Dietary Trp Research Articles

Effects of dietary tryptophan and threonine supplementation above nutritional recommendations on performance, diarrhoea, and intestinal health parameters in weaned piglets

Pigs may have an enhanced need for the amino acids (AA) tryptophan (Trp) and threonine (Thr) around weaning. This study aimed to evaluate the effect of additional dietary Trp and Thr above nutrient requirements; on performance, the probability of diarrhoea, intestinal permeability, and morphology in weaned pigs. A total of 120 piglets (7.20 ± 0.26 kg), weaned at day 28, were randomly allocated to five dietary treatments and individually housed. A standard diet with maximum crude protein (CP) according to Danish nutrient recommendations was used as control diet (HP). The other dietary treatments consisted of the HP diet with additional 20% Thr (THR), 20% Trp (TRP) or 20% of both (THR+TRP) relative to the recommendations for these AA (standardised ileal digestible (SID); 7.8 g SID Thr/kg and 2.6 g SID Trp/kg). Finally, a low-protein diet according to recommendations was included as a negative control (203 g CP/kg DM; LP). Diets were designed to be isoenergetic and fed ad libitum from 0 to 4 weeks post-weaning. Faecal consistency was evaluated daily using a 4-scale visual scoring system. Blood was collected on day 4, 14, 21, and 28 and small intestinal and colonic tissue were obtained from HP, LP, and THR+THR pigs at day 28. Average daily gain and feed intake were unaffected by diet (P > 0.10), whereas the feed conversion ratio was increased with 11% in LP compared with HP pigs (P < 0.05). Additionally, Thr and Trp did not affect the probability for diarrhoea (P > 0.10), neither in separate weeks nor across the entire period. The number of antibiotic treatment days were 3.92 days higher for TRP compared with THR+TRP pigs (P = 0.01), with the other three diets being intermediate. The concentration of the intestinal permeability markers diamine oxidase and d-lactate in blood was unaffected by the diets. The systemic inflammatory markers haptoglobin and C-reactive protein did not differ between feeding groups. The THR+TRP diet increased the area of neutral mucin-producing cells in the colon with 83% compared with the HP diet (P = 0.02), but other intestinal morphology measurements were unaffected by the diets. In conclusion, supplementation with Thr and Trp together stimulated neutral mucin production in the large intestine and reduced the number of days where antibiotics treatments against diarrhoea is necessary.

Excessive dietary L-tryptophan regulated amino acids metabolism and serotonin signaling in the colon of weaning piglets with acetate-induced gut inflammation.

L-Tryptophan (Trp) was shown to improve the gut barrier and growth of weaning piglets. However, whether excessive dietary Trp regulates amino acids (AAs) metabolism and gut serotonin (5-HT) homeostasis in piglets with gut inflammation is not clear yet. We hypothesize that excessive dietary Trp alleviates acetate-induced colonic inflammation and gut barrier damage in weaning piglets partially through the regulation of colonic AAs metabolism and 5-HT signaling. Fifty-four 21-day-old weaned piglets were divided into six groups: control, acetate, 0.2%Trp, 0.2%Trp + acetate, 0.4% Trp, and 0.4%Trp + acetate. Piglets were fed a basal diet supplemented with 0%, 0.2%, or 0.4% of Trp throughout the 12-day experiment. During days 0-7, all piglets had free access to diet and drinking water. On day 8, piglets were intrarectal administered with 10mL of 10% acetate saline solution or 0.9% saline. During days 8-12, all piglets were pair-fed the same amount of feed per kg bodyweight. Results showed that excessive dietary Trp alleviated acetate-induced reductions in daily weight gain and increase in feed/gain ratio. Trp restored (P < 0.05) acetate-induced increase in concentrations of free aspartate, glutamate/glutamine, glycine, 5-HT, and 3-methylindole in the colon, downregulation of zonula occludens-1 and 5-HT reuptake transporter (SERT) expression and upregulation of IL-1β, IL-8, TLR4, and 5-HT receptor 2A (HTR2A) expression, and the increase in ratios of p-STAT3/ STAT3 and p-p65/p65 in the colon. The above findings suggested that excessive dietary Trp in the proper amount regulated colonic AAs metabolism, 5-HT homeostasis, and signaling that may contribute as important regulators of gut inflammation during the weaning transition.

Increased dietary Trp, Thr, and Met supplementation improves growth performance and protein deposition of salmonella-challenged growing pigs under poor housing conditions.

Highly intensified rearing conditions and precarious sanitary management predispose pigs to immune system activation, altered amino acid (AA) metabolism, and decreased growth performance. Thus, the main objective of this study was to evaluate the effects of increased dietary tryptophan (Trp), threonine (Thr), and methionine + cysteine (Met + Cys) supplementation on performance, body composition, metabolism, and immune responses of group-housed growing pigs under challenging sanitary conditions. A hundred and twenty pigs (25.4 ± 3.7 kg) were randomly assigned to a 2 × 2 factorial arrangement, consisting of two sanitary conditions (SC, good [GOOD] or salmonella-challenge and poor housing condition [Salmonella Typhimurium (ST) + POOR]) and two diets, control (CN) or supplemented with AA (Trp, Thr, and Met + Cys:Lys ratios 20% higher than those of the CN diet [AA>+]). Pigs were followed during the growing phase (25-50 kg) and the trial lasted 28 d. The ST + POOR SC pigs were challenged with Salmonella Typhimurium and raised in a poor housing condition. The ST + POOR SC increased rectal temperature, fecal score, serum haptoglobin, and urea concentration (P < 0.05) and decreased serum albumin concentration (P < 0.05) compared with GOOD SC. Body weight, average daily feed intake, average daily gain (ADG), feed efficiency (G:F), and protein deposition (PD) were greater in GOOD SC than in ST + POOR SC (P < 0.01). However, pigs housed in ST + POOR SC fed with AA+ diet had lower body temperature (P < 0.05), increased ADG (P < 0.05) and nitrogen efficiency (P < 0.05), and a tendency for improved PD and G:F (P < 0.10) compared with CN diet fed pigs. Regardless of the SC, pigs fed AA+ diet had lower serum albumin (P < 0.05) and tended to decrease serum urea levels (P < 0.10) compared with CN diet. The results of this study suggest that the ratio of Trp, Thr, and Met + Cys to Lys for pigs are modified by sanitary conditions. Furthermore, supplementation of diets with a blend of Trp, Thr, and Met + Cys improves performance, especially under salmonella-challenge and poor housing conditions. Dietary tryptophan, threonine, and methionine supplementation can modulate immune status and influence resilience to sanitary challenges.

Effects of Dietary Tryptophan on Growth Performance, Plasma Parameters, and Internal Organs of 1-28-Day-Old Sichuan White Geese.

Although the nutrient requirements of geese during the growing stage are known, the dietary requirement of amino acids during the starting period remains unclear. Optimum nutrient supplementation during the starting period is crucial for improved survival rates, body-weight gain, and marketing weight in geese. Our study focused on the effect of dietary tryptophan (Trp) supplementation on the growth performance, plasma parameters, and internal-organ relative weights in 1-28-day-old Sichuan white geese. A total of 1080 1-day-old geese were divided randomly into six Trp-supplemented (0.145%, 0.190%, 0.235%, 0.280%, 0.325%, and 0.370%) groups. Average daily feed intake (ADFI), average daily gain (ADG), and duodenal relative weight were highest in the 0.190% group, brisket protein level and jejunal relative weight in the 0.235% group, and plasma total protein and albumin levels in the 0.325% group (P < 0.05). Dietary Trp supplementation did not significantly affect the relative weights of the spleen, thymus, liver, bursa of Fabricius, kidneys, and pancreas. Moreover, the 0.145% - 0.235% groups showed significantly decreased liver fat (P < 0.05). Based on the non-linear regression analysis of ADG and ADFI, the dietary Trp levels between 0.183% and 0.190% were estimated to be optimal for 1-28-day-old Sichuan white geese. In conclusion, optimal dietary Trp supplementation in 1-28-day-old Sichuan white geese resulted in increased growth performance (0.180% - 0.190%) along with improved proximal intestinal development and brisket protein deposition (0.235%). Our findings provide basic evidence and guidance for optimal levels of Trp supplementation in geese.

Dietary supplementation with tryptophan increases the plasma concentrations of tryptophan, kynurenine, and melatonin in Yili mares

Context Tryptophan (Trp) is the precursor of melatonin (MT) and the latter plays vital physiological roles in mares. Aims The purpose of this experiment was to investigate the effects of dietary Trp supplementation on the plasma Trp, kynurenine (Kyn), 5-hydroxytryptophan (5-HT), and melatonin (MT) concentrations in female Yili horses. Methods Twenty Yili mares aged 2 years with mean bodyweight (BW) of 263.5 ± 14.77 kg and of similar stature were selected and randomly allocated to the control (CON; basal diet), basal diet plus Trp at 20 mg/kg BW (TRP1), basal diet plus Trp at 40 mg/kg BW (TRP2), or basal diet plus Trp at 60 mg/kg BW (TRP3) group. Key results The plasma total Trp, Kyn, and MT concentrations in all Trp groups steadily increased, reached their peak values, and gradually decreased after Trp supplementation between 0 h and 12 h. However, the plasma 5-HT concentration displayed the opposite trend. Peak plasma total Trp and 5-HT concentrations were attained between 1 h and 3 h, while those of KYN and MT appeared between 4 h and 6 h after Trp supplementation. The plasma total Trp and Kyn concentrations were significantly higher in TRP2 and TRP3 than in CON between 1 h and 12 h (P &lt; 0.05) after Trp supplementation. The plasma 5-HT concentration was significantly (P &lt; 0.05) lower in TRP1 than in CON at 3 h, 4 h, 6 h, 9 h, and 12 h after Trp supplementation. The plasma MT concentrations in TRP1 and TRP2 were significantly (P &lt; 0.05) higher than in CON at 3 h, 4 h, and 12 h, and at 0 h, 1 h, and 12 h after Trp supplementation (P &lt; 0.05). Conclusions Dietary Trp supplementation can increase the plasma total Trp, Kyn, and MT concentrations in Yili mares and the optimal Trp dosage was 20 mg/kg BW. Implication The addition of Trp to a basal diet or feed may increase the plasma total Trp, Kyn, and MT concentrations in female horses.

Evaluation of tryptophan biomass as an alternative to conventional crystalline tryptophan in broiler diets

The current experiment was conducted to evaluate tryptophan (Trp) biomass as an alternative to conventional crystalline Trp in broiler diets. In a growth trial, a total of 288 eight-d-old chicks were randomly allotted to 1 of 3 treatments with 8 replicates. A negative control (NC) diet was formulated to contain 40% less amounts of digestible Trp than its requirement. A positive control (PC) diet was formulated to meet digestible Trp requirement by supplementing with crystalline Trp. An additional diet was prepared by supplementing Trp biomass to have equal amounts of digestible Trp in the PC diet. In a metabolism trial, a total of 54 forty two-d-old chickens were allotted 1 of 3 dietary treatments used in the growth trial with 9 replicates to evaluate the effect of dietary Trp biomass on gross energy (GE) and nitrogen (N) utilization in broiler diets. Results indicated that PC and Trp biomass treatments had greater ( P < 0.05) body weight gain (BWG) and feed intake (FI) than NC treatment. The Trp biomass treatment showed no differences in BW, BWG, and FI compared with PC treatment. The PC treatment had less ( P < 0.05) blood heterophil to lymphocyte ratio than NC treatment. The PC and Trp biomass treatments had greater ( P < 0.05) villus height to crypt depth ratio than NC treatment. Inclusion of Trp biomass did not affect GE and N utilization in broiler diets. In conclusion, Trp biomass can be used as a potential alternative to conventional crystalline Trp in broiler diets.

Dietary Tryptophan-Mediated Aryl Hydrocarbon Receptor Activation by the Gut Microbiota Alleviates Escherichia coli-Induced Endometritis in Mice.

ABSTRACTIntestinal microbiota-mediated aryl hydrocarbon receptor (AhR) activation plays an important role in host–microbiota interactions and disease development. However, whether AhR activation mediates infection-induced inflammation in remote organs is not clear. The purpose of this study is to assess the effects and underlying mechanism of AhR activation and gut microbiota-mediated dietary tryptophan (Trp) metabolism on infection-induced inflammation using an Escherichia coli (E. coli)-induced endometritis model in mice. We found that AhR activation by 6-formylindolo (3,2-b) carbazole (Ficz), which is an AhR agonist derived from the photooxidation of Trp, alleviated E. coli-induced endometritis by repairing barrier function and inhibiting inflammatory responses, while inhibition of AhR by CH223191, which is a synthetic AhR antagonist, aggravated E. coli-induced endometritis. Gut dysbiosis damaged AhR activation and exacerbated E. coli-induced endometritis in mice, which responded to the reduced abundance of AhR ligand producers, such as Lactobacillus spp. Supplementation with dietary Trp ameliorated E. coli-induced endometritis in a microbiota-dependent manner, which was associated with the production of AhR ligands. Administration of AhR ligands, including indole and indole aldehyde, but not indole-3-propionic acid, rescued the protective effect of Trp on E. coli-induced endometritis in dysbiotic mice. Moreover, consumption of Lactobacillus reuteri (L. reuteri) containing AhR ligand-producing capability also alleviated E. coli-induced endometritis in mice in an AhR-dependent manner. Our results demonstrate that microbiota-mediated AhR activation is a key factor in fighting pathogen-caused inflammation, which leads to a potential strategy to regulate the gut microbiota and metabolism by dietary Trp or probiotics for the intervention of infectious diseases and reproductive health.IMPORTANCE Infection-induced endometritis is a common and frequently occurring disease in humans and animals. Accumulating evidence suggests an important role of the gut microbiota in the development of infection-induced inflammation. Whether and how gut microbiota-mediated AhR activation regulates the pathogenesis of pathogen-induced endometritis remains unknown. The current study found that AhR activation ameliorated E. coli-induced endometritis, and inhibition of AhR produced negative results. Gut dysbiosis reduced the abundance of AhR ligand producers including Lactobacillus spp., damaged AhR activation, and exacerbated E. coli-induced endometritis. Supplementation with dietary Trp, AhR ligands, and L. reuteri containing AhR ligand-producing capability alleviated E. coli-induced endometritis in mice. Our results suggest an important role of microbiota-mediated AhR activation in the pathogenesis of endometritis and provide potential strategies for the intervention of infectious diseases and reproductive health by regulating the gut microbiota and metabolism.

Commensal Lactobacillus reuteri tryptophan catabolism promotes host susceptibility to CNS autoimmunity

Abstract Members of the Lactobacillus genus have a long-standing history in food processing and probiotic industries, generally being characterized as safe and/or beneficial for the mammalian host. Despite this fact, current literature points to pro- and anti-inflammatory roles, with little consensus as to the mechanisms governing these divergent outcomes. We and others have previously shown that commensal colonization with Lactobacillus reuteri (L. reuteri) enhances host susceptibility to experimental autoimmune encephalomyelitis (EAE), a murine model of multiple sclerosis. To identify underlying mechanisms, we characterized the genome of commensal L. reuteri isolates, present within our model microbiomes, using whole genome sequencing and comparative genomics. The enzymatic machinery necessary to catabolize dietary tryptophan (Trp) into immunomodulatory indole derivatives, was enriched in the L. reuteri genome. Metabolite profiling of L. reuteri monocultures and serum of L. reuteri-colonized mice revealed active depletion of kynurenines and production of a wide array of Trp-derived AhR ligands, including indole acetate, indole acrylate, tryptamine, and imidazole derivatives, suggesting that Trp catabolism by L. reuteri may drive the enhancement of autoimmunity. Consistently, dietary Trp was required for L. reuteri dependent EAE exacerbation, while depletion of Trp suppressed disease activity and inflammatory T cell responses in the CNS. Our data suggests that Trp catabolism by gut commensals can enhance autoimmunity by production of immunoregulatory indole derivatives and by competition with the host for production of Trp metabolites such as kynurenines. Supported by NIH R01 NS097596 T32 Training Grant 5T32AI055402-15 F31 Ruth L. Kirschstein NRSA Fellowship 5 F31 NS120381-02

RNA-seq reveals insights into molecular mechanisms of metabolic restoration via tryptophan supplementation in low birth weight piglet model.

Low birth weight (LBW) is associated with metabolic disorders in early life. While dietary l-tryptophan (Trp) can ameliorate postprandial plasma triglycerides (TG) disposal in LBW piglets, the genetic and biological basis underlying Trp-caused alterations in lipid metabolism is poorly understood. In this study, we collected 24 liver samples from 1-mo-old LBW and normal birth weight (NBW) piglets supplemented with different concentrations of dietary Trp (NBW with 0% Trp, N0; LBW with 0% Trp, L0; LBW with 0.4% Trp, L4; LBW with 0.8% Trp, L8; N = 6 in each group.) and conducted systematic, transcriptome-wide analysis using RNA sequencing (RNA-seq). We identified 39 differentially expressed genes (DEG) between N0 and L0, and genes within “increased dose effect” clusters based on dose-series expression profile analysis, enriched in fatty acid response of gene ontology (GO) biological process (BP). We then identified RNA-binding proteins including SRSF1, DAZAP1, PUM2, PCBP3, IGF2BP2, and IGF2BP3 significantly (P < 0.05) enriched in alternative splicing events (ASE) in comparison with L0 as control. There were significant positive and negative relationships between candidate genes from co-expression networks (including PID1, ANKRD44, RUSC1, and CYP2J34) and postprandial plasma TG concentration. Further, we determined whether these candidate hub genes were also significantly associated with metabolic and cardiovascular traits in humans via human phenome-wide association study (Phe-WAS), and analysis of mammalian orthologs suggests a functional conservation between human and pig. Our work demonstrates that transcriptomic changes during dietary Trp supplementation in LBW piglets. We detected candidate genes and related BP that may play roles on lipid metabolism restoration. These findings will help to better understand the amino acid support in LBW metabolic complications.

Association Between Dietary Protein Intake and Sleep Quality in Middle-Aged and Older Adults in Singapore.

Poor sleep has been associated with the increased risk of developing detrimental health conditions. Diet and certain nutrients, such as dietary protein (PRO) may improve sleep. This cross-sectional study aimed to investigate the relationship between PRO intake, their amino acid components, and sources with sleep quality in middle-aged and older adults residing in Singapore. A dataset of 104 healthy subjects between the age of 50 and 75 years old were used. Collected data included 3-day food record and sleep quality [sleep duration, global sleep score (GSS), sleep latency (SL), and sleep efficiency (SE)]. The collected 3-day food records were extracted for PRO, tryptophan (Trp), and large neutral amino acid (LNAA) intake. PRO intake was further categorized into plant and animal PRO. A multivariate multiple linear regression (MLR) was performed to assess the association between PRO intake and sleep quality. Dietary Trp:LNAA ratio was positively associated with sleep duration (βtotal: 108.234 h; p: 0.005) after multiple covariates adjustment. Similarly, plant Trp (βplant: 2.653 h/g; p: 0.020) and plant Trp:LNAA (βplant: 54.006 h; p: 0.008) was positively associated with sleep duration. No significant associations were observed for both SL and SE. Sleep duration in middle-aged and older Singaporean adults was positively associated with dietary Trp and Trp:LNAA, especially when obtained from plant sources.

Effects of dietary leucine and tryptophan on serotonin metabolism and growth performance of growing pigs.

An experiment was conducted to test the hypothesis that increased dietary Trp is needed in high-Leu diets for growing pigs to prevent a drop in plasma serotonin and hypothalamic serotonin concentrations and to maintain growth performance of animals. A total of 144 growing pigs (initial weight: 28.2 ± 1.9 kg) were assigned to 9 treatments in a randomized complete block design with 2 blocks, 2 pigs per pen, and 8 replicate pens per treatment. The 9 diets were formulated in a 3 × 3 factorial with 3 levels of dietary Leu (101%, 200%, or 299% standardized ileal digestible [SID] Leu:Lys), and 3 levels of dietary Trp (18%, 23%, or 28% SID Trp:Lys). A basal diet that met requirements for SID Leu and SID Trp was formulated and 8 additional diets were formulated by adding crystalline L-Leu and (or) L-Trp to the basal diet. Individual pig weights were recorded at the beginning of the experiment and at the conclusion of the 21-d experiment. On the last day of the experiment, 1 pig per pen was sacrificed, and blood and hypothalamus samples were collected to measure plasma urea N, plasma serotonin, and hypothalamic serotonin concentrations. Results indicated that increasing dietary Trp increased (P < 0.05) hypothalamic serotonin, whereas increases (P < 0.05) in average daily gain (ADG) and average daily feed intake (ADFI) were observed only in pigs fed diets containing excess Leu. Increasing dietary Leu reduced (P < 0.05) ADG, ADFI, and hypothalamic serotonin. However, the increase in ADG and ADFI caused by dietary Trp was greater if 299% SID Leu:Lys was provided than if 101% SID Leu:Lys was provided (interaction, P < 0.05). Plasma Leu concentration was positively affected by dietary Leu and negatively affected by dietary Trp, but the negative effect of Trp was greater if 299% SID Leu:Lys was provided than if 101% SID Leu:Lys was provided (interaction, P < 0.05). Plasma concentration of Trp was positively affected by increased dietary Trp and increased dietary Leu, but the increase in plasma concentration of Trp was greater if Leu level was at 101% SID Leu:Lys ratio than at 299% SID Leu:Lys ratio (interaction, P < 0.05). In conclusion, increased dietary Leu reduced ADG, ADFI, and hypothalamic serotonin concentration, and influenced metabolism of several indispensable amino acids, but Trp supplementation partly overcame the negative effect of excess Leu. This demonstrates the importance of Trp in regulation of hypothalamic serotonin, and therefore, feed intake of pigs.

Reproductive and immuno-biochemical response of silver barb (Barbonymus gonionotus) fed dietary l-tryptophan

Tryptophan (Trp) influences several physiological functions, including reproduction, stress and immune function in fishes. The present study investigates the effect of dietary Trp supplementation on growth, reproduction, health of Silver barb, Barbonymus gonionotus. A basal diet (control/T1) with varying level of L-Trp at 0.4% (T2), 0.8% (T3) and 1.6% (T4) were fed to experimental fishes (71.04 ​± ​1.62 ​g) for 60 days period. Results indicate higher growth in groups fed 0.4% L-Trp compared to control (p ​< ​0.05). Percent survival was found to be low in all fed groups; however, 0.4% L-Trp (83.33 ​± ​3.33) was not significant as compared to control (93.33 ​± ​3.33). Significant effect (p ​< ​0.05) of dietary L-Trp was evident on the expression level of GnRH-II gene, with 6.26-fold-changes observed at 0.4% level. Reproductive functions (gonado-somatic index, fecundity and egg diameter) were better in groups fed 0.4% L-Trp (p ​< ​0.05). Ovarian histology indicates advanced maturation in fed groups, compared to the control. However, plasma melatonin showed elevated level in 0.8% and 1.6% L-Trp fed groups (p ​< ​0.05). Hemato-biochemical indices as a measure of the health status of the fish indicates elevated total leukocyte and decreased erythrocyte counts in fed groups (p ​< ​0.05). Blood glucose was lower (48.11 ​± ​1.63 ​mg. dl−1), whereas respiratory burst activity (0.60 ​± ​0.02) was higher in 0.4% Trp compared to other groups (p ​< ​0.05). In conclusion, dietary L-Trp supplementation at 0.4% helps to augment growth performance in Silver barb, besides improving reproductive performance.

Nutritional requirement of tryptophan for meat-type Japanese quails: Performance and carcass attributes

Tryptophan (Trp) as an essential amino acid for monogastric animals and preweaning ruminants plays crucial roles in physiological responses. An experiment was conducted to estimate the Trp requirements of quail chicks for optimum performance including body weight gain (BWG) and feed conversion ratio (FCR), and carcass attribute by different regression models. A total of 420, 21-day-old quail chicks were randomly allotted to one of seven experimental diets containing 2.12, 2.25, 2.38, 2.51, 2.64, 2.77, and 2.90 g Trp/kg from d 21 to 35. The treatments had 4 pen replicates and 15 birds each. Feed intake showed linear (P = 0.071) and quadratic (P = 0.078) increasing trend with increasing dietary levels of Trp during the whole of experiment. Feed conversion ratio, BWG, breast meat yield (BMY), thigh meat yield (TMY), edible section (ES) responded linearly or quadratically to graded levels of dietary Trp (P < 0.05). Regarding data structure in different regression models, the statistical evaluation of the models including one-slope broken line, two-slope broken line, and composite desirability function (D) as multi-criteria approach, was done by considering high R2, root mean square error (RMSE), and low standard deviation of residual (Sy.x) of the model. Based on statistical merit, the estimated Trp requirements of BWG, FCR, ES, BMY, and TMY were estimated as 2.68, 2.35, 2.69, 2.53, and 2.64 g Trp/kg of diet from 21 to 35 d. According to the D in order to get single value of Trp requirement for maximum BWG and minimum FCR, the optimized estimation of dietary Trp was 2.77 g/kg of diet. This study shows the importance of analysis methods used for requirement. The relative higher Trp needs of growing Japanese quails than that recommended by NRC (1994) call more attention while feed formulation for modern strains of Japanese quails.

251 Dietary Tryptophan Supplementation Improves Fat and Glucose Metabolism in Low Birthweight Piglets

Abstract Low birthweight (LBW) is associated with complications such as insulin resistance, obesity and metabolic disturbances of glucose and fat metabolism in early life. Dietary tryptophan (Trp) has been shown to reduce liver fat and suppress hyperglycemia in different species. The objective of this study was to assess the effect of dietary Trp on growth and glucose and fat metabolism in LBW pigs. Piglets (7-days old) weighing &amp;lt; 2 kg were considered as LBW while those weighting &amp;gt; 2 kg were considered as normal birthweight (NBW) and randomly allocated to 4 milk-replacer based treatments (n = 7–8): 1) NBW-0% Trp (NBW-T0), 2) LBW-0% Trp (LBW-T0), 3) LBW-0.4% Trp (LBW-T0.4), and 4) LBW-0.8% Trp (LBW-T0.8) for 3 weeks. Growth parameters and body weight were measured biweekly. At week 3, blood and tissue samples were collected in overnight-fasted pigs after a meal test. The mRNA and protein abundance of key glucose and lipid metabolism markers were determined using qPCR and western blot, respectively. Univariate GLM with Dunnett’s post-hoc test (SPSS®) was used to analyze the data. Growth parameters did not change among groups. Plasma triglycerides concentration was lower in LBW-T0.4 and LBW-T0.8 compared to LBW-T0. Blood glucose was lower in LBW-T0.8 than LBW-T0 at 60 min following the meal test. LBW-T0.8 had a lower transcript and protein abundance of liver glucose transporter-2 relative to LBW-T0. Compared to LBW-T0, LBW-T0.8 had a higher mRNA abundance of glucokinase and tended to have a lower transcript of phosphoenolpyruvate carboxykinase in liver. Relative to LBW-T0, LBW-T0.4 tended to have a lower protein abundance of sodium-glucose co-transporter 1 in jejunum. Compared to LBW-T0, LBW-T0.4 and LBW-T0.8 had a lower transcript of liver acetyl-CoA carboxylase and LBW-T0.4 had a higher transcript of liver 3-hydroxyacyl-CoA dehydrogenase. In conclusion, Trp supplementation reduced the lipogenesis and gluconeogenesis, but increased the glycolysis in LBW piglets.

Effects of dietary tryptophan on muscle growth, protein synthesis and antioxidant capacity in hybrid catfish Pelteobagrus vachelli♀ × Leiocassis longirostris♂.

The present study evaluated effects of dietary supplementation with tryptophan (Trp) on muscle growth, protein synthesis and antioxidant capacity in hybrid catfish Pelteobagrus vachelli♀ × Leiocassis longirostris♂. Fish were fed six different diets containing 2·6 (control), 3·1, 3·7, 4·2, 4·7 and 5·6 g Trp/kg diet for 56 d, respectively. Results showed that dietary Trp significantly (1) improved muscle protein content, fibre density and frequency of fibre diameter; (2) up-regulated the mRNA levels of PCNA, myf5, MyoD1, MyoG, MRF4, IGF-I, IGF-II, IGF-IR, PIK3Ca, TOR, 4EBP1 and S6K1; (3) increased phosphorylation levels of AKT, TOR and S6K1; (4) decreased contents of MDA and PC, and increased activities of CAT, GST, GR, ASA and AHR; (5) up-regulated mRNA levels of CuZnSOD, CAT, GST, GPx, GCLC and Nrf2, and decreased Keap1 mRNA level; (6) increased nuclear Nrf2 protein level and the intranuclear antioxidant response element-binding ability, and reduced Keap1 protein level. These results indicated that dietary Trp improved muscle growth, protein synthesis as well as antioxidant capacity, which might be partly related to myogenic regulatory factors, IGF/PIK3Ca/AKT/TOR and Keap1/Nrf2 signalling pathways. Finally, based on the quadratic regression analysis of muscle protein and MDA contents, the optimal Trp requirements of hybrid catfish (21·82-39·64 g) were estimated to be 3·94 and 3·93 g Trp/kg diet (9·57 and 9·54 g/kg of dietary protein), respectively.

Effect of Dietary Tryptophan on Growth, Intestinal Microbiota, and Intestinal Gene Expression in an Improved Triploid Crucian Carp.

Tryptophan (Trp) has received increasing attention in the maintenance of intestinal function. In this study, improved triploid crucian carp (ITCC) fed diets containing 6.35 g kg−1 Trp had higher average daily gain (ADG) and improved villus height (VH) and crypt depth (CD) in the intestine compared to the control group. To elucidate the potential mechanisms, we used RNA sequencing (RNA-seq) to investigate changes in the intestinal transcriptome and 16S rRNA gene sequencing to measure the intestinal microbiota in response to 6.35 g kg−1 Trp feeding in ITCC. Dietary Trp altered intestinal gene expression involved in nutrient transport and metabolism. Differentially expressed transcripts (DETs) were highly enriched in key pathways containing protein digestion and absorption and the AMPK signaling pathway. 16S rRNA sequencing showed that 6.35 g kg−1 Trp significantly increased the abundance of the genus Cetobacterium, and the Firmicutes/Bacteroidetes ratio at the phylum level (P < 0.05). In addition, bacterial richness indices (Simpson index) significantly increased (P < 0.05) community evenness in response to 6.35 g kg−1 Trp. In conclusion, appropriate dietary Trp improves the growth performance, and influences the intestinal flora of ITCC. This study might be helpful to guide the supply of dietary exogenous Trp in ITCC breeding.

Tryptophan in the diet ameliorates motor deficits in a rotenone-induced rat Parkinson's disease model via activating the aromatic hydrocarbon receptor pathway.

Background and purposeParkinson's disease (PD), a common neurodegenerative disorder with motor and nonmotor symptoms, does not have effective treatments. Dietary tryptophan (Trp) supplementation has potential benefits for the treatment of multiple disorders. However, whether additional Trp in the diet could be beneficial for PD remains to beinvestigated. In the present study, the neuroprotective role of dietary Trp on a rotenone‐induced rat model of PD was determined.MethodsThe rotenone was injected to build the PD model, and then the rats were treated with Trp in the diet. And then, an open field test, western blot analysis, and enzyme linked immunosorbent assay (ELISA) were performed.ResultsWe observed that dietary Trp significantly ameliorated impaired motor function, upregulated tyrosine hydroxylase expression, inhibited the nuclear transport of Nuclear factor‐kappa B (NF‐κB) in substantia nigra (SN), and downregulated the protein levels of IL‐1β, IL‐6, and TNF‐α in serum in rotenone‐treated rats. However, these patterns were reversed in response to treatment with ampicillin, an agent that can clean intestinal Trp metabolism flora. Moreover, after using CH223191, an inhibitor of the aromatic hydrocarbon receptor (AhR) pathway, dietary Trp could not exert neuroprotective roles in the rotenone‐induced rat model of PD.ConclusionThese results suggest that Trp in the diet can protect against rotenone‐induced neurotoxicity to ameliorate motor deficits, which may be mediated through activating AhR pathway.

Amino Acid Trp: The Far Out Impacts of Host and Commensal Tryptophan Metabolism.

Tryptophan (Trp) is an essential amino acid primarily derived from the diet for use by the host for protein synthesis. The intestinal tract is lined with cells, both host and microbial, that uptake and metabolize Trp to also generate important signaling molecules. Serotonin (5-HT), kynurenine and its downstream metabolites, and to a lesser extent other neurotransmitters are generated by the host to signal onto host receptors and elicit physiological effects. 5-HT production by neurons in the CNS regulates sleep, mood, and appetite; 5-HT production in the intestinal tract by enterochromaffin cells regulates gastric motility and inflammation in the periphery. Kynurenine can signal onto the aryl hydrocarbon receptor (AHR) to elicit pleiotropic responses from several cell types including epithelial and immune cells, or can be further metabolized into bioactive molecules to influence neurodegenerative disease. There is a remarkable amount of cross-talk with the microbiome with regard to tryptophan metabolites as well. The gut microbiome can regulate the production of host tryptophan metabolites and can use dietary or recycled trp to generate bioactive metabolites themselves. Trp derivatives like indole are able to signal onto xenobiotic receptors, including AHR, to elicit tolerogenic effects. Here, we review studies that demonstrate that tryptophan represents a key intra-kingdom signaling molecule.

166 Optimal tryptophan:lysine Ratio for 25–40 Kg Growing Pigs Fed Diets Containing 35 % Distillers Dried Grains with Solubles

Abstract Distillers dried grains with solubles (DDGS) has a high concentration of Leu, and the Trp requirement for growing pigs may be increased if diets contain excess Leu. Therefore, the objective of this experiment was to determine the optimum standardized ileal digestible (SID) Trp:Lys ratio in growing pigs fed diets with excess Leu from DDGS. A diet based on corn, soybean-meal, and 35% DDGS was formulated to be deficient in Trp and Lys, according to NRC requirements (0.13% SID Trp; 0.88% SID Lys; 15% SID Trp:Lys ratio). Four diets were prepared by adding L-Trp to the basal diet, which resulted in analyzed SID Trp:Lys ratios of 18, 20, 23, and 24% in these diets. One-hundred and twenty growing pigs (26.3 ± 2.0 kg) were allotted to one of the 5 dietary treatments with 3 pigs per pen and 8 pen replicates in a completely randomized design. Diets were fed for 21d and blood samples were collected on d-21. Data were analyzed by linear and quadratic contrasts in SAS. The optimal SID Trp:Lys ratio was estimated using linear broken-line (LBL) and quadratic broken-line (QBL) regressions for ADG and G:F, using NLIN procedure in SAS. Results indicated that average daily feed intake, ADG, G:F, and final body weight increased (linear and quadratic, P &amp;lt; 0.01) and plasma-urea-nitrogen decreased (linear and quadratic, P &amp;lt; 0.05) as dietary SID Trp:Lys increased (Table 1). The SID Trp:Lys ratio to optimize ADG was 20.9 and 23.4% by LBL and QBL, respectively. The G:F was optimized at 18.7 and 20.2% by LBL and QBL, respectively. The average SID Trp:Lys ratio for the 4 measurements was 20.8% which is greater than the current NRC requirement (SID 17.3%). In conclusion, diets formulated with 35% DDGS may need more dietary Trp than current NRC values.

171 Effects of Dietary Valine, Isoleucine, and Tryptophan Supplementations to Diets Containing Excess Leucine on Nitrogen Balance of Growing Pigs

Abstract An experiment was conducted to test the hypothesis that increasing concentrations of dietary Val, Ile, or Trp alone or in combination will alleviate negative effects of excess dietary Leu on N balance of growing pigs. Seventy-two barrows (initial body weight: 33.9 ± 2.6 kg) were housed in metabolism crates and randomly assigned to 1 of 8 diets and 3 blocks with 3 pigs per diet in each block in a 12-d experiment. Treatments were arranged in a 2 × 2 × 2 factorial with the main effects of L-Val (0 or 0.1%), L-Ile (0 or 0.1%), and L-Trp (0 or 0.05%) that were added to a basal diet containing corn and a high-protein corn product (48% crude protein; 5.9% Leu). The basal diet contained 1.00 % standardized ileal digestible (SID) Lys and 171% SID Leu:Lys. Data were analyzed using the PROC MIXED of SAS with concentrations of Val, Ile, and Trp, and all interactions as main effects and replicate as a random effect. No 3-way interactions were observed (Table 1). Results indicated that fecal N output increased if Ile was added to diets without added Val, but that was not the case if Val was added (interaction, P &amp;lt; 0.05). Addition of Ile to diets reduced N retention, but N retention increased with Trp addition to diets without Val addition, but not if Trp was added to diets with added Val (interaction, P &amp;lt; 0.05). The biological value of protein increased if Trp was added to diets without addition of Ile, but if Ile was added, Trp addition did not increase the biological value of protein (interaction, P &amp;lt; 0.05). In conclusion, adding Ile to a diet with excess Leu reduced N retention, but if Trp was added alone or in combination with Ile or Val, N retention increased.