Arginine and its metabolites stimulate proliferation, differentiation, and physiological function of porcine trophoblast cells through ß-catenin and mTOR pathways.

Arginine, which is metabolized into ornithine, proline, and nitric oxide, plays an important role in embryonic development. The present study was conducted to investigate the molecular mechanism of arginine in proliferation, differentiation, and physiological function of porcine trophoblast cells (pTr2) through metabolic pathways. The results showed that arginine significantly increased cell viability (P < 0.05). The addition of arginine had a quadratic tendency to increase the content of progesterone (P = 0.06) and protein synthesis rate (P = 0.03), in which the maximum protein synthesis rate was observed at 0.4 mM arginine. Arginine quadratically increased (P < 0.05) the intracellular contents of spermine, spermidine and putrescine, as well as linearly increased (P < 0.05) the intracellular content of NO in a dose-dependent manner. Arginine showed a quadratic tendency to increase the content of putrescine (P = 0.07) and a linear tendency to increase NO content (P = 0.09) in cell supernatant. Moreover, increasing arginine activated (P < 0.05) the mRNA expressions for ARG, ODC, iNOS and PCNA. Furthermore, inhibitors of arginine metabolism (L-NMMA and DFMO) both inhibited cell proliferation, while addition of its metabolites (NO and putrescine) promoted the cell proliferation and cell cycle, the mRNA expressions of PCNA, EGF and IGF-1, and increased (P < 0.05) cellular protein synthesis rate, as well as estradiol and hCG secretion (P < 0.05). In conclusion, our results suggested that arginine could promote cell proliferation and physiological function by regulating the metabolic pathway. Further studies showed that arginine and its metabolites modulate cell function mainly through ß-catenin and mTOR pathways.

Fermented Corn-Soybean Meal Improved Growth Performance and Reduced Diarrhea Incidence by Modulating Intestinal Barrier Function and Gut Microbiota in Weaned Piglets.

This study aimed to investigate the effects of fermented corn-soybean meal mixed feed (FMF) on growth performance, intestinal barrier function, gut microbiota and short-chain fatty acids in weaned piglets. A total of 128 weaned piglets [Duroc×(Landrace×Yorkshire), male, 21-day-old] were randomly allocated to four groups. Piglets were fed a control diet (CON) or the control diet supplemented with 10%, 50% or 100% FMF (FMF-10, FMF-50 or FMF-100, respectively) for 14 d. The results showed that the FMF-100 group had higher average daily gain and average daily feed intake and lower diarrhea incidence than the CON group (p < 0.05). The FMF-50 and FMF-100 groups had greater villus height in the duodenum and jejunum, and the FMF-10 and FMF-100 groups had higher villus height-to-crypt depth ratio in the duodenum and jejunum than the CON group. Additionally, the FMF-100 group had higher protein expression of duodenal, jejunal and ileal ZO-1 and jejunal claudin-1; higher mRNA expression of duodenal and ileal TJP1 and jejunal CLDN1 and IL10; and lower jejunal IL1B mRNA expression (p < 0.05). The FMF-50 group showed higher jejunal ZO-1 and claudin-1 protein levels, higher mRNA expression levels of IL10 and TJP1 and lower levels of TNF in the jejunum; the FMF-10 group had higher mRNA expression levels of IL10 and lower levels of TNF in the jejunum than the CON group (p < 0.05). Furthermore, the FMF-10 and FMF-50 groups had higher colonic Lactobacillus abundance and butyrate levels; the FMF-100 group had higher abundance of colonic butyrate, Lactobacillus and Faecalibacterium than the CON group (p < 0.05). Collectively, our results suggest that FMF could improve intestinal mucosal barrier function, gut microbiota and their metabolites, thereby enhancing average daily gain and reducing diarrhea incidence in weaned piglets.

Dietary dibutyryl cAMP supplementation regulates the fat deposition in adipose tissues of finishing pigs via cAMP/PKA pathway.

This study investigated potential mechanism of dibutyryl-cAMP (db-cAMP) on porcine fat deposition. (1) Exp.1, 72 finishing pigs were allotted to 3 treatments (0, 10 or 20 mg/kg dbcAMP) with 6 replicates. dbcAMP increased the hormone sensitive lipase (HSL) activity and expression of ß-adrenergic receptor (ß-AR) and growth hormone receptor (GHR), but decreased expression of peroxisome proliferator-activated receptor gamma 2 (PPAR-γ2) and adipocyte fatty acid binding protein (A-FABP) in back fat. dbcAMP upregulated expression of ß-AR, GHR, PPAR-γ2 and A-FABP, but decreased insulin receptor (INSR) expression in abdominal fat. Dietary dbcAMP increased HSL activity and expression of G protein-coupled receptor (GPCR), cAMP-response element-binding protein (CREB) and insulin-like growth factor-1 (IGF-1), but decreased fatty acid synthase (FAS) and lipoprotein lipase (LPL) activities, and expression of INSR, cAMP-response element-binding protein (C/EBP-α) and A-FABP in perirenal fat. (2) Exp. 2, dbcAMP suppressed the proliferation and differentiation of porcine preadipocytes in a time- and dose-dependent manner, which might be associated with increased activities of cAMP and protein kinase A (PKA), and expression of GPCR, ß-AR, GHR and CREB via inhibiting C/EBP-α and PPAR-γ2 expression. Collectively, dbcAMP treatment may reduce fat deposition by regulating gene expression related to adipocyte differentiation and fat metabolism partially via cAMP-PKA pathway.

Evaluation of dietary metabolizable energy concentrations on meat quality and lipid metabolism-related gene expression in yellow-feathered chickens.

This study evaluated the effects of different dietary metabolizable energy (ME) concentrations on the meat quality, carcass traits, volatile flavour and lipid metabolism-related gene expression levels in yellow-feathered chickens. In total, 600 Huxu female chickens aged 90 days were randomly assigned to six dietary treatments, each with 10 replicates of 10 birds. During the finisher phase, the birds were fed diets containing 2880 (low), 2940, 3000, 3060, 3120 and 3180 (high) kcal ME/kg. The results showed that the average daily gain of chickens increased as the dietary ME concentration increased, while the feed to gain improved (p < 0.05), and the intramuscular fat content of breast muscle increased (p < 0.05). The energy concentration had no effect on the breast muscle pH (45 min and 24 h), colour parameter (L*) or percentage of drip loss (p > 0.05), but the shear force values decreased significantly (p < 0.05). The diameter and area of the breast muscle fiber decreased and the muscle fibre density increased as the dietary ME concentration increased (p < 0.05). The highest ME concentration (3180 kcal) increased the percentages of aldehydes (hexanal, heptanal, 2,4-nonadienal, octanal, nonanal and 2-decenal), alcohols (2-nonen-1-ol, trans-2-undecen-1-ol, 7-hexadecenal, 2-hexyl-1-decanoal and n-nonadecanol-1,3,7,11-trimethyl-1-dodecanol), alkanes (2,6-dimethyl-heptadecane) and carboxylic acids (9-hexadecenoic acid), but reduced the percentages of octadecanal, octadecane, heneicosane and tetradecanal (p < 0.05). In addition, the mRNA gene expression levels of fatty acid-binding protein 3 and apolipoprotein B were significantly upregulated in the liver, whereas that of cholesteryl ester transfer protein was significantly downregulated. In conclusion, increasing the ME diet to 3180 kcal/kg significantly improved the quality and flavour of the meat from yellow-feathered broilers. our finding may help poultry producers to improve the taste of meat by regulating genes related to lipid metabolism, thereby achieving the flavour and taste characteristics preferred by consumers.

Nutritional and Physiological Regulation of Water Transport in the Conceptus.

Water transport during pregnancy is essential for maintaining normal growth and development of conceptuses (embryo/fetus and associated membranes). Aquaporins (AQPs) are a family of small integral plasma membrane proteins that primarily transport water across the plasma membrane. At least 11 isoforms of AQPs (AQPs 1-9, 11, and 12) are differentially expressed in the mammalian placenta (amnion, allantois, and chorion), and organs (kidney, lung, brain, heart, and skin) of embryos/fetuses during prenatal development. Available evidence suggests that the presence of AQPs in the conceptus mediates water movement across the placenta to support the placentation, the homeostasis of amniotic and allantoic fluid volumes, as well as embryonic and fetal survival, growth and development. Abundances of AQPs in the conceptus can be modulated by nutritional status and physiological factors affecting the pregnant female. Here, we summarize the effects of maternal dietary factors (such as intakes of protein, arginine, lipids, all-trans retinoic acid, copper, zinc, and mercury) on the expression of AQPs in the conceptus. We also discuss the physiological changes in hormones (e.g., progesterone and estrogen), oxygen supply, nitric oxide, pH, and osmotic pressure associated with the regulation of fluid exchange between mother and fetus. These findings may help to improve the survival, growth, and development of embryo/fetus in livestock species and other mammals (including humans).

Niacin Improves Intestinal Health through Up-Regulation of AQPs Expression Induced by GPR109A.

(1) Background: Changes in the expression of aquaporins (AQPs) in the intestine are proved to be associated with the attenuation of diarrhea. Diarrhea is a severe problem for postweaning piglets. Therefore, this study aimed to investigate whether niacin could alleviate diarrhea in weaned piglets by regulating AQPs expression and the underlying mechanisms; (2) Methods: 72 weaned piglets (Duroc × (Landrace × Yorkshire), 21 d old, 6.60 ± 0.05 kg) were randomly allotted into 3 groups for a 14-day feeding trial. Each treatment group included 6 replicate pens and each pen included 4 barrows (n = 24/treatment). Piglets were fed a basal diet (CON), a basal diet supplemented with 20.4 mg niacin/kg diet (NA) or the basal diet administered an antagonist for the GPR109A receptor (MPN). Additionally, an established porcine intestinal epithelial cell line (IPEC-J2) was used to investigate the protective effects and underlying mechanism of niacin on AQPs expression after Escherichia coli K88 (ETEC K88) treatment; (3) Results: Piglets fed niacin-supplemented diet had significantly decreased diarrhea rate, and increased mRNA and protein level of ZO-1, AQP 1 and AQP 3 in the colon compared with those administered a fed diet supplemented with an antagonist (p < 0.05). In addition, ETEC K88 treatment significantly reduced the cell viability, cell migration, and mRNA and protein expression of AQP1, AQP3, AQP7, AQP9, AQP11, and GPR109A in IPEC-J2 cells (p < 0.05). However, supplementation with niacin significantly prevented the ETEC K88-induced decline in the cell viability, cell migration, and the expression level of AQPs mRNA and protein in IPEC-J2 cells (p < 0.05). Furthermore, siRNA GPR109A knockdown significantly abrogated the protective effect of niacin on ETEC K88-induced cell damage (p < 0.05); (4) Conclusions: Niacin supplementation increased AQPs and ZO-1 expression to reduce diarrhea and intestinal damage through GPR109A pathway in weaned piglets.

Effects of early sub-therapeutic antibiotic administration on body tissue deposition, gut microbiota and metabolite profiles of weaned piglets.

BACKGROUND: This study aimed to evaluate the effects of sub-therapeutic antibiotic (STA) administration and its subsequent withdrawal on the body tissue deposition, gut microbiota, and metabolite profiles of piglets. The piglets in the experimental group were fed with STA (30 mg kg-1 bacitracin methylene disalicylate, 75 mg kg-1 chlortetracycline, 300 mg kg-1 calcium oxytetracycline) for 14 days and the target bodyweight of the withdrawal period was 25 kg. RESULTS: The experiment was divided into two periods: the administration period and the withdrawal period. The results showed that STA did not improve piglets' growth performance during the two periods. Piglets treated with STA had lower body water deposition during the withdrawal period and tended to increase body lipid deposition during the withdrawal period and the whole period in comparison with the piglets in the control group. It was found that STA markedly altered the colonic microbiota and their metabolites in the piglets. Sub-therapeutic antibiotics were initially effective in decreasing the abundance of pathogenic bacteria during the administration period; however, STA could not continue the effect during the withdrawal period, leading to a rebound of pathogenic bacteria such as Alloprevotella and the increased abundance of other pathogenic bacteria like Oscillibacter. Remarkably, STA treatment decreased Blautia abundance. This bacterium plays a potential protective role against obesity. Metabolomic analysis indicated that STA mainly altered amino acid metabolism, lipid metabolism, and carbohydrate metabolism during the two periods. Spearman's correlation analysis showed that the gut microbiota was highly correlated with microbial metabolite changes. CONCLUSION: These results suggest that early STA administration may alter body tissue deposition later in life by reshaping the gut microbiota and their metabolite profiles. © 2022 Society of Chemical Industry.

Dietary stevia residue extract supplementation improves the performance and antioxidative capacity of growing-finishing pigs.

BACKGROUND: Improper disposal of stevia residue causes environmental pollution and waste of resources. The extract of stevia residue is rich in chlorogenic acid and isochlorogenic acids, and has a great potential in livestock and poultry breeding. Therefore, this study aimed to investigate the effects of dietary stevia residue extract (SRE) supplementation on the performance, meat quality, antioxidative capacity and gut microbiota in growing-finishing pigs. RESULTS: The results showed that increasing the concentration of SRE supplementation linearly increased (P < 0.05) body weight from day 1 to 35. Supplementation with SRE significantly increased (P < 0.05) average daily gain (ADG) from day 1 to 75. 100 mg kg-1 SRE supplementation significantly increased (P < 0.05) hot carcass weight and gastric index. Moreover, increasing the concentration of SRE linearly increased (P < 0.05) the score of appearance of longissimus thoracis, as well as serum albumin, triglyceride and high-density lipoprotein cholesterol content. Further study found that increasing the concentration of SRE linearly increased (P < 0.05) serum total superoxide dismutase activity, and showed a significant quadratic relationship (P < 0.05) with activity of serum catalase, while linearly decreasing (P < 0.05) muscle malondialdehyde (MDA) content. Furthermore, supplementation with 100 mg kg-1 SRE significantly decreased (P < 0.05) serum MDA content, while 600 and 800 mg kg-1 SRE supplementation significantly decreased (P < 0.05) muscle MDA content. However, SRE supplementation had no significant effect on gut microbiota (P > 0.05). CONCLUSION: These data indicated that dietary SRE supplementation improves the performance and antioxidative capacity of growing-finishing pigs. We recommend that the optimal supplemental level of SRE in the diet of growing-finishing pigs is 100 mg kg-1 . © 2022 Society of Chemical Industry.

Effects of phytase and 25-hydroxyvitamin D3 supplementation on growth performance and bone development in weaned piglets in Ca- and P-deficient dietary.

BACKGROUND: The beneficial function of phytase and 25-hydroxyvitamin D3 (HyD) on the feed utilization rate has been widely investigated. However, studies concerning its influence on weaned piglets largely lag behind. The aim of this study was to investigate the effects of phytase and HyD supplementation on the growth performance and bone development in weaned piglets under dietary Ca and P deficiency. RESULTS: The results showed that dietary Ca and P deficiency decreased (P < 0.05) the content of serum P in 6-10 kg piglets, as well as reducing (P < 0.05) the contents of serum Ca and P, average daily gain (ADG), bone mineral density (BMD), breaking force (BF), bone ash and femur Ca in 10-20 kg piglets. Compared with the control group, the feed-to-gain ratio (F/G) of 6-10 kg piglets in the Phy group was decreased (P < 0.05), whereas the ADG, blood Ca and P, BMD, BF, bone ash, P apparent digestibility, Ca and P retention rate of 10-20 kg piglets were increased (P < 0.05). The contents of serum osteocalcin and HyD in 6-10 kg piglets and ADG were higher than in the control group (P < 0.05), as well as the contents of serum Ca and HyD in 10-20 kg piglets in the HyD treatment group. Supplementation with both Phy and HyD decreased the F/D (P < 0.05) and increased the contents of serum Ca, P and HyD in 6-10 kg piglets as well as enhancing the ADG, BMD, BF, bone ash, femur Ca and P, serum Ca and P, HyD, and the apparent digestibility and retention of Ca and P (P < 0.05) in 10-20 kg piglets. Supplementation with Phy and HyD in Ca- and P-deficient dietary decreased bone resorption, and improved tight arrangement of collagen fibers and oblique fibers in weaned piglets. CONCLUSION: These data indicated that supplementation with both 1500 U kg-1 Phy and 50 µg kg-1 HyD could enhance dietary Ca and P utilization and promote bone development in low Ca and P dietary, and supplementation with both Phy and HyD had a significant synergy effect compared to single supplement. © 2021 Society of Chemical Industry.

Meta-analysis of energy intake of growing-finishing pigs in China.

Data from 655 treatments of 116 studies were used in a meta-analysis to determine the daily digestible energy (DE), metabolizable energy (ME) and net energy (NE) intake of Chinese growing-finishing pigs, and to predict feed efficiency responses to change in dietary DE, ME and NE. Three alternative functions (i.e., polynomial, Bridges and asymptotic function) were employed for fitting daily DE, ME or NE intakes to mean body weight. The results showed that the three models from the current study provided reasonable fit (all R2  > 0.83) for the energy intake data. However, under the same energy system, the polynomial function had the smallest Akaike's information criteria (AIC) and residual standard deviation (RSD), followed by Bridges and asymptotic functions. The three model-generated energy intakes of growing pigs were significantly less than that of the Chinese Feeding Standard of Swine, but similar to that of the National Research Council (2012), while the values of finishing pigs were greater than both standards. Compared with those that predict feed efficiency based on DE or ME, the equation with NE as a predictor had the minimized AIC and RSD. It was also found that feed efficiency increased with increasing dietary energy density (DED), but this response varied with pig body weight, and the lighter pigs were more sensitive to DED than heavier pigs.

Supplemental Choline Modulates Growth Performance and Gut Inflammation by Altering the Gut Microbiota and Lipid Metabolism in Weaned Piglets.

BACKGROUND: Whether dietary choline and bile acids affect lipid use via gut microbiota is unclear. OBJECTIVES: This study aimed to investigate the effect of choline and bile acids on growth performance, lipid use, intestinal immunology, gut microbiota, and bacterial metabolites in weaned piglets. METHODS: A total of 128 weaned piglets [Duroc × (Landrace × Yorkshire), 21-d-old, 8.21 ± 0.20 kg body weight (BW)] were randomly allocated to 4 treatments (8 replicate pens per treatment, each pen containing 2 males and 2 females; n = 32 per treatment) for 28 d. Piglets were fed a control diet (CON) or the CON diet supplemented with 597 mg choline/kg (C), 500 mg bile acids/kg (BA) or both (C + BA) in a 2 × 2 factorial design. Growth performance, intestinal function, gut microbiota, and metabolites were determined. RESULTS: Compared with diets without choline, choline supplementation increased BW gain (6.13%), average daily gain (9.45%), gain per feed (8.18%), jejunal lipase activity (60.2%), and duodenal IL10 gene expression (51%), and decreased the mRNA abundance of duodenal TNFA (TNFα) (40.7%) and jejunal toll-like receptor 4 (32.9%) (P < 0.05); additionally, choline increased colonic butyrate (29.1%) and the abundance of Lactobacillus (42.3%), while decreasing the bile acid profile (55.8% to 57.6%) and the abundance of Parabacteroides (75.8%), Bacteroides (80.7%), and unidentified-Ruminococcaceae (32.5%) (P ≤ 0.05). Compared with diets without BA, BA supplementation decreased the mRNA abundance of colonic TNFA (37.4%), NF-κB p65 (42.4%), and myeloid differentiation factor 88 (42.5%) (P ≤ 0.01); BA also increased colonic butyrate (20.9%) and the abundance of Lactobacillus (39.7%) and Faecalibacterium (71.6%) and decreased that of Parabacteroides (67.7%) (P < 0.05). CONCLUSIONS: Choline supplementation improved growth performance and prevented gut inflammation in weaned piglets by altering gut microbiota and lipid metabolism. BA supplementation suppressed intestinal inflammation with no effect on growth performance, which was associated with changed gut microbiota and metabolites.

Dietary L-arginine supplementation during days 14-25 of gestation enhances aquaporin expression in the placentae and endometria of gestating gilts.

This study tested the hypothesis that dietary L-arginine (Arg) supplementation to pregnant gilts enhanced the expression of water channel proteins [aquaporins (AQPs)] in their placentae and endometria. Gilts were fed twice daily 1 kg of a corn and soybean meal-based diet supplemented with 0.0%, 0.4%, or 0.8% Arg between Days 14 and 25 of gestation. On Days 25 and 60 of gestation, gilts were hysterectomized to obtain placentae and endometria. On Day 25 of gestation, supplementation with 0.4% Arg increased (P < 0.05) the abundance of placental AQP9 protein, whereas supplementation with 0.8% Arg increased (P < 0.05) placental AQP1 and AQP9 proteins, compared with controls. On Day 60 of gestation, supplementation with 0.4% Arg increased (P < 0.05) endometrial AQP1 protein, whereas supplementation with 0.8% Arg increased (P < 0.05) endometrial AQP5 and AQP9 proteins. Supplementation with 0.8% Arg increased the endometrial expression of AQP1, AQP5, and AQP9 proteins located in the luminal epithelium and glandular epithelium of endometria, and placental transport of 3H2O. Collectively, these results indicate that dietary Arg supplementation stimulates the expression of selective AQPs in porcine placenta and endometria, thereby enhancing water transport from mother to fetus and expanding the chorioallantoic membranes during the period of placentation.

Effects of dietary supplementation with l-arginine on the intestinal barrier function in finishing pigs with heat stress.

Previous studies showed heat stress reduces body weight gain and feed intake associated with damaged intestinal barrier function, and l-arginine (L-Arg) enhanced intestinal barrier function in young animals under stress. The aim of this study was to evaluate effects of L-Arg on serum hormones, intestinal morphology, nutrients absorption and epithelial barrier functions in finishing pigs with heat stress. Forty-eight finishing pigs (Landrace) were balanced for sex and then randomly assigned to six groups: TN group, thermal neutral (22°C, ~80% humidity) with a basal diet; HS group, heat stress (cyclical 35°C for 12 hr and 22°C for 12 hr, ~80% humidity) with a basal diet; PF group, thermal neutral (22°C, ~80% humidity) and pair-fed with the HS; the TNA, HSA and PFA groups were the basal diet of TN group, HS group and PF group supplemented with 1% L-Arg. Results showed that HS decreased (p < .05) the thyroxine concentrations and increased (p < .05) the insulin concentrations in serum compared with the TN group, but 1% L-Arg had no significant effects on them. Both HS and PF significantly increased (p < .05) the mRNA expression of cationic amino acid transporters (CAT1 and CAT2) and decreased the mRNA expression of solute carrier family 5 member 10 (SGLT1) in the jejunum compared with the TN group. Compared with the TN group, HS reduced the expression of tight junction (TJ) protein zonula occluden-1 (ZO-1) and occludin, but PF only decreased ZO-1 expression in the jejunum. Results exhibited that dietary supplementation with 1% L-Arg improved the intestinal villous height, the ratio of villous height to crypt depth, and the expression of occludin and porcine beta-defensin 2 (pBD2) in the jejunum of intermittent heat-treated finishing pigs. In conclusion, dietary supplementation with 1% L-Arg could partly attenuate the intermittent heat-induced damages of intestinal morphology and epithelial barrier functions in finishing pigs.

Valine increases milk fat synthesis in mammary gland of gilts through stimulating AKT/MTOR/SREBP1 pathway†.

Lactating mammary glands are among the most active lipogenic organs and provide a large percentage of bioactive lipids and calories for infant growth. The branched-chain amino acid (BCAA) valine is known to modulate fatty acids synthesis in adipose tissue; however, its effects on fat metabolism and the underlying mechanisms in mammary glands remain to be determined. Valine supplementation during late pregnancy significantly increased the contents of total milk fat, triglyceride, sphingomyelin, and polyunsaturated fatty acids in the colostrum of gilts. Further study in porcine mammary epithelial cells (PMECs) confirmed that valine upregulated the phosphorylation levels of AKT-activated MTOR and subsequently induced the nuclear accumulation of sterol regulatory element binding protein 1 (SREBP1), thus increasing the expression of proteins related to fatty acids synthesis and intracellular triacylglycerol content. Inhibition of AKT/MTOR signaling or silencing of SREBP1 in PMECs downregulates the expression of proteins related to fatty acids synthesis and intracellular triacylglycerol content. Our findings indicated that valine enhanced milk fat synthesis of colostrum in porcine mammary glands via the AKT/MTOR/SREBP1 signaling pathway.

Valine supplementation during late pregnancy in gilts increases colostral protein synthesis through stimulating mTOR signaling pathway in mammary cells.

Mammary gland development during late pregnancy in sows is a major factor affecting the composition of colostrum and milk and the pre-weaning growth of piglets, while valine is essential for protein and nitrogen metabolism in mammary gland of sow. However, the effects of valine and its underlying mechanism on mammary gland development during late pregnancy are still unclear. Here, we hypothesized that dosage of dietary valine during late pregnancy will affect protein synthesis of colostrum in gilts. The results showed that supplementation of valine during late pregnancy significantly increased content of protein (P < 0.01), fat (P = 0.02) and solids-non-fat (P = 0.04) in colostrum. Our in vitro study also confirmed that valine supplementation increased protein synthesis and cell proliferation in porcine mammary epithelial cells (PMEC). Furthermore, these changes were associated with elevated phosphorylation levels of mammalian target of rapamycin (mTOR), and ribosomal protein S6 kinase (S6) and eukaryotic initiation factor 4E-binding protein-1 (4EBP1) in valine-supplemented cells, which could be effectively blocked by the antagonists of mTOR. These findings indicated that valine enhanced mammary gland development and protein synthesis in colostrum via the mTOR signaling pathway. These results, using an in vivo and in vitro model, helped to understand the beneficial effects of dietary valine supplementation on gilts.

L-Arginine Inhibited Inflammatory Response and Oxidative Stress Induced by Lipopolysaccharide via Arginase-1 Signaling in IPEC-J2 Cells.

This study aimed to explore the effect of L-arginine on lipopolysaccharide (LPS)-induced inflammatory response and oxidative stress in IPEC-2 cells. We found that the expression of toll-like receptor 4 (TLR4), myeloid differentiation primary response 88 (MyD88), cluster of differentiation 14 (CD14), nuclear factor-kappaBp65 (NF-κBp65), chemokine-8 (IL-8), tumor necrosis factor (TNF-α) and chemokine-6 (IL-6) mRNA were significantly increased by LPS. Exposure to LPS induced oxidative stress as reactive oxygen species (ROS) and malonaldehyde (MDA) production were increased while glutathione peroxidase (GSH-Px) were decreased in LPS-treated cells compared to those in the control. LPS administration also effectively induced cell growth inhibition through induction of G0/G1 cell cycle arrest. However, compared with the LPS group, cells co-treatment with L-arginine effectively increased cell viability and promoted the cell cycle into the S phase; L-arginine exhibited an anti-inflammatory effect in alleviating inflammation induced by LPS by reducing the abundance of TLR4, MyD88, CD14, NF-κBp65, and IL-8 transcripts. Cells treated with LPS+L-arginine significantly enhanced the content of GSH-Px, while they decreased the production of ROS and MDA compared with the LPS group. Furthermore, L-arginine increased the activity of arginase-1 (Arg-1), while Arg-1 inhibitor abolished the protection of arginine against LPS-induced inflammation and oxidative stress. Taken together, these results suggested that L-arginine exerted its anti-inflammatory and antioxidant effects to protect IPEC-J2 cells from inflammatory response and oxidative stress challenged by LPS at least partly via the Arg-1 signaling pathway.

Effects of low-molecular-weight chitosan on the growth performance, intestinal morphology, barrier function, cytokine expression and antioxidant system of weaned piglets.

BACKGROUND: Chitosan was used as an alternative to promote the growth of weaned piglets. And low-molecular-weight chitosan (LC) is one of chitosan derivatives and maintain beneficial biological properties of chitoson. The present experiment was carried out to examine the effects of LC on the growth performance, intestinal morphology, barrier function, cytokine expression, and antioxidant system of weaned piglets. RESULTS: A total of 40 piglets weaned at 21 d of age, with average body weight 6.37 ± 0.08 kg, were randomly assigned (5 pens/diet; 4 pigs/pen) to 2 treatments (a basal diet and the basal diet supplemented with 50 mg/kg LC) and were fed for 28 d. Compared with the control group, average daily feed intake (ADFI), and the expression of intestinal barrier protein ZO-1 was increased (P < 0.05) when the piglets fed the diet supplemented with LC. No significant differences were found in average daily gain (ADG, P > 0.05), gain-to-feed ratio (G:F, P > 0.05), the incidence of diarrhea (P > 0.05), or the antioxidant capacity (P > 0.05) between two groups. The expression of IL-1ß and TNF-α in jejunal mucosa were significantly decreased (P < 0.05) in piglets fed the LC-supplemented diet in comparison to the control. CONCLUSION: The results of this study indicate that dietary supplementation with LC at 50 mg/kg was effective for enhancing the growth performance in weaned piglets, improving intestinal barrier function and alleviating intestinal inflammation.

Lactobacillus reuteri LR1 Improved Expression of Genes of Tight Junction Proteins via the MLCK Pathway in IPEC-1 Cells during Infection with Enterotoxigenic Escherichia coli K88.

Intestinal epithelial barrier damage disrupts immune homeostasis and leads to many intestinal disorders. Lactobacillus reuteri strains have probiotic functions in their modulation of the microbiota and immune system in intestines. In this study, the effects of L. reuteri LR1, a new strain isolated from the feces of weaning piglets, on intestinal epithelial barrier damage in IPEC-1 cells caused by challenge with enterotoxigenic Escherichia coli (ETEC) K88 were examined. It was found that L. reuteri LR1, in large part, offset the ETEC K88-induced increase in permeability of IPEC-1 cell monolayers and decreased the adhesion and invasion of the coliform in IPEC-1 cells. In addition, L. reuteri LR1 increased transcript abundance and protein contents of tight junction (TJ) proteins zonula occluden-1 (ZO-1) and occludin in ETEC K88-infected IPEC-1 cells, whereas it had no effects on claudin-1 and F-actin expression. Using colloidal gold immunoelectron microscopy, these effects of L. reuteri LR1 on ZO-1 and occludin content in IPEC-1 cells were confirmed. By using ML-7, a selective inhibitor of myosin light-chain kinase (MLCK), the beneficial effect of L. reuteri LR1 on contents of ZO-1 and occludin was shown to be dependent on the MLCK pathway. In conclusion, L. reuteri LR1 had beneficial effects on epithelial barrier function consistent with increasing ZO-1 and occludin expression via a MLCK-dependent manner in IPEC-1 cells during challenge with ETEC K88.

Lactobacillus plantarum Enhanced IL-22 Production in Natural Killer (NK) Cells That Protect the Integrity of Intestinal Epithelial Cell Barrier Damaged by Enterotoxigenic Escherichia coli.

Interleukin (IL)-22-producing Natural Killer (NK) cells protect the gut epithelial cell barrier from pathogens. A strain of probiotics, Lactobacillus plantarum (L. plantarum, LP), was previously found by our laboratory to significantly improve the mucosal barrier integrity and function of the small intestine in pigs. However, it was unclear whether LP benefited the intestinal mucosal barrier via interactions with the intestinal NK cells. The present study, therefore, was focused on the therapeutic effect of NK cells that were stimulated by LP on attenuating enterotoxigenic Escherichia coli (ETEC)-induced the damage to the integrity of the epithelial cell barrier. The results showed that LP can efficiently increase protein levels of the natural cytotoxicity receptor (NCR) family, and the expression levels of IL-22 mRNA and protein in NK cells. Transfer of NK cells stimulated by LP conferred protection against ETEC K88-induced intestinal epithelial barrier damage in NCM460 cells. We found that NK cells stimulated by LP could partially offset the reduction in NCM460 cell monolayers transepithelial electrical resistance (TEER) caused by ETEC K88, and increase ZO-1 and occludin mRNA and protein expressions by ETEC K88-infected NCM460 cells. Furthermore, adding NK cells that were stimulated by LP to ETEC K88-infected NCM460cells, IL-22R1, p-Stat3, and p-Tyk2 expression by NCM460 cells was increased. Mechanistic experiment showed that NK cells stimulated by LP lost the function of maintaining TEER of NCM460 cells challenged with ETEC K88, when polyclonal anti-IL-22 antibody was used to block IL-22 production. Collectively, our results suggested that LP stimulation of NK could enhance IL-22 production, which might be able to provide defense against ETEC-induced damage to the integrity of intestinal epithelial barrier.

Significance of Increasing n-3 PUFA Content in Pork on Human Health.

Evidence for the health-promoting effects of food rich in n-3 polyunsaturated fatty acids (n-3 PUFA) is reviewed. Pork is an important meat source for humans. According to a report by the US Department of Agriculture ( http://www.ers.usda.gov/topics ), the pork consumption worldwide in 2011 was about 79.3 million tons, much higher than that of beef (48.2 million tons). Pork also contains high levels of unsaturated fatty acids relative to ruminant meats (Enser, M., Hallett, K., Hewett, B., Fursey, G. A. J. and Wood, J. D. (1996) . Fatty acid content and composition of English beef, lamb, and pork at retail. Meat Sci. 44:443-458). The available literature indicates that the levels of eicosatetraenoic and docosahexaenoic in pork may be increased by fish-derived or linseed products, the extent of which being dependent on the nature of the supplementation. Transgenic pigs and plants show promise with high content of n-3 PUFA and low ratio of n-6/n-3 fatty acids in their tissues. The approaches mentioned for decreasing n-6/n-3 ratios have both advantages and disadvantages. Selected articles are critically reviewed and summarized.