Dietary alanyl-glutamine improves growth performance of weaned piglets through maintaining intestinal morphology and digestion-absorption function

RNA-seq analysis of small intestine transcriptional changes induced by starvation stress in piglets

Piglets may experience a variety of stress injuries, but the molecular regulatory mechanisms underlying these injuries are not well understood. In this study, we analysed the ileum of Large White (LW) and Mashen (MS) piglets at different times of starvation using chemical staining and transcriptome analysis. The intestinal barrier of piglets was damaged after starvation stress, but the intestinal antistress ability of MS piglets was stronger than LW piglets. A total of 8021 differentially expressed genes (DEGs) were identified in two breeds. Interestingly, the immune capacity (CHUK, TLR3) of MS piglets increased significantly after short-term starvation stress, while energy metabolism (NAGS, PLA2G12B, AGCG8) was predominant in LW piglets. After long-term starvation stress, the level of energy metabolism (PLIN5, PLA2G12B) was significantly increased in MS piglets. The expression of immune (HLA-DQB1, IGHG4, COL3A1, CD28, LAT) and disease (HSPA1B, MINPPI, ADH1C, GAL3ST1) related genes were significantly increased in two breeds of piglets. These results suggest that short-term stress mainly enhances immunity and energy metabolism in piglets, while long-term starvation produces greater stress on piglets, making it difficult for them to compensate for the damage to their bodies through self-regulation. This information can help improve the stress resistance of piglets through molecular breeding.

Effects of Sea-Buckthorn Flavonoids on Growth Performance, Serum Inflammation, Intestinal Barrier and Microbiota in LPS-Challenged Broilers

The experiment investigated the effects of sea-buckthorn flavonoids (SF) on lipopolysaccharide (LPS)-challenged broilers. A total of 288 one-day-old male broilers were randomly assigned to 4 groups, with 6 replicates of 12 broilers each. The experiment lasted for 20 days. The diet included two levels of SF (0 or 1000 mg/kg) and broilers intraperitoneally injected with 500 μg/kg LPS on 16, 18, and 20 days, or an equal amount of saline. LPS challenge decreased final body weight, average daily gain, and average daily feed intake, increased feed-to-gain ratio, and elevated serum IL-1β, IL-2, TNF-α, D-LA, and endotoxin levels. Moreover, it resulted in a reduction in the IL-10 level. LPS impaired the intestinal morphology of the duodenum, jejunum, and ileum, down-regulated the mRNA relative expression of Occludin, ZO-1, and MUC-2 in the jejunum mucosa, up-regulated the mRNA relative expression of TLR4, MyD88, NF-κB, and IL-1β, and increased the relative abundance of Erysipelatoclostridium in broilers (p < 0.05). However, SF supplementation mitigated the decrease in growth performance, reduced serum IL-1β, IL-2, and D-LA levels, increased IL-10 levels, alleviated intestinal morphological damage, up-regulated mRNA expression of Occludin and ZO-1, down-regulated the mRNA expression of TLR4, NF-κB, and IL-lβ in jejunum mucosal (p < 0.05), and SF supplementation presented a tendency to decrease the relative abundance of proteobacteria (0.05 < p < 0.1). Collectively, incorporating SF can enhance the growth performance, alleviate serum inflammation, and improve the intestinal health of broilers, effectively mitigating the damage triggered by LPS-challenges.

Glutamine-derived peptides: Current progress and future directions

Glutamine, the most abundant amino acid in the body, plays a critical role in preserving immune function, nitrogen balance, intestinal integrity, and resistance to infection. However, its limited solubility and instability present challenges for its use a functional nutrient. Consequently, there is a preference for utilizing glutamine-derived peptides as an alternative to achieve enhanced functionality. This article aims to review the applications of glutamine monomers in clinical, sports, and enteral nutrition. It compares the functional effectiveness of monomers and glutamine-derived peptides and provides a comprehensive assessment of glutamine-derived peptides in terms of their classification, preparation, mechanism of absorption, and biological activity. Furthermore, this study explores the potential integration of artificial intelligence (AI)-based peptidomics and synthetic biology in the de novo design and large-scale production of these peptides. The findings reveal that glutamine-derived peptides possess significant structure-related bioactivities, with the smaller molecular weight fraction serving as the primary active ingredient. These peptides possess the ability to promote intestinal homeostasis, exert hypotensive and hypoglycemic effects, and display antioxidant properties. However, our understanding of the structure-function relationships of glutamine-derived peptides remains largely exploratory at current stage. The combination of AI based peptidomics and synthetic biology presents an opportunity to explore the untapped resources of glutamine-derived peptides as functional food ingredients. Additionally, the utilization and bioavailability of these peptides can be enhanced through the use of delivery systems in vivo. This review serves as a valuable reference for future investigations of and developments in the discovery, functional validation, and biomanufacturing of glutamine-derived peptides in food science.

Aerial parts of Angelica sinensis supplementation for improved broiler growth and intestinal health

This research examined the impact of incorporating Angelica sinensis's aerial components (APA), commonly referred to as "female ginseng", into broilers' diet. Two hundred eighty-eight 1-day-old Cobb 500 broilers were randomly assigned to the 4 experimental groups with 6 replications and 12 birds/replicate. The 4 groups were fed the diets included 4 concentrations of APA (0, 1, 2, and 3%, respectively). The study spanned 42 d, categorized as the starter phase (1-21 d) and the finisher phase (22-42 d). Notably, broilers fed with 3% APA demonstrated a pronounced surge in feed consumption and weight gain during the 22 to 42 d and over the full 42-d period (P < 0.05). Furthermore, when examining the broilers' intestinal structure, there was a notable increase in the villus height and villi ratio across the duodenum, jejunum, and ileum, with a decrease in crypt depth upon 3% APA inclusion (P < 0.05). On a molecular note, certain genes connected to the intestinal mechanical barrier, such as Zona Occludens 1 and Claudin-2, saw significant elevation in the jejunum (P < 0.05). The jejunum also displayed heightened levels of antimicrobial peptides like lysozyme, mucin 2, sIgA, IgG, and IgM, showcasing an enhanced chemical and immune barrier (P < 0.05). Delving into the 16SrDNA sequencing of intestinal content, a higher microbial diversity was evident with a surge in beneficial bacteria, particularly Firmicutes, advocating a resilient and balanced microecosystem. The findings imply that a 3% APA dietary addition bolsters growth metrics and fortifies the intestinal barrier's structural and functional integrity in broilers.

Effect of glutamine on the systemic innate immune response in broiler chickens challenged with Salmonella pullorum

BACKGROUND

The objective of this study was to evaluate the effects of glutamine on the growth performance and systemic innate immune response in broiler chickens challenged with Salmonella pullorum. A total of 600 one-day-old Arbor Acres broiler chickens were assigned randomly to 6 dietary treatments with 10 replicates for a 21-day feeding experiment. The experimental treatments were as follows: the control treatment (birds fed the basal diet), the Gln1 treatment, and the Gln 2 treatment (birds fed the basal diet supplemented with 0.5%, and 1.0% Glutamine, respectively). At 3 d of age, half of the birds from each treatment were challenged oral gavage with 2.0 × 104 CFU/mL of S. pullorum suspension (1.0 mL per bird) or an equivalent amount of sterile saline alone, which served as a control.

RESULTS

The results showed that S. pullorum infection had adverse effects on the average daily feed intake, average daily gain, and feed conversion ratio of broiler chickens compared with those of the CON treatment on d 7, decreased the spleen and bursa of fabricius relative weights (except on d 21), serum immunoglobulin A (IgA),immunoglobulin G (IgG), and immunoglobulin M (IgM) concentrations, and spleen melanoma differentiation-associated gene 5 (MDA5) and laboratory of genetics and physiology gene 2 (LGP2) mRNA expression levels, and increased the mRNA expression levels of spleen Nodinitib-1 (NOD1), Toll-like receptors 2,4 (TLR2, TLR4), DNA-dependent activator of IFN-regulatory factors (DAI), mitochondrial antiviral-signaling protein (MAVS), P50, P65, and RelB on d 4, 7, 14, and 21. Supplementation with Gln improved the relative weights of the spleen and bursa of Fabricius (except on d 21), increased the serum IgA, IgG, and IgM concentrations and the mRNA expression levels of spleen MDA5 and LGP2, and decreased the mRNA expression levels of spleen NOD1, TLR2, TLR4, DAI, MAVS, P50, P65, and RelB of S. pullorum-challenged broiler chickens.

CONCLUSION

These results indicate that Gln might stimulate the systemic innate immune responses of the spleen in broiler chickens challenged with S. pullorum.

Preparation of Glutamine-Enriched Fermented Feed from Corn Gluten Meal and Its Functionality Evaluation

China faces a persistent deficiency in feed protein resources. Enhancing the utilization efficiency of indigenous feed protein resources emerges as a viable strategy to alleviate the current deficit in protein feed supply. Corn gluten meal (CGM), characterized by a high proportion of crude protein and glutamine, is predominantly employed in animal feed. Nonetheless, the water-insolubility of CGM protein hampers its protein bioavailability when utilized as feed material. The aim of this study was to augment protein bioavailability, liberate glutamine peptides from CGM, and produce glutamine-enriched CGM fermented feed. We executed a co-fermentation protocol using Bacillus subtilis A5, Lactobacillus 02002, and acid protease to generate the CGM fermented feed. Subsequent in vivo experiments with broilers were conducted to assess the efficacy of the fermented product. The findings revealed that the soluble protein, glutamine, small peptides, and lactic acid contents in the fermented feed increased by 69.1%, 700%, 47.6%, and 125.9%, respectively. Incorporating 15% and 30% CGM fermented feed into the diet markedly enhanced the growth performance and intestinal health of broilers, positively modulated the cecal microbiota structure, and augmented the population of beneficial bacteria, specifically Lactobacillus. These results furnish both experimental and theoretical foundations for deploying CGM fermented feed as an alternative protein feed resource.

The use of functional amino acids in different categories of pigs - A review

The present review deals with a particularly important topic: the use of functional amino acids in different categories of pigs. It is especially relevant in the context of the current efforts to reduce the use of antibiotics in pig farming and the search for possible alternatives to replace them. The review is based on the definition that functional amino acids (FAAs) are classified as dispensable amino acids, but with additional biological functions, i.e., not only are they used for protein formation, but they are also involved in regulating essential metabolic pathways to improve health, survival, growth, and development. We describe the mechanism of action of individual FAAs and their potential use in pigs, including glutamate, glutamine, arginine, branched-chain amino acids (i.e., leucine, isoleucine, and valine), tryptophan and glycine. The work is divided into three parts. The first part deals with the FAAs and their role in the overall health of sows and their offspring. The second part describes the use of functional amino acids in piglets after weaning. Part three examines the use of functional amino acids in growing and fattening pigs and their impact on meat quality.

Gut Health and Influencing Factors in Pigs

The gastrointestinal tract (GIT) is a complex, dynamic, and critical part of the body, which plays an important role in the digestion and absorption of ingested nutrients and excreting waste products of digestion. In addition, GIT also plays a vital role in preventing the entry of harmful substances and potential pathogens into the bloodstream. The gastrointestinal tract hosts a significant number of microbes, which throughout their metabolites, directly interact with the hosts. In modern intensive animal farming, many factors can disrupt GIT functions. As dietary nutrients and biologically active substances play important roles in maintaining homeostasis and eubiosis in the GIT, this review aims to summarize the current status of our knowledge on the most important areas.

Identification and Quantification of Proliferating Cells in Skeletal Muscle of Glutamine Supplemented Low- and Normal-Birth-Weight Piglets

One way to improve the growth of low-birth-weight (LBW) piglets can be stimulation of the cellular development of muscle by optimized amino acid supply. In the current study, it was investigated how glutamine (Gln) supplementation affects muscle tissue of LBW and normal-birth-weight (NBW) piglets. Longissimus and semitendinosus muscles of 96 male piglets, which were supplemented with 1 g Gln/kg body weight or alanine, were collected at slaughter on day 5 or 26 post natum (dpn), one hour after injection with Bromodeoxyuridine (BrdU, 12 mg/kg). Immunohistochemistry was applied to detect proliferating, BrdU-positive cells in muscle cross-sections. Serial stainings with cell type specific antibodies enabled detection and subsequent quantification of proliferating satellite cells and identification of further proliferating cell types, e.g., preadipocytes and immune cells. The results indicated that satellite cells and macrophages comprise the largest fractions of proliferating cells in skeletal muscle of piglets early after birth. The Gln supplementation somewhat stimulated satellite cells. We observed differences between the two muscles, but no influence of the piglets' birth weight was observed. Thus, Gln supplements may not be considered as effective treatment in piglets with low birth weight for improvement of muscle growth.

Embelin alleviates weaned piglets intestinal inflammation and barrier dysfunction via PCAF/NF-κB signaling pathway in intestinal epithelial cells

BACKGROUND

Intestinal barrier plays key roles in maintaining intestinal homeostasis. Inflammation damage can severely destroy the intestinal integrity of mammals. This study was conducted to investigate the protective effects of embelin and its molecular mechanisms on intestinal inflammation in a porcine model. One hundred sixty 21-day-old castrated weaned pigs (Duroc × Landrace × Yorkshire, average initial body weight was 7.05 ± 0.28 kg, equal numbers of castrated males and females) were allotted to four groups and fed with a basal diet or a basal diet containing 200, 400, or 600 mg embelin/kg for 28 d. The growth performance, intestinal inflammatory cytokines, morphology of jejunum and ileum, tight junctions in the intestinal mucosa of piglets were tested. IPEC-1 cells with overexpression of P300/CBP associating factor (PCAF) were treated with embelin, the activity of PCAF and acetylation of nuclear factor-κB (NF-κB) were analyzed to determine the effect of embelin on PCAF/NF-κB pathway in vitro.

RESULTS

The results showed that embelin decreased (P < 0.05) serum D-lactate and diamine oxidase (DAO) levels, and enhanced the expression of ZO-1, occludin and claudin-1 protein in jejunum and ileum. Moreover, the expression levels of critical inflammation molecules (interleukin-1β, interleukin-6, tumor necrosis factor-α, and NF-κB) were down-regulated (P < 0.05) by embelin in jejunal and ileal mucosa. Meanwhile, the activity of PCAF were down-regulated (P < 0.05) by embelin. Importantly, transfection of PCAF siRNAs to IPEC-1 cell decreased NF-κB activities; embelin treatment downregulated (P < 0.05) the acetylation and activities of NF-κB by 31.7%-74.6% in IPEC-1 cells with overexpression of PCAF.

CONCLUSIONS

These results suggested that embelin ameliorates intestinal inflammation in weaned pigs, which might be mediated by suppressing the PCAF/NF-κB signaling pathway.

Effects of Dietary Supplementation with Glutamine on the Immunity and Intestinal Barrier Gene Expression in Broiler Chickens Infected with Salmonella Enteritidis

The effects of glutamine (Gln) on immunity and intestinal barrier gene expression levels in broilers challenged with Salmonella Enteritidis were evaluated. A total of 400 1-day-old broilers were randomly assigned to four groups, 10 repetition treatments per group with 10 broiler chickens for a 21-day feeding trial. The groups were the normal control group (CON, no infected group, fed with a basal diet); the S. Enteritidis-infected control group (SCC, infected with 2.0 × 104 CFU/mL of S. Enteritidis, fed a basal diet); and the Gln 1 and 2 groups, who were challenged with S. Enteritidis and fed a basal diet plus Gln at 0.5% and 1.0%, respectively. The results show that S. Enteritidis had adverse effects on the average daily feed intake, average daily gain, and the feed conversion ratio of infected broilers compared with those of CON broilers on d 7 (p < 0.05); decreased serum immunoglobulin A (IgA), immunoglobulin M (IgM), and immunoglobulin G (IgG) concentrations, and intestinal mucosa Bcl-2 mRNA expression levels (p < 0.05); increased the Lysozyme (LZM, only serum), NO, inducible NO synthase (iNOS) (except at 4 d), and total nitric oxide synthase (TNOS) (except at 4 d) activities in serum and the intestinal mucosa; and increased intestinal mucosa polymeric immunoglobulin receptor (pIgR) (except at 21 d), Avian beta-defensin 5 (AvBD5), AvBD14, Bax, and Bak mRNA expression levels during the experimental period (p < 0.05). Supplementation with Gln improved growth performance; increased serum IgA, IgG, and IgM concentrations and intestinal mucosa Bcl-2 mRNA expression levels (p < 0.05); decreased the LZM (only serum), NO, iNOS (except at 4 d), and TNOS (except at 4 d) activities in serum and the intestinal mucosa; and decreased intestinal mucosa pIgR (except at 21 d), AvBD5, AvBD14, Bax, and Bak mRNA expression levels during the experimental period (p < 0.05). These results suggest that Gln might lessen the inflammatory reaction of the small intestine and enlarge the small bowel mucosa immune and barrier function in broiler chickens challenged with S. Enteritidis.

Lactobacillus rhamnosus GG ameliorates DON-induced intestinal damage depending on the enrichment of beneficial bacteria in weaned piglets

BACKGROUND

Deoxynivalenol (DON) is one of the most common environmental pollutants that induces intestinal inflammation and microbiota dysbiosis. Lactobacillus rhamnosus GG (LGG) is a probiotic that not only has anti-inflammatory effects, but also shows protective effect on the intestinal barrier. However, it is still unknown whether LGG exerts beneficial effects against DON-induced intestinal damage in piglets. In this work, a total of 36 weaned piglets were randomized to one of four treatment groups for 21 d. The treatment groups were CON (basal diet); LGG (basal diet supplemented with 1.77 × 10¹¹ CFU/kg LGG); DON (DON-contaminated diet) and LGG + DON (DON-contaminated diet supplemented with 1.77 × 10¹¹ CFU/kg LGG).

RESULT

Supplementation of LGG can enhance growth performance of piglets exposed to DON by improving intestinal barrier function. LGG has a mitigating effect on intestinal inflammation induced by DON exposure, largely through repression of the TLR4/NF-κB signaling pathway. Furthermore, supplementation of LGG increased the relative abundances of beneficial bacteria (e.g., Collinsella, Lactobacillus, Ruminococcus_torques_group and Anaerofustis), and decreased the relative abundances of harmful bacteria (e.g., Parabacteroides and Ruminiclostridium_6), and also promoted the production of SCFAs.

CONCLUSIONS

LGG ameliorates DON-induced intestinal damage, which may provide theoretical support for the application of LGG to alleviate the adverse effects induced by DON exposure.

Maternal VD3 supplementation during gestation improves intestinal health and microbial composition of weaning piglets

Vitamin D₃ (VD₃) has been reported to improve the reproductive performance of sows. This study was conducted to investigate the long-term effect of maternal VD₃ supplementation during gestation on the intestinal health of piglets. Twenty-three Landrace × Yorkshire gilts were randomly allocated into two groups to receive one of the following two diets during gestation: basal diet (CON group, 800 IU VD₃ per kg diet, n = 12) and VD₃ supplemented diet (VD₃ group, 2000 IU VD₃ per kg diet, n = 11). All sows were then fed with the same diet during lactation. Results showed that maternal VD₃ supplementation during lactation tended to decrease (p = 0.08) the body weight loss of sows during lactation compared to the CON group. Besides, the relative length and weight of the small intestine (SI) and the villus height of the duodenum and ileum in weaning piglets were much higher (p < 0.05) in the VD₃ group than those in the CON group, though their body weight was not changed. Meanwhile, maternal VD₃ supplementation significantly upregulated the expression levels of IGF-1, IGF-2R, VDR, GLUT-2 and CAT1 in the duodenum (p < 0.05), and increased the expression levels of IGF-1, IGF-1R, IGF-2R, VDR, Occludin, ZO-1, MUC2, PEPT1 and CAT1 (p < 0.05) in the jejunum of suckling piglets compared with the CON group. Besides, the concentration of SigA in the jejunum of suckling piglets was higher (p < 0.05) in the VD₃ group than that in the CON group. In addition, maternal VD₃ supplementation significantly increased the contents of short chain fatty acids and the relative abundance of Lactobacillus and Faecalibacterium (p < 0.05) in the feces of weaning piglets compared to the CON group. Moreover, the relative abundance of unidentified_Lachnospiraceae in the feces of weaning piglets tended to be higher (p = 0.05), while that of unidentified_Spirochaetaceae was lower (p < 0.05) in the VD₃ group than those in the CON group. Taken together, maternal VD₃ supplementation during gestation could improve the intestinal function and microbiota in suckling piglets.

Structural diversity and concentration dependence of pyrazine formation: Exogenous amino substrates and reaction parameters during thermal processing of l-alanyl-l-glutamine Amadori compound

The Amadori compound of glucose and l-alanyl-l-glutamine (Ala-Gln-ARP) was prepared and characterized by UPLC-MS/MS and NMR. There were no pyrazines produced by heated Ala-Gln-ARP alone due to the asynchronicity of regenerated l-alanyl-l-glutamine and α-dicarbonyl compounds. High temperature (130 °C) and long reaction time could facilitate the 2,5-dimethylpyrazine formation at a small concentration (33.4 ± 3.47 μg/L). The exogenous amino substrates would lower the formation temperature of pyrazines and make it to be generated effectively. Extra supplied l-alanyl-l-glutamine could generate 2,5-dimethylpyrazine at 110 °C, while higher temperature of 140 °C could strengthen the formation of 2,5-dimethylpyrazine (793 ± 119 μg/L) and stimulate the generation of other pyrazines, including methylpyrazine and 2,6-dimethylpyrazine. The exogenous alanine, glutamic acid, and glutamine was also beneficial to enhance the pyrazines formation, especially the glutamic acid. Furthermore, alkaline pH of thermal reaction made pyrazines increase significantly than in neutral medium and further enriched their species such as unsubstituted pyrazine and trimethylpyrazine.

Addition of L-Glutamine + Glutamic Acid and L-Arginine to the diet of weaned piglets

This study aimed to evaluate the supplementation of L-glutamine + glutamic acid and/or L-arginine on the productive performance, incidence of diarrhea, intestinal morphological of weaned piglets. Sixty-four 28-day-old weaned piglets were distributed in four treatments: DC - control diet; DG - glutamine diet (1% L-glutamine + glutamic acid); DA - arginine diet (1% L-arginine); and DGA - glutamine + arginine diet (0.5% L-glutamine + glutamic acid and 0.5% L-arginine) with eight replicates and two animals per experimental unit. The addition of 1% L-arginine to the piglet diet improved weight gain and feed conversion over 28 to 35 days of age. In the period of 28 to 49 days of age, supplementation with 1% L-glutamine + glutamic acid increased the animals' weight gain and reduced the incidence of diarrhea. Supplementation with amino acids in combination had a positive effect on the morphometric parameters of the intestinal mucosa compared to the control diet. Supplementation with 1% L-glutamine + glutamic acid increased the number of anti-PCNA+ cells and goblet cells. Taken together, our findings suggest that supplementation with L-glutamine + glutamic acid and L-arginine can improve the productive performance and enhance the integrity of the intestinal mucosa of weaned piglets.

Pharmacological Applications and Action Mechanisms of Phytochemicals as Alternatives to Antibiotics in Pig Production

Antibiotics are widely used for infectious diseases and feed additives for animal health and growth. Antibiotic resistant caused by overuse of antibiotics poses a global health threat. It is urgent to choose safe and environment-friendly alternatives to antibiotics to promote the ecological sustainable development of the pig industry. Phytochemicals are characterized by little residue, no resistance, and minimal side effects and have been reported to improve animal health and growth performance in pigs, which may become a promising additive in pig production. This paper summarizes the biological functions of recent studies of phytochemicals on growth performance, metabolism, antioxidative capacity, gut microbiota, intestinal mucosa barrier, antiviral, antimicrobial, immunomodulatory, detoxification of mycotoxins, as well as their action mechanisms in pig production. The review may provide the theoretical basis for the application of phytochemicals functioning as alternative antibiotic additives in the pig industry.

The use of dipeptide supplementation as a means of mitigating the negative effects of dietary soybean meal on Zebrafish Danio rerio

Soybean meal (SBM) inclusion in aquaculture diets has been found to negatively affect growth and induce intestinal inflammation in fish. The objective of this study was to determine the effect of health-promoting dipeptide supplementation into SBM-based feeds on growth performance, intestinal health, and muscle free amino acid composition, an indicator of dietary amino acid availability, in a zebrafish model. There were five treatment groups in this study. The first group ((+) Control) received a fishmeal-based diet. The second group ((-) Control) received SBM-based diet. The last three groups (Ala-Glu, Car, and Ans) were fed SBM-based diets, supplemented with alanyl-glutamine, carnosine, and anserine respectively. The Ala-Glu and Car groups experienced a significantly higher weight gain than the (-) Control group, weighing 35.38% and 33.96% more, respectively at the conclusion of the study. There were no significant differences in gene expression among the groups, but Ala-Glu had the highest expression of both nutrient absorption genes measured, PepT1 and fabp2. Ala-Glu had significantly longer intestinal villi, and a significantly higher villus length-to-width ratio than the (-) Control group. The Car group had a significantly higher post-prandial tissue concentration of lysine, compared to the (-) Control group. The increase in villus surface area and expression of nutrient absorption genes represent an improvement in intestinal absorptive capacity in the Ala-Glu group. The results from this study provide support for the use of alanyl-glutamine and carnosine supplementation as a means of improving growth performance of zebrafish fed with a high level SBM-based diet.

Invited Review: Maintain or Improve Piglet Gut Health around Weanling: The Fundamental Effects of Dietary Amino Acids

Gut health has significant implications for swine nutrient utilization and overall health. The basic gut morphology and its luminal microbiota play determinant roles for maintaining gut health and functions. Amino acids (AA), a group of essential nutrients for pigs, are not only obligatory for maintaining gut mucosal mass and integrity, but also for supporting the growth of luminal microbiota. This review summarized the up-to-date knowledge concerning the effects of dietary AA supplementation on the gut health of weanling piglets. For instance, threonine, arginine, glutamine, methionine and cysteine are beneficial to gut mucosal immunity and barrier function. Glutamine, arginine, threonine, methionine and cysteine can also assist with relieving the post-weaning stress of young piglets by improving gut immunological functions, antioxidant capacity, and/or anti-inflammatory ability. Glutamine, glutamate, glycine and cysteine can assist to reconstruct the gut structure after its damage and reverse its dysfunction. Furthermore, methionine, lysine, threonine, and glutamate play key roles in affecting bacteria growth in the lumen. Overall, the previous studies with different AA showed both similar and different effects on the gut health, but how to take advantages of all these effects for field application is not clear. It is uncertain whether these AA effects are synergetic or antagonistic. The interactions between the effects of non-nutrient feed additives and the fundamental effects of AA warrant further investigation. Considering the global push to minimize the antibiotics and ZnO usage in swine production, a primary effort at present may be made to explore the specific effects of individual AA, and then the concert effects of multiple AA, on the profile and functions of gut microbiota in young pigs.

Dietary seaweed-derived polysaccharides improve growth performance of weaned pigs through maintaining intestinal barrier function and modulating gut microbial populations

Background

Seaweed-derived polysaccharides (SDP) represent an attractive source of prebiotic nutraceuticals for the food and animal husbandry industry. However, the mechanism by which SDP from Enteromorpha mediates pig growth are not fully understood. This study aimed to investigate how SDP supplementation influences the growth performance and intestinal health in weaned pigs.

Results

In Exp. 1, 240 weaned pigs were randomly assigned to four dietary treatments and fed with a basal diet or a basal diet containing 200, 400 or 800 mg/kg SDP, respectively, in a 21-day trial. Pigs on the 400 or 800 mg/kg SDP-supplemented group had greater ADG and lower F/G ratio than those on the control group (P<0.05). In Exp. 2, 20 male weaned pigs were randomly assigned to two treatments and fed with a basal diet (CON group) or a basal diet supplemented with 400 mg/kg SDP (the optimum does from Exp. 1), in a 21-day trial. Pigs fed the SDP diet had greater ADG, the concentrations of serum IL-6 and TNF-α and the activities of glutathione peroxidase, superoxide dismutase and catalase (P<0.05), and lower F/G, diarrhea rate, as well as serum D-lactate concentrations and diamine oxidase activity (P<0.05). Moreover, dietary SDP supplementation enhanced secretory immunoglobulin A content, villus height and villous height: crypt depth ratio in small intestine, as well as the lactase and maltase activities in jejunum mucosa (P<0.05). SDP supplementation elevated the mRNA levels of inflammatory response-related genes (IL-6, TNF-α, TLR4, TLR6 and MyD88), and the mRNA and protein levels of ZO-1, claudin-1 and occludin in jejunum mucosa (P<0.05). Importantly, SDP not only increased the Lactobacillus population but also reduced the Escherichia coli population in cecum (P<0.05). Furthermore, SDP increased acetic acid and butyric acid concentrations in cecum (P<0.05).

Conclusions

These results not only suggest a beneficial effect of SDP on growth performance and intestinal barrier functions, but also offer potential mechanisms behind SDP-facilitated intestinal health in weaned pigs.

Bacteriophage as an Alternative to Antibiotics Promotes Growth Performance by Regulating Intestinal Inflammation, Intestinal Barrier Function and Gut Microbiota in Weaned Piglets

This study aimed to investigate the effects of dietary bacteriophage supplementation on growth performance, intestinal morphology, barrier function, and intestinal microbiota of weaned piglets fed antibiotic-free diet. A total of 120 weaned piglets were allotted to four dietary treatments with five pens/treatment and six piglets/pen in a 21-d feeding trial. The control diet was supplemented with 25 mg/kg quinocetone and 11.25 mg/kg aureomycin in the basal diet, while the three treatment diets were supplemented with 200, 400, or 600 mg/kg bacteriophage in the basal diet, respectively. There was no difference for growth performance and all measured indices of serum and intestinal tissues between 200 mg/kg bacteriophage group and the control group with antibiotics (P > 0.05). More importantly, compared with the control diet, dietary 400 mg/kg bacteriophage inclusion increased average daily gain and average daily feed intake, and decreased feed/gain ratio and diarrhea incidence of weaned piglets (P < 0.05). Also, piglets fed 400 mg/kg bacteriophage had elevated villi height (VH) in jejunum and ileum, reduced crypt depth (CD) in jejunum and ileum, and elevated VH/CD ratio in duodenum, jejunum and ileum (P < 0.05). Compared to the control group, piglets fed 400 mg/kg bacteriophage had lower interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α), and higher interleukin-10 (IL-10) concentration in serum, and higher secretory immunoglobulin A (sIgA), intestinal trefoil factor (ITF), and tumor growth factor-alpha (TGF-α) content in the ileal mucosa (P < 0.05). Besides, dietary addition with 400 mg/kg bacteriophage decreased the D-lactate concentration and diamine oxidase (DAO) activity in serum, and increased the relative mRNA expression of ZO-1, Claudin-1, Occludin, TLR2, TLR4, and TLR9, as well as the relative protein expression of Occludin in the jejunum (P < 0.05). However, the growth performance and all analyzed parameters in serum and intestinal tissues were not further improved when piglets fed 600 vs. 400 mg/kg bacteriophage (P > 0.05). MiSeq sequencing analysis showed that bacteriophage regulated the microbial composition in caecum digesta, as indicated by higher observed_species, Chao1, and ACE richness indices, as well as changes in the relative abundance of Firmicutes, Bacteroidetes, and Tenericutes (P < 0.05). Collectively, 400 mg/kg bacteriophage can be used as an antibiotics alternative for promoting the growth of weaned piglets. The underlying mechanism is associated with a positive effect of bacteriophage on intestinal inflammation, intestinal barrier function and gut microbiota in weaned piglets.

Dietary guanidinoacetic acid improves the growth performance and skeletal muscle development of finishing pigs through changing myogenic gene expression and myofibre characteristics

This study aimed to evaluate the effects of dietary guanidine acetic acid (GAA) supplementation on growth performance, carcass traits and the expression of muscle growth-related genes in finishing pigs. A total of 128 (81.03 ± 1.09 kg body weight) crossbred pigs (Duroc × Landrace ×Yorkshire) were blocked by body weight and allotted to 16 pens (eight pigs per pen), and pens were randomly assigned within blocks to one of five dietary treatments, with a basal diet (control group) or a basal diet supplemented with 0.03%, 0.06% and 0.09% GAA respectively. During the 60-day trial, GAA increased the average dairy gain (ADG) and average daily feed intake (ADFI) (p < .05). The back fat thickness of pigs fed 0.06% GAA was lower than other groups (p < .05). Pigs fed 0.06% GAA had improved lean meat percentage, loin muscle area, shear force and cross-sectional area of muscle fibre in comparison with control group (p < .05). The drop loss and the muscle fibre density in pigs fed 0.06% GAA were lower than control (p < .05). In addition, dietary GAA enhanced the expression of myosin heavy chain gene (MYH4), myogenic determination (Myod) and myogenic factor 5 (Myf5) in longissimus dorsi and carnitine palmitoyltransferase-1(CPT-1) in liver (p < .05). Meanwhile, GAA decreased the expression of Myostatin in longissimus dorsi and fatty acid synthase (FAS) in liver (p < .05). In conclusion, our results showed that appropriate dietary GAA supplementation (0.06%) promotes skeletal muscle development through changing myogenic gene expression and myofibre characteristics.