Dietary arginine supplementation enhances intestinal expression of SLC7A7 and SLC7A1 and ameliorates growth depression in mycotoxin-challenged pigs

Supplementation of Arginine or N-Carbamylglutamate Affects Jejunum Development, Global Arginine Bioavailability Ratio, and Stress-Related Indices in Young Rex Rabbits

This study aimed to investigate the effects of arginine (Arg) or N-carbamylglutamate (NCG) on jejunum development, the global arginine bioavailability ratio (GABR), and stress-related indices in young rex rabbits. Forty-five litters of newborn rabbits with similar litter weights and sizes were randomly divided into five groups and fed a basal diet (con group), basal diet + 0.3% Arg (0.3% Arg group), basal diet + 0.6% Arg (0.6% Arg group), basal diet + 0.03% NCG (0.03% NCG group), or basal diet + 0.06% NCG (0.06% NCG group). After weaning at 35 days, eight healthy young rabbits with similar body weights were selected from each group and slaughtered on the 36th day. Serum and jejunum samples were collected for index analysis. Arg or NCG significantly affected the jejunum structure development in the young rabbits. The villus height (V) in the treatment groups was significantly higher than that in the con group (p < 0.05) and was highly significantly improved in the 0.6% Arg group (p < 0.01). The crypt depth (C) in 0.6% Arg and 0.06% NCG groups was significantly lower than that in the con, 0.3% Arg, and 0.03% NCG groups (p < 0.05). Compared with the con group, the V/C ratio was significantly increased in the treatment groups (p < 0.05) and was excessively and significantly increased in the 0.6% Arg and 0.06% NCG groups (p < 0.01). Compared with the con group, the Nitric-Oxide (NO) levels and inducible Nitric-Oxide Synthase (iNOS) activity in serum were significantly increased in the treatment groups. The NO levels in the jejunum were also increased in the treatment groups; however, there were no significant differences (p > 0.05). The iNOS activity and mRNA expression in the jejunum of the 0.6% Arg and 0.06% NCG groups were significantly higher than those in the con group (p < 0.05). Compared with the con group, the concentration of serum corticosterone in the 0.3% Arg, 0.6% Arg, and 0.06% NCG groups was significantly reduced. Adding Arg or NCG to the basal diet significantly increased the concentration and gene mRNA expression levels of heat shock protein 70 (HSP70) in the jejunum (p < 0.05). The expression level in the 0.6% Arg and 0.06% NCG groups was significantly higher than that in the con group (p < 0.01). At 36 days, Arg and NCG improved the GABR. In the 0.6% Arg group, the GABR was increased by 16.92%. The GABR was <0.8 at the time of weaning. The Arg levels in the body did not meet the needs of the young animals. In the trial, Arg or NCG supplementation in the diet significantly increased iNOS activity and gene mRNA expression, promoting NO synthesis. Thus, it can improve jejunal morphological and structural development. Adding Arg or NCG increased HSP70 mRNA expression levels, enhanced intestinal stress tolerance, and improved intestinal health. During the lactation period, adding Arg or NCG increased the GABR, but the GABR was <0.8 during weaning.

Promising Phytogenic Feed Additives Used as Anti-Mycotoxin Solutions in Animal Nutrition

Mycotoxins are a major threat to animal and human health, as well as to the global feed supply chain. Among them, aflatoxins, fumonisins, zearalenone, T-2 toxins, deoxynivalenol, and Alternaria toxins are the most common mycotoxins found in animal feed, with genotoxic, cytotoxic, carcinogenic, and mutagenic effects that concern the animal industry. The chronic negative effects of mycotoxins on animal health and production and the negative economic impact on the livestock industry make it crucial to develop and implement solutions to mitigate mycotoxins. In this review, we summarize the current knowledge of the mycotoxicosis effect in livestock animals as a result of their contaminated diet. In addition, we discuss the potential of five promising phytogenics (curcumin, silymarin, grape pomace, olive pomace, and orange peel extracts) with demonstrated positive effects on animal performance and health, to present them as potential anti-mycotoxin solutions. We describe the composition and the main promising characteristics of these bioactive compounds that can exert beneficial effects on animal health and performance, and how these phytogenic feed additives can help to alleviate mycotoxins' deleterious effects.

Low crude protein formulation with supplemental amino acids for its impacts on intestinal health and growth performance of growing-finishing pigs

BACKGROUND

Low crude protein (CP) formulations with supplemental amino acids (AA) are used to enhance intestinal health, reduce costs, minimize environmental impact, and maintain growth performance of pigs. However, extensive reduction of dietary CP can compromise growth performance due to limited synthesis of non-essential AA and limited availability of bioactive compounds from protein supplements even when AA requirements are met. Moreover, implementing a low CP formulation can increase the net energy (NE) content in feeds causing excessive fat deposition. Additional supplementation of functional AA, coupled with low CP formulation could further enhance intestinal health and glucose metabolism, improving nitrogen utilization, and growth performance. Three experiments were conducted to evaluate the effects of low CP formulations with supplemental AA on the intestinal health and growth performance of growing-finishing pigs.

METHODS

In Exp. 1, 90 pigs (19.7 ± 1.1 kg, 45 barrows and 45 gilts) were assigned to 3 treatments: CON (18.0% CP, supplementing Lys, Met, and Thr), LCP (16.0% CP, supplementing Lys, Met, Thr, Trp, and Val), and LCPT (16.1% CP, LCP + 0.05% SID Trp). In Exp. 2, 72 pigs (34.2 ± 4.2 kg BW) were assigned to 3 treatments: CON (17.7% CP, meeting the requirements of Lys, Met, Thr, and Trp); LCP (15.0% CP, meeting Lys, Thr, Trp, Met, Val, Ile, and Phe); and VLCP (12.8% CP, meeting Lys, Thr, Trp, Met, Val, Ile, Phe, His, and Leu). In Exp. 3, 72 pigs (54.1 ± 5.9 kg BW) were assigned to 3 treatments and fed experimental diets for 3 phases (grower 2, finishing 1, and finishing 2). Treatments were CON (18.0%, 13.8%, 12.7% CP for 3 phases; meeting Lys, Met, Thr, and Trp); LCP (13.5%, 11.4%, 10.4% CP for 3 phases; meeting Lys, Thr, Trp, Met, Val, Ile, and Phe); and LCPG (14.1%, 12.8%, 11.1% CP for 3 phases; LCP + Glu to match SID Glu with CON). All diets had 2.6 Mcal/kg NE.

RESULTS

In Exp. 1, overall, the growth performance did not differ among treatments. The LCPT increased (P < 0.05) Claudin-1 expression in the duodenum and jejunum. The LCP and LCPT increased (P < 0.05) CAT-1, 4F2hc, and B0AT expressions in the jejunum. In Exp. 2, overall, the VLCP reduced (P < 0.05) G:F and BUN. The LCP and VLCP increased (P < 0.05) the backfat thickness (BFT). In Exp. 3, overall, growth performance and BFT did not differ among treatments. The LCPG reduced (P < 0.05) BUN, whereas increased the insulin in plasma. The LCP and LCPG reduced (P < 0.05) the abundance of Streptococcaceae, whereas the LCP reduced (P < 0.05) Erysipelotrichaceae, and the alpha diversity.

CONCLUSIONS

When implementing low CP formulation, CP can be reduced by supplementation of Lys, Thr, Met, Trp, Val, and Ile without affecting the growth performance of growing-finishing pigs when NE is adjusted to avoid increased fat deposition. Supplementation of Trp above the requirement or supplementation of Glu in low CP formulation seems to benefit intestinal health as well as improved nitrogen utilization and glucose metabolism.

Dietary taurine effect on intestinal barrier function, colonic microbiota and metabolites in weanling piglets induced by LPS

Diarrhea in piglets is one of the most important diseases and a significant cause of death in piglets. Preliminary studies have confirmed that taurine reduces the rate and index of diarrhea in piglets induced by LPS. However, there is still a lack of relevant information on the specific target and mechanism of action of taurine. Therefore, we investigated the effects of taurine on the growth and barrier functions of the intestine, microbiota composition, and metabolite composition of piglets induced by LPS. Eighteen male weaned piglets were randomly divided into the CON group (basal diet + standard saline injection), LPS group (basal diet + LPS-intraperitoneal injection), and TAU + LPS group (basal diet + 0.3% taurine + LPS-intraperitoneal injection). The results show that taurine significantly increased the ADG and decreased the F/G (p < 0.05) compared with the group of CON. The group of TAU + LPS significantly improved colonic villous damage (p < 0.05). The expression of ZO-1, Occludin and Claudin-1 genes and proteins were markedly up-regulated (p < 0.05). Based on 16s rRNA sequencing analysis, the relative abundance of Lactobacilluscae and Firmicutes in the colon was significantly higher in the LPS + TAU group compared to the LPS group (p < 0.05). Four metabolites were significantly higher and one metabolite was significantly lower in the TAU + LPS group compared to the LPS group (p < 0.01). The above results show that LPS disrupts intestinal microorganisms and metabolites in weaned piglets and affects intestinal barrier function. Preventive addition of taurine enhances beneficial microbiota, modulates intestinal metabolites, and strengthens the intestinal mechanical barrier. Therefore, taurine can be used as a feed additive to prevent intestinal damage by regulating intestinal microorganisms and metabolites.

Review: Methods and biomarkers to investigate intestinal function and health in pigs

Society is becoming increasingly critical of animal husbandry due to its environmental impact and issues involving animal health and welfare including scientific experiments conducted on farm animals. This opens up two new fields of scientific research, the development of non- or minimally invasive (1) methods and techniques using faeces, urine, breath or saliva sampling to replace existing invasive models, and (2) biomarkers reflecting a disease or malfunction of an organ that may predict the future outcome of a pig's health, performance or sustainability. To date, there is a paucity of non- or minimally invasive methods and biomarkers investigating gastrointestinal function and health in pigs. This review describes recent literature pertaining to parameters that assess gastrointestinal functionality and health, tools currently used to investigate them, and the development or the potential to develop new non- and minimally invasive methods and/or biomarkers in pigs. Methods described within this review are those that characterise gastrointestinal mass such as the citrulline generation test, intestinal protein synthesis rate, first pass splanchnic nutrient uptake and techniques describing intestinal proliferation, barrier function and transit rate, and microbial composition and metabolism. An important consideration is gut health, and several molecules with the potential to act as biomarkers of compromised gut health in pigs are reported. Many of these methods to investigate gut functionality and health are considered 'gold standards' but are invasive. Thus, in pigs, there is a need to develop and validate non-invasive methods and biomarkers that meet the principles of the 3 R guidelines, which aim to reduce and refine animal experimentation and replace animals where possible.

Apparent jejunal amino acid digestibility, gut morphology, and the expression of intestinal amino acid transporters in pigs fed protein or free amino acids

Dietary amino acids (AA) supplied as protein or in free form are not only digested and absorbed at different rates but can also induce differences in the intestinal physiology of pigs. We compared the apparent jejunal AA digestibility, intestinal morphology, and gene expression of AA transporters of pigs fed diets providing different forms of AA. Thirty growing pigs (33.7 ± 4.1 kg) were fed one of three experimental diets that provided AA either as protein from feather meal (INT), as free AA and small peptides obtained by extensive acid hydrolysis of feathers (HYD), or as a mix of individual purified AA with the same AA profile as HYD (FAA). Pigs were fed the same quantity of feed, energy, and AA. After 14 d, pigs were slaughtered 3 h after feeding a meal with indigestible markers. Digesta and tissue were collected from different sections of the small intestine. Jejunal digesta was used to measure apparent jejunal digestibility of AA. Samples of the duodenum, jejunum, and ileum were used to measure intestinal morphology and the gene expression of intestinal AA transporters. The measured apparent jejunal digestibility of AA of INT was lower compared to HYD and FAA (P < 0.05). The apparent jejunal digestibility of Cys, Gly, His, Met, and Pro was lower for FAA compared to HYD (P < 0.05). This may be due to the small peptides in HYD, which are absorbed faster than individual AA. The villi area in the ileum of HYD fed pigs was the highest (P < 0.05) among the treatments, which may be associated with the reabsorption of endogenous proteins, which occurs mostly in the ileum. In the duodenum, HYD and FAA had lower expression of PepT1 (P < 0.01) probably due to the rapid transit time of digesta compared to INT fed pigs. Pigs fed HYD expressed more ASCT2 (P = 0.02) and CAT-1 (P = 0.04) in the jejunum compared to the pigs fed the other diets. The expression of these transporters along the intestine depended on the relative abundance of readily absorbable dietary AA. Results showed that dietary AA form can have an influence on the morphology and on the expression of different AA transporters along the different sections of the small intestine.

Effects of melatonin on intestinal function and bacterial compositions in sucking piglets

Melatonin has been reported to affect intestinal function by targeting microbiome, morphological structure, barrier integrity and nutrient absorptive system. While the effect of melatonin on intestinal development in newborn infants is obscure, thus, this study firstly attempted to investigate the hypothesis that melatonin treatment improves intestinal development in sucking piglets. 14 healthy newborn piglets received 10 ml melatonin solution (1 mg/ml) or drinking water (n = 7) for 21 days. The results showed that oral administration of melatonin increased liver relative weight (p < 0.05) but failed to affect growth performance in sucking piglets (p > 0.05). Immunostaining jejunal samples from melatonin group showed high expressions of nnos and claudin1, indicating that melatonin improved intestinal neural development and barrier integrity. Also, melatonin promoted intestinal absorptive function evidenced by the increased serum proline concentration in melatonin-treated piglets compared with the control (p < 0.05). Gut microbiota compositions were tested by 16S rDNA sequencing and the results showed that melatonin increased the relative abundance of Actinobacteria compared with the control (p < 0.05) at the phylum level. However, Selenomonadales was markedly reduced compared with the control at the order level (p < 0.05). Gut and faecal volatile fatty acids were tested to evaluate the microbiota metabolism, but no difference was noticed in volatile fatty acid concentrations (p > 0.05). Melatonin improved intestinal development by affecting neural development, barrier integrity, nutrient absorption and microbiota in sucking piglets.

Dietary N-carbamylglutamate and L-arginine supplementation improves redox status and suppresses apoptosis in the colon of intrauterine growth-retarded suckling lambs

Previous studies have revealed that dietary N-carbamylglutamate (NCG) or L-arginine (Arg) improves small intestinal integrity and immune function in suckling Hu lambs that have experienced intrauterine growth retardation (IUGR). Whether these nutrients alter redox status and apoptosis in the colon of IUGR lambs is still unknown. This study, therefore, aimed at investigating whether dietary supplementation of Arg or NCG alters colonic redox status, apoptosis and endoplasmic reticulum (ER) stress and the underlying mechanism of these alterations in IUGR suckling Hu lambs. Forty-eight 7-d old Hu lambs, including 12 with normal birth weight (4.25 ± 0.14 kg) and 36 with IUGR (3.01 ± 0.12 kg), were assigned to 4 treatment groups (n = 12 each; 6 males and 6 females) for 3 weeks. The treatment groups were control (CON), IUGR, IUGR + Arg and IUGR + NCG. Relative to IUGR lambs, superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) content, as well as proliferation index, were higher (P < 0.05) whereas reactive oxygen species (ROS), malondialdehyde (MDA) levels and apoptotic cell numbers were lower (P < 0.05) in colonic tissue for both IUGR + Arg and NCG lambs. Both mRNA and protein levels of C/EBP homologous protein 10 (CHOP10), B-cell lymphoma/leukaemia 2 (Bcl-2) -associated X protein (Bax), apoptosis antigen 1 (Fas), activating transcription factor 6 (ATF6), caspase 3, and glucose-regulated protein 78 (GRP78) were lower (P < 0.05) while glutathione peroxidase 1 (GPx1), Bcl-2 and catalase (CAT) levels were higher (P < 0.05) in colonic tissue for IUGR + Arg and IUGR + NCG lambs compared with IUGR lambs. Based on our results, dietary NCG or Arg supplementation can improve colonic redox status and suppress apoptosis via death receptor-dependent, mitochondrial and ER stress pathways in IUGR suckling lambs.

Effects of dietary arginine in ameliorating the deleterious effects induced by mycotoxins on growth, immune system, body organs in growing pigs

Mycotoxin contamination in pig feeds has a negative impact on growth performance, the immune system, and major body organs. Arginine (Arg) plays an important role in animals’ body biochemistry and physiology. This study aimed to determine the effect of dietary Arg supplementation on mitigating the negative effects of mycotoxins in growing pigs. A total of 72 growing pigs (Landrace × Large white) with initial mean body weight (BW) = 55 ± 2.5 kg were allotted to four treatment groups with three replicates per group of six pigs per replicate in a completely randomized design. The treatments included a non-toxin diet with 1.2% Arg (NT1.2) and mycotoxin-challenged treatments supplemented with 1.2% Arg (TX1.2), 1.3% Arg (TX1.3), and 1.4% Arg (TX1.4). Statistical analysis of data included the effects of dietary level of Arg. The results indicated a significantly higher BW (p < 0.05), average daily gain (p < 0.05), and gain-to-feed ratio (p < 0.05) in the NT1.2 group than in the TX1.2, TX1.3, and TX1.4 groups. The relative weight of the liver was higher (p < 0.05) in the TX1.2 compared to that of the NT1.2 group, although it was not different from that of TX1.3 and TX1.4. The level of tumor necrosis factor-alpha was significantly up-regulated (p < 0.05) in the liver tissue of the TX1.2 group compared to that of the other treatments. Overall, dietary Arg supplementation remedied liver injury and alleviated the compromised immune system caused by mycotoxin toxicity.

The optimal dietary arginine level of laying hens fed with low-protein diets

Background

Arginine (Arg) is an essential amino acid (EAA) in poultry, an important substrate for protein synthesis and a precursor of several molecules. Supplementation of EAAs with low protein (LP) diet increases the utilization efficiency of dietary crude protein (CP). However, if the EAA requirement is changed in hens fed a LP diet remains to be elucidated. The aim of the present study was to evaluate the optimal level of dietary Arg in the LP diet of hens. A total of 1350 Hy-Line Brown laying hens were randomly allocated to six dietary treatments: a basal diet (16% CP, positive control), or an isoenergetic LP diet (14% CP, 0.80% Arg) supplemented 0, 0.05%, 0.10%, 0.15%, and 0.20% L-Arg, corresponding to 0.80%, 0.85%, 0.90%, 0.95% and 1.00% dietary Arg, respectively.

Results

The feed efficiency was decreased (P < 0.05) by 0.80% and 1.00% Arg-LP diets, compared to control. Within LP diets, dietary Arg level had significant quadratic effects (P < 0.05) on laying rate, egg mass, and feed efficiency. Compared to control, the plasma CAT activity or T-AOC content were decreased by 0.80% (P < 0.001). However, the hens offered 0.85% and 0.90% Arg-LP diets had higher CAT activity (P < 0.001) than 0.80% Arg-LP diet. In contrast, 1.00% Arg-LP group had the highest MDA and the lowest T-AOC content in plasma, liver, duodenal and jejunal mucosa (P < 0.05). Compared to control, the villus height was decreased by 0.80%, 0.95% and 1.00% Arg-LP diets, while the villus height to crypt depth (V/C) ratio was reduced by 0.95% and 1.00% Arg-LP diets in duodenum.

Conclusion

The result demonstrates that LP diet (14% CP) deficient in Arg (0.80% Arg) result in augmented oxidative damage and impaired development of intestinal mucosa. According to the quadratic broken-line regression model, the optimal dietary arginine levels for Hy-Line Brown laying hens fed with low protein diet (14% CP) aged 33 to 40 weeks are 0.85%, 0.86%, and 0.86% to obtained the maximum laying rate, egg mass, and feed efficiency, respectively.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40104-022-00719-x.

Integrated Metabolomics and Transcriptomics Analyses Reveal Metabolic Mechanisms in Porcine Intestinal Epithelial Cells under Zearalenone Stress

Zearalenone (ZEA) is a mycotoxin that frequently occurs in agricultural crops and related products and seriously threatens both animal feed and human food safety. To identify key metabolites and regulators involved in ZEA toxicological processes, we performed metabolomic and transcriptomic analyses of porcine IPEC-J2 intestinal epithelial cells upon ZEA exposure using liquid chromatography-mass spectrometry (LC-MS)/MS and RNA-seq techniques. A total of 325 differential metabolites and 5646 differentially expressed genes were detected. Integrated analyses of metabolomic and transcriptomic data indicated that metabolic processes including lipid metabolism, amino acid metabolism, and carbohydrate metabolism were most affected. Exogenous addition of the key metabolite l-arginine significantly facilitated ZEA metabolism and ameliorated ZEA-induced reactive oxygen species levels and cell apoptosis. Furthermore, l -arginine contributed to the expression of phase II detoxification genes (SULT2B1, GSTA1, GSTM3, and GPX4). l-Arginine addition also increased the protein levels of LC3-II and Beclin 1, and downregulated p62/SQSTM1 levels, indicating its regulatory roles in autophagic flux activation upon ZEA exposure. This study provided global insights into metabolic and transcriptional changes as well as key metabolites and regulators underlying the cellular response to ZEA exposure, and paved the way for the identification of metabolic and molecular targets for biomonitoring and controlling contamination by ZEA.

Dietary N-carbamylglutamate or L-arginine improves fetal intestinal amino acid profiles during intrauterine growth restriction in undernourished ewes

Our previous studies demonstrated that prenatal in utero growth restriction impairs postnatal intestinal function. Thus, improving postpartal intestinal absorption capacity and growth by manipulating the maternal diet prepartum is of importance. This work was conducted to determine whether supplementation of N-carbamylglutamate (NCG) or rumen-protected L-arginine (RP-Arg) increased fetal intestinal amino acid (AA) profiles in intrauterine growth retardation (IUGR) fetuses. On d 35 of gestation, Hu ewes (n = 32) carrying twin fetuses were randomized into 4 groups (8 ewes and 16 fetuses in each group), where diets were as follows: 100% of nutrient requirements recommended by National Research Council (NRC, 2007) (CON); 50% of nutrient requirements recommended by NRC (2007) (RES); RES + RP-Arg (20 g/d), (RES + ARG); and RES + NCG (5 g/d), (RES + NCG). On d 110 of gestation, both fetal and maternal tissues were collected and weighed. Compared with RES, solute carrier family 1, member 5 (SLC1A5) was upregulated (P < 0.05) within fetal jejunum, duodenum and ileum when supplementing NCG and RP-Arg. Relative to RES, RP-Arg or NCG supplementation to RES resulted in upregulation (P < 0.05) of peptide transporter 1 protein abundance within the fetal ileum. NCG or RP-Arg supplementation to RES also upregulated phosphorylated mechanistic target of rapamycin (pmTOR)-to-mTOR ratio in the fetal ileum induced by IUGR (P < 0.05). As a result, during IUGR, supplementation of Arg or NCG affected intestinal AA profiles in the fetus in part through controlling mTOR signal transduction as well as AA and peptide transport. Future studies should be conducted to understand the role (if any) of the placenta on the improvement of growth and AA profiles independent of the fetal intestine. This would help demonstrate the relative contribution of intestinal uptake in fetal life.

Effects of chlortetracycline on growth performance and intestinal functions in weaned piglets

AIM

Weaning stress can cause serious damage to piglet's health. Chlortetracycline (CTC) is widely used to ameliorate weaning stress and prevent infectious diseases in weaned piglets. However, antibiotics as growth promoters have to be limited because of increased antimicrobial resistance. In this study, we evaluated the effects of CTC on growth performance and intestinal functions in order to provide evidence for seeking antibiotic substitutes in weaned piglets.

METHODS AND RESULTS

A total of 20 weaned piglets were fed a basal diet or a diet supplemented with 75 mg/kg CTC. CTC decreased the crypt depth and increased the ratio of villus height to crypt depth, whilst failing to affect growth performance and serum biochemical parameters and cytokines. 16S rRNA sequencing suggested that CTC supplementation had no effect on the diversity and composition of colonic microbiota.

CONCLUSION

We speculated that gut microbiota is no longer sensitive to a low concentration of CTC due to the long-term use and low bioavailability of CTC in weaned piglets.

Effects of supplemental d-methionine in comparison to l-methionine on nitrogen retention, gut morphology, antioxidant status, and mRNA abundance of amino acid transporters in weanling pigs

An N-balance experiment was conducted to test the hypothesis that d-Methionine (d-Met) has the same bioavailability and efficacy as l-Methionine (l-Met) when fed to weanling pigs. A Met-deficient basal diet containing 0.24% standardized ileal digestible (SID) Met was formulated. Six additional diets were formulated by adding 0.036%, 0.072%, or 0.108% d-Met or l-Met to the basal diet, and these diets, therefore, contained 77%, 87%, or 97% of the requirement for SID Met. Fifty-six barrows (10.53 ± 1.17 kg) were housed in metabolism crates and allotted to the seven diets with eight replicate pigs per diet. Feces and urine were collected quantitatively with 7-d adaptation and 5-d collection periods. Blood and tissue samples from pigs fed the basal diet and pigs fed diets containing 0.108% supplemental Met were collected on the last day. Results indicated that N retention (%) linearly increased (P < 0.01) as supplemental d-Met or l-Met increased in diets. Based on N retention (%) as a response, the linear slope-ratio regression estimated the bioavailability of d-Met relative to l-Met to be 101% (95% confidence interval: 57%-146%). The villus height and crypt depth in the jejunum were not affected by the Met level or Met source. Total antioxidant capacity or thiobarbituric acid reactive substance concentrations in plasma or tissue samples from pigs fed the control diet or diets containing 0.108% supplemental d-Met or l-Met were not different. Abundance of mRNA for some AA transporters analyzed in intestinal mucosa of pigs also did not differ. Therefore, it is concluded that d-Met and l-Met are equally bioavailable for weanling pigs.

Dietary N-carbamylglutamate or l-arginine supplementation improves hepatic energy status and mitochondrial function and inhibits the AMP-activated protein kinase-peroxisome proliferator-activated receptor γ coactivator-1α-transcription factor A pathway in intrauterine-growth-retarded suckling lambs

The objective of this study was to investigate the effects of dietary administration of l-arginine (Arg) or N-carbamylglutamate (NCG) on hepatic energy status and mitochondrial functions in suckling Hu lambs with intrauterine growth retardation (IUGR). Forty-eight newborn Hu lambs of 7 d old were allocated into 4 treatment groups of 12 lambs each, in triplicate with 4 lambs per replicate (2 males and 2 females) as follows: CON (lambs of normal birth weight, 4.25 ± 0.14 kg), IUGR (3.01 ± 0.12 kg), IUGR + 1% Arg (2.99 ± 0.13 kg), or IUGR + 0.1% NCG (3.03 ± 0.11 kg). The experiment lasted for 21 d, until d 28 after birth, and all lambs were fed milk replacer as a basal diet. Compared with IUGR lambs, NCG or Arg administration increased (P < 0.05) the adenosine triphosphate (ATP) level and the activities of complexes I/III/IV, isocitrate dehydrogenase and citrate synthase in the liver. Compared with CON lambs, the relative mRNA levels of adenosine monophosphate-activated protein kinase α1 (AMPKα1), peroxisome proliferator-activated receptor γ coactivator-1α (PGC1α) and transcription factor A (TFAM) were increased (P < 0.05) in the liver of IUGR lambs, but were decreased (P < 0.05) in the liver of NCG- or Arg-treated lambs compared with those in the IUGR lambs. Compared with IUGR lambs, NCG or Arg administration decreased (P < 0.05) the total AMPKα (tAMPKα)-to-phosphorylated AMPKα (pAMPKα) ratio and the protein expression of PGC1α and TFAM. The results suggested that dietary Arg or NCG supplements improved hepatic energy status and mitochondrial function and inhibited the AMPK-PGC1α-TFAM pathway in IUGR suckling lambs.

Maternal yeast-based nucleotide supplementation decreased stillbirth by regulating nutrient metabolism

BACKGROUND

As an enzymatic product of yeast, yeast-based nucleotide (YN) is rich in nucleotides. To test the effects of maternal dietary supplementation with YN during late pregnancy on placental nutrient transport and nutrient metabolism in neonatal piglets, 64 pregnant sows (day 85 ± 3) were assigned into two groups: (i) control (CON) and (ii) treatment (YN; 4 g kg^-1 ). Blood, placenta and liver samples of neonates during delivery were collected.

RESULTS

The results showed that maternal YN supplementation decreased stillbirth rate and intra-uterine growth restriction rate (P < 0.05). In addition, maternal YN supplementation increased total serum protein, albumin and total cholesterol (P < 0.05). Furthermore, in neonatal piglets in the YN group, both serum amino acidand nucleotide profiles were affected, as well as liver amino acid, and fatty acid profiles were regulated (P < 0.05). Moreover, maternal YN supplementation increased liver mRNA expression of SLC28A3, SLC29A1, SLC29A2, PC, PCK1, FBP1, SREBP1c, HSL and CYP7a1 of neonatal piglets (P < 0.05). Meanwhile, there was a decrease in placental gene expression of EAAT2, EAAT3, LAT1 and PAT1, as well as lower protein expression of peroxisome proliferator-activated receptor (PPAR)γ, AKT, phosphorylated-AKT, phosphorylated-mammalian target of rapamycin (mTOR) and Raptor, in the YN group (P < 0.05).

CONCLUSION

Taken together, these results indicate that maternal YN supplementation regulates placental nutrient transport by regulating the mTOR complex 1-PPAR pathway, and affects the liver metabolism of nucleotides, amino acids and fatty acids in neonatal piglets, thereby improving the reproductive performance of sow to a certain extent. © 2020 Society of Chemical Industry.

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.

Research Progress on Oxidative Stress and Its Nutritional Regulation Strategies in Pigs

Oxidative stress refers to the dramatic increase in the production of free radicals in human and animal bodies or the decrease in the ability to scavenging free radicals, thus breaking the antioxidation-oxidation balance. Various factors can induce oxidative stress in pig production. Oxidative stress has an important effect on pig performance and healthy growth, and has become one of the important factors restricting pig production. Based on the overview of the generation of oxidative stress, its effects on pigs, and signal transduction pathways, this paper discussed the nutritional measures to alleviate oxidative stress in pigs, in order to provide ideas for the nutritional research of anti-oxidative stress in pigs.

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.

Yeast-based nucleotide supplementation in mother sows modifies the intestinal barrier function and immune response of neonatal pigs

In the present study, we aimed to evaluate the effects of maternal yeast-based nucleotide (YN) supplementation on the intestinal immune response and barrier function in neonatal pigs, as well as the diarrhoea rate and growth performance in suckling piglets. Sixty-four late-gestation sows were assigned to the following groups: the CON (fed a basal diet) and YN groups (fed a basal diet with 4 g YN/kg diet). The experiment started on d 85 of gestation and ended on d 20 of lactation. Diarrhoea rate and average daily gain of the piglets were recorded, and samples of blood and intestines from neonatal piglets were collected before they consumed colostrum during farrowing. Compared with the CON group, maternal YN supplementation increased the weaning weight of litter and decreased the diarrhoea rate (P < 0.01). In addition, maternal YN supplementation promoted the ileal villus development in the neonates compared with that in the CON group (P < 0.01). Maternal YN supplementation also increased the ileal secretory immunoglobulin A (sIgA) level compared with that in the CON group (P < 0.05). The real-time PCR results showed that maternal dietary YN supplementation increased the jejunal and ileal expression of interleukin (IL)-17, IL-8, IL-1β, IL-10 and tumor necrosis factor (TNF)- α in the neonates compared with that in the CON group (P < 0.05). Overall, maternal nucleotide supplementation improved the villus development and innate immunity of neonatal piglets during late pregnancy. This may be associated with the decrease in diarrhoea and the increase in weaning weight of the litter of suckling piglets.

Effect of a Phytogenic Water Additive on Growth Performance, Blood Metabolites and Gene Expression of Amino Acid Transporters in Nursery Pigs Fed with Low-Protein/High-Carbohydrate Diets

Simple Summary

Low-protein (LP) diets can be potentially used to reduce the excretion of nitrogenous compounds and feed cost in commercial swine production; however, new strategies are required to be developed to improve the growth performance of pigs receiving these diets. Little is known about the effect of phytogenic additives on the performance of pigs fed with LP diets and the underlying factors involved. The objective of this study was to assess the effect of a phytogenic water additive (PWA) on growth performance, nutrient digestibility, blood metabolites, plasma amino acid (AA) concentration, and gut and skeletal muscle AA transporters in nursery pigs fed with LP diets. Supplemental PWA increased the concentration of circulating essential AA, reduced the transcript of some of the AA transporters in the small intestine and skeletal muscle, improved growth performance when the dietary protein was adequate, and increased muscle lean%, but reduced muscle fat% when the dietary protein was deficient. The used PWA in this study had differential effects on blood calcium and its digestibility depending on the level of dietary protein. This study suggests that PWA can be used for improving the meat composition in protein-restricted pigs, but PWA improves growth performance only when dietary protein is adequate.

Abstract

The objective of this study was to investigate the effect of a phytogenic water additive (PWA) on growth performance and underlying factors involved in pigs fed with low-protein (LP)/high-carbohydrate diets. Forty-eight weaned barrows were allotted to six treatments for 4 weeks: CON-NS, control (CON) diet-no PWA; CON-LS, CON diet-low dose PWA (4 mL/L); CON-HS, CON diet-high dose PWA (8 mL/L); LP-NS, LP diet-no PWA; LP-LS, LP diet-low dose PWA; LP-HS, LP diet-high dose PWA. Relative to CON-NS, pigs fed with CON-HS had increased average daily gain, body weight and serum calcium (Ca) and phosphorous (P) and had decreased mRNA abundance of solute carrier family 7 member 11 and solute carrier family 6 member 19 in jejunum. Compared to LP-NS, pigs fed with LP-HS had increased muscle lean%, decreased muscle fat%, decreased serum Ca and increased serum P. Compared to their NS counterparts, CON-LS, CON-HS, and LP-LS increased the concentration of plasma essential AA and those fed with CON-HS and LP-HS tended to reduce the abundance of the solute carrier family 7 member 1 transcript in skeletal muscle. Thus, PWA improved the performance of weaned pigs fed with protein-adequate diets likely through increased blood essential AA and affected the muscle composition when dietary protein was deficient.

Effects of Chronic Exposure to Low Levels of Dietary Aflatoxin B1 on Growth Performance, Apparent Total Tract Digestibility and Intestinal Health in Pigs

This study aimed to investigate the effects of chronic exposure to low levels of dietary aflatoxin B1 (AFB1) on growth performance, apparent total tract digestibility and intestinal health in pigs. In a 102-day experiment, fourteen barrows (Duroc×Landrace×Yorkshire, initial BW = 38.21 ± 0.45 kg) were randomly divided into control (CON, basal diet) and AFB1 groups (the basal diet supplemented with 280 μg/kg AFB1). Results revealed that the AFB1 exposure decreased the final BW, ADFI and ADG in pigs (p < 0.10). AFB1 exposure also decreased the apparent total tract digestibility of dry mater and gross energy at 50 to 75 kg and 105 to 135 kg stages, and decreased the apparent total tract digestibility of ether extract at 75 to 105 kg stage (p < 0.05). Meanwhile, AFB1 exposure increased serum diamine oxidase activity and reduced the mRNA abundance of sodium-glucose cotransporter 1, solute carrier family 7 member 1 and zonula occluden-1 in the jejunal mucosa (p < 0.05). Furthermore, AFB1 exposure decreased superoxide dismutase activity (p < 0.05) and increased 8-hydroxy-2'-deoxyguanosine content (p < 0.10) in jejunal mucosa. AFB1 exposure also increased tumor necrosis factor-α, interleukin-1β and transforming growth factor-β mRNA abundance in jejunal mucosa and upregulated Escherichia coli population in colon (p < 0.05). The data indicated that chronic exposure to low levels of dietary AFB1 suppressed growth performance, reduced the apparent total tract digestibility and damaged intestinal barrier integrity in pigs, which could be associated with the decreased intestinal antioxidant capacity and the increased pro-inflammatory cytokine production.

Effect of fumonisin B1 on oxidative stress and gene expression alteration of nutrient transporters in porcine intestinal cells

Fumonisin B₁ (FB₁ ) is a common environmental mycotoxin produced by molds such as Fusarium verticillioides. The toxin poses health risks to domestic animals, including pigs, through FB₁ -contaminanted feed. However, the cytotoxicity of FB₁ to porcine intestines has not been fully analyzed. In the present study, the effects of FB₁ on oxidative stress and nutrient transporter-associated genes of the porcine intestinal IPEC-J2 cells were explored. FB₁ decreased IPEC-J2 proliferation but did not trigger reactive oxygen species (ROS) overproduction. Meanwhile, FB₁ reduced the expression levels of the transporters l-type amino acid transporter-1 (y⁺ LAT1), solute carrier family 7 member 1 (SLC7A1), solute carrier family 1 member 5 (ASCT2), and excitatory amino acid carrier 1 (EAAC1); in addition, FB₁ reduced the levels of the fatty acid transporters long-chain fatty acid transport protein 1 (FATP1) and long-chain fatty acid transport protein 4 (FATP4) as well as glucose transporters Na⁺ /glucose cotransporter 1 (SGLT1) and glucose transporter 2 (GLUT2). FB₁ stimulation increased the expression levels of peptide transporter peptide transporter 1 (PepT1) and metal ion transport-related gene zinc transporter 1 (ZNT1). Moreover, metal ion transporter divalent metal transporter 1 (DMT1) expression was depressed by a higher dosage of FB₁ . The data indicate that FB₁ results in aberrant expression of nutrient transporters in IPEC-J2 cells, thereby exerting its toxicity even though it fails to exert ROS-dependent oxidative stress.

Effects of Dietary Histidine on Growth Performance, Serum Amino Acids, and Intestinal Morphology and Microbiota Communities in Low Protein Diet-Fed Piglets

Previous study showed that low protein diet-fed pigs are characterized by lower histidine concentration in the serum and muscle, suggesting that histidine may involve in protein-restricted response. Thus, the current study mainly investigated the effects of dietary histidine on growth performance, blood biochemical parameters and amino acids, intestinal morphology, and microbiota communities in low protein diet-challenged-piglets. The results showed that protein restriction inhibited growth performance, blood biochemical parameters and amino acids, and gut microbiota but had little effect on intestinal morphology. Dietary supplementation with histidine markedly enhanced serum histidine level and restored tryptophan concentration in low protein diet-fed piglets, while growth performance and intestinal morphology were not markedly altered in histidine-treated piglets. In addition, histidine exposure failed to affect bacterial diversity (observed species, Shannon, Simpson, Chao1, ACE, and phylogenetic diversity), but histidine-treated piglets exhibited higher abundances of Butyrivibrio and Bacteroides compared with the control and protein-restricted piglets. In conclusion, dietary histidine in low protein diet enhanced histidine concentration and affected gut microbiota (Butyrivibrio and Bacteroides) but failed to improve growth performance and intestinal morphology.

Branched-chain amino acids, especially of leucine and valine, mediate the protein restricted response in a piglet model

Branched-chain amino acids (BCAAs) are reduced in various protein restricted models, while the detailed role of BCAAs in protein restricted response is still obscure. Thus, the current study mainly investigated the amino acid metabolism in protein restricted piglets and the effects of BCAA balance in a low-protein diet on growth performance, amino acid metabolism, intestinal structure, and gut microbiota with focus on which BCAAs contributed to the protein restricted response. The results showed that protein restriction increased serum Ser, Thr, Ala, Lys, and Trp but reduced His, Cys, Val, and Ile levels. Intestinal amino acid transporters mainly mediated the mechanism of amino acid uptake. The BCAA balance refreshed the serum BCAA pool, which further improved growth performance in protein restricted piglets. Leu, Val, and Ile balances increased serum BCAA concentrations, respectively, and Leu and Val but not Ile enhanced the feed intake and weight gain in protein restricted piglets. In addition, protein restriction impaired the villus structure and increased the number of goblet cells in the ileum. Also, gut microbiota (Spirochaetales, Gammaproteobacteria, Lactobacillales at the order level) were altered in protein restricted pigs, while the BCAA balance markedly improved Gammaproteobacteria, Lactobacillales, and Aeromonadales proliferation, which might mediate growth promotion and amino acid metabolism. In conclusion, protein restriction markedly affected the host amino acid metabolism (i.e., Ser, Thr, Lys, His, BCAAs). The BCAA balance (especially for supplementation with Leu and Val) improved the amino acid metabolism, growth performance, and gut microbiota communities.

Transcriptomic reprogramming of the oceanic diatom Skeletonema dohrnii under warming ocean and acidification

Under ocean warming and acidification, diatoms use a unique acclimation and adaptation strategy by saving energy and utilizing it for other cellular processes. However, the molecular mechanisms that underlie this reprogramming of energy utilization are currently unknown. Here, we investigate the metabolic reprogramming of the ecologically important diatom Skeletonema dohrnii grown under two different temperature (21°C and 25°C) and pCO₂ (400 and 1000 ppm) levels, utilizing global transcriptomic analysis. We find that evolutionary changes in the baseline gene expression, which we termed transcriptional up- and downregulation, is the primary mechanism used by diatoms to acclimate to the combined conditions of ocean warming and acidification. This transcriptional regulation shows that under higher temperature and pCO₂ conditions, photosynthesis, electron transport and carboxylation were modified with increasing abundances of genes encoding ATP, NADPH and carbon gaining for the carbon-dioxide-concentrating mechanisms (CCMs). Our results also indicate that changes in the transcriptional regulation of CCMs led to a decrease in the metabolic cost to save energy by promoting amino acid synthesis and nitrogen assimilation for the active protein processing machinery to adapt to warming and ocean acidification. This study generated unique metabolic insights into diatoms and suggests that future climate change conditions will cause evolutionary changes in oceanic diatoms that will facilitate their acclimation strategy.

Use of encapsulated L-lysine-HCl and DL-methionine improves postprandial amino acid balance in laying hens

The supplementation of dietary limiting amino acids (AA) with crystalline AA makes the use of low-protein diets an option in poultry production. The differing absorption rates of crystalline and protein-bound AA may lead to temporally imbalanced AA in the postabsorptive period. In this study, two experiments were conducted to evaluate the effect of encapsulated L-lysine-HCl (L-Lys-HCl) and DL-methionine (DL-Met) on the laying performance of hens. In exp. 1, a total of 135 forty-seven-wk-old Hy-Line Brown hens were subjected to three dietary treatments for 8 wk: basal diet supplemented with 0.14% L-Lys-HCl and 0.17% DL-Met to satisfy the NRC (1994) total Lys and Met recommendation (control) and basal diet supplemented with encapsulated L-Lys-HCl and DL-Met at the levels of 60% (60CLM, 0.084% L-Lys-HCl and 0.102% DL-Met) or 80% of control (80CLM, 0.112% L-Lys-HCl and 0.136% DL-Met), respectively. In exp. 2, 24 fifty-five-wk-old Hy-Line Brown hens were individually reared in cages and subjected to the same treatments as in exp. 1. The plasma concentrations of free AA and nitrogen metabolites were measured 2, 4, and 6 h after fed. The results showed that dietary AA treatment had no significant influence on body weight (BW), feed intake, laying rate, egg weight, egg mass, or feed efficiency. The expression levels of AA transporters CAT-1, y+LAT1, b0,+AT, B0AT, rBAT, EAAT3, and PepT1 in the duodenum, jejunum, and ileum were not influenced (P > 0.05) by dietary treatment. There was an interaction of dietary AA treatment and time (P < 0.05) and the 80CLM hens exhibited higher concentrations of Lys (P < 0.05) than the controls at 2-h time point. In contrast, plasma Met concentration was not influenced (P > 0.05), while Cys was reduced in the 60CLM hens at every time point. The 80CLM hens had higher taurine concentrations than those receiving the control diet at every postprandial time point. In conclusion, these findings demonstrate that by using encapsulated form, the supplemental levels of synthetic L-Lys-HCl and DL-Met can be effectively reduced by approximately 20% with no negative effect on laying performance. The result suggests that encapsulated Lys and Met may ameliorate the postabsorptive AA balance and contribute to the reduced dietary AA supplemental levels.

Dietary supplementation with Bacillus subtilis DSM 32315 alters the intestinal microbiota and metabolites in weaned piglets

AIM

The study was conducted to investigate the effects of dietary Bacillus subtilis (BS) DSM 32315 on the intestinal microbiota composition and metabolites of weaned pigs.

METHODS AND RESULTS

Sixty-four piglets were allocated to two groups (control and BS), each group including eight replicates with four piglets. Dietary BS DSM 32315 increased (P < 0·05) the abundances of jejunal Leucobacter and Cupriavidus, ileal Thermus, Coprococcus and Bifidobacterium, as well as colonic Succiniclasticum; and increased the concentrations of ileal straight-chain fatty acids, colonic propionate, branched-chain fatty acids (BCFAs), and tyramine, but decreased (P < .05) the colonic indole concentration. The ileal and colonic microbial community structure tended to cluster into two groups. LEfSe analysis identified five microbial biomarkers in jejunum and eight biomarkers in ileum in the BS group, and three biomarkers in colon in the control group. The ileal Bifidobacterium abundance was positively correlated (P < 0·05) with isovalerate concentration, while the colonic Actinobacteria and Lactobacillus abundances were negatively correlated (P < 0·05) with indole concentration.

CONCLUSION

These findings suggest that dietary supplementation with BS DSM 32315 could alter the diversity, composition, and metabolites of intestinal microbiota in weaned piglets.

SIGNIFICANCE AND IMPACT OF THE STUDY

Weaned piglets are often accompanied with impaired gastrointestinal tract and intestinal disorder affecting their growth. This study demonstrated that dietary BS DSM 32315 presented a beneficial role in gut health via regulating intestinal microbiota composition and metabolites.

Administration of Exogenous Melatonin Improves the Diurnal Rhythms of the Gut Microbiota in Mice Fed a High-Fat Diet

The gut microbiota is strongly shaped by a high-fat diet, and obese humans and animals are characterized by low gut microbial diversity and impaired gut microbiota compositions. Comprehensive data on mammalian gut metagenomes shows gut microbiota exhibit circadian rhythms, which is disturbed by a high-fat diet. On the other hand, melatonin is a natural and ubiquitous molecule showing multiple mechanisms of regulating the circadian clock and lipid metabolism, while the role of melatonin in the regulation of the diurnal patterns of gut microbial structure and function in obese animals is not yet known. This study delineates an intricate picture of melatonin-gut microbiota circadian rhythms and may provide insight for obesity intervention.

Melatonin, a circadian hormone, has been reported to improve host lipid metabolism by reprogramming the gut microbiota, which also exhibits rhythmicity in a light/dark cycle. However, the effect of the administration of exogenous melatonin on the diurnal variation in the gut microbiota in mice fed a high-fat diet (HFD) is unclear. Here, we further confirmed the antiobesogenic effect of melatonin on mice fed an HFD for 2 weeks. Samples were collected every 4 h within a 24-h period, and diurnal rhythms of clock gene expression (Clock, Cry1, Cry2, Per1, and Per2) and serum lipid indexes varied with diurnal time. Notably, Clock and triglycerides (TG) showed a marked rhythm in the control in melatonin-treated mice but not in the HFD-fed mice. The rhythmicity of these parameters was similar between the control and melatonin-treated HFD-fed mice compared with that in the HFD group, indicating an improvement caused by melatonin in the diurnal clock of host metabolism in HFD-fed mice. Moreover, 16S rRNA gene sequencing showed that most microbes exhibited daily rhythmicity, and the trends were different for different groups and at different time points. We also identified several specific microbes that correlated with the circadian clock genes and serum lipid indexes, which might indicate the potential mechanism of action of melatonin in HFD-fed mice. In addition, effects of melatonin exposure during daytime or nighttime were compared, but a nonsignificant difference was noticed in response to HFD-induced lipid dysmetabolism. Interestingly, the responses of microbiota-transplanted mice to HFD feeding also varied at different transplantation times (8:00 and 16:00) and with different microbiota donors. In summary, the daily oscillations in the expression of circadian clock genes, serum lipid indexes, and the gut microbiota appeared to be driven by short-term feeding of an HFD, while administration of exogenous melatonin improved the composition and diurnal rhythmicity of some specific gut microbiota in HFD-fed mice.

IMPORTANCE The gut microbiota is strongly shaped by a high-fat diet, and obese humans and animals are characterized by low gut microbial diversity and impaired gut microbiota compositions. Comprehensive data on mammalian gut metagenomes shows gut microbiota exhibit circadian rhythms, which is disturbed by a high-fat diet. On the other hand, melatonin is a natural and ubiquitous molecule showing multiple mechanisms of regulating the circadian clock and lipid metabolism, while the role of melatonin in the regulation of the diurnal patterns of gut microbial structure and function in obese animals is not yet known. This study delineates an intricate picture of melatonin-gut microbiota circadian rhythms and may provide insight for obesity intervention.

Dietary supplementation of l-arginine and N-carbamylglutamate enhances duodenal barrier and mitochondrial functions and suppresses duodenal inflammation and mitophagy in suckling lambs suffering from intrauterine-growth-restriction

The current work aimed at investigating the effects of the dietary supplementation of N-carbamylglutamate (NCG) or l-arginine (Arg) on the duodenal mitophagy, mitochondrial function, inflammation, and barrier function in suckling lambs suffering from intrauterine-growth-retardation (IUGR). Forty-eight neonate Hu lambs were used in this study: 12 lambs with normal birth weight (NBW: 4.25 ± 0.14 kg) and 36 lambs with IUGR (3.01 ± 0.13 kg). Seven day old lambs were assigned to 4 treatment groups (12 lambs in each group) as follows: control group (CON), IUGR group, IUGR + Arg, and IUGR + NCG. Lambs were fed the experimental diets for 21 days from 7 days to 28 days of age. Compared with IUGR lambs, the Arg or NCG-treated IUGR lambs had a markedly higher duodenal transepithelial electrical resistance (TER) and lower fluorescein isothiocyanate dextran (FD4) (P < 0.05), respectively. The duodenal mitochondrial membrane potential change (ΔΨ_m), relative mitochondrial DNA (mtDNA) content, adenosine triphosphate (ATP) level, together with the activities of the respiratory complexes I, III, and IV were markedly higher in Arg or NCG-treated IUGR lambs than those in non-supplemented IUGR lambs (P < 0.05). The expressions of the integrity-related proteins (occludin and zonula occludens-1 (ZO-1)), antioxidant- and apoptosis-related proteins (B-cell lymphoma/leukaemia 2 (Bcl2), superoxide dismutase 2 (SOD2), catalase (CAT), and glutathione peroxidase 1 (GPx1)), and the nitric oxide-dependent pathway-related proteins (epithelial NO synthase (eNOS) and inducible NO synthase (iNOS)) were higher in NCG or Arg-supplemented IUGR lambs than those in nontreated IUGR lambs (P < 0.05). The duodenal expressions of the mitophagy-related proteins (microtubule-associated protein light chain 3 (LC3) I, LC3 II, Belin1, PTEN induced putative kinase 1 (PINK1), and Parkin) and the immune function-related proteins (myeloid differentiation factor 88 (MyD88), IL-6, nuclear factor kappa B (p65), toll-like receptor (TLR4) and TNF-α) were reduced (P < 0.05) in NCG or Arg-supplemented IUGR lambs compared with non-supplemented IUGR lambs. These results demonstrated that the dietary supplementation of Arg or NCG enhanced the duodenal barrier function and mitochondrial function, mitigated duodenal inflammation, and suppressed mitophagy in suckling lambs suffering from IUGR.

The Role of Arginine in Disease Prevention, Gut Microbiota Modulation, Growth Performance and the Immune System of Broiler Chicken – A Review

The effect of dietary arginine on disease prevention, immune system modulation, the gut micro-biota composition and growth of broiler chicken was reviewed. The main aim of poultry production is the maximization of profit at the least possible cost. This objective can mainly be achieved by ensuring that there is no interference in growth or disease outbreak and by feeding chicken with the best possible level of nutrients. With the ban on antibiotic growth promoters, attention is shifted towards other nutrition methods to prevent diseases and promote growth. More attention is therefore given to protein diets in animal nutrition due to their importance as essential part of active biological compounds in the body, assisting in the breakdown of body tissue and helping in the physiological processes of the animal. Arginine plays important function in serving as building blocks of proteins and polypeptides. It performs other roles during the regulation of important biochemical functions such as maintenance, growth, reproduction and immunity. Arginine cannot be synthesized by the body so it has to be supplemented in the diet. When arginine is supplemented above the recommended level, the gut mucosa is protected, immunosuppression is alleviated, diseases like necrotic enteritis, infectious bursal disease and coccidiosis in broiler chickens are prevented. There is an improvement in growth resulting from the increase in intestinal absorption, barrier function and microbiota composition.

Digestive abilities, amino acid transporter expression, and metabolism in the intestines of piglets fed with spermine

This study evaluated the effects of spermine supplementation on the digestion, transport, and metabolism of nutrients in the jejuna of piglets. Of the 80 piglets examined, 40 received 0.4 mmol/kg body weight spermine, and the other half were randomly distributed such that the restricted nutrient intake supplemented with the saline solution for 7 hr and 3, 6, or 9 days in pairs. Spermine supplementation increased the lipase and trypsin activities (p < .05), and spermine increased the mRNA levels of maltase, sucrase, and aminopeptidase N (APN) but decreased the lactase gene expression (p < .05). Moreover, spermine increased the mRNA expression levels of amino acid transporters (p < .05). Spermine increased the jejunum glycerolphosphocholine, lipid, and taurine levels and decreased the choline and amino acids levels (p < .05). In summary, spermine can promote the digestion, transport, and metabolism of nutrients in piglets. PRACTICAL APPLICATIONS: Meat, fish, dairy products, and fruits contain polyamines (i.e., spermine, spermidine, and putrescine). Spermine plays an important role in the cell proliferation, growth, and differentiation, and spermine supplementation can improve the growth of broilers, growth performance of early weaning piglets, and intestinal maturation. The results of this study suggest that spermine can improve the digestion, transport, and metabolism of nutrients in piglets.

N-carbamylglutamate and l-arginine promote intestinal function in suckling lambs with intrauterine growth restriction by regulating antioxidant capacity via a nitric oxide-dependent pathway

Data indicate that intrauterine growth restriction (IUGR) in newborns can be partly alleviated through the supply of l-arginine (Arg) and N-carbamylglutamate (NCG). The current work aimed to explore whether Arg and NCG promote intestinal function by regulating antioxidant capacity in suckling lambs with IUGR via a nitric oxide (NO)-dependent pathway. Forty eight newly born Hu lambs with normal weights at birth (CON) or suffering from IUGR were randomly divided into 4 groups (n = 12 per group), namely, the CON, IUGR, IUGR + 1% Arg, and IUGR + 0.1% NCG groups. The animals were used for experiments from the age of day 7 to 28. Compared with the lambs in the IUGR group, the lambs in the Arg or NCG group had higher (P < 0.05) final body weights. The plasma insulin, NO, and NO synthase (NOS) concentrations in the IUGR group were higher (P < 0.05) compared with those in IUGR + 1% Arg or IUGR + 0.1% NCG. The jejunal level of the tumor necrosis factor α (TNF-α) in the IUGR lambs was greater (P < 0.05) compared with that in IUGR + 1% Arg or IUGR + 0.1% NCG. The plasma and jejunal total antioxidant capacity (T-AOC) values for the IUGR + 1% Arg or IUGR + 0.1% NCG group were greater (P < 0.05) compared with those for the IUGR group. Compared with the IUGR + 1% Arg or IUGR + 0.1% NCG lambs, the IUGR lambs had lower (P < 0.05) abundance of mRNA and protein abundance of glutathione peroxidase 1 (GPx1), catalase (CAT), superoxide dismutase 2 (SOD2), nuclear factor erythroid 2-related factor 2 (Nrf2), quinone oxidoreductase 1 (NQO1), heme oxygenase (HO-1), zonula occludens-1 (ZO-1), occludin, inducible NOS (iNOS), and epithelial NOS (eNOS). Overall, the data suggest that the Arg or NCG supplementation to suckling lambs with IUGR enhances the intestinal function by regulating the oxidant status via the NO-dependent pathway.

Dietary xylo-oligosaccharide improves intestinal functions in weaned piglets

This study aimed at investigating the effects of dietary xylo-oligosaccharide (XOS) on intestinal functions (i.e., intestinal morphology, tight junctions, gut microbiota and metabolism) and growth performance in weaned piglets. 19 weaned piglets were randomly divided into two groups (n = 9/10): a control group (basic diet) and a XOS treated group in which piglets were fed 0.01% XOS for 28 days. Growth performance, blood cells and biochemical parameters, serum cytokines, intestinal morphology, tight junctions, gut microbiota, and the metabolic profiles of the gut digesta were analyzed. The results showed that dietary supplementation with XOS had little effects on growth performance, blood cells and biochemical parameters, and intestinal morphology. However, the inflammatory status and intestinal barrier were improved in XOS-fed piglets evidenced by the reduction of IFN-γ and upregulation of ZO-1. Microbiota analysis showed that XOS enhanced α-diversity and affected the relative abundances of Lactobacillus, Streptococcus, and Turicibacter at the genus level. The alterations in the microbiota might be further involved in carbohydrate metabolism, cell motility, cellular processes and signaling, lipid metabolism, and metabolism of other amino acids by functional prediction. A metabolomics study identified three differentiated metabolites, including coenzyme Q6, zizyphine A, and pentadecanal, which might be produced by the microbiota and further affect host metabolism. In conclusion, dietary XOS improved the inflammatory status, gut barrier, and microbiota communities, which might be used as a potential feed additive to prevent gut dysfunction caused by weaning in the pig industry.

Influence of supplemented coated-cysteamine on morphology, apoptosis and oxidative stress status of gastrointestinal tract

BACKGROUND

Cysteamine was coated to cover its odor and maintain the stability. However, coated cysteamine (CC) has not been clearly evaluated for its effects on the gastrointestinal mucosa status. We hypothesize that the appropriate CC supplementation in diet impacts the stomach and intestinal mucosa variously through regulating the morphology, apoptosis, and oxidative stress status in model of pigs.

RESULTS

The results showed that villus height increased (P < 0.05), and crypt depth decreased (P < 0.05) in the ileum when pigs were fed the diet with low cysteamine (LCS) compared with the control diet. The ileal lesion score in the LCS group was significantly (P < 0.01) lower than that in the control group, while the gastric lesion score in the CC group was significantly (P < 0.01) higher compared with that of the control group. It also showed that the activities of total superoxide dismutase (T-SOD) and diamine oxidase (DAO) were upregulated (P < 0.05) in the LCS group. In addition, Bax and caspase 3 immunore-activity increased (P < 0.01), and Bcl-2 immunoreactivity decreased (P < 0.01) in the gastric mucosa of pigs fed the diet with high cysteamine (HCS). The Bax and caspase 3 immunoreactivity decreased (P < 0.01), and Bcl-2 immunoreactivity increased (P < 0.01) in ileum mucosa of pigs fed the HCS diet.

CONCLUSIONS

Although moderate dietary coated cysteamine showed positive effects on GI mucosal morphology, apoptosis, and oxidative stress status, the excess coated cysteamine may cause apoptosis leading to GI damage in pigs.

Zearalenone induced oxidative stress in the jejunum in postweaning gilts through modulation of the Keap1-Nrf2 signaling pathway and relevant genes1

Researches have shown that dietary zearalenone (ZEA) caused oxidative stress in the liver and reproductive organs of postweaning gilts. However, information on the effects of ZEA on oxidative stress of the small intestine in the piglets is limited. The objective of this study was to determine the effects of ZEA exposure on oxidative stress, the Kelch-like erythroid cell-derived protein with CNC homology (ECH)-associated protein 1 (Keap1)-nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway and on immunohistochemistry of the jejunum in postweaning gilts. A 35-d feeding experiment using 40 postweaning gilts (Landrace × Yorkshire × Duroc) with an average BW of 14.01 ± 0.86 kg in 4 groups fed corn-soybean meal-based diets containing 0, 0.5, 1.0, and 1.5 mg ZEA/kg was conducted. The jejunum was obtained at the end of the experiment and used for analyses. The results showed that the activities of total superoxide dismutase and glutathione peroxidase and the relative expressions of Keap1 mRNA and protein in the jejunum linearly and quadratically decreased (P < 0.05) with increasing concentrations of ZEA in the diets. The malondialdehyde content, the integrated optical density of Nrf2 and glutathione peroxidase 1 (GPX1), and the relative expressions of Nrf2, GPX1, quinone oxidoreductase 1 (NQO1), and modifier subunit of glutamate-cysteine ligase (GCLM) mRNA and proteins linearly and quadratically increased (P < 0.05) with increasing levels of ZEA. Immunohistochemical analysis showed that Nrf2 and GPX1 immunoreactivity was enhanced by the ZEA treatments, and block localization of yellow and brown immunoreactive substances in the jejunum was observed with increasing levels of ZEA. The results suggest that ingested ZEA induced oxidative stress in the jejunum in postweaning gilts through upregulation of the Keap1-Nrf2 signaling pathway and downstream target genes NQO1, HO1, and GCLM, indicating the important role of the Keap1-Nrf2 signaling pathway in oxidative stress induced by ZEA in the jejunum of the postweaning piglets.

N-Carbamylglutamate and l-Arginine Promote Intestinal Absorption of Amino Acids by Regulating the mTOR Signaling Pathway and Amino Acid and Peptide Transporters in Suckling Lambs with Intrauterine Growth Restriction

BACKGROUND

Previous studies have revealed that dietary N-carbamylglutamate (NCG) and l-arginine (Arg) improve intestinal integrity, oxidative state, and immune function in Hu suckling lambs with intrauterine growth restriction (IUGR). Whether these treatments alter intestinal nutrient absorption is unknown.

OBJECTIVE

The aim of this study was to determine the influence of dietary NCG and Arg treatment during the suckling period on intestinal amino acid (AA) absorption, alterations in the mechanistic target of rapamycin (mTOR) signaling pathway, and the abundance of AA and peptide transporters in IUGR lambs.

METHODS

On day 7 after birth, 48 newborn Hu lambs were selected from a cohort of 424 twin lambs. Normal-birth-weight and IUGR Hu lambs were allocated randomly (n = 12/group) to a control (4.09 ± 0.12 kg), IUGR (3.52 ± 0.09 kg), IUGR + 0.1% NCG (3.49 ± 0.11 kg), or IUGR + 1% Arg (3.53 ± 0.10 kg).

RESULTS

At day 28, compared with the IUGR group, the IUGR groups receiving NCG and Arg had 7.4% and 7.2% greater (P < 0.05) body weight, respectively. Compared with the IUGR group, the serum concentration of insulin was greater (P < 0.05) and the cortisol was lower (P < 0.05) in the IUGR groups receiving NCG and Arg. Compared with the IUGR group, the IUGR groups receiving NCG and Arg had 13.2%-62.6% greater (P < 0.05) serum concentrations of arginine, cysteine, isoleucine, and proline. Dietary NCG or Arg to IUGR lambs resulted in greater protein abundance (P < 0.05) of peptide transporter 1 (41.9% or 38.2%) in the ileum compared with the unsupplemented IUGR lambs, respectively. Furthermore, dietary NCG or Arg treatment normalized the IUGR-induced variation (P < 0.05) in the ileal ratio of phosphorylated mTOR to total mTOR protein.

CONCLUSION

Both NCG and Arg can help mitigate the negative effect of IUGR on nutrient absorption in neonatal lambs.

Macleaya cordata extract alleviated oxidative stress and altered innate immune response in mice challenged with enterotoxigenic Escherichia coli

This study examines the effects of dietary Macleaya cordata extract (MCE) on bacterial burden and resistance to enterotoxigenic Escherichia coli (ETEC) in ICR mice. ICR mice were randomly distributed into one of the following groups: (i) basal diet; (ii) basal diet with 200 mg kg^-1 MCE; (iii) basal diet challenged with ETEC; and (iv) basal diet with 200 mg kg^-1 MCE and challenged with ETEC. Following a 7-day period of pre-treatment, CTRL-ETEC and MCE-ETEC mice were subjected to oral infection using 5×10⁸E. coli SEC 470. The results showed dietary 200 mg kg^-1 MCE markedly reduced intestinal ETEC burden (P < 0.05) and the disease-associated mortality was significantly alleviated in the MCE treated group (P < 0.05). In addition, dietary MCE markedly alleviated ETEC-induced oxidative stress, evidenced by the lowered methane dicarboxylic aldehyde (MDA) abundance and enhanced activities of catalase and glutathione peroxidase (P < 0.05). Furthermore, MCE mice exhibited higher immune activity, which might have further mediated ETEC infection. These results indicate MCE plays a preventative role with respect to ETEC infection. Future research should aim to develop MCE as a therapeutic approach to the promotion of intestinal health and a safeguard against ETEC infection.

Effects of dietary arginine supplementation in pregnant mares on maternal metabolism, placental structure and function and foal growth

Foals born to primiparous mares are lighter and less mature than those born to multiparous dams. Factors driving this difference are not totally understood. Using 7 multiparous and 6 primiparous standardbred mares, we demonstrated that, in late gestation, primiparous mares were less insulin resistant compared to multiparous mares, and that their foals had reduced plasma amino-acid concentrations at birth compared to foals born to multiparous mares. Vascular development, as observed through structure and gene expression, and global DNA methylation were also reduced in primiparous placentas. Another group of 8 primiparous mares was orally supplemented with L-arginine (100 g/day, 210d to term). L-arginine improved pregnancy-induced insulin resistance and increased maternal L-arginine and L-ornithine plasma concentrations but foal plasma amino acid concentrations were not affected at birth. At birth, foal weight and placental biometry, structure, ultra-structure and DNA methylation were not modified. Placental expression of genes involved in glucose and fatty acid transfers was increased. In conclusion, maternal insulin resistance in response to pregnancy and placental function are reduced in primiparous pregnancies. Late-gestation L-arginine supplementation may help primiparous mares to metabolically adapt to pregnancy and improve placental function. More work is needed to confirm these effects and ascertain optimal treatment conditions.

Radioprotective Effect of Walnut Oligopeptides Against Gamma Radiation-Induced Splenocyte Apoptosis and Intestinal Injury in Mice

Walnut oligopeptides (WOPs) intake is associated with the augment of the antioxidant defense system and immune system. The chief object of this study is to evaluate the radioprotective effect of walnut oligopeptides extracted from walnut seed protein against ⁶⁰Coγ-irradiation induced damage in mice. Female BALB/c mice were administered WOPs through drinking water for 14 days until a single dose of whole-body ⁶⁰Coγ-irradiation. The 30-day survival test was carried out in the first group (8 Gy), and the other two groups (3.5 Gy) were sacrificed at 3 days and 14 days post-irradiation. Blood and organ samples of mice in the three groups were collected, the histopathological analysis and immunohistochemistry were conducted. The number of peripheral blood leukocytes, bone marrow DNA content, inflammatory cytokines, antioxidant capacity, and intestinal permeability were measured. We found that the administration of WOPs augmented antioxidant defense system, accelerated hematopoietic recovery and showed the significant trend toward higher survival rate and less weight loss compared with non-administrated control mice. In addition, WOPs administration appeared to be important to limit IR-induced splenocyte apoptosis and inflammatory cascade as well as reduce intestine epithelial barrier dysfunction and promote epithelial integrity. These results suggest that pre and post-treatment of WOPs may help to ameliorate acute damage, which is induced by ionizing radiation in mice and accelerate its recovery.

l-Arginine Protects Ovine Intestinal Epithelial Cells from Lipopolysaccharide-Induced Apoptosis through Alleviating Oxidative Stress

This research aims to explore the effect of l-arginine (Arg) upon lipopolysaccharide (LPS)-induced induction of the oxidative stress as well as subsequent apoptosis within ovine intestinal epithelial cells (IOECs). Through a 16 h incubation, cells were divided into four groups and the medium was replaced with different medium as follows: (1) control (Con), Arg-free Dulbecco's modified Eagle's F12 Ham medium (DMEM); (2) Arg treatment, Arg-free DMEM supplemented with 100 μM Arg; (3) LPS treatment, Arg-free DMEM supplemented with 10 μg/mL LPS; (4) LPS with Arg treatment, Arg-free DMEM supplemented with both 10 μg/mL LPS and 100 μM Arg. After culturing for 24 h in different mediums, some characteristics of cells in the four groups were measured. Addition of Arg increased cell viability induced with LPS compared with the LPS group ( p < 0.05). Arg significantly decreased the release of dehydrogenase (LDH) and the production of malonaldehyde (MDA) ( p < 0.05) within IOECs challenged by the LPS. Compared with the LPS group, cells treated with Arg and Arg + LPS increased ( p < 0.05) mRNA as well as protein expression of glutathione peroxidase 1 (GPx1), catalase (CAT), superoxide dismutase 2 (SOD2), B-cell lymphoma 2 (Bcl2), quinone oxidoreductase 1 (NQO1), heme oxygenase (HO-1), and nuclear factor erythroid 2-related factor 2 (Nrf2). IOEC treatment with Arg reduced significantly ( p < 0.05) apoptosis induced by the LPS (12.58 ± 0.79%). The results showed that Arg promoted the protein expression of Nrf2, up-regulated expression of the phase II metabolizing enzymes (NQO1 and HO-1), as well as antioxidative enzymes (GPx1, CAT, and SOD2) for alleviating oxidative injury and protected IOECs from LPS-induced apoptosis.

Effects of dietary gamma-aminobutyric acid supplementation on the intestinal functions in weaning piglets

This study aims to investigate the effects of dietary gamma-aminobutyric acid (GABA) supplementation on the growth performance, intestinal immunity, intestinal GABAergic system, amino acid profiles and gut microflora of the weaned piglets. Totally sixteen healthy piglets were randomly assigned into two groups to be fed with the basal diet (Con group) or the basal diet with GABA (20 mg kg-1) supplementation. Body weights and feed intakes were monitored weekly. Piglets were sacrificed after 3 weeks of GABA supplementation to collect the blood, ileum, ileal mucosa and luminal content. Immune-associated factors, GABAergic system, amino acid profiles, and microbiota in the ileum and serum amino acid profiles were explored. The results showed that GABA supplementation improved the growth performance and modulated the intestinal immunity with inhibiting the gene expressions of IL-22, proinflammatory cytokines (IL-1 and IL-18), and Muc1, but promoted the expressions of anti-inflammatory cytokines (IFN-γ, IL-4, and IL-10), TLR6 and MyD88. GABA regulated a few components of the intestinal GABAergic system, increased the levels of most amino acids in the ileal mucosa but reduced the serum amino acid profiles. GABA regulated the population and diversity of intestinal microbiota, such as the abundances of the dominant microbial populations, the community richness, and diversity of the ileal microbiota. In conclusion, GABA supplementation modulated the intestinal functions, including intestinal immunity, intestinal amino acid profiles and gut microbiota, and the results can be helpful for understanding the functions of GABA in the intestine.

d- andl-Aspartate regulates growth performance, inflammation and intestinal microbial community in young pigs

Dietary 1%d-Asp andl-Asp affect the growth performance and inflammation in young pigs, which might be associated with gut microbiota.

Physiological Effects of Dietary Amino Acids on Gut Health and Functions of Swine

Gut health has significant implications for swine overall health status and nutrient utilization, due to its various functions including digestion and absorption of nutrients, secretion of mucins and immunoglobulins, and selective barrier protection against harmful antigens and pathogens. Both the basic anatomical structure of the gut (such as epithelial cells) and its luminal microbiota play important roles for maintaining gut health and functions. The interactions between epithelial cells and luminal microbiota have significant impact on host nutrition and health through the metabolism of dietary components. Amino acids, which are major nutrients for pigs, are not only obligatory for maintaining the intestinal mucosal mass and integrity, but also for supporting the growth of microorganisms in the gut. Dietary amino acids are the major fuel of the small intestinal mucosa. Particularly, glutamate, glutamine, and aspartate are the major oxidative fuel of the intestine. Emerging evidence shows that arginine activates the mTOR signaling pathway in the small intestine. Utilization of glycine by the small intestinal mucosa to synthesize glutathione is a very important physiological pathway, and the role of glycine as a powerful cytoprotectant has also been recognized. The major end products of methionine and cysteine metabolism are glutathione, homocysteine and taurine, which play important roles in the intestinal immune and anti-oxidative responses. Threonine is highly utilized by the gut and is particularly important for mucin synthesis and maintenance of gut barrier integrity. Moreover, either a deficiency or an excess of dietary threonine can reduce the synthesis of intestinal mucosal proteins and mucins in young pigs. Various new functions of amino acids on gut health and functions have been discovered in recent years. Thus, this review is to provide some up-to-date knowledge for industry application of dietary amino acids in order to enhance swine gut health and functions, and also it is to provide a comprehensive reference for further scientific research in this regard.

The variation in hectolitre weight of wheat grain fed with or without enzyme supplementation influences nutrient digestibility and subsequently affects performance in pigs

A 2 × 2 factorial experiment was conducted to investigate the effect of feeding a wheat-based diet of two different hectolitre weights (66 vs. 74 kg/hl), achieved through different agronomical conditions, with or without the supplementation of a β-glucanase and β-xylanase enzyme mix on young pigs. The parameter categories which were assessed included growth performance, coefficient of apparent total tract digestibility (CATTD), faecal consistency, faecal microbial populations and faecal volatile fatty acid (VFA) concentrations. Sixty-four pigs (11.6 kg SD 0.97) were assigned to one of four dietary treatments: (T1) low hectolitre weight wheat diet, (T2) low hectolitre weight wheat diet containing 0.1 g/kg β-glucanase and β-xylanase enzyme supplement, (T3) high hectolitre weight wheat diet and (T4) high hectolitre weight wheat diet containing 0.1 g/kg β-glucanase and β-xylanase enzyme supplement. The inclusion of wheat was 500 g/kg in the diet. The low hectolitre weight grain had a higher level of zearalenone, aflatoxin and ochratoxin contamination compared to the high hectolitre weight grain. The high hectolitre weight wheat had a higher gross energy (GE), crude protein (CP) and lysine contents compared to the low hectolitre weight wheat. Pigs offered the low hectolitre weight diet had a lower average daily gain (ADG) (p < 0.001), a lower gain to feed (G:F) ratio (p < 0.001) and a higher faecal score (more diarrhoea) (p < 0.001) compared to pigs offered the high hectolitre weight. The low hectolitre weight diet had a reduced CATTD (p < 0.05) of nitrogen (N) and gross energy (GE) compared with pigs offered the high hectolitre weight diet. In conclusion, the higher level of mycotoxins and lower content of GE, CP and lysine in the low-quality wheat reduced ADG and the CATTD of nutrients in pigs offered this diet. The inclusion of a β-glucanase and β-xylanase enzyme mix had no effect on growth performance or nutrient digestibility.

Amino Acid Transport Across the Mammalian Intestine

The small intestine mediates the absorption of amino acids after ingestion of protein and sustains the supply of amino acids to all tissues. The small intestine is an important contributor to plasma amino acid homeostasis, while amino acid transport in the large intestine is more relevant for bacterial metabolites and fluid secretion. A number of rare inherited disorders have contributed to the identification of amino acid transporters in epithelial cells of the small intestine, in particular cystinuria, lysinuric protein intolerance, Hartnup disorder, iminoglycinuria, and dicarboxylic aminoaciduria. These are most readily detected by analysis of urine amino acids, but typically also affect intestinal transport. The genes underlying these disorders have all been identified. The remaining transporters were identified through molecular cloning techniques to the extent that a comprehensive portrait of functional cooperation among transporters of intestinal epithelial cells is now available for both the basolateral and apical membranes. Mouse models of most intestinal transporters illustrate their contribution to amino acid homeostasis and systemic physiology. Intestinal amino acid transport activities can vary between species, but these can now be explained as differences of amino acid transporter distribution along the intestine. © 2019 American Physiological Society. Compr Physiol 9:343-373, 2019.