Mannan oligosaccharides selenium ameliorates intestinal mucosal barrier, and regulate intestinal microbiota to prevent Enterotoxigenic Escherichia coli -induced diarrhea in weaned piglets.

Enterotoxigenic Escherichia coli (ETEC) is a common diarrheal pathogen in humans and animals. To prevent and treat ETEC induced diarrhea, we synthesized mannan oligosaccharide selenium (MOSS) and studied its beneficial effect on ETEC-induced diarrhea. A total of 32 healthy weaned piglets (6.69 ± 0.01 kg) were randomly divided into four groups: NC group (Basal diet), MOSS group (0.4 mg/kg MOSS supplemented diet), MOET group (0.4 mg/kg MOSS supplemented diet + ETEC treatment), ETEC group (ETEC treatment). NC and ETEC group fed with basal diet, MOSS and MOET group fed with the MOSS supplemented diet. On the 8th and 15th day of the experiment, MOET and ETEC group were gavaged with ETEC, and NC and MOSS group were gavaged with stroke-physiological saline solution. Our data showed that dietary MOSS supplementation increased average daily gain (ADG) and average daily feed intake (ADFI) and significantly decreased diarrhea index and frequency in ETEC-treated piglets. MOSS did not affect the α diversity and ß diversity of ileal microbial community, but it significantly decreased the proportion of lipopolysaccharide biosynthesis in ileal microbial community. MOSS supplementation regulated colonic microbiota community composition, which significantly increased carbohydrate metabolism, and inhibited lipopolysaccharide biosynthesis pathway in colonic microbial community. Moreover, MOSS significantly decreased inflammatory stress, and oxidative stress in ETEC treated piglets. Furthermore, dietary MOSS supplementation significantly decreased intestinal barrier permeability, and alleviated ETEC induced intestinal mucosa barrier irritation. In conclusion, our study showed that dietary MOSS supplementation ameliorated intestinal mucosa barrier, and regulated intestinal microbiota to prevent ETEC induced diarrhea in weaned piglets.

Effects of glutamine, glutamate, and aspartate on intestinal barrier integrity and amino acid pool of the small intestine in piglets with normal or low energy diet.

Aspartate (asp), glutamate (glu), and glutamine (gln) are the major energy fuels for the small intestine, and it had been indicated in our previous study that the mix of these three amino acid supplementations could maintain intestinal energy homeostasis. This study aimed to further investigate whether the treatment of gln, glu, and asp in low energy diet affects the intestinal barrier integrity and amino acid pool in weaning piglets. A total of 198 weaned piglets were assigned to 3 treatments: control (basal diet + 1.59% L-Ala); T1 (basal diet + 1% L-Gln + 0.5% L-Glu + 0.1% L-Asp); and T2 (low energy diet + 1% L-Gln + 0.5% L-Glu + 0.1% L-Asp). The blood, jejunum, and ileum were obtained on day 5 or on day 21 post-weaning, respectively. Our results showed that T1 and T2 treatments increased the abundances of occludin, claudin-1, and claudin-3 in the small intestine while decreasing the serum diamine oxidase (DAO) and D-lactate levels in weaning piglets. Meanwhile, T1 and T2 treatments significantly increased the positive rate of proliferating cell nuclear antigen (PCNA) of the small intestine, promoting intestinal cell proliferation. We also found that supplementation with glu, gln, and asp improved the serum amino acid pool and promoted ileal amino acid transporter gene expression of slc3a2, slc6a14, and slc7a11 in weaned piglets. Additionally, on day 21 post-weaning, T1 and T2 treatments stimulated the phosphorylation of the mTOR-S6K1-4EBP1 signaling pathway in the small intestine, which may implicate the enhanced protein synthesis rate. In summary, dietary supplementation of gln, glu, and asp was beneficial to the intestinal barrier function and amino acid pool regulation, while the benefits of gln, glu, and asp treatment might be diminished by the low-energy diet. The results demonstrated that the supplementation of gln, glu, and asp under low energy levels was preferentially supplied as the energy fuel to restore the gut barrier function in piglets on day 5 post-weaning. With the increase in age and intestinal maturation (on day 21 post-weaning), gln, glu, and asp supplementation could also show an effect on the regulation of the amino acid pool and protein synthesis.

Corrigendum: The amino acids sensing and utilization in response to dietary aromatic amino acid supplementation in LPS-induced inflammation piglet model.

[This corrects the article DOI: 10.3389/fnut.2021.819835.].

The nanocomposites of modified attapulgite with vitamin E and mannan oligosaccharide regulated the intestinal epithelial barrier and improved intestinal microbiota composition to prevent diarrhea in weaned piglets.

BACKGROUND: Overuse of antibiotics contributes to bacterial resistance in animals. Therefore, it is necessary to find a new way to ensure animal health and promote animal growth. This experiment was conducted to investigate the effect of mannan oligosaccharide (MOS)/vitamin E (VE)/attapulgite (APT) nanocomposites (SLK1, SLK3, SLK5) on growth performance and intestinal health in weaned piglets. Each 1 kg of SLK1, SLK3 or SLK5 contains 50 g of vitamin E, and each had a different MOS concentration [SLK1 (50 g kg -1 MOS), SLK3 (100 g kg -1 MOS), SLK5 (150 g kg -1 MOS)]. In total, 135 piglets were randomly divided into five groups (normal control group, traditional antibiotic substitutes group, SLK1 group, SLK3 group and SLK5 group), and growth performance, diarrhea index, intestinal epithelial barrier function and intestinal microbial composition were measured. RESULTS: SLK1 and SLK5 significantly decreased diarrhea frequency in weaned piglets (p < 0.05). Furthermore, SLK5 significantly increased survival rate of weaned piglets compared to the traditional antibiotic substitutes group (p < 0.05). SLK5 also increased villus height of ileum, and increased goblet number of the jejunum (p < 0.05). 16S rRNA sequencing showed that SLK5 significantly regulated intestinal colonic microbiota composition (p < 0.05). Specifically, SLK5 significantly increased the abundance of Phascolarctobacterium succinatutens in the cecum and increased the abundance of Lactobacillus and Bifidobacterium in the colon (p < 0.05). In addition, dietary supplementation with 1 kg T-1 SLK5 also significantly increased the propionate content in the colon, which is significantly correlated with Phascolarctobacterium (p < 0.05). CONCLUSION: Dietary supplementation with 1 kg T-1 SLK5 improved intestinal epithelial barrier function, and regulated intestinal microbiota composition to prevent diarrhea in weaned piglets. © 2023 Society of Chemical Industry.

Dietary supplementation modified attapulgite promote intestinal epithelial barrier and regulate intestinal microbiota composition to prevent diarrhea in weaned piglets.

Attapulgite is a kind of natural clay mineral. Its unique pore structure makes it an ideal adsorption material and carrier material. However, the beneficial effect of modified attapulgites (SLK) in livestock is still unknown. The study was aimed to investigate the beneficial effect of modified attapulgites on diarrhea. 135 piglets were randomly divided into 5 groups and fed with control diet, traditional antibiotic substitute (TAS) supplementation diet, 0.5 mg/kg SLK supplementation diet, 1 mg/kg SLK supplementation diet, and 1.5 mg/kg SLK supplementation diet. This experiment lased two weeks. According to our result, 1.5 mg/kg SLK supplementation diet significantly decreased diarrhea score and diarrhea frequency, and effectively increased survival rate (P < 0.05). Dietary supplementation with 1.5 mg/kg SLK significantly increased high density lipoprotein cholesterol (HDLC), and choline esterase (CHE) concentration in serum (P < 0.05). AS compared with TAS group, 1.5 mg/kg SLK supplementation diet significantly decreased villus height and increased goblet number in jejunum, and increased villus height and decreased goblet number in ileum (P < 0.05). 1.5 mg/kg SLK supplementation diet also significantly changed cecal microbial community composition, including increased Limosilactobacillus abundance (P < 0.05). 1.5 mg/kg SLK supplementation diet significantly increased colonic microbial community composition, including decreased Escherichia-shigella abundance and increased Limosilactobacillus abundance (P < 0.05). Moreover, 1.5 mg/kg SLK supplementation diet significantly increased valerate, propionate, butyrate, and total short chain fatty acid contents in colon (P < 0.05). Valerate, propionate, butyrate, and total short chain fatty acid significantly associated with Lactobacillus. Fourerenilla and Fourerenilla.unclassfied significantly associated with acetate contents in colon (P < 0.05). In conclusion, dietary supplementation with modified apptapulgites significantly regulate intestinal microbial community composition and alleviate intestinal epithelial barrier to prevent diarrhea in piglets.

Vitamin A Ameliorated Irinotecan-Induced Diarrhea in a Piglet Model Involving Enteric Glia Modulation and Immune Cells Infiltration.

Vitamin A (VA) and its metabolite, retinoic acid (RA), play important roles in modulating intestinal mucosal immunity, yet little is known about their regulatory effects on enteric nervous system function. The study aims to explore the protective effects of dietary VA on diarrhea in a piglet model involving enteric glia and immune cell modulation. Twenty-eight weaned piglets were fed either the basal or VA (basal diet supplemented with 18,000 IU/kg VA) diet and with or without irinotecan (CPT-11) injection. CPT-11 induced increased diarrhea incidence, immune infiltration, and reactive enteric gliosis. A diet supplemented with 18,000 IU/kg VA ameliorated the adverse effects of CPT-11 on the gut barrier. VA reduced diarrhea incidence and attenuated enteric glial gliosis, immune cell infiltrations, and inflammatory responses of CPT-induced piglets. An in vitro experiment with 1 nmol/L RA showed direct protective effects on monocultures of enteric glial cells (EGCs) or macrophages in LPS-simulated inflammatory conditions. Furthermore, 1 ng/mL glial-derived neurotropic factors (GDNF) could inhibit M1-macrophage polarization and pro-inflammatory cytokines production. In summary, VA exerted protective effects on the intestinal barrier by modulating enteric glia and immune cells, perhaps enhancing epithelial recovery under CPT-11 challenge. Our study demonstrated that RA signaling might promote the roles of enteric glia in intestinal immunity and tissue repair, which provided a reference for the VA supplementation of patient diets.

Effects of xylanase on growth performance, nutrient digestibility, serum metabolites, and fecal microbiota in growing pigs fed wheat-soybean meal-based diets.

This experiment investigated the effects of xylanase on growth performance, nutrient digestibility, serum metabolites, and fecal microbiota in growing pigs fed wheat-soybean meal-based diets. Seventy-two crossbred pigs (Duroc × [Landrace × Large White]) pigs (body weight of 23.30 ± 1.51 kg) were allotted two treatments with six pens per treatment and six pigs per pen. The diets were a wheat-soybean meal-based diet (Control group) and a wheat-soybean meal-based diet supplemented with 500 U/kg xylanases (XYL group). The experiment was divided into two periods (phase 1: days 1 to 35 and phase 2: days 36 to 70). Xylanase improved G:F during phase 1 and the entire experiment (P < 0.05) and tended to improve G:F during phase 2 (P = 0.09). Compared with the control group, pigs in the XYL group had greater apparent total tract digestibility of dry matter, organic matter, and gross energy on days 35 and 70 (P < 0.05) and had greater apparent ileal digestibility of amino acids (histidine, lysine, methionine, and serine) on day 70 (P < 0.05). The fecal microbiota in the XYL group contained greater abundances of g_Terrisporobacter, g_Lactobacillus, g_Clostridium_sensu_stricto_1, and g_Romboutsia than the Control group on day 70. Xylanase increased the fecal Lactobacillus populations on day 35 (P < 0.05). On days 35 and 70, xylanase reduced the fecal E. coli populations (P < 0.05). Supplementing xylanase to wheat-soybean meal-based diets collectively improved fecal microbiota, and nutrient digestibility, thereby improving growth performance in growing pigs.

The potentiality of wheat on nutritive value is not fully realized because of the presence of (NSP). The arabinoxylan in the wheat represents about 70% of the total NSP, which may bring about the encapsulation of nutrients and increase digesta viscosity. In this experiment, we found that a wheat­soybean meal-based diet supplemented with 500 U/kg xylanases could improve the fecal microbiota and nutrient digestibility, thereby improving growth performance in growing pigs.

Glutamine, glutamate, and aspartate differently modulate energy homeostasis of small intestine under normal or low energy status in piglets.

Weaning stress may cause reduced energy intake for maintenance of mucosal structure. Gln, Glu, and Asp are major energy sources for the small intestine. This study investigated whether Gln, Glu, and Asp improve the intestinal morphology via regulating the energy metabolism in weaning piglets. A total of 198 weaned piglets were assigned to 3 treatments: Control (Basal diet + 1.59% L-Ala); T1 (Basal diet + 1% L-Gln + 0.5% L-Glu + 0.1% L-Asp); T2 (Low energy diet + 1% L-Gln + 0.5% L-Glu + 0.1% L-Asp). Jejunum and ileum were obtained on d 5 or 21 post-weaning. T1 enhanced growth performance. T1 and T2 treatments improved small intestinal morphology by increasing villus height, goblet cell number and decreasing crypt depth. Days post-weaning affected the efficacy of T2, but not T1, on energy metabolism. At normal energy supplementation, Gln, Glu, and Asp restored small intestinal energy homeostasis via replenishing the Krebs' cycle and down-regulating the AMPK (adenosine monophosphate activated protein kinase) pathway. As these are not sufficient to maintain the intestinal energy-balance of piglets fed with a low energy diet on d 5 post-weaning, the AMPK, glycolysis, beta-oxidation, and mitochondrial biogenesis are activated to meet the high energy demand of enterocytes. These data indicated that Gln, Glu, and Asp could restore the energy homeostasis of intestinal mucosa of weaning piglets under normal energy fed. Low energy feeding may increase the susceptibility of piglets to stress, which may decrease the efficacy of Gln, Glu, and Asp on the restoration of energy balance. These findings provide new information on nutritional intervention for insufficient energy intake in weaning piglets.

The microbiota-gut-brain axis: A novel nutritional therapeutic target for growth retardation.

Growth retardation (GR), which commonly occurs in childhood, is a major health concern globally. However, the specific mechanism remains unclear. It has been increasingly recognized that changes in the gut microbiota may lead to GR through affecting the microbiota-gut-brain axis. Microbiota interacts with multiple factors such as birth to affect the growth of individuals. Microbiota communicates with the nerve system through chemical signaling (direct entry into the circulation system or stimulation of enteroendocrine cells) and nervous signaling (interaction with enteric nerve system and vagus nerve), which modulates appetite and immune response. Besides, they may also influence the function of enteric glial cells or lymphocytes and levels of systemic inflammatory cytokines. Environmental stress may cause leaky gut through perturbing the hypothalamic-pituitary-adrenal axis to further result in GR. Nutritional therapies involving probiotics and pre-/postbiotics are being investigated for helping the patients to overcome GR. In this review, we summarize the role of microbiota in GR with human and animal models. Then, existing and potential regulatory mechanisms are reviewed, especially the effect of microbiota-gut-brain axis. Finally, we propose nutritional therapeutic strategies for GR by the intervention of microbiota-gut-brain axis, which may provide novel perspectives for the treatment of GR in humans and animals.

Baicalin-Zinc Complex Alleviates Inflammatory Responses and Hormone Profiles by Microbiome in Deoxynivalenol Induced Piglets.

This study aimed to investigate the beneficial effect of baicalin-zinc complex (BZN) on intestinal microorganisms in deoxynivalenol (DON)-challenged piglets and the association between intestinal microorganisms and host immunity and hormone secretion. Forty weaned piglets were randomly divided into four treatments with 10 piglets in each treatment: (1) control (Con) group (pigs fed basal diet); (2) DON group (pigs fed 4 mg DON/kg basal diet); (3) BZN group (pigs fed 0.5% BZN basal diet); and (4) DBZN group (pigs fed 4 mg DON/kg and 0.5% BZN basal diet). The experiment lasted for 14 days. The BZN supplementation in DON-contaminated diets changed the intestinal microbiota composition and increased intestinal microbial richness and diversity of piglets. The BZN supplementation in DON-contaminated diets also alleviated the inflammatory responses of piglets and modulated the secretion of hormones related to the growth axis. Moreover, microbiota composition was associated with inflammatory and hormone secretion. In conclusion, BZN alleviated inflammatory response and hormone secretion in piglets, which is associated with the intestinal microbiome.

Effects of dietary rosemary extract supplementation on growth performance, nutrient digestibility, antioxidant capacity, intestinal morphology, and microbiota of weaning pigs.

Rosemary (Rosmarinus officinalis L.) extract (RE) has multiple pharmacological and biological activities, including the use as a food additive and medicine. This study was conducted to investigate the effects of dietary RE supplementation on the growth performance, nutrient digestibility, antioxidant capacity, intestinal morphology, and microbiota of weaning piglets. A total of 192 crossbred weaned piglets [Duroc × (Large White × Landrace)] (initial body weight = 6.65 ± 0.33 kg, weaned days = 23 ± 1 d) were group housed (six pigs per pen; n = 8 pens/treatment). Pigs were fed a corn-soybean meal-based control diet or the basal diet supplemented with 100, 200, or 400 mg/kg RE. Pigs were allowed ad libitum access to fed for 21 d. The growth performance and apparent total tract digestibility of nutrients, and intestinal morphology and antioxidant status were evaluated. The components of the microbial microflora were also determined in the cecal samples. Compared with the control, dietary supplementation with RE increased the final body weight, average daily gain, and average daily feed intake (linear, P = 0.038, 0.016, and 0.009, respectively), and decreased the diarrhea ratio in piglets (linear, P < 0.05). The digestibility of crude protein (linear, P = 0.034) and gross energy (linear, P = 0.046) increased with treatment with RE. Piglets fed RE showed longer villus height (linear, P = 0.037 and 0.028, respectively) and villus height/crypt depth (linear, P = 0.004 and 0.012; quadratic, P = 0.023 and 0.036, respectively) in the jejunum and ileum, in addition to a lesser crypt depth in the jejunum (linear, P = 0.019) and ileum (quadratic, P = 0.042). The addition of RE increased the activity of superoxide dismutase (linear, P = 0.035 and 0.008, respectively) and glutathione peroxidase activity (linear, P = 0.027 and 0.039, respectively) and decreased the content of malondialdehyde (linear, P = 0.041 and 0.013; quadratic, P = 0.023 and 0.005, respectively) in the serum and liver. Dietary RE supplementation, compared with the control, increased the number of Bifidobacterium (linear, P = 0.034) and Bacteroidetes (linear, P = 0.029), while decreased Escherichia coli (linear, P = 0.008; quadratic, P = 0.014) in the cecal contents. Thus, dietary RE supplementation can improve growth performance, nutrient digestibility, antioxidant capacity, intestinal morphology, and the microbiota in weaned piglets, and 200 mg/kg may be considered the optimum dosage.

Serum biochemical parameters and amino acids metabolism are altered in piglets by early-weaning and proline and putrescine supplementations.

The study was to investigate the effect of early-weaning stress and proline (Pro) and putrescine (Put) supplementations on serum biochemical parameters and amino acids (AA) metabolism in suckling and post-weaning pigs. Blood and small intestinal mucosa were harvested from suckling piglets at 1, 7, 14, and 21 d of age and piglets on d 1, 3, 5, and 7 after weaning at 14 d of age, as well as from piglets received oral administration of Pro and Put from 1 to 14 d old. In suckling piglets, the serum glucose, albumin and total cholesterol levels were increased (P < 0.05) with increasing age, whereas the serum globulin, urea nitrogen (BUN), alkaline phosphatase (ALP) and aspartate aminotransferase (AST) levels were lowered (P < 0.05). The concentrations of most serum AA and the AA transporters related gene expressions were highest in 7-d-old piglets (P < 0.05), whereas the phosphorylation status of the mammalian target of the rapamycin (mTOR) signaling pathway in the small intestine increased in piglets from 1 to 21 d old (P < 0.05). Weaning at 14 d old increased (P < 0.05) the BUN and triglycerides levels in serum, as well as jejunal solute carrier family 7 member 6 (SLC7A6), ileal SLC36A1 and SLC1A1 mRNA abundances at d 1 or 3 post-weaning. Weaning also inhibited (P < 0.05) the phosphorylation levels of mTOR and its downstream ribosomal protein S6 kinase 1 (S6K1) and 4E-binding protein-1 (4EBP1) in the small intestine of weanling pigs. Oral administration of Put and Pro decreased (P < 0.05) serum ALP levels and increased (P < 0.05) intestinal SLC36A1 and SLC1A1 mRNA abundances and mTOR pathway phosphorylation levels in post-weaning pigs. Pro but not Put treatment enhanced (P < 0.05) serum Pro, arginine (Arg) and glutamine (Gln) concentrations of weaning-pigs. These findings indicated that early-weaning dramatically altered the biochemical blood metabolites, AA profile and intestinal mTOR pathway activity, and Pro and Put supplementations improved the AA metabolism and transportation as well as activated the intestinal mTOR pathway in weanling-pigs. Our study has an important implication for the broad application of Pro and Put in the weaning transition of piglets.

The Amino Acids Sensing and Utilization in Response to Dietary Aromatic Amino Acid Supplementation in LPS-Induced Inflammation Piglet Model.

Dietary supplementation with aromatic amino acids (AAAs) has been demonstrated to alleviate intestinal inflammation induced by lipopolysaccharide (LPS) in the piglets. But the mechanism of AAA sensing and utilization under inflammatory conditions is not well-understood. The study was conducted with 32 weanling piglets using a 2 × 2 factorial arrangement (diet and LPS challenge) in a randomized complete block design. Piglets were fed as basal diet or the basal diet supplemented with 0.16% tryptophan (Trp), 0.41% phenylalanine (Phe), and 0.22% tyrosine (Tyr) for 21 days. The results showed that LPS treatment significantly reduced the concentrations of cholecystokinin (CCK) and total protein but increased leptin concentration, the activities of alanine transaminase, and aspartate aminotransferase in serum. Dietary supplementation with AAAs significantly increased the serum concentrations of CCK, peptide YY (PYY), and total protein but decreased the blood urea nitrogen. LPS challenge reduced the ileal threonine (Thr) digestibility, as well as serum isoleucine (Ile) and Trp concentrations, but increased the serum concentrations of Phe, Thr, histidine (His), alanine (Ala), cysteine (Cys), and serine (Ser) (P < 0.05). The serum-free amino acid concentrations of His, lysine (Lys), arginine (Arg), Trp, Tyr, Cys, and the digestibilities of His, Lys, Arg, and Cys were significantly increased by feeding AAA diets (P < 0.05). Dietary AAA supplementation significantly increased the serum concentrations of Trp in LPS-challenged piglets (P < 0.05). In the jejunal mucosa, LPS increased the contents of Ala and Cys, and the mRNA expressions of solute carrier (SLC) transporters (i.e., SLC7A11, SLC16A10, SLC38A2, and SLC3A2), but decreased Lys and glutamine (Gln) contents, and SLC1A1 mRNA expression (P < 0.05). In the ileal mucosa, LPS challenge induced increasing in SLC7A11 and SLC38A2 and decreasing in SLC38A9 and SLC36A1 mRNA expressions, AAAs supplementation significantly decreased mucosal amino acid (AA) concentrations of methionine (Met), Arg, Ala, and Tyr, etc. (P < 0.05). And the interaction between AAAs supplementation and LPS challenge significantly altered the expressions of SLC36A1 and SLC38A9 mRNA (P < 0.05). Together, these findings indicated that AAAs supplementation promoted the AAs absorption and utilization in the small intestine of piglets and increased the mRNA expressions of SLC transports to meet the high demands for specific AAs in response to inflammation and immune response.

Regulatory role of l-proline in fetal pig growth and intestinal epithelial cell proliferation.

l-proline (Pro) is a precursor of ornithine, which is converted into polyamines via ornithine decarboxylase (ODC). Polyamines plays a key role in the proliferation of intestinal epithelial cells. The study investigated the effect of Pro on polyamine metabolism and cell proliferation on porcine enterocytes in vivo and in vitro. Twenty-four Huanjiang mini-pigs were randomly assigned into 1 of 3 groups and fed a basal diet that contained 0.77% alanine (Ala, iso-nitrogenous control), 1% Pro or 1% Pro + 0.0167% α-difluoromethylornithine (DFMO) from d 15 to 70 of gestation. The fetal body weight and number of fetuses per litter were determined, and the small and large intestines were obtained on d 70 ± 1.78 of gestation. The in vitro study was performed in intestinal porcine epithelial (IPEC-J2) cells cultured in Dulbecco's modified Eagle medium-high glucose (DMEM-H) containing 0 µmol/L Pro, 400 µmol/L Pro, or 400 µmol/L Pro + 10 mmol/L DFMO for 4 d. The results showed that maternal dietary supplementation with 1% Pro increased fetal weight; the protein and DNA concentrations of the fetal small intestine; and mRNA levels for potassium voltage-gated channel, shaker-related subfamily, member 1 (Kv1.1) in the fetal small and large intestines (P < 0.05). Supplementing Pro to either gilts or IPEC-J2 cells increased ODC protein abundances and polyamine concentrations in the fetal intestines and IPEC-J2 cells (P < 0.05). In comparison with the Pro group, the combined administration of Pro and DFMO reduced the expression of ODC protein and spermine concentration in the fetal intestine, as well as the concentrations of putrescine, spermidine and spermine in IPEC-J2 cells (P < 0.05). Meanwhile, the percentage of cells in the S-phase and the mRNA levels of proto-oncogenes c-fos and c-myc were increased in response to Pro supplementation, whereas depletion of cellular polyamines with DFMO increased tumor protein p53 (p53) mRNA levels (P < 0.05). Taken together, dietary supplementation with Pro improved fetal pig growth and intestinal epithelial cell proliferation via enhancing polyamine synthesis.

Dietary Addition of Antioxidant Complex Packs and Functional Amino Acids Can Improve the Digestion, Absorption, and Immunity of Huanjiang Minipigs.

To study the effect of functional amino acids and the antioxidant function compound package on Huanjiang minipigs and to lay a foundation for the formulation of green and efficient feed for Huanjiang minipigs, we added functional amino acids and the antioxidant function compound package to piglet feed for 28 days. After feeding, we detected the growth performance, biochemical indexes, inflammatory indexes, and intestinal disaccharidase of piglets. It was found that functional amino acids and the antioxidant compound package had certain effects on the growth performance and biochemical indexes of piglets and could reduce the level of IL-6 and increase the level of LZM and SIgA of piglets, and the levels of lactase and maltase in the intestine also increased significantly. The results showed that the compound package of functional amino acids and antioxidation could improve the growth performance and immunity of piglets and promote the digestion and absorption of nutrients in piglets.

Effects of dietary gamma-aminobutyric acid supplementation on amino acid profile, intestinal immunity, and microbiota in ETEC-challenged piglets.

Enterotoxigenic Escherichia coli (ETEC) infection is the most common cause of diarrhea in piglets, and ETEC could increase intestinal gamma-aminobutyric acid (GABA)-producing bacteria to affect intestinal immunity. However, the effect of GABA on ETEC-infected piglets is still unclear. This study aims at investigating the impact of dietary GABA supplementation on the growth performance, diarrhea, intestinal morphology, serum amino acid profile, intestinal immunity, and microbiota  in the ETEC-infected piglet model. Eighteen piglets were randomly divided into two groups, in which the piglets were fed with a basal diet with 20 mg kg-1 GABA supplementation or not. The experiment lasted for three weeks, and the piglets were challenged with ETEC K88 on the fifteenth day. The results showed that dietary GABA reduced the feed conversion ratio, promoted the kidney organ index but did not affect the diarrheal score and small intestinal morphology in ETEC-challenged piglets. Ileal mucosal amino acids (such as carnosine and anserine) and serum amino acids (including threonine and GABA) were increased upon GABA supplementation. GABA enhanced ileal gene expression of TNF-α, IFN-γ, pIgR, and MUC2, while inhibited the ileal expression of IL-18 in ETEC-challenged piglets. GABA supplementation also highly regulated the intestinal microbiota by promoting community richness and diversity and reducing the abundance of the dominant microbial population of the ileal microbiota. Collectively, GABA improves growth performance, regulates the serum amino acid profile, intestinal immunity, and gut microbiota in ETEC-challenged piglets. This study is a fine attempt to reveal the function of GABA in ETEC-infected piglets. It would contribute to the understanding of the roles of exogenous nutrition on the host response to ETEC infection.

Baicalin-Copper Complex Modulates Gut Microbiota, Inflammatory Responses, and Hormone Secretion in DON-Challenged Piglets.

The present experiment assessed the inflammatory responses, hormone secretion, and gut microbiota of weanling piglets administered baicalin-copper complex (BCU) or deoxynivalenol (DON) supplementation diets. Twenty-eight piglets were randomly assigned to four groups: control diet (Con group), a 4 mg DON/kg diet (DON group), a 5 g BCU/kg diet (BCU group), a 5 g BCU + 4 mg DON/kg diet (DBCU group). After 14 days, the results showed that dietary BCU supplementation remarkably increased the relative abundance of Clostrium bornimense and decreased the relative abundance of Lactobacillus in the DBCU group (p < 0.05). BCU decreased the serum concentration of IgG, IL-2, IFN-γ, and IgA in DON treated piglets (p < 0.05), and promoted the serum concentration of IL-1ß, IgG, IL-2, IFN-γ, IgA, IL-6, IgM, and TNFα in normal piglets (p < 0.05). BCU increased the concentrations of serum IGF1, insulin, NPY, GLP-1, and GH, and decreased the concentrations of serum somatostatin in no DON treated piglets (p < 0.05). Dietary BCU supplementation significantly promoted the secretion of somatostatin, and inhibited the secretion of leptin in piglets challenged with DON (p < 0.05). BCU regulated the expression of food intake-related genes in the hypothalamus and pituitary of piglets. Collectively, dietary BCU supplementation alleviated inflammatory responses and regulated the secretion of appetite-regulating hormones and growth-axis hormones in DON challenged piglets, which was closely linked to changes of intestinal microbes.

Dietary glutamine, glutamate, and aspartate supplementation improves hepatic lipid metabolism in post-weaning piglets.

A previous study has demonstrated that early weaning significantly suppressed hepatic glucose metabolism in piglets. Glutamate (Glu), aspartate (Asp) and glutamine (Gln) are major metabolic fuels for the small intestine and can alleviate weaning stress, and therefore might improve hepatic energy metabolism. The objective of this study was to investigate the effects of administration of Glu, Asp and Gln on the expression of hepatic genes and proteins involved in lipid metabolism in post-weaning piglets. Thirty-six weaned piglets were assigned to the following treatments: control diet (Control; basal diet + 15.90 g/kg alanine); Asp, Gln and Glu-supplemented diet (Control + AA; basal diet + 1.00 g/kg Asp + 5.00 g/kg Glu + 10.00 g/kg Gln); and the energy-restricted diet supplemented with Asp, Gln and Glu (Energy- + AA; energy deficient diet + 1.00 g/kg Asp + 5.00 g/kg Glu + 10.00 g/kg Gln). Liver samples were obtained on d 5 and 21 post-weaning. Piglets fed Energy- + AA diet had higher liver mRNA abundances of acyl-CoA oxidase 1 (ACOX1), succinate dehydrogenase (SDH), mitochondrial transcription factor A (TFAM) and sirtuin 1 (SIRT1), as well as higher protein expression of serine/threonine protein kinase 11 (LKB1), phosphor-acetyl-CoA carboxylase (P-ACC) and SIRT1 compared with piglets fed control diet (P < 0.05) on d 5 post-weaning. Control + AA diet increased liver malic enzyme 1 (ME1) and SIRT1 mRNA levels, as well as protein expression of LKB1 and P-ACC on d 5 post-weaning (P < 0.05). On d 21 post-weaning, compared to control group, Glu, Gln and Asp supplementation up-regulated the mRNA levels of ACOX1, ME1 and SIRT1 (P < 0.05). These findings indicated that dietary Glu, Gln and Asp supplementation could improve hepatic lipid metabolism to some extent, which may provide nutritional intervention for the insufficient energy intake after weaning in piglets.

Amino acids regulate energy utilization through mammalian target of rapamycin complex 1 and adenosine monophosphate activated protein kinase pathway in porcine enterocytes.

As major fuels for the small intestinal mucosa, dietary amino acids (AA) are catabolized in the mitochondria and serve as sources of energy production. The present study was conducted to investigate AA metabolism that supply cell energy and the underlying signaling pathways in porcine enterocytes. Intestinal porcine epithelial cells (IPEC-J2) were treated with different concentrations of AA, inhibitor, or agonist of mammalian target of rapamycin complex 1 (mTORC1) and adenosine monophosphate activated protein kinase (AMPK), and mitochondrial respiration was monitored. The results showed that AA treatments resulted in enhanced mitochondrial respiration, increased intracellular content of pyruvic acid and lactic acid, and increased hormone-sensitive lipase mRNA expression. Meanwhile, decreased citrate synthase, isocitrate dehydrogenase alpha, and carnitine palmitoyltransferase 1 mRNA expression were also observed. We found that AA treatments increased the protein levels of phosphorylated mammalian target of rapamycin (p-mTOR), phosphorylated-p70 ribosomal protein S6 kinase, and phosphorylated-4E-binding protein 1. What is more, the protein levels of phosphorylated AMPK α (p-AMPKα) and nicotinamide adenine dinucleotide (NAD)-dependent protein deacetylase sirtuin-1 (SIRT1) were decreased by AA treatments in a time depending manner. Mitochondrial bioenergetics and the production of tricarboxylic acid cycle intermediates were decreased upon inhibition of mTORC1 or AMPK. Moreover, AMPK activation could up-regulate the mRNA expressions of inhibitor of nuclear factor kappa-B kinase subunit beta (Ikbkß), integrin-linked protein kinase (ILK), unconventional myosin-Ic (Myo1c), ribosomal protein S6 kinase beta-2 (RPS6Kß2), and vascular endothelial growth factor (VEGF)-ß, which are downstream effectors of mammalian target of rapamycin (mTOR). The mRNA expressions of phosphatidylinositol 4,5-bisphosphate 3-kinase catalytic subunit delta isoform (PIK3CD) and 5'-AMP-activated protein kinase subunit gamma-1 (PRKAG1), which are upstream regulators of mTOR, were also up-regulated by AMPK activation. On the other hand, AMPK activation also down-regulated FK506-binding protein 1A (FKBP1A), serine/threonine-protein phosphatase 2A 55 kDa regulatory subunit B beta isoform, phosphatase and tensin homolog (PTEN), and unc-51 like autophagy activating kinase 1 (Ulk1), which are up-stream regulators of mTORC1. Taken together, these data indicated that AA regulated cellular energy metabolism through mTOR and AMPK pathway in porcine enterocytes. These results demonstrated interactions of AMPK and mTORC1 pathways in AA catabolism and energy metabolism in intestinal mucosa cells of piglets, and also provided reference for using AA to remedy human intestinal diseases.

Effects of dietary amylose/amylopectin ratio and amylase on growth performance, energy and starch digestibility, and digestive enzymes in broilers.

This study was conducted to investigate the effects of dietary amylose/amylopectin (AM/AP) ratio and amylase on growth performance, apparent digestibility of energy and starch, serum biochemical index, and digestive enzymes. The experiment used a 4 × 3 factor design, and 960 one-day-old Arbor Acres (AA) broilers were randomly divided into 12 groups fed diets containing different AM/AP ratio of 0.11, 0.23, 0.35 and 0.47 and combined with 0, 3,000 and 6,000 U/kg amylase. Results showed that 0.23-0.35 AM/AP ratio increased growth performance, while dietary addition of 6,000 U/kg amylase significantly reduced average daily weight gain in broilers. The energy digestibility was significantly reduced along with the increase of dietary AM/AP ratio and in the 6,000 U/Kg amylase-supplemented groups. The digestibility of starch also decreased significantly with the increase of dietary AM/AP ratio, but high dose (6,000 U/Kg) of amylase increased. High AM/AP diet reduced serum insulin concentration, which was increased in amylase-supplemented groups. Furthermore, exogenous amylase increased amylase activity in the jejunal chyme. In conclusion, dietary 0.23-0.35 AM/AP ratio was suggested to maintain a higher growth performance in broilers and high AM/AP ratio diets reduced energy and starch digestibility and serum insulin concentration, which was reversed by dietary amylase.