Sulfur amino acid deficiency upregulates intestinal methionine cycle activity and suppresses epithelial growth in neonatal pigs

Impact of Lysine to Methionine Ratios on Antioxidant Capacity and Immune Function in the Rumen of Tibetan Sheep: An RNA-Seq Analysis

With global protein prices on the rise, lowering protein levels in animal feed, together with balancing diet composition and reducing nitrogen emissions, can both reduce the environmental impact of agriculture and save on feed costs. However, the formulation of an ideal amino acid (AA) composition is crucial for better protein utilization by livestock. This study aimed to investigate the effects of different lysine to methionine ratios on the antioxidant capacity and immune function of the rumen in Tibetan sheep. Ninety male Tibetan sheep, weaned at 2 months of age, were randomly divided into three groups (1:1, 2:1 and 3:1 lysine ratios) and subjected to a 100-day feeding trial. RNA sequencing (RNA-seq) was utilized to analyse the impact of different AA ratios on gene expression in rumen tissue, whereas the levels of antioxidant enzymes (total antioxidant capacity [T-AOC], superoxide dismutase [SOD], glutathione peroxidase [GSH-Px] and catalase [CAT]) and immunoglobulins (immunoglobulin A [IgA], immunoglobulin G [IgG] and immunoglobulin M [IgM]) were evaluated. The results indicated that the 1:1 group significantly upregulated the expression of PTGS2, PLA2G12A and PLA2G4 genes, enhancing antioxidant enzyme activity, reducing free radical production and modulating systemic immune responses. COL16A1 and KCNK5 were highly expressed in the protein digestion and absorption pathway, maintaining the structural integrity and function of the rumen epithelium. BMP4 and TGFBR2 were significantly enriched in the cytokine-cytokine receptor interaction pathway and positively correlated with CAT and T-AOC. ITGA8 was upregulated in the 1:1 group, participating in the regulation of various cellular signalling pathways. ATP2B1 was enriched in the cyclic guanosine monophosphate (cGMP)- protein kinase G (PKG) signalling and mineral absorption pathways, primarily influencing oxidative stress and immune responses by regulating intracellular calcium ion concentration. This study demonstrates that a 1:1 lysine to methionine ratio is most beneficial for enhancing the antioxidant capacity and immune function of the rumen in Tibetan sheep.

Methionine and vitamin E supplementation improve production performance, antioxidant potential, and liver health in aged laying hens

Sulfur metabolites of methionine (Met) and vitamin E (VE) have antioxidant potential and can maintain liver health in chickens. This study explored the underlying mechanisms of Met sources, the ratio of total sulfur amino acids to lysine (TSAA: Lys), and VE levels on production performances, antioxidant potential, and hepatic oxidation in aged laying hens. Eight hundred and sixty-four, Hy-Line Brown laying hens (70-week age) were divided into 12 treatment groups, each having 6 repeats and 12 birds/each repeat. The dietary treatments consisted of DL-Met (DL-Met), DL-2-hydroxy-4-(methylthio)-butanoic acid (OH-Met), 3 ratios of TSAA: Lys (0.90, 0.95, and 1.00), and 2 levels of VE (20 and 40 g/ton). Albumen height and Haugh unit significantly increased at a lower level of VE (P < 0.05). Triglycerides (TG), total cholesterol (TC), low-density lipoprotein (LDL), and very low-density lipoprotein (VLDL) in serum and superoxide dismutase (SOD) and catalase activities (CAT) in the liver significantly reduced at 0.95 TSAA: Lys ratio (P < 0.05). Fatty acid synthase (FAS), lipoprotein lipase (LPL), nuclear factor erythroid 2-related factor 2 (Nrf2), and carnitine palmitoyltransferase-1 alpha (CPT-1α) also upregulated at this TSAA: Lys ratio (P < 0.05). Compared with the DL-Met group, the OH-Met group had lower Dipeptidyl Peptidase 4 (DPP4) and higher TC, LDL, and VLDL concentrations (P < 0.05).The expression of FAS,CPT-1α), glutathione (GSH), glutathione disulfide (GSSG), glutathione synthetase (GSS), and Nrf2 were significantly higher in OH-Met compared with the DL-Met group (P < 0.05). OH-Met at 0.95 and DL-Met at 0.90 TSAA: Lys ratio showed higher CAT and lower aspartate aminotransferase (AST) activities. Moreover, OH-Met at 0.90 and DL-Met at 0.95 of the TSAA: Lys ratio had a significant reduction of malondialdehyde (MDA) (P < 0.05). Overall, these results suggest that OH-Met source with a lower level of VE positively influenced production performance and improved liver health in aged laying hens through improved lipid metabolism and hepatic antioxidant function.

Unlocking the potential of methionine: a dietary supplement for preventing colitis

The incidence rate of colitis and conversion of colitis into colorectal cancer is increasing. However, the results of drug treatments are inconsistent with variable side effects; therefore, it is necessary to find alternative ways of treating colitis, e.g. through dietary supplements. One such dietary supplement could be sulfur-containing amino acids, which are known to have anti-inflammatory, antioxidant, and gut microbiota homeostasis effects. Therefore, the aim of the present study was to explore the effect of methionine supplementation in the diet of mice on experimental dextran sulfate sodium (DSS)-induced colitis. Here, 24 male C57BL/6J mice were split into three experimental treatment groups in such a way that each treatment group had four replicates and each replicate had two mice. The control group was colitis-free, while colitis was induced by the administration of DSS in the DSS groups. In the DSS and DSS plus methionine (DSS + Met) groups, DSS was provided in drinking water containing 3% DSS on days 1-5 and later provided with purified water on days 6-7. It was found that supplementing with methionine could activate pathways like Nrf2, and inhibit pathways like TLR4 and Nlrp3 to realize anti-inflammatory and antioxidant effects. Moreover, methionine could alter the microbiota of the gut in the experimental mice, whereby exploration of the gut microbiota demonstrated that methionine supplementation in the diet increased the abundance of parabacteroides and the production of propionate and butyrate. The current study shows that the dietary prophylactic supplementation of methionine has a beneficial effect on resisting colitis, providing new insights for the prevention of colitis.

An Estimation of the Requirements of the Standardized Ileal Digestible Tryptophan, Valine, Isoleucine and Methionine on Young Pigs' (Up to 50 kg) Feed Efficiency: A Meta-Regression Analysis

Currently, the NRC amino acid (AA) requirements for pigs published in 2012 are used as a reference in variable swine industries. However, recent results in several articles suggest that the standardized ileal digestible (SID) AA-lysine (Lys) ratio significantly evolved over the last two decades, while some publications report inconsistent outcomes. Therefore, the present study used a meta-regression analysis to assess the relative ratio to lysine to maximize the feed efficiency of four essential amino acids (tryptophan, valine, isoleucine, and methionine) in pig diets. According to the PRISMA guidelines, articles examining the target AA requirement using a basal diet supplemented with varying levels of crystalline AA (tryptophan, valine, isoleucine, or methionine) were identified across Scopus, PubMed, and Science Direct. As a result, 23, 22, 16, and 9 articles using tryptophan, valine, isoleucine, and methionine were selected and categorized into experiments for inclusion in our meta-analysis. The results suggested that the requirements of tryptophan, valine, isoleucine, and methionine in our meta-regression analysis were superior to NRC recommendations, regardless of the regression models and the growth phases with significant RSQ values (RSQ ≈ 1). Also, the QUAD and CLP regression models emphasized higher requirements than the LP model for the great majority of amino acids and growth phases. The results of the QUAD and CLP models were selected as estimations of the amino acid requirements for pigs under challenged conditions, whereas the LP model was chosen to estimate the amino acid requirements of genetically improved pigs under a modern housing system. The results of this meta-regression analysis could be used to refresh the information on the NRC amino acids (AA) requirements for swine.

Taurine Alleviates Experimental Colitis by Enhancing Intestinal Barrier Function and Inhibiting Inflammatory Response through TLR4/NF-κB Signaling

Taurine (Tau) is a semiessential amino acid in mammals with preventive and therapeutic effects on several intestinal disorders. However, the exact function of taurine in ulcerative colitis (UC) is still largely unclear. In this study, we used two taurine-deficient mouse models (CSAD-/- and TauT-/- mice) to explore the influence of taurine on the progression of UC in both dextran sulfate sodium (DSS)-induced colitis and LPS-stimulated Caco-2 cells. We found that cysteine sulfinic acid decarboxylase (CSAD) and taurine transporter (TauT) expressions and taurine levels were markedly reduced in colonic tissues of mice treated with DSS. The CSAD and TauT knockouts exacerbated DSS-induced clinical symptoms and pathological damage and aggravated the intestinal barrier dysfunction and the colonic mucosal inflammatory response. Conversely, taurine pretreatment enhanced the intestinal barrier functions by increasing goblet cells and upregulating tight junction protein expression. Importantly, taurine bound with TLR4 and inhibited the TLR4/NF-κB pathway, ultimately reducing proinflammatory factors (TNF-α and IL-6) and oxidative stress. Our findings highlight the essential role of taurine in maintaining the intestinal barrier integrity and inhibiting intestinal inflammation, indicating that taurine is a promising supplement for colitis treatment.

Natural mating ability is associated with gut microbiota composition and function in captive male giant pandas

The issue of poor sexual performance of some male giant pandas seriously impairs the growth and the genetic diversity of the captive population, yet there is still no clear understanding of the cause of the loss of this ability and its underlying mechanism. In this study, we analyzed the gut microbiota and its function in 72 fecal samples obtained from 20 captive male giant pandas, with an equal allocation between individuals capable and incapable of natural mating. Additionally, we investigated fecal hormone levels and behavioral differences between the two groups. A correlation analysis was then conducted among these factors to explore the influencing factors of their natural mating ability. The results showed significant differences in the composition of gut microbiota between the two groups of male pandas. The capable group had significantly higher abundance of Clostridium sensu stricto 1 (p adjusted = .0021, GLMM), which was positively correlated with fatty acid degradation and two-component system functions (Spearman, p adjusted < .05). Additionally, the capable group showed higher gene abundance in gut microbiota function including purine and pyrimidine metabolism and galactose metabolism, as well as pathways related to biological processes such as ribosome and homologous recombination (DEseq2, p adjusted < .05). We found no significant differences in fecal cortisol and testosterone levels between the two groups, and no difference was found in their behavior either. Our study provides a theoretical and practical basis for further studying the behavioral degradation mechanisms of giant pandas and other endangered mammal species.

Dietary cystine restriction increases the proliferative capacity of the small intestine of mice

Currently, over 88 million people are estimated to have adopted a vegan or vegetarian diet. Cysteine is a semi-essential amino acid, which availability is largely dependent on dietary intake of meat, eggs and whole grains. Vegan/vegetarian diets are therefore inherently low in cysteine. Sufficient uptake of cysteine is crucial, as it serves as substrate for protein synthesis and can be converted to taurine and glutathione. We found earlier that intermolecular cystine bridges are essential for the barrier function of the intestinal mucus layer. Therefore, we now investigate the effect of low dietary cystine on the intestine. Mice (8/group) received a high fat diet with a normal or low cystine concentration for 2 weeks. We observed no changes in plasma methionine, cysteine, taurine or glutathione levels or bile acid conjugation after 2 weeks of low cystine feeding. In the colon, dietary cystine restriction results in an increase in goblet cell numbers, and a borderline significant increase mucus layer thickness. Gut microbiome composition and expression of stem cell markers did not change on the low cystine diet. Remarkably, stem cell markers, as well as the proliferation marker Ki67, were increased upon cystine restriction in the small intestine. In line with this, gene set enrichment analysis indicated enrichment of Wnt signaling in the small intestine of mice on the low cystine diet, indicative of increased epithelial proliferation. In conclusion, 2 weeks of cystine restriction did not result in apparent systemic effects, but the low cystine diet increased the proliferative capacity specifically of the small intestine and induced the number of goblet cells in the colon.

Low feed intake at weaning reduces intestinal glutathione levels and promotes cysteine oxidation to taurine in pigs

Weaning stress in pigs is associated with low feed intake and poor nutrient utilization. Cysteine is a sulfur amino acid with key roles in pig production, but how cysteine metabolism and requirements are affected by weaning stress should be better defined. The objective of this study was to determine the collective impact of weaning and feed restriction on tissue cysteine metabolism. Pigs were weaned at 21-d age without access to feed (W; 6.90 ± 0.81 kg; n = 9; reflecting acute nutritional stress) or were not weaned and remained with the sow (nonweaned [NW]; 6.81 ± 0.65 kg; n = 8). At euthanasia (23-d age), blood, bile, liver, jejunum, and ileum tissues were collected. Plasma, bile, and tissue amino acid and amino thiol concentrations were analyzed by HPLC. The activity of glutamate cysteine ligase (GCL) and glutathione synthetase (GSS), enzymes needed for glutathione (GSH) production, and cysteine dioxygenase 1 (CDO1) were determined with activity assays followed by HPLC analysis of reaction products. Plasma (271 vs. 192 ± 19 µmol/L; P < 0.001) and liver (417 vs. 298 ± 33 nmol/g; P < 0.05) Cys concentrations were increased in W compared to NW pigs. Despite greater plasma Cys, jejunum and ileum Cys content were not affected by weaning (P > 0.10), whereas γ-glutamylcysteine (γ-GlyCys), the immediate precursor of GSH, declined in both jejunum (14.3 vs. 9.7 ± 1.4 nmol/g; P < 0.01) and ileum (11.2 vs. 6.4 ± 0.8 nmol/g; P < 0.001) in W pigs. Glutathione content was lower in the jejunum (1,379 vs. 1,720 ± 70 nmol/g; P < 0.05) and ileum (1,497 vs. 1,740 ± 74 nmol/g; P < 0.05) in W pigs. In the jejunum, GCL activity tended to be greater (0.56 vs. 0.39 ± 0.07 nmol γ-GluCys • mg-1 • min-1; P < 0.10), whereas GSS activity tended to be lower (1.11 vs. 1.38 ± 0.10 nmol GSH • mg-1 • min-1; P < 0.10) in W compared to NW pigs. In the ileum, the activities of GCL and GSS were not affected by weaning (P > 0.10). Although liver CDO1 activity was not different between groups (P < 0.10), liver taurine was greater in W compared to NW pigs (5,115 vs. 2,336 ± 912 nmol/g; P = 0.001). Bile concentrations of Cys (1,203 vs. 279 ± 103 µmol/L; P < 0.001) and cysteinylglycine (203 vs. 117 ± 33 µmol/L; P < 0.10), the direct product of GSH degradation, were greater in W compared to NW pigs. Collectively, these results suggest that systemic Cys is not effectively utilized for gut GSH production in newly weaned pigs; instead, it is oxidized to taurine and eliminated in bile.

Dietary methionine sources and levels modulate the intestinal health status of broiler chickens

Given the key role of methionine in biological processes, adequate methionine should be provided to meet the nutritional requirements. DL-2-hydroxy-4-(methylthio)-butanoic acid (DL-HMTBA) has been considered as an important source of methionine. However, the effects of different sources and levels of methionine on the intestinal health status have not been clarified yet. An experiment was carried out to investigate the effects of different dietary sources and levels of methionine on the intestinal epithelial barrier, inflammatory cytokines expression, ileal morphology, microbiota composition, and cecal short chain fatty acids (SCFA) profiles. For this purpose, 720 male Arbor Acre broiler chicks at 1 d old were randomly assigned to a 2 × 3 factorial arrangement with 2 methionine sources (DL-methionine and DL-HMTBA) and 3 total sulfur amino acids (TSAA) levels (80%, 100%, and 120% of Arbor Acre recommendation). The results showed that DL-HMTBA supplementation promoted intestinal physical barrier at both gene expression level of claudin-1 and serum diamine oxidase level (P < 0.05), and the inflammatory cytokine IL-6 mRNA expression was down-regulated by dietary DL-HMTBA supplementation compared with the DL-methionine group (P < 0.05). Meanwhile, an upregulated gene expression of claudin-1 and zonula occluden-1 (ZO-1) were observed in the low-TSAA treatment on d 14 (P < 0.05), whereas this treatment increased the expression of IL-1β and IL-6 (P < 0.05). Villus height to crypt depth ratio was high (P < 0.05) in the middle-level TSAA group. Furthermore, DL-HMTBA supplementation optimized the microbiota of the ileum especially the relative abundance of Lactobacillus, where the digestion and absorption were completed, and elevated the concentrations of SCFA (acetate, propionate, and butyrate) in the cecal content on d 21 (P < 0.01). In conclusion, dietary DL-HMTBA supplementation improved the intestinal barrier function, immune homeostasis and optimized the microbiota to promote intestinal health status in broiler chickens.

Enhanced ileum function in weaned piglets via Laminaria digitata and alginate lyase dietary inclusion: A combined proteomics and metabolomics analysis

Laminaria digitata, a brown seaweed with prebiotic properties, can potentially enhance the resilience of weaned piglets to nutritional distress. However, their cell wall polysaccharides elude digestion by monogastric animals' endogenous enzymes. In vitro studies suggest alginate lyase's ability to degrade such polysaccharides. This study aimed to assess the impact of a 10% dietary inclusion of L. digitata and alginate lyase supplementation on the ileum proteome and metabolome, adopting a hypothesis-generating approach. Findings indicated that control piglets escalated glucose usage as an enteric energy source, as evidenced by the increased abundance of PKLR and PCK2 proteins and decreased tissue glucose concentration. Additionally, the inclusion of seaweed fostered a rise in proteins linked to enhanced enterocyte structural integrity (ACTBL2, CRMP1, FLII, EML2 and MYLK), elevated peptidase activity (NAALADL1 and CAPNS1), and heightened anti-inflammatory activity (C3), underscoring improved intestinal function. In addition, seaweed-fed piglets showed a reduced abundance of proteins related to apoptosis (ERN2) and proteolysis (DPP4). Alginate lyase supplementation appeared to amplify the initial effects of seaweed-only feeding, by boosting the number of differential proteins within the same pathways. This amplification is potentially due to increased intracellular nutrient availability, making a compelling case for further exploration of this dietary approach. SIGNIFICANCE: Pig production used to rely heavily on antibiotics and zinc oxide to deal with post-weaning stress in a cost-effective way. Their negative repercussions on public health and the environment have motivated heavy restrictions, and a consequent search for alternative feed ingredients/supplements. One of such alternatives is Laminaria digitata, a brown seaweed whose prebiotic components that can help weaned piglets deal with nutritional stress, by improving their gut health and immune status. However, their recalcitrant cell walls have antinutritional properties, for which alginate lyase supplementation is a possible solution. By evaluating ileal metabolism as influenced by dietary seaweed and enzyme supplementation, we aim at discovering how the weaned piglet adapts to them and what are their effects on this important segment of the digestive system.

Enhancing Metabolism and Milk Production Performance in Periparturient Dairy Cattle through Rumen-Protected Methionine and Choline Supplementation

For dairy cattle to perform well throughout and following lactations, precise dietary control during the periparturient phase is crucial. The primary issues experienced by periparturient dairy cows include issues like decreased dry matter intake (DMI), a negative energy balance, higher levels of non-esterified fatty acids (NEFA), and the ensuing inferior milk output. Dairy cattle have always been fed a diet high in crude protein (CP) to produce the most milk possible. Despite the vital function that dairy cows play in the conversion of dietary CP into milk, a sizeable percentage of nitrogen is inevitably expelled, which raises serious environmental concerns. To reduce nitrogen emissions and their production, lactating dairy cows must receive less CP supplementation. Supplementing dairy cattle with rumen-protected methionine (RPM) and choline (RPC) has proven to be a successful method for improving their ability to use nitrogen, regulate their metabolism, and produce milk. The detrimental effects of low dietary protein consumption on the milk yield, protein yield, and dry matter intake may be mitigated by these nutritional treatments. In metabolic activities like the synthesis of sulfur-containing amino acids and methylation reactions, RPM and RPC are crucial players. Methionine, a limiting amino acid, affects the production of milk protein and the success of lactation in general. According to the existing data in the literature, methionine supplementation has a favorable impact on the pathways that produce milk. Similarly, choline is essential for DNA methylation, cell membrane stability, and lipid metabolism. Furthermore, RPC supplementation during the transition phase improves dry matter intake, postpartum milk yield, and fat-corrected milk (FCM) production. This review provides comprehensive insights into the roles of RPM and RPC in optimizing nitrogen utilization, metabolism, and enhancing milk production performance in periparturient dairy cattle, offering valuable strategies for sustainable dairy farming practices.

Dietary Taurine Improves Growth Performance and Intestine Health via the GSH/GSSG Antioxidant System and Nrf2/ARE Signaling Pathway in Weaned Piglets

Early weaning of piglets was prone to increase reactive oxygen species, disrupt the redox balance, decrease antioxidant capacity, cause oxidative stress and intestinal oxidative damage, and lead to diarrhea in piglets. This research aimed to study dietary taurine (Tau) supplementation at a level relieving intestinal oxidative damage in early-weaned piglets. A total of 48 piglets were assigned to four groups of 12 individuals and fed a basal diet with 0.0% Tau (CON), 0.2% Tau (L-Tau), 0.3% Tau (M-Tau), or 0.4% Tau (H-Tau), respectively. The animal experiment lasted 30 days. The final weight, weight gain, average daily gain, and feed conversion rate increased with the increase in dietary Tau (Linear, p < 0.05; Quadratic p < 0.05), while the diarrhea index of piglets decreased with the increase in dietary Tau (Linear, p < 0.05). Serum malondialdehyde, nitric oxide (NO), D-lactose, and oxidized glutathione (GSSG) concentrations decreased with the increase in dietary Tau (Linear, p < 0.05). The O2•- and •OH clearance rate in serum, liver, and jejunum mucosa increased with the increase in dietary Tau (Linear, p < 0.05). Serum superoxide dismutase (SOD) activity, glutathione peroxidase (GPX) activity, catalase (CAT) activity, and peroxidase (POD) activity and total antioxidant capacity increased with the increase in dietary Tau (Linear, p < 0.05). The serum glutathione (GSH) concentration and the ratio of GSH to GSSG increased with the increase in dietary Tau (Linear, p < 0.05). The POD and glutathione synthase activity in the liver and jejunum mucosa increased with the increase in dietary Tau (Linear, p < 0.05). The mRNA abundances of HO-1 and GPX1 in the H-Tau group were higher than that in the L-Tau, M-Tau, and CON groups (p < 0.05). The mRNA abundances of SOD1 and Nrf2 in the M-Tau and H-Tau groups were higher than in the L-Tau and CON groups (p < 0.05). The mRNA abundance of SOD2 in the L-Tau, M-Tau, and H-Tau groups was higher than in the CON group (p < 0.05). The VH and the ratio of VH to CD of jejunum and ileum increased with the increase in dietary Tau (Linear, p < 0.05). The mRNA abundances of occludens 1 and claudin 1 in the H-Tau group were higher than that in the CON, L-Tau, and M-Tau (p < 0.05). The mRNA abundance of occludin in the L-Tau, M-Tau, and H-Tau groups was higher than that in CON (p < 0.05). The abundance of Firmicutes increased with the increase in dietary Tau (Linear, p < 0.05), while Proteobacteria and Spirochaetota decreased with the increase in dietary Tau (Linear, p < 0.05). Collectively, dietary supplementation of 0.3% and 0.4% Tau in feed could significantly improve the growth performance and enhance the antioxidant capacity of piglets.

Effects of Silage Diet on Meat Quality through Shaping Gut Microbiota in Finishing Pigs

With increasing demand for high-quality pork, development of green and healthy feed for finishing pigs is urgently needed. In this study, the effects and mechanisms of mulberry and paper mulberry silages on growth performance, meat quality, and intestinal health of finishing pigs were explored. Intestinal microbiota were profiled, and microbially produced short-chain fatty acids (SCFAs) were measured. The average daily gain (ADG) and feed conversion rate (FCR) with mulberry and paper mulberry silages were not significantly different from those of the control. Meat quality as measured by pork marbling and fatty acids in the longissimus dorsi was better with mulberry silage. The highest concentration of SCFAs was also with mulberry silage. According to 16S rRNA sequencing, Clostridium_sensu_stricto_1, Terrisporobacter, and Lachnospiraceae, which are important in SCFA production, were biomarkers of mulberry silage. PICRUSt functional analysis of intestinal microbes indicated that galactose metabolism, starch and sucrose metabolism, and carbohydrate digestion and absorption decreased significantly in silage treatments but increased in the control. Correlations between intestinal microbes and SCFAs and fatty acids indicated Clostridium_sensu_stricto_1, Terrisporobacter, and Lachnospiraceae were closely associated with SCFA and fatty acid contents. The results indicated that mulberry silage could increase SCFA content through shaping intestinal microbes to affect the deposition of fatty acids, which laid a solid theoretical foundation for improving pork quality. IMPORTANCE To avoid competition between people and animals for food, it is essential to develop nontraditional feeds. In this study, the effects of the silages of the unconventional feed resources mulberry and paper mulberry on meat quality of finishing pigs were examined. With mulberry silage in the diet, meat quality improved as indicated by meat color, marbling score, and beneficial fatty acids in the longissimus dorsi muscle. Pigs fed mulberry silage had the highest concentrations of short-chain fatty acids (SCFAs), and 16S rRNA sequencing identified Clostridium_sensu_stricto_1, Terrisporobacter, and Lachnospiraceae as biomarkers, which are important in SCFA production. Functions of intestinal microbes in the two silage groups primarily involved amino acid metabolism and SCFA production. Correlations between intestinal microbes and SCFAs and fatty acids indicated that Clostridium_sensu_stricto-1, Terrisporobacter, and Lachnospiraceae were closely associated with SCFA contents in the intestine and fatty acids in the longissimus dorsi.

Highly efficient oriented bioconversion of food waste to lactic acid in an open system: Microbial community analysis and biological carbon fixation evaluation

The valorization of organic solid waste to lactic acid (LA) in open fermentation systems has attracted tremendous interest in recent years. In this study, a highly efficient oriented LA bioconversion system from food waste (FW) in open mode was established. The maximum LA production was 115 g/L, with a high yield of 0.97 g-LA/g-total sugar. FW is a low-cost feedstock for LA production, containing indigenous hydrolysis and LA-producing bacteria (LAB). Saccharification and real-time pH control were found to be essential for maintaining LAB dominantly in open systems. Furthermore, microbial community analysis revealed that Enterococcus mundtii adapted to complex FW substrates and dominated the subsequent bioconversion process. The oriented LA bioconversion exhibited the capacity for biological carbon fixation by reducing CO₂ emissions by at least 21 kg per ton of FW under anaerobic conditions.

Technical note: simultaneous determination of amino thiols in pig tissue by ultra-high performance liquid chromatography with fluorescence detection

Sulfur amino acid nutrition and metabolism are linked to animal disease. While validated methods for the determination of amino thiol levels in plasma or serum are available, there is a dearth of validated methods for their measurement in tissue. A robust and reproducible ultra-high performance liquid chromatography method has been validated for the simultaneous determination of concentrations of cysteine (Cys), cysteinylglycine (CysGly), homocysteine (Hcys), γ-glutamylcysteine (γ-GluCys), and glutathione (GSH) in pig tissue. Tissue was homogenized and deproteinized with trichloroacetic acid. Amino thiols in the acid-soluble fraction of the tissue homogenate were reduced with tris-(2-carboxyethyl)-phosphine hydrochloride and derivatized with 4-(aminosulfonyl)-7-fluoro-2,1,3-benzoxadiazole (ABD-F). Amino thiols were resolved under reversed-phase gradient conditions on a Waters Acquity BEH C18 column (1.7 µm, 2.1 mm × 100 mm) within 4.5 min and detected with fluorescence. The peak area ratio of analyte to 2-mercaptopropionylglycine internal standard, added to external calibration standards and samples, was used to develop linear calibration curves. Linear calibrations were performed over the range of 15-1,500 nmol/g for Cys, CysGly, Hcys, and γ-GluCys and 150-15,000 nmol/g for GSH. Linearity, lower limit of detection, lower limit of quantitation, accuracy, precision, sample stability, and carryover were evaluated. We demonstrate excellent linearity for all analytes within their respective concentration range (r2 > 0.99) and excellent recovery of amino thiols from spiked samples (mean ± SD across tissues; Cys, 100.0 ± 2.2%; CysGly, 95.4 ± 5.1%; Hcys, 96.6 ± 2.0%; γ-GluCys, 102.2 ± 2.7%; and GSH, 100.6 ± 3.3%). The intra-day and inter-day precisions did not exceed 5% and 10%, respectively. Repeated freezing and thawing of tissue homogenate did not affect measured amino thiol concentrations, ABD-labeled amino thiols were stable for 1 wk after derivatization, and there was no sample carryover across consecutive injections. We confirm the identity of each ABD-labeled amino thiol with Orbitrap mass spectrometry. Finally, we apply the method to the determination of amino thiol concentrations in liver and jejunum tissues in newly weaned pigs and show that despite elevated Cys and maintained GSH concentrations in liver, both γ-GluCys and GSH decline in jejunum of weaned pigs.

Comparative effects of dietary methionine and cysteine supplementation on redox status and intestinal integrity in immunologically challenged-weaned pigs

Sulfur-containing amino acids such as methionine and cysteine play critical roles in immune system and redox status. A body of evidence shows that metabolic aspects of supplemented Met and Cys may differ in the body. Therefore, the study aimed to investigate the effects of dietary Met and Cys supplementation in immunologically challenged weaned pigs. Forty weaned piglets (6.5 ± 0.3 kg) were randomly allocated to five treatment groups. The treatment included: (1) sham-challenged control (SCC), (2) challenged control (CC), (3) MET (CC + 0.1% _DL-Met), (4) CYS (CC + 0.1% _L-Cys), and (5) MET + CYS (CC + 0.1% _DL-Met + 0.1% _L-Cys). On day 7, all pigs were intramuscularly injected with either Escherichia coli O55:B5 lipopolysaccharides (LPS) or phosphate-buffered saline. Blood, liver, and jejunum samples were analyzed for immune response and redox status. The CC group had lower (P < 0.05) villus surface area and higher (P < 0.05) flux of 4-kDa fluorescein isothiocyanate dextran (FD4) than the SCC group. A lower (P < 0.05) glutathione (GSH) concentration was observed in the jejunum of pigs in the CC group than those in the SCC group. Dietary Cys supplementation increased (P < 0.05) villus surface area, GSH levels, and reduced (P < 0.05) the flux of FD4 in the jejunum of LPS-challenged pigs. Dietary Met supplementation enhanced (P < 0.05) hepatic GSH content. Pigs challenged with LPS in the MET group had lower serum IL-8 concentration than those in the CC group. There was a Met × Cys interaction (P < 0.05) in serum IL-4 and IL-8 concentrations, and Trolox equivalent antioxidant capacity. Dietary _L-Cys supplementation restored intestinal integrity and GSH levels that were damaged by lipopolysaccharides administration. Dietary _DL-Met supplementation improved hepatic GSH and reduced systemic inflammatory response, but antagonistic interaction with dietary _L-Cys supplementation was observed in the inflammatory response and redox status.

Formulating Diets for Improved Health Status of Pigs: Current Knowledge and Perspectives

Our understanding of nutrition has been evolving to support both performance and immune status of pigs, particularly in disease-challenged animals which experience repartitioning of nutrients from growth towards the immune response. In this sense, it is critical to understand how stress may impact nutrient metabolism and the effects of nutritional interventions able to modulate organ (e.g., gastrointestinal tract) functionality and health. This will be pivotal in the development of effective diet formulation strategies in the context of improved animal performance and health. Therefore, this review will address qualitative and quantitative effects of immune system stimulation on voluntary feed intake and growth performance measurements in pigs. Due to the known repartitioning of nutrients, the effects of stimulating the immune system on nutrient requirements, stratified according to different challenge models, will be explored. Finally, different nutritional strategies (i.e., low protein, amino acid-supplemented diets; functional amino acid supplementation; dietary fiber level and source; diet complexity; organic acids; plant secondary metabolites) will be presented and discussed in the context of their possible role in enhancing the immune response and animal performance.

The Combined Escherichia coli Nissle 1917 and Tryptophan Treatment Modulates Immune and Metabolome Responses to Human Rotavirus Infection in a Human Infant Fecal Microbiota-Transplanted Malnourished Gnotobiotic Pig Model

Human rotavirus (HRV) is a major cause of childhood diarrhea in developing countries where widespread malnutrition contributes to the decreased oral vaccine efficacy and increased prevalence of other enteric infections, which are major concerns for global health. Neonatal gnotobiotic (Gn) piglets closely resemble human infants in their anatomy, physiology, and outbred status, providing a unique model to investigate malnutrition, supplementations, and HRV infection. To understand the molecular signatures associated with immune enhancement and reduced diarrheal severity by Escherichia coli Nissle 1917 (EcN) and tryptophan (TRP), immunological responses and global nontargeted metabolomics and lipidomics approaches were investigated on the plasma and fecal contents of malnourished pigs transplanted with human infant fecal microbiota and infected with virulent (Vir) HRV. Overall, EcN + TRP combined (rather than individual supplement action) promoted greater and balanced immunoregulatory/immunostimulatory responses associated with greater protection against HRV infection and disease in malnourished humanized piglets. Moreover, EcN + TRP treatment upregulated the production of several metabolites with immunoregulatory/immunostimulatory properties: amino acids (N-acetylserotonin, methylacetoacetyl-CoA), lipids (gamma-butyrobetaine, eicosanoids, cholesterol-sulfate, sphinganine/phytosphingosine, leukotriene), organic compound (biliverdin), benzenoids (gentisic acid, aminobenzoic acid), and nucleotides (hypoxathine/inosine/xanthine, cytidine-5'-monophosphate). Additionally, the levels of several proinflammatory metabolites of organic compounds (adenosylhomocysteine, phenylacetylglycine, urobilinogen/coproporphyrinogen) and amino acid (phenylalanine) were reduced following EcN + TRP treatment. These results suggest that the EcN + TRP effects on reducing HRV diarrhea in neonatal Gn pigs were at least in part due to altered metabolites, those involved in lipid, amino acid, benzenoids, organic compounds, and nucleotide metabolism. Identification of these important mechanisms of EcN/TRP prevention of HRV diarrhea provides novel targets for therapeutics development. IMPORTANCE Human rotavirus (HRV) is the most common cause of viral gastroenteritis in children, especially in developing countries, where the efficacy of oral HRV vaccines is reduced. Escherichia coli Nissle 1917 (EcN) is used to treat enteric infections and ulcerative colitis while tryptophan (TRP) is a biomarker of malnutrition, and its supplementation can alleviate intestinal inflammation and normalize intestinal microbiota in malnourished hosts. Supplementation of EcN + TRP to malnourished humanized gnotobiotic piglets enhanced immune responses and resulted in greater protection against HRV infection and diarrhea. Moreover, EcN + TRP supplementation increased the levels of immunoregulatory/immunostimulatory metabolites while decreasing the production of proinflammatory metabolites in plasma and fecal samples. Profiling of immunoregulatory and proinflammatory biomarkers associated with HRV perturbations will aid in the identification of treatments against HRV and other enteric diseases in malnourished children.

One-carbon metabolism in children with marasmus and kwashiorkor

BACKGROUND

Kwashiorkor is a childhood syndrome of edematous malnutrition. Its precise nutritional precipitants remain uncertain despite nine decades of study. Remarkably, kwashiorkor's disturbances resemble the effects of experimental diets that are deficient in one-carbon nutrients. This similarity suggests that kwashiorkor may represent a nutritionally mediated syndrome of acute one-carbon metabolism dysfunction. Here we report findings from a cross-sectional exploration of serum one-carbon metabolites in Malawian children.

METHODS

Blood was collected from children aged 12-60 months before nutritional rehabilitation: kwashiorkor (N = 94), marasmic-kwashiorkor (N = 43) marasmus (N = 118), moderate acute malnutrition (N = 56) and controls (N = 46). Serum concentrations of 16 one-carbon metabolites were quantified using LC/MS techniques, and then compared across participant groups.

FINDINGS

Twelve of 16 measured one-carbon metabolites differed significantly between participant groups. Measured outputs of one-carbon metabolism, asymmetric dimethylarginine (ADMA) and cysteine, were lower in marasmic-kwashiorkor (median µmol/L (± SD): 0·549 (± 0·217) P = 0·00045 & 90 (± 40) P < 0·0001, respectively) and kwashiorkor (0·557 (± 0·195) P < 0·0001 & 115 (± 50) P < 0·0001), relative to marasmus (0·698 (± 0·212) & 153 (± 42)). ADMA and cysteine were well correlated with methionine in both kwashiorkor and marasmic-kwashiorkor.

INTERPRETATION

Kwashiorkor and marasmic-kwashiorkor were distinguished by evidence of one-carbon metabolism dysfunction. Correlative observations suggest that methionine deficiency drives this dysfunction, which is implicated in the syndrome's pathogenesis. The hypothesis that kwashiorkor can be prevented by fortifying low quality diets with methionine, along with nutrients that support efficient methionine use, such as choline, requires further investigation.

FUNDING

The Hickey Family Foundation, the American College of Gastroenterology, the NICHD, and the USDA/ARS.

Effect of microaerophilic treatment on swine wastewater (SWW) treatment: Engineering and microbiological aspects

The microaerobic process on swine wastewater (SWW) treatment was investigated, evaluating its effect on organic matter hydrolysis and removal, biogas production, operational stability, and microbial community structure. UASB reactors operating under higher organic loading rates (OLRs) and lower hydraulic retention times (HRTs) than those found in the SWW treatment literature were also assessed. The microaerophilic reactor R2 presented a higher total and particulate organic matter removals and operational stability than the anaerobic reactor R1, reaching COD_P removals of 79.4 ± 4.6%. In the specific methanogenic activity (SMA) tests, the microaerobic sludge (R2) showed hydrolytic and acetogenic/methanogenic activity superior to inoculum and anaerobic sludge (R1). The microbiological evaluation of R2 revealed the high presence of hydrolytic microorganisms, therefore justifying the higher hydrolytic activity found in the SMA tests and higher particulate organic matter removal found in the microaerobic reactor.

Optimal Standardized Ileal Digestible Total Sulfur Amino Acids to Lysine REQUIREMENTS Are Increased in Nursery Pigs Raised under Antibiotic-Free Feeding Regime

Simple Summary

Total sulfur amino acids play a critical role in numerous biological functions, including antioxidative status and immunity, as well as protein synthesis. Weaning pigs commonly face multiple stressors which can impair their gut integrity and growth performance. Antibiotic removal from the diets in weaning pigs can stimulate immune response and divert nutrients from growth to optimize immune function. The objective of the current two studies was to determine the optimal ratio of the standardized ileal digestible (SID) total sulfur amino acid to lysine (TSAA:Lys) in nursery pigs under an antibiotics-free feeding regime. The results demonstrated that the optimal SID TSAA:Lys for nursery pigs raised without antibiotics during the first 21 d post-weaning was 62 to 72% in terms of growth performance, whereas the optimal SID TSAA:Lys was approximately 58% in terms of growth performance in the late nursery phase.

Abstract

This study aimed to investigate the effect of increasing the standardized ileal digestible (SID) total sulfur amino acid to lysine (TSAA:Lys) on the growth performance of nursery pigs raised with or without antibiotics (AGP) and to determine the optimal SID TSAA:Lys in nursery pigs raised without AGP. In Exp. 1, 924 nursery pigs (7.9 ± 1.3 kg), blocked by initial BW and sex, were randomly allotted to one of six treatments, with seven pens per treatment and twenty-two pigs per pen. The treatments were arranged in a 2 × 3 factorial design, with two AGP levels (0 or 50 mg/kg Carbodox) and three levels of SID TSAA:Lys (51.0, 58.5 or 66.0%). In Exp. 2, 990 weaned piglets (5.1 ± 0.9 kg), blocked by initial BW and sex, were randomly allotted to one of five dietary treatments (SID TSAA:Lys at 51, 58, 65, 72 or 79%) in the absence of AGP, with nine pens per treatment and twenty-two pigs per pen. Competing heteroskedastic models including broken-line linear (BLL), broken-line quadratic (BLQ), and quadratic polynomial (QP) were fitted for the growth performance data to estimate the optimal TSAA:Lys. In Exp. 1, AGP supplementation increased (p < 0.05) ADG and ADFI during the 21 d period. Increasing SID TSAA:Lys in the diets with AGP did not affect growth performance; however, increasing SID TSAA:Lys in the diets without AGP resulted in a linear increase (p < 0.05) in ADG and G:F. In Exp. 2, the best-fitting models for ADG and G:F from d 0 to 21 post-weaning were BLL, which yielded the optimal SID TSAA:Lys of 62% and 72%, respectively. The best-fitting models for ADG and G:F from d 21 to 42 post-weaning were BLL, which yielded the optimal SID TSAA:Lys of 59% and 58%, respectively. In conclusion, SID TSAA to Lys requirements under an antibiotic-free feeding regime during the first 21 d post-weaning were 62% and 72% in terms of ADG and G:F, respectively, whereas an SID TSAA:Lys of approximately 58% was required to maximize ADG and G:F for the late nursery phase.

Effect of gestation dietary methionine-to-lysine ratio on methionine metabolism and antioxidant ability of high-prolific sows

The uptake and metabolism of methionine (Met) are critical for epigenetic regulation, redox homeostasis, and embryo development. Our previous study showed that appropriate supplementation of dietary Met promoted the birth weight and placental angiogenesis of high-prolific sows. To further explore the metabolic effect of Met on pregnant sows, we have evaluated the influence of dietary Met level on Met metabolism, and the relationship between metabolites of Met and reproductive performance, antioxidant ability, and placental angiogenesis throughout the gestation of high-prolific sows. Sixty sows (the 3rd parity, Large White) were randomly divided into 5 groups that were fed diets with standardized ileal digestible (SID) methionine-to-lysine (Met:Lys) ratios of 0.27 (control), 0.32, 0.37, 0.42, and 0.47 from the mating day (gestational d 0, G0d) until the farrowing day. HPLC-MS/MS analysis was used to simultaneously evaluate the metabolites related to Met, e.g. S-adenosylmethionine (SAM), S-adenosylhomocysteine (SAH), homocysteine (Hcy), cysteine (Cys), and glutathione (GSH). The concentration of SAM and SAH in plasma had significant fluctuations, especially in late pregnancy. Increasing dietary Met supplementation significantly improved the plasma SAM and methylation potential (SAM-to-SAH ratio) at d 114 of pregnancy (G114d). Moreover, a positive association of the plasma SAM concentration at G114d was observed with the litter weight of born alive (P < 0.05; R 2 = 0.58). Furthermore, Hcy concentration in plasma was at the lowest level for 0.37 ratio group at G114d. However, it significantly increased during late pregnancy. Moreover, there were negative correlations between plasma Hcy concentration at G114d (P < 0.05) and the placental vascular density in the fold and stroma (P < 0.05). Compared with the control group, the expression of vascular endothelial growth factor-A (VEGF-A) in the placenta tissue of 0.37 ratio group increased significantly (P < 0.05). Collectively, these findings indicate that dietary Met:Lys ratio (0.37 to 0.57) in the pregnant diet dose not influence the antioxidant ability of the high-prolific sows; however, the improvement of fetal development and placental angiogenesis of high-prolific sows by supplementation of Met are closely associated to the key Met-related metabolite of SAM and Hcy, respectively.

Transcription of Cystathionine β-Lyase (MetC) Is Repressed by HeuR in Campylobacter jejuni, and Methionine Biosynthesis Facilitates Colonocyte Invasion

A previously identified transcriptional regulator in Campylobacter jejuni, termed HeuR, was found to positively regulate heme utilization. Additionally, transcriptomic work demonstrated that the putative operons CJJ81176_1390 to CJJ81176_1394 (CJJ81176_1390-1394) and CJJ81176_1214-1217 were upregulated in a HeuR mutant, suggesting that HeuR negatively regulates expression of these genes. Because genes within these clusters include a cystathionine β-lyase (metC) and a methionine synthase (metE), it appeared HeuR negatively regulates C. jejuni methionine biosynthesis. To address this, we confirmed mutation of HeuR reproducibly results in metC overexpression under nutrient-replete conditions but did not affect expression of metE, while metC expression in the wild type increased to heuR mutant levels during iron limitation. We subsequently determined that both gene clusters are operonic and demonstrated the direct interaction of HeuR with the predicted promoter regions of these operons. Using DNase footprinting assays, we were able to show that HeuR specifically binds within the predicted -35 region of the CJJ81176_1390-1394 operon. As predicted based on transcriptional results, the HeuR mutant was able to grow and remain viable in a defined medium with and without methionine, but we identified significant impacts on growth and viability in metC and metE mutants. Additionally, we observed decreased adherence, invasion, and persistence of metC and metE mutants when incubated with human colonocytes, while the heuR mutant exhibited increased invasion. Taken together, these results suggest that HeuR regulates methionine biosynthesis in an iron-responsive manner and that the ability to produce methionine is an important factor for adhering to and invading the gastrointestinal tract of a susceptible host. IMPORTANCE As the leading cause of bacterium-derived gastroenteritis worldwide, Campylobacter jejuni has a significant impact on human health. Investigating colonization factors that allow C. jejuni to successfully infect a host furthers our understanding of genes and regulatory elements necessary for virulence. In this study, we have begun to characterize the role of the transcriptional regulatory protein, HeuR, on methionine biosynthesis in C. jejuni. When the ability to synthesize methionine is impaired, detrimental impacts on growth and viability are observed during growth in limited media lacking methionine and/or iron. Additionally, mutations in the methionine biosynthetic pathway result in decreased adhesion, invasion, and intracellular survival of C. jejuni when incubated with human colonocytes, indicating the importance of regulating methionine biosynthesis.

Metabolic and nutritional responses of Nile tilapia juveniles to dietary methionine sources

Commercial diets for tilapia juveniles contain high levels of plant protein sources. Soybean meal has been utilised due to its high protein content; however, soy-based diets are limited in methionine (Met) and require its supplementation to fulfil fish requirements. dl-Methinone (dl-Met) and Ca bis-methionine hydroxyl analogue (MHA-Ca) are synthetic Met sources supplemented in aquafeeds, which may differ in biological efficiency due to structural differences. The present study evaluated the effect of both methionine sources on metabolism and growth of Nile tilapia. A growth trial was performed using three isonitrogenous and isoenergetic diets, containing plant ingredients as protein sources: DLM and MHA diets were supplemented on equimolar levels of Met, while REF diet was not supplemented. Hepatic free Met and one-carbon metabolites were determined in fish fed for 57 d. Metabolism of dl-Met and MHA was analysed by an in vivo time-course trial using ¹⁴C-labelled tracers. Only dl-Met supplementation significantly increased final body weight and improved feed conversion and protein efficiency ratios compared with the REF diet. Our findings indicate that Met in DLM fed fish follows the transsulphuration pathway, while in fish fed MHA and REF diets it is remethylated. The in vivo trial revealed that ¹⁴C-dl-Met is absorbed faster and more retained than ¹⁴C-MHA, resulting in a greater availability of free Met in the tissues when fish is fed with DLM diet. Our study indicates that dietary dl-Met supplementation improves growth performance and N retention, and that Met absorption and utilisation are influenced by the dietary source in tilapia juveniles.

Imbalanced dietary methionine-to-sulfur amino acid ratio can affect amino acid profiles, antioxidant capacity, and intestinal morphology of piglets

Animal protein sources such as fishmeal and plasma powder are excellent and indispensable sources of energy, amino acids, and minerals in animal production. Amino acid imbalance, especially methionine-to-sulfur amino acid (Met:SAA) ratio, caused by an imbalance of animal protein meal leads to growth restriction. This study was conducted to evaluate the effects of imbalanced Met:SAA ratio supplementation of different animal protein source diets on growth performance, plasma amino acid profiles, antioxidant capacity and intestinal morphology in a piglet model. Twenty-four weaned piglets (castrated males; BW = 10.46 ± 0.34 kg), assigned randomly into 3 groups (8 piglets/group), were fed for 28 d. Three experimental diets of equal energy and crude protein levels were as follows: 1) a corn-soybean basal diet with a Met:SAA ratio at 0.51 (BD); 2) a plasma powder diet with a low Met:SAA ratio at 0.41 (L-MR); 3) a fishmeal diet with a high Met:SAA ratio at 0.61 (H-MR). Results revealed that compared to BD, L-MR significantly decreased (P < 0.05) the activities of plasma total antioxidant capacity and glutathione peroxidase, plasma amino acid profiles, and significantly reduced (P < 0.05) villus height and crypt depth in the duodenum and jejunum. Additionally, L-MR significantly reduced (P < 0.05) the mRNA expression level of solute carrier family 7 member 9 (SlC7A9) in the ileum, and significantly increased (P < 0.05) mRNA expression levels of zonula occludens-1 (ZO-1) in the duodenum, and Claudin-1, ZO-1, sodium-coupled neutral amino acid transporters 2 (SNAT2) and SlC7A7 in the jejunum. H-MR significantly increased (P < 0.05) plasma SAA levels, and significantly reduced (P < 0.05) average daily feed intake, villus height, and villus height-to-crypt depth (VH:CD) ratio in the ileum compared to BD. In conclusion, L-MR may result in oxidative stress and villous atrophy but proves beneficial in improving intestinal barrier function and the activity of amino acid transporters for compensatory growth. H-MR may impair intestinal growth and development for weaned piglets. The research provides a guidance on the adequate Met:SAA ratio (0.51) supplementation in diet structure for weaned piglets.

Modulation of Crustacean Innate Immune Response by Amino Acids and Their Metabolites: Inferences From Other Species

Aquaculture production of crustaceans (mainly shrimp and crabs) has expanded globally, but disease outbreaks and pathogenic infections have hampered production in the last two decades. As invertebrates, crustaceans lack an adaptive immune system and mainly defend and protect themselves using their innate immune system. The immune system derives energy and metabolites from nutrients, with amino acids constituting one such source. A growing number of studies have shown that amino acids and their metabolites are involved in the activation, synthesis, proliferation, and differentiation of immune cells, as well as in the activation of immune related signaling pathways, reduction of inflammatory response and regulation of oxidative stress. Key enzymes in amino acid metabolism have also been implicated in the regulation of the immune system. Here, we reviewed the role played by amino acids and their metabolites in immune-modulation in crustaceans. Information is inferred from mammals and fish where none exists for crustaceans. Research themes are identified and the relevant research gaps highlighted for further studies.

Preliminary study of mechanisms of intestinal inflammation induced by plant proteins in juvenile hybrid groupers (♀Epinephelus fuscoguttatus×♂E. lanceolatu)

Fish fed a high plant protein diet exhibit intestinal inflammation, the mechanism of which needs to be clarified. We preliminarily elucidate the mechanism of the TLRs/MyD88-PI₃K/Akt signalling pathway in intestinal inflammation induced by plant proteins. The diets contained 60% fish meal (FM, controls), or had 45% of the fish meal protein replaced by soybean meal (SBM), peanut meal (PM), cottonseed meal (CSM) or cottonseed protein concentrate (CPC). After an 8-week feeding trial, fish were challenged by injection of Vibrio parahaemolyticus bacteria for 7 days until the fish stabilized. The results showed that the specific growth rate (SGR) of the FM group was higher than other groups. The SGR of the CPC group was higher than those of the SBM, PM and CSM groups. The catalase (CAT) contents in the serum of fish fed a plant protein diet were higher than in FM fish. The abundances of Rhodobacteraceae and Microbacteriaceae in the MI (mid intestine) were higher in the CPC group. The TLR-2 expressions in the MI and DI of plant protein-fed fish were up-regulated. The expressions of IL-6 in the PI and MI, of hepcidin and TLR-3 in the MI, and of TLR-3 in the DI, were all lower than those of fish fed FM. In the PI, MI and DI, the protein expressions of P-PI₃K/T-PI₃K in the SBM and PM groups were higher than in the FM group. After the challenge, the cumulative mortalities in the FM and CPC groups were lower than those of the SBM, PM and CSM groups. These results suggested that plant protein diets reduced antioxidant capacity and glycolipid metabolism, hindered the development of the intestine and reduced intestinal flora diversity. TLR-3 is involved in the immune regulation of the PI in CPC group, MI and DI in SBM, PM, CSM and CPC groups, while might be involved in the immune regulation of the PI in SBM, PM and CSM groups. Furthermore, PI₃K/Akt signaling does not participate in the regulation of PI and MI in the CSM group, MI and DI in the CPC group.

Effects of supplementation of DL-methionine on tissue and plasma antioxidant status during heat-induced oxidative stress in broilers

Exposure to high ambient temperature has been shown to impair growth performance and to cause oxidative stress in broilers. This study investigated the hypothesis that supplementation with methionine (Met) as DL-Met (DLM) more than the National Research Council recommendations improves growth performance and alleviates oxidative stress in broilers exposed to high ambient temperature. One-day-old male Cobb-500 broilers (n = 68) were allotted to 4 groups and phase-fed 3 basal diets during days 1 to 10, 11 to 21, and 22 to 35. One group was kept under thermoneutral temperature conditions and received the basal diets with Met + cysteine (Cys) concentrations according to recommendations of NRC. The other 3 groups were kept in a room with an increased ambient temperature from week 3 to 5 and were fed either the basal diet or the basal diets supplemented with 2 levels of DLM in which Met + Cys concentrations exceeded NRC recommendations by around 20% (group DLM1) and 40% (group DLM2), respectively. As expected, the broilers exposed to high ambient temperature showed a lower feed intake, lower body weight gains, a higher feed:gain ratio, and biochemical indications of oxidative stress in comparison to broilers kept under thermoneutral temperature conditions. Supplementation of DLM did not improve the growth performance in broilers exposed to high ambient temperature. However, the broilers supplemented with DLM had increased concentrations of glutathione in liver and breast muscle (groups DLM1 and DLM2), increased concentrations of tocopherols in the liver (group DLM2), and reduced concentrations of 7α-hydroxycholesterol and 7-ketocholesterol in heat-processed thigh muscle (groups DLM1 and DLM2) in comparison to the control group exposed to high ambient temperature. Concentrations of thiobarbituric acid-reactive substances and vitamin C in plasma, liver, and muscle were not different between the 3 groups exposed to heat stress. Nevertheless, the study shows that supplementation of DLM in slight excess of the Met concentration required for maximum growth performance improved the antioxidant status in tissues and reduced the susceptibility of muscle toward oxidation in heat-stressed broilers.

Substitution of Dietary Sulfur Amino Acids by dl-2-Hydroxy-4-Methylthiobutyric Acid Reduces Fractional Glutathione Synthesis in Weaned Piglets

BACKGROUND

Cys is limiting for reduced glutathione (GSH) synthesis and can be synthesized from Met. We hypothesized that the dietary Met hydroxyl analogue dl-2-hydroxy-4-methylthiobutyric acid (dl-HMTBA) affects Cys and GSH metabolism and oxidative stress defense differently than Met.

OBJECTIVE

The objective was to elucidate whether dl-HMTBA supplementation of a Met-deficient diet affects Cys flux, GSH fractional synthetic rate (FSR), and the basal oxidative stress level relative to Met supplementation in pigs.

METHODS

Twenty-nine male German Landrace piglets aged 28 d were allocated to 3 dietary groups: a basal diet limiting in Met (69% of Met plus Cys requirement) supplemented with either 0.15% l-Met (LMET; n = 9), 0.15% dl-Met (DLMET; n = 11), or 0.17% dl-HMTBA (DLHMTBA; n = 9) on an equimolar basis. At age 54 d the pigs received a continuous infusion of [1-13C]-Cys to calculate Cys flux and Cys oxidation. After 3 d, GSH FSR was determined by [2,2-2H2]-glycine infusion, and RBC GSH and oxidized GSH concentrations were measured. At age 62 d the animals were killed to determine hepatic mRNA abundances of enzymes involved in GSH metabolism, GSH concentrations, and plasma oxidative stress defense markers.

RESULTS

The Cys oxidation was 21-39% and Cys flux 5-15% higher in the fed relative to the feed-deprived state (P < 0.001). On average, GSH FSR was 49% lower (P < 0.01), and RBC GSH and total GSH concentrations were 12% and 9% lower, respectively, in DLHMTBA and DLMET relative to LMET pigs (P < 0.05). In the feed-deprived state, Gly flux, the GSH:oxidized glutathione (GSSG) ratio, RBC GSSG concentrations, plasma oxidative stress markers, and the hepatic GSH content did not differ between groups.

CONCLUSIONS

Although GSH FSR was higher in LMET compared with DLMET or DLHMTBA feed-deprived pigs, these differences were not reflected by lower oxidative stress markers and antioxidant defense enzymes in LMET pigs.

Dietary supplementation with free methionine or methionine dipeptide improves environment intestinal of broilers challenged with Eimeria spp

This study examined the influence of a diet enriched with free methionine (dl-Met) or methionine dipeptide (dl-MMet) on the intestinal health of Eimeria-challenged (EC) and unchallenged (UC) broilers. A non-supplemented, methionine-deficient diet (NS) was used as control. Treatments were arranged in a 2 × 3 factorial completely randomized design with eight replications. Broilers in the EC group were infected with sporulated oocysts of Eimeria spp. (E. acervulina, E. maxima, E. praecox, and E. mitis) at 14 d of age. Performance analysis, light and electron microscopy of the jejunum, analysis of genes related to apoptosis and cell proliferation in the jejunum, and blood tests were performed at 6 days post-inoculation (dpi). EC broilers had poorer performance than UC broilers, regardless of diet (P < 0.001). Broilers fed the dl-Met diet had greater weight gain (P = 0.004) and lower feed conversion ratio (P = 0.019) than broilers fed other diets. Jejunal sections from EC broilers fed the NS diet showed short (P = 0.001) and wide villi (P < 0.001) with increased crypt depth (P < 0.001) and reduced villus / crypt ratio (P = 0.001), jejunal absorptive surface area (P < 0.001), number of neutral goblet cells (Eimeria challenge: P = 0.048; diet P = 0.016), and mucin 2 (MUC2) gene expression (P = 0.018). EC birds fed the dl-MMet diet had higher enterocyte height (P < 0.001). Birds fed the dl-MMet diet had low lamina propria width (P = 0.009). UC broilers fed the dl-Met diet had the highest number of acidic goblet cells (P = 0.005), whereas EC broilers assigned the dl-MMet diet showed the highest number of intraepithelial lymphocytes (P = 0.033). Reduced expression of caspase-3 (CASP3) (P = 0.005), B-cell lymphoma 2 (BCL2) (P < 0.001), mechanistic target of rapamycin (MTOR) (P < 0.001), and ribosomal protein S6 kinase B1 (RPS6KB1) (P < 0.001) genes was observed in EC animals. MTOR expression levels were highest in birds fed the dl-MMet diet (P = 0.004). Plasma activities of aspartate aminotransferase (AST) was influenced by both diet (P = 0.002) and Eimeria challenge (P = 0.005), with EC broilers assigned the NS diet showing the highest levels. EC broilers fed the NS diet had higher creatine kinase (CK) activity (P = 0.049). EC broilers had lower plasma uric acid (P = 0.004) and higher serum mucoproteins level (P < 0.001). These results indicate that methionine dipeptide supplementation is able to mitigate the harmful intestinal effects of Eimeria spp. in broilers.

Beneficial antioxidant status of piglets from sows fed selenomethionine compared with piglets from sows fed sodium selenite

BACKGROUND

Studies in mammals proved dietary organic selenium (Se) being superior to inorganic Se regarding effects on growth performance, antioxidative status, immune response, and Se homeostasis. However, the picture of possible effects of different Se sources and - levels can be expanded. The present field study evaluated the effects on weight gain, hematological and selected biochemical variables as well as plasma concentrations of vitamin E (vitE), total Se and selenobiomolecules in piglets throughout the suckling period.

METHODS

Piglets were monitored from birth to 38 days of age (d). The mother sows' diets were enriched with l-selenomethionine (SeMet-0.26 and -0.43 mg Se/kg feed) or sodium selenite (NaSe-0.40 and -0.60 mg Se/kg feed) from 1 month prior to farrowing until the end of lactation period. Piglets received pelleted feed supplemented with Se similarly to the sows' diets from one week of age. Selenite at 0.40 mg Se/kg (NaSe-0.40) represents a common Se source and -level in pig feed and served as control diet.

RESULTS

From 24d, piglets in SeMet-groups had higher mean body weight (BW) compared with piglets from sows fed NaSe-0.40. Furthermore, from five-d and above, piglets from sows fed NaSe-0.60 had significantly higher BW than offspring from sows fed NaSe-0.40. Neonatal piglets in group SeMet-0.43 had significantly lower red blood cell counts (RBC), hemoglobin (Hgb) and hematocrit (Hct) concentrations compared with piglets from sows fed with NaSe-0.40. Neonatal and 5d-old piglets in group SeMet-0.26 showed higher gamma-glutamyl transferase activity than piglets in group NaSe-0.40. From five d and above, group NaSe-0.60 excelled with increased specific hematological variables culminating at age 38d with increased Hct, mean corpuscular volume (MCV), and MC hemoglobin (MCH) as well as increased activities of aspartate transaminase and lactate dehydrogenase compared with the other groups. Generally, offspring in the SeMet groups had higher total Se-concentrations in plasma than those from sows fed selenite, and showed a dose-response effect on plasma Se-concentrations. Furthermore, SeMet-fed piglets had higher plasma levels of the selenoproteins (Sel) glutathione peroxidase 3 (GPx3) and SelP as well as selenoalbumin. Plasma vitE levels were significantly negatively correlated with RBC throughout trial period.

CONCLUSIONS

Maternal supplementation with SeMet during gestation influenced hematology and clinical biochemistry in neonatal piglets in a different way than in offspring from sows receiving selenite enriched diets. Growth performance was positively influenced by both dietary Se source and Se level. Higher plasma levels of GPx3 observed in piglets receiving SeMet probably improved the protection against birth or growth related oxidative stress. These might prime the piglets for demanding situations as indicated by higher weight gain in offspring from sows fed with SeMet-supplemented diets. Our results on some enzyme activities might indicate that piglets fed NaSe-0.60 had to cope with increased levels of oxidative stress compared with those originating from sows fed SeMet or lower dietary levels of selenite. We assume that combining inorganic and organic Se sources in complete feed for breeding sows might be beneficial fro reproduction and the offspring's performance.

Dietary Betaine Improves Intestinal Barrier Function and Ameliorates the Impact of Heat Stress in Multiple Vital Organs as Measured by Evans Blue Dye in Broiler Chickens

In a 2 × 2 factorial design, 60 male Ross-308 broilers were fed either a control or 1 g/kg betaine diet and housed under thermoneutral (TN) or heat stress (HS) conditions. Broilers were acclimated to diets for 1 week under TN (25 °C), then either kept at TN or HS, where the temperature increased 8 h/day at 33 °C and 16 h/day at 25 °C for up to 10 days. Respiration rate (RR) was measured at four time points, and on each of 1, 2, 3, 7 and 10 days of HS, 12 broilers were injected with 0.5 mg/kg of Evans Blue Dye (EBD) solution to quantify regional changes in tissue damage. Betaine was quantified in tissues, and ileal damage was assessed via morphometry and transepithelial resistance (TER). Heat stress elevated RR (p < 0.001) and resulted in reduced villous height (p = 0.009) and TER (p < 0.001), while dietary betaine lowered RR during HS (p < 0.001), increased betaine distribution into tissues, and improved ileal villous height (p < 0.001) and TER (p = 0.006). Heat stress increased EBD in the muscle and kidney of chickens fed the control diet but not in those receiving betaine. Overall, these data indicate that supplemented betaine is distributed to vital organs and the gastrointestinal tract, where it is associated with improved tolerance of HS. Furthermore, EBD markers help reveal the effects of HS on organs dysfunction.

Combination of ultrasound-assisted ethyl chloroformate derivatization and switchable solvent liquid-phase microextraction for the sensitive determination of l-methionine in human plasma by GC-MS

A green and fast analytical method for the determination of l-methionine in human plasma is presented in this study. Preconcentration of the analyte was carried out by switchable solvent liquid phase microextraction after ethyl chloroformate derivatization reaction. Instrumental detection of the analyte was performed by means of gas chromatography-mass spectrometry. N,N-Dimethyl benzylamine was used in the synthesis of switchable solvent. Protonated N,N-dimethyl benzylamine volume, volume/concentration of sodium hydroxide, and vortex period were meticulously fixed to their optimum values. Besides, ethyl chloroformate, pyridine, and ethanol volumes were optimized in order to get high derivatization yield. After the optimization studies, limit of detection and quantitation values were attained as 3.30 and 11.0 ng/g, respectively, by the developed switchable solvent liquid phase microextraction gas chromatography-mass spectrometry method that corresponding to 76.7-folds enhancement in detection power of the gas chromatography-mass spectrometry system. Applicability and accuracy of the switchable solvent liquid phase microextraction-gas chromatography-mass spectrometry method were also checked by spiking experiments. Percent recovery results were ranged from 97.8 to 100.5% showing that human plasma samples could be analyzed for its l-methionine level by the proposed method.

Different dietary methionine to lysine ratios in the lactation diet: effects on the performance of sows and their offspring and methionine metabolism in lactating sows

Background

Over the last decade, the nutritional requirements of lactating modern genotype sows have increased. The current nutritional recommendations might be unable to meet the needs of increased litter size and milk production, and thus the nutritional requirements need to be re-evaluated. The current study was conducted to investigate the effects of dietary methionine to lysine (Met:Lys) ratios on the performance of and methionine metabolism in lactating sows.

Results

During the 1^st week of lactation, piglets reared on sows in the 0.37 to 0.57 Met:Lys ratio groups grew faster than those reared on sows in the control group (0.27) (P < 0.01). The 0.37-ratio group showed increased levels of GSH-Px in plasma during lactation (P < 0.01) and decreased concentrations of urea nitrogen in the plasma of sows (P < 0.05). Compared with the 0.27-ratio group, the levels of T-AOC and GSH-Px in the plasma and homocysteine in the milk of lactating sows were significantly increased in sows in the 0.47-ratio group (P < 0.01). In sows fed a 0.57-ratio diet, the levels of glutathione and taurine in the plasma and milk were improved significantly during lactation. However, the content of TBARS in the blood (P < 0.05 at day 7 and P = 0.06 at weaning day) was increased (P < 0.01). Moreover, there were linear increases in the levels of homocysteine in the blood and milk of sows during the lactation period (P < 0.01) with increased dietary Met:Lys ratios in the lactation diet.

Conclusions

The current study indicated that increasing the dietary Met:Lys ratio (0.37~0.57) in the lactation diet had no significant effect on the overall performance of sows or the colostrum and milk composition, but it increased piglet mean BW and piglet ADG during the first week of lactation. Increasing dietary methionine levels had no significant effect on antioxidant function in lactation sows, even though it increased levels of GSH and GSH-Px in the plasma of sows during lactation. However, the content of homocysteine in the plasma and milk increased during lactation due to a high level of dietary methionine.

Effects of methionine partially replaced by methionyl-methionine dipeptide on intestinal function in methionine-deficient pregnant mice

This study was to compare the effects of parenteral supplementation of methionyl-methionine (Met-Met) or Met on intestinal barrier function in Met-deficient pregnant mice. Pregnant mice were randomly divided into three groups. The Control group was provided a diet containing Met and received i.p. injection of saline. The Met group was fed the same diet but without Met and received daily i.p. injection of 35% of the Met contained in the control diet. The Met-Met group was treated the same as the Met group, except that 25% of the Met injected was replaced with Met-Met. Met-Met promoted villus surface area in ileum compared with Met alone. In addition, the mRNA abundance of amino acid and glucose transporters in the small intestine was altered with Met-Met. Moreover, Met-Met increased tight junction protein and decreased apoptosis-related proteins expression in the jejunum and ileum. These results suggest that Met-Met can promote intestinal function over Met alone in Met-deficient mice.

Effects of dietary methionine supplementation on growth performance, intestinal morphology, antioxidant capacity and immune function in intra-uterine growth-retarded suckling piglets

This study investigated the effects of dietary supplementation with L -methionine (L -Met), DL -methionine (DL -Met) and calcium salt of the methionine hydroxyl analog (MHA-Ca) on growth performance, intestinal morphology, antioxidant capacity and immune function in intra-uterine growth-retarded (IUGR) suckling piglets. Six normal birthweight (NBW) female piglets and 24 same-sex IUGR piglets were selected at birth. Piglets were fed nutrient adequate basal diet supplemented with 0.08% L -alanine (NBW-CON), 0.08% L -alanine (IUGR-CON), 0.12% L -Met (IUGR-LM), 0.12% DL -Met (IUGR-DLM) and 0.16% MHA-Ca (IUGR-MHA-Ca) from 7 to 21 days of age respectively (n = 6). The results indicated that IUGR decreased average daily milk (dry matter) intake and average daily gain and increased feed conversion ratio of suckling piglets (p < 0.05). Compared with the NBW-CON piglets, IUGR also impaired villus morphology and reduced antioxidant capacity and immune homeostasis in the intestine of IUGR-CON piglets (p < 0.05). Supplementation with L -Met enhanced jejunal villus height (VH) and villus area and ileal VH of IUGR piglets compared with IUGR-CON piglets (p < 0.05). Similarly, DL -Met supplementation increased VH and the ratio of VH to crypt depth in the jejunum compared with IUGR-CON pigs (p < 0.05). Supplementation with L -Met and DL -Met (0.12%) tended to increase reduced glutathione content and reduced glutathione: oxidized glutathione ratio and decrease protein carbonyl concentration in the jejunum of piglets when compared with the IUGR-CON group (p < 0.10). However, supplementation with MHA-Ca had no effect on the intestinal redox status of IUGR piglets (p > 0.10). In conclusion, supplementation with either L -Met or DL -Met has a beneficial effect on the intestinal morphology and antioxidant capacity of IUGR suckling piglets.

The influence of zinc-methionine bioplex supplementation to pregnant and lactating sheep on selected wool parameters

The most important nutrients affecting wool production include sulfur amino acids, such as methionine, and minerals, such as zinc, and their deficiency may cause wool production decrease. The aim of this study was to evaluate an effect of zinc and methionine chelate addition on the qualitative characteristics of Merino ewes wool and zinc content in wool fibers and on their surface. Histological evaluation of fibers was also performed. The study included 22 Polish Merino ewes divided into two groups: control and experimental (0.4 g chelates daily per head). The experiment lasted for 4 months (3.5 months of pregnancy and 2 weeks of early lactation). The length, thickness and breaking force of wool fibers were higher in the experimental group compared to the control group. Higher content of zinc in wool of sheep from the experimental group was also demonstrated. The histological structure of fibers from both groups did not differ, as the content of zinc on their surface. It can be concluded on the basis of the obtained results that the addition of chelates favorably influenced the thickness compensation of wool fibers and amount of wool obtained from sheep during pregnancy and early lactation, as well as mechanical features of wool.

Substitution of Dietary Sulfur Amino Acids by DL-2-hydroxy-4-Methylthiobutyric Acid Increases Remethylation and Decreases Transsulfuration in Weaned Piglets

BACKGROUND

DL-2-hydroxy-4-methylthiobutyric acid (DL-HMTBA), an L-methionine (L-Met) hydroxyl analogue, has been suggested to be a dietary L-Met source. How dietary DL-HMTBA compared with L-Met affects whole-body L-Met kinetics in growing individuals is unknown.

OBJECTIVES

We determined to what extent DL-HMTBA supplementation of an L-Met-deficient diet affects whole-body L-Met and L-cysteine (L-Cys) kinetics, protein synthesis (PS), and the L-Met incorporation rate in liver protein (L-MetInc) compared with L-Met and DL-Met supplementation in a piglet model.

METHODS

Forty-five, 28-d-old weaned piglets (male, German Landrace) were allocated to 4 dietary groups: L-Met-deficient diet [Control: 69% of recommended L-Met plus L-Cys supply; 0.22% standardized ileal digestible (SID) L-Met; 0.27% SID L-Cys; n = 12] and Control diet supplemented equimolarly to 100% of recommended intake with either L-Met (n = 12; LMET), DL-Met (n = 11; DLMET), or DL-HMTBA (n = 10; DLHMTBA). At 47 d of age, the piglets were infused with L-[1-13C; methyl-2H3]-Met and [3,3-2H2]-Cys to determine the kinetics and PS rates. Plasma amino acid (AA) concentrations, hepatic mRNA abundances of L-Met cycle and transsulfuration (TS) enzymes, and L-MetInc were measured.

RESULTS

During feed deprivation, L-Met kinetics did not differ between groups, and were ≤3 times higher in the fed state (P < 0.01). Remethylation (RM) was 31% and 45% higher in DLHMTBA than in DLMET and Control pigs, respectively, and the RM:transmethylation (TM) ratio was 50% higher in DLHMTBA than in LMET (P < 0.05). Furthermore, TS and the TS:TM ratio were 32% lower in DLHMTBA than in LMET (P < 0.05). L-MetInc was 42% lower in DLMET and DLHMTBA than in L-Met-deficient Control pigs, whereas plasma AA and hepatic mRNA abundances were similar among DL-HMTBA-, L-Met-, and DL-Met-supplemented pigs.

CONCLUSIONS

In piglets, DL-HMTBA compared with L-Met and DL-Met supplementation increases RM and reduces the TS rate to conserve L-Met, but all 3 Met isomers support growth at a comparable rate.

Dietary sulfur amino acids affect jejunal cell proliferation and functions by affecting antioxidant capacity, Wnt/β-catenin, and the mechanistic target of rapamycin signaling pathways in weaning piglets

Intestinal epithelial cells undergo rapid renewal along the crypt-villus axis (CVA), which ensures intestinal functions. Weaning stress differentially effects intestinal epithelial cell metabolism and physiological states along the CVA. Sulfur amino acids (SAA) play a key role in intestinal epithelial cell functioning. This study evaluated the effects of SAA dietary supplementation on weaning pig jejunal epithelial cells along the CVA. Sixteen Duroc × Landrace × Yorkshire piglets (6.16 ± 0.22 kg BW) were weaned at 21 d of age and were blocked by BW and gender and the randomly assigned to 1 of 2 groups fed diets consisting of low (0.53%) or high (0.85%) levels of SAA for a 7-d period. All piglets were euthanized for tissue sampling on day 7 postweaning. Jejunal epithelial cells were isolated along the CVA to yield 3 "cell fractions" (upper villus, middle villus, and crypt cells). The number of proliferating cells per crypt of piglets fed the high SAA diet was lower (P < 0.05) than that for low SAA diet. High SAA diet piglets tended to have decreased (P = 0.059) sucrase activities compared low SAA diet piglets. A high SAA diet increased (P < 0.05) total antioxidant capacity, catalase, and superoxide dismutase activities compared with a low SAA diet. mRNA expression levels of claudin-1, Slc5a1, and Slc7a9 in high SAA diet piglets were lower (P < 0.05) than for low SAA diet piglets. There were no interactions between dietary SAA and cell sections along the CVA for enzyme activities and mRNA expression in any of the weaned piglets. Protein amounts and phosphorylation levels related to Wnt/β-catenin and mechanistic targeting of rapamycin (mTOR) signaling pathways were affected by SAA in weaning piglets. These findings indicate that dietary SAA affects jejunal cell proliferation and functions in weaning piglets. There appears to be no interactions between dietary SAA and cell sections along the CVA. The effects of SAA may be partly through affecting antioxidant capacity, and Wnt/β-catenin and mTOR signaling pathway.

Infant diet and maternal gestational weight gain predict early metabolic maturation of gut microbiomes

Commensal gut bacterial communities (microbiomes) are predicted to influence human health and disease1,2. Neonatal gut microbiomes are colonized with maternal and environmental flora and mature toward a stable composition over 2-3 years3,4. To study pre- and postnatal determinants of infant microbiome development, we analyzed 402 fecal metagenomes from 60 infants aged 0-8 months, using longitudinal generalized linear mixed models (GLMMs). Distinct microbiome signatures correlated with breastfeeding, formula ingredients, and maternal gestational weight gain (GWG). Amino acid synthesis pathway accretion in breastfed microbiomes complemented normative breastmilk composition. Prebiotic oligosaccharides, designed to promote breastfed-like microflora5, predicted functional pathways distinct from breastfed infant microbiomes. Soy formula in six infants was positively associated with Lachnospiraceae and pathways suggesting a short-chain fatty acid (SCFA)-rich environment, including glycerol to 1-butanol fermentation, which is potentially dysbiotic. GWG correlated with altered carbohydrate degradation and enriched vitamin synthesis pathways. Maternal and postnatal antibiotics predicted microbiome alterations, while delivery route had no persistent effects. Domestic water source correlates suggest water may be an underappreciated determinant of microbiome acquisition. Clinically important microbial pathways with statistically significant dietary correlates included dysbiotic markers6,7, core enterotype features8, and synthesis pathways for enteroprotective9 and immunomodulatory10,11 metabolites, epigenetic mediators1, and developmentally critical vitamins12, warranting further investigation.

Prematurity reduces citrulline-arginine-nitric oxide production and precedes the onset of necrotizing enterocolitis in piglets

Necrotizing enterocolitis (NEC) is associated with low plasma arginine and vascular dysfunction. It is not clear whether low intestinal citrulline production, the precursor for arginine synthesis, occurs before and thus predisposes to NEC or if it results from tissue damage. This study was designed to test the hypothesis that whole body rates of citrulline, arginine, and nitric oxide synthesis are low in premature pigs and that they precede NEC. Piglets delivered by cesarean section at 103 days [preterm (PT)], 110 days [near-term (NT)], or 114 days [full-term (FT)] of gestation were given total parenteral nutrition and after 2 days orogastrically fed infant formula for 42 h to induce NEC. Citrulline and arginine fluxes were determined before and during the feeding protocol. Gross macroscopic and histological NEC scores and plasma fatty acid binding protein (iFABP) concentration were determined as indicators of NEC. Intestinal gene expression for enzymes of the arginine pathway were quantitated. A lower ( P < 0.05) survival rate was observed for PT (8/27) than for NT (9/9) and FT pigs (11/11). PT pigs had higher macroscopic gross ( P < 0.05) and histological NEC ( P < 0.05) scores and iFABP concentration ( P < 0.05) than pigs of more advanced gestational age. PT pigs had lower citrulline production and arginine fluxes ( P < 0.05) throughout and a reduced gene expression in genes of the citrulline-arginine pathway. In summary, intestinal enzyme expression and whole body citrulline and arginine fluxes were reduced in PT pigs compared with animals of more advance gestational age and preceded the development of NEC. NEW & NOTEWORTHY Arginine supplementation prevents necrotizing enterocolitis (NEC), the most common gastrointestinal emergency of prematurity. Citrulline (precursor for arginine) production is reduced during NEC, and this is believed to be a consequence of intestinal damage. In a swine model of NEC, we show that intestinal gene expression of the enzymes for citrulline production and whole body citrulline and arginine fluxes are reduced and precede the onset of NEC in premature pigs. Reduced citrulline production during prematurity may be a predisposition to NEC.

The effects of dietary sulfur amino acids on growth performance, intestinal morphology, enzyme activity, and nutrient transporters in weaning piglets

Early weaning results in intestinal dysfunction in piglets, while sulfur amino acids (SAA) are involved in improving intestinal functions. We tested a hypothesis that dietary supplementation with SAA can improve intestinal functions of weaning piglets and analyzed the effects of different dietary SAA levels on intestinal functions. A total of 80 piglets (Duroc × Landrace × Yorkshire) were weaned at 21 d of age and randomly assigned to one of the five diets that contained 0.53%, 0.63%, 0.74%, 0.85%, or 0.96% SAA, which corresponded to 70%, 85%, 100%, 115%, or 130% of the SAA:Lys ratio recommended by the National Research Council (2012). The 14 d feeding experiment involved 16 pens per diet and one piglet per pen. Eight randomly selected piglets from each treatment were euthanized for tissue sampling on day 7 and 14 post weaning. Supplementation with SAA led to a rise over time in G:F (linear, P = 0.001; quadratic, P = 0.001). Between day 0 and 14 of treatment, the jejunal crypt depth decreased (linear, P = 0.018; quadratic, P = 0.015), while that of the duodenal villus (linear, P = 0.049) and ileal villus width (linear, P = 0.029; quadratic, P = 0.034) increased. The activities of jejunal alkaline phosphatase (ALP) were quadratically increased (P = 0.040) from day 0 to 14 due to dietary SAA. Dietary SAA also elevated the activities of jejunal lactase (linear, P = 0.003; quadratic, P = 0.004), jejunal sucrase (linear, P = 0.032; quadratic, P = 0.027), and jejunal contents of glutathione (GSH) from day 0 to 7, as well as the activity of jejunal maltase (linear, P = 0.014; quadratic, P = 0.001) between day 0 and 14. During the first wk, dietary SAA linearly increased the amounts of intestinal-type fatty acid-binding protein (I-FABP) (P = 0.048) and SGLT-1 (P = 0.021) and linearly decreased the amount of GLUT2 (P = 0.029) proteins in the jejunum. The abundance of jejunal I-FABP (P = 0.044) and PEPT1 (P = 0.049) protein linearly increased from day 0 to 14 in response to this supplementation. These findings indicate that there is a dose-dependent response to dietary SAA on feed efficiency and intestinal parameters of weanling pigs.