bodyweight gain during days 1-14 (p > 0.10). However, Zn concentrations in the tibia, pancreas, and liver and pancreas MT concentration and MT mRNA abundance increased in all Zn-supplemented treatments compared with the control (p < 0.05), and these indices increased linearly (p < 0.001) with increasing added Zn levels on days 7 and 14. The RBV of Zn as Zn-Met was similar to that as Zn-Gly or ZnSO4 (p > 0.40) on days 7 and 14, based on tibia and pancreas Zn. In contrast, on days 7 and 14, the RBVs of Zn were in the following order: Zn-Met > Zn-Gly > ZnSO4 (p < 0.05), based on pancreas MT concentration. The bioavailable Zn from Zn-Met was 1.20 or 1.25 times that from Zn-Gly on day 7 or 14, respectively, evaluated by pancreas MT content. The RBV of Zn as Zn-Met was similar to that as Zn-Gly or ZnSO4 on day 7, whereas it was higher than that as Zn-Gly or ZnSO4 on day 14, based on pancreas MT mRNA abundance. In conclusion, Zn-Met had higher bioavailable Zn than Zn-Gly for the starter broilers fed with the corn-soybean meal diet, using pancreas MT concentration as the response criterion.

The transcriptome landscapes of allantochorion and vitelline-chorion in equine day 30 conceptus

During equine early gestation, trophectoderm forms chorion tissue, which is composed of two parts that one is covering allantoin, called allantochorion (AC) and another is covering yolk sac, which here we call vitelline-chorion (VC). Given that little is known about the equine trophoblast-derived chorion differentiation at an early stage, we first compared the transcriptome of AC and VC of day 30 equine conceptus based on RNA-sequencing. As a result, we found that compared to VC, there are 484 DEGs, including 305 up- and 179 down-regulated genes in AC. GO and KEGG analysis indicated that up-regulated genes in AC are mainly cell proliferation and cell adhesion-related genes, participating in allantois expansion and allantochorionic-placenta formation; dominant genes in VC are extracellular exosome and other cell adhesion-related genes implicated in direct and indirect conceptus-maternal communication. Additionally, as for the progenitor chorion tissue of equine chorionic gonadotropin secreting endometrium cup-the chorionic girdle (CG), which locates at the junction of the dilating AC and regressing VC, we revealed its unique gene expression pattern and the gene regulation during its further differentiation in vitro. Collectively, this study sheds light on the molecular events regarding the trophoblast differentiation and function at an early stage of the equine preimplantation conceptus.

SeMet attenuates AFB1-induced intestinal injury in rabbits by activating the Nrf2 pathway

The aim of this study was to investigate the role of selenomethionine (SeMet) in alleviating AFB1 induced intestinal injury by inhibiting intestinal oxidative stress. Forty 35-day-old rabbits were divided randomly into 4 groups (control group, AFB1 group, 0.2 mg/kg Se + AFB1 group, 0.4 mg/kg Se + AFB1 group). From the first day of the experiment, the two treatment groups were fed 0.2 mg/kg SeMet or 0.4 mg/kg SeMet daily for 21 days. On the 17th day, all rabbits in the model group and the two treatment groups were given intragastric AFB1 daily for 5 days. The ADG, ADFI and FCR of the rabbits were examined. Rabbit jejunum tissue was collected for hematoxylin- eosin staining (HE), PCNA detection, immunofluorescence and WB. Intestinal tissue IL-1β, IL-6 and TNF-α were examined by enzyme-linked immunosorbent assay (ELISA). The results showed that the production performance was decreased, the levels of ROS and MDA were increased in intestinal tissues, the activity of antioxidant enzymes was decreased and the expression levels of Nrf2 and HO-1 were decreased in AFB1-exposed rabbits. In addition, AFB1 induces an inflammatory response in the jejunum and promotes the expression of TNF-α, IL-6 and IL-1β. SeMet pretreatment significantly improved the performance of the rabbits, alleviated intestinal oxidative stress and the inflammatory response. Therefore, we confirmed that SeMet protects against AFB1 induced oxidative damage and improves productivity in rabbits by activating the Nrf2/HO-1 signaling pathway.

Lactobacillus salivarius and Lactobacillus agilis feeding regulates intestinal stem cells activity by modulating crypt niche in hens

Previously, we found that Lactobacillus salivarius, Lactobacillus agilis, and Lactobacillus aviarius were associated with excellent egg nutrition in native chicken. Next, the optimal Lactobacillus combination is worth studying. Here, a total of 120 HyLine hens (30 hens per group contained 3 replicate cells, 10 hens/cell) in the laying peak period were randomly divided into (1) control, (2) L. salivarius + L. agilis, (3) L. salivarius + L. aviarius, and (4) L. agilis + L. aviarius groups, fed with diet only or with corresponding Lactobacilli (10⁸ colony-forming units/hen/day) for 30 days. As a result, L. salivarius + L. agilis feeding could (1) improve egg-laying rate, egg weight, and albumen's amino acid levels; (2) increase Lactobacillus abundance, decrease Escherichia coli abundance, upregulate the tryptophan metabolism pathway-related molecules, and downregulate the primary bile acid biosynthesis pathway-related molecules in intestinal contents; and (3) upregulate oxidative-phosphorylation pathway-related genes, reactive oxygen species levels, and mRNA abundance of Wnt3a, Dll1, Lgr5, CCDN1, and CDK2 in the crypt. Collectively, L. salivarius + L. agilis feeding in hens could improve intestinal microflora and metabolism profile, promote crypt's local energy metabolism and reactive oxygen species levels, and thus enhance Paneth cells and intestinal stem cells activity.Key points• Lactobacilli co-feeding could improve laying performance and egg nutrition.• Lactobacilli co-feeding could improve intestinal microflora and metabolism profile.• Lactobacilli co-feeding could enhance Paneth cells and intestinal stem cells activity.

Interorgan Metabolism, Nutritional Impacts, and Safety of Dietary L-Glutamate and L-Glutamine in Poultry

L-glutamine (Gln) is the most abundant amino acid (AA) in the plasma and skeletal muscle of poultry, and L-glutamate (Glu) is among the most abundant AAs in the whole bodies of all avian tissues. During the first-pass through the small intestine into the portal circulation, dietary Glu is extensively oxidized to CO₂, but dietary Gln undergoes limited catabolism in birds. Their extra-intestinal tissues (e.g., skeletal muscle, kidneys, and lymphoid organs) have a high capacity to degrade Gln. To maintain Glu and Gln homeostasis in the body, they are actively synthesized from branched-chain AAs (abundant AAs in both plant and animal proteins) and glucose via interorgan metabolism involving primarily the skeletal muscle, heart, adipose tissue, and brain. In addition, ammonia (produced from the general catabolism of AAs) and α-ketoglutarate (α-KG, derived primarily from glucose) serve as substrates for the synthesis of Glu and Gln in avian tissues, particularly the liver. Over the past 20 years, there has been growing interest in Glu and Gln metabolism in the chicken, which is an agriculturally important species and also a useful model for studying some aspects of human physiology and diseases. Increasing evidence shows that the adequate supply of dietary Glu and Gln is crucial for the optimum growth, anti-oxidative responses, productivity, and health of chickens, ducklings, turkeys, and laying fowl, particularly under stress conditions. Like mammals, poultry have dietary requirements for both Glu and Gln. Based on feed intake, tissue integrity, growth performance, and health status, birds can tolerate up to 12% Glu and 3.5% Gln in diets (on the dry matter basis). Glu and Gln are quantitatively major nutrients for chickens and other avian species to support their maximum growth, production, and feed efficiency, as well as their optimum health and well-being.

Effects of dietary fatty acids on gut health and function of pigs pre- and post-weaning

Fatty acids (FA) play a major role in relation to mucosal immune responses, epithelial barrier functions, oxidative stress, and inflammatory reactions. The dietary FA composition and the molecular structures (chain length and number of double bonds) influence digestion, absorption and metabolism, and the bioactivity of the FA. Piglets post-weaning having an immature intestine and not fully formed immune functions are very vulnerable to invading microorganisms. Manipulation of the milk FA composition via sow nutrition, or inclusion of dietary fat sources in the feed for newly weaned pigs, may be used as a strategic tool to enhance pig performance and their gut health and function pre- and post-weaning. Medium-chain fatty acids (MCFA) are absorbed directly into the portal blood and may contribute to immediate energy for the enterocytes. In addition, the MCFA, similarly to the short-chain fatty acids (SCFA), possess antibacterial effects and may thereby prevent overgrowth of pathogenic bacteria in the gastrointestinal tract. The essential FA, linoleic (LA) and α-linolenic (ALA) FA, form the building blocks for the long-chain polyunsaturated n-3 and n-6 FA. The conversion of ALA and LA into n-3 and n-6 eicosanoids, respectively, influences the molecular structures of metabolites and inflammatory reactions and other immune responses upon bacterial challenges. Dietary manipulation of the lactating sow influences the transfer of the n-3 and n-6 polyunsaturated fatty acids (PUFA) from the sow milk to the piglet and the incorporation of the FA into piglet enteric tissues and cell membranes, which exerts bioactivity of importance for immune responses and the epithelial barrier function. Especially, the n-3 PUFA present in fish oil seem to influence the gut health and function of pigs, and this is of importance during the transition periods such as post-weaning in which piglets are prone to inflammation. The proportion of unsaturated FA in the cell membranes influences the susceptibility to oxidative stress. Oxidative stress accompanies infectious diseases, and the development of lipid peroxides and other reactive oxygen products may be harmful to the epithelial barrier function. Fatty acid peroxides from the feed may also be absorbed with other lipid-solubles and thereby harm the intestinal function. Hence, antioxidative protection is important for the enteric cells. In conclusion, manipulation of the dietary FA composition can influence the gut health and function in pigs and may support a normal immune system and modulate resistance to infectious diseases during especially stressful phases of a pig's life such as post-weaning.

Food Supplements to Mitigate Detrimental Effects of Pelvic Radiotherapy

Pelvic radiotherapy has been frequently reported to cause acute and late onset gastrointestinal (GI) toxicities associated with significant morbidity and mortality. Although the underlying mechanisms of pelvic radiation-induced GI toxicity are poorly understood, they are known to involve a complex interplay between all cell types comprising the intestinal wall. Furthermore, increasing evidence states that the human gut microbiome plays a role in the development of radiation-induced health damaging effects. Gut microbial dysbiosis leads to diarrhea and fatigue in half of the patients. As a result, reinforcement of the microbiome has become a hot topic in various medical disciplines. To counteract GI radiotoxicities, apart from traditional pharmacological compounds, adjuvant therapies are being developed including food supplements like vitamins, prebiotics, and probiotics. Despite the easy, cheap, safe, and feasible approach to protect patients against acute radiation-induced toxicity, clinical trials have yielded contradictory results. In this review, a detailed overview is given of the various clinical, intestinal manifestations after pelvic irradiation as well as the role of the gut microbiome herein. Furthermore, whilst discussing possible strategies to prevent these symptoms, food supplements are presented as auspicious, prophylactic, and therapeutic options to mitigate acute pelvic radiation-induced GI injury by exploring their molecular mechanisms of action.