Effects of dietary leucine supplementation on the gene expression of mammalian target of rapamycin signaling pathway and intestinal development of broilers

Growth performance, serum parameters, inflammatory responses, intestinal morphology and microbiota of weaned piglets fed 18% crude protein diets with different ratios of standardized ileal digestible isoleucine to lysine

The present study was to explore the Ile requirement of piglets fed 18% crude protein (CP) diets. Two hundred and fifty 28-day-old Duroc × Landrace × Yorkshire piglets (8.37 ± 1.92 kg) were randomly divided into 5 dietary treatments (10 piglets per replicate, 5 barrows and 5 gilts per replicate) with 45%, 50%, 55%, 60%, 65% standardized ileal digestible (SID) Ile-to-Lys ratios, and the SID Lys was formulated to 1.19%. The experimental design consisted of two phases (d 1 to 14 and d 15 to 28). Results showed that average daily gain (ADG) had a tendency to quadratically increase as the SID Ile-to-Lys ratio increased (P = 0.09), and the optimum SID Ile-to-Lys ratios required to maximize ADG were 48.33% and 54.63% for broken-line linear model and quadratic polynomial model, respectively. Different SID Ile-to-Lys ratios had no significant effects on average daily feed intake and gain-to-feed ratio. Dry matter (P < 0.01), CP (P = 0.01), ether extract (P = 0.04), gross energy (P < 0.01) and organic matter (P < 0.01) digestibility increased quadratically. Serum total cholesterol levels decreased linearly (P = 0.01) and quadratically (P < 0.01); aspartate aminotransferase (P < 0.01), interleukin-1β (P = 0.01), and tumor necrosis factor-α (P < 0.01) levels decreased quadratically; immunoglobulin G (P = 0.03) and immunoglobulin M (P = 0.01) concentrations increased quadratically. Serum Ser levels decreased linearly (P < 0.01) and quadratically (P = 0.01); Glu (P = 0.02), Arg (P = 0.05), and Thr (P = 0.03) levels decreased quadratically; Gly (P < 0.01) and Leu (P = 0.01) levels decreased linearly; Ile (P < 0.01) concentration increased linearly. Duodenal villus height (P < 0.01) and villus height to crypt depth ratio (P < 0.01) increased quadratically. The deficiency or excess of Ile decreased short chain fatty acid-producing bacteria abundance and increased pathogenic bacteria abundance. Overall, taking ADG as the effect index, the optimum SID Ile-to-Lys ratios of piglets offered 18% CP diets were 48.33% and 54.63% based on two different statistical models, respectively, and the deficiency or excess of lle negatively affected piglet growth rates and health status.

Beta-hydroxy-β-methyl butyrate-supplemented diet for broiler chickens is more conducive to dietary protein reduction than a leucine-supplemented diet until 21 days old

BACKGROUND

Dietary l-leucine or its metabolite 𝛽-hydroxy-𝛽-methylbutyrate (HMB) has a crucial role in the muscle protein metabolism of broilers during the first few-week growing period. The present study aimed to evaluate the effects of l-leucine (LLPD) or HMB (HLPD) supplementation in a low-protein diet (20%, LPD) until 21 days old on performance, carcass weight, muscle yield and meat quality, as well as intestinal morphometry, in broiler chickens.

RESULTS

From days 1-42, LPD decreased body weight gain and feed intake (FI) and increased feed conversion ratio compared to a standard protein diet (22%, SPD). The LLPD and HLPD did not affect FI, but the LLPD decreased the body weight gain and increased the feed conversion ratio compared to the SPD. The LPD group had lower body and muscle weights than other groups. Compared to LPD, HLPD increased dressing percentage. The LPD decreased the serum insulin-like growth factor-1 content compared to the SPD and LLPD. The duodenal villus height of the LPD and LLPD broilers was smaller than those of the SPD and HLPD birds. The HLPD broilers had lower duodenal villus width than the SPD birds. The duodenal crypt depth and ileal mucosal thickness were higher in the HLPD group than in other groups. The HLPD and LLPD enhanced the ileal villus height compared to the SPD. The LLPD and HLPD treatments did not affect meat quality traits compared to the SPD treatment.

CONCLUSION

Dietary HMB could be a conducive approach to reducing dietary protein for broilers until 21 days old. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

The effects of arginine and branched-chain amino acid supplementation to reduced-protein diet on intestinal health, cecal short-chain fatty acid profiles, and immune response in broiler chickens challenged with Eimeria spp

We investigated the effects of supplementing arginine (Arg) and branched-chain amino acids (BCAA) in broilers fed reduced-protein diets and challenged with Eimeria spp. All birds were fed the same starter diet meeting Cobb 500 nutrient specifications from d 1 to 9. Four grower diets: positive control (PC) with 20.0% crude protein (CP); reduced-protein negative control (NC) with 17.5% CP; or NC supplemented with Arg or BCAA at 50% above recommendations (ARG or BCAA) were fed to the birds from d 9 to 28. Birds were allocated in a 2 × 4 factorial arrangement (4 diets, each with or without challenge), with 8 replicates per treatment. On d 14, the challenge groups were orally gavaged with mixed Eimeria spp. Intestinal permeability was higher (P < 0.05) in NC than PC, whereas the permeability of ARG and BCAA groups did not differ significantly from PC. On d 28, a significant interaction (P < 0.01) was observed in CD8⁺: CD4⁺ ratios in cecal tonsils (CT), Eimeria challenge increased the ratios in all groups except for the ARG group. On d 21, a significant interaction was found for CD4⁺CD25⁺ percentages in CT (P < 0.01) that Eimeria challenge increased the percentages only in PC and NC groups. On d 21 and 28, significant interactions (P < 0.01) were found for macrophage nitric oxide (NO) production. In nonchallenged birds, NO was higher in the ARG group than other groups, but in challenged birds, NO was higher in both ARG and BCAA groups. On d 21, a significant interaction was found for bile anticoccidial IgA concentrations (P < 0.05) that Eimeria challenge increased IgA only in NC and ARG groups. The results suggest that a reduced-protein diet exacerbates the impact of the Eimeria challenge on intestinal integrity, but this could be mitigated by Arg and BCAA supplementations. Arginine and BCAA supplementations in reduced-protein diets could be beneficial for broilers against Eimeria infection by enhancing the immune responses. The beneficial effects of Arg supplementation tended to be more pronounced compared to BCAA supplementation.

Nutrigenomic profiling of reduced specification diets and phytogenic inclusion effects on critical TLR signaling, MAPK-apoptosis and PI3K-Akt-mTOR gene components along the broiler gut

The effects of concurrent reduction of dietary metabolizable energy (ME) and crude protein (CP) levels combined or not with the dietary inclusion of a phytogenic feed additive (PFA) were studied using a nutrigenomics approach. In particular, the expression of 26 critical genes relevant for inflammation control (TLR pathway), cellular apoptosis (MAPK pathway) cell growth and nutrient metabolism (PI3K-Akt-mTOR pathway) was profiled along the broiler intestine. Two dietary types (L and H) differing in metabolizable energy and crude protein levels (L: 95% and H: 100% of optimal Cobb 500 recommendations for ME and CP requirements) supplemented or not with PFA (- or +) and their interactions (L-, L+, H-, H+) were evaluated. There were only 3 total interactions (mTOR, IL8, and HRAS P < 0.05) between diet type and PFA inclusion indicating limited concurrent effects. Diet type, L upregulated genes related with inflammation mainly in the jejunum, ileum, and cecum (P < 0.05) and MAPK pathway in the ileum and cecum (P < 0.05). Moreover, diet type L negatively affected the expression of genes related to PI3K-Akt-mTOR pathway mainly in duodenum and cecum (P < 0.05). On the other hand, PFA inclusion downregulated (P < 0.05) genes related with TLR signaling pathway (TLR2B, MyD88, TLR3, IL8, LITAF) along the intestine and MAPK pathway genes (APO1, FOS) in jejunum (P < 0.05). Finally, PFA supplementation regulated nutrient sensing and metabolism in the cecum in a manner perceived as beneficial for growth. In conclusion, the study results highlight that the reduced ME and CP specifications, especially in the absence of PFA, regulate inflammation, apoptosis and nutrient metabolism processes at homeostatic control levels that hinder maximizing the availability of dietary energy and nutrients for growth purposes. Inclusion of PFA helped to adjust the respective homeostatic responses and control to levels supporting broiler performance, especially at reduced specification diets.

Maternal Amino Acid Mixtures Supplementation during Late Gestation and Lactation Improved Growth Performance of Piglets through Improving Colostrum Composition and Antioxidant Capacity

During late gestation and lactation, oxidative stress in sows can affect their health and reproductive performance. Supplemental amino acid contributes to the antioxidant capacity of pigs. This study was conducted to evaluate the effects of different combinations of Gln, Leu and γ-GABA (amino acid mixtures, AAMs) during late gestation and lactation on the performance of the sows and their offspring. Fifty large white × landrace sows were randomly assigned to 5 groups (n = 10), including a control group and four AAMs groups (AAMs1, Gln + Leu; AAMs2 (Gln + GABA; AAMs3, Leu + GABA; AAMs4, Gln + Leu + GABA). AAMs supplementation improved the antioxidant capacity of sows, including significantly enhanced total antioxidant capacity in AAMs2, 3 and 4 groups and reduced malonaldehyde concentration in AAMs1, 3 and 4 groups. Additionally, all AAMs significantly increased lactoprotein, total solid and IgA levels of colostrum in sows during lactation. Average body weight of piglets on day 21 after birth in all AAMs groups were significantly increased. Furthermore, the significantly increased total antioxidant capacity was observed in the piglets of every AAMs group. In conclusion, supplementing AAMs during late gestation and lactation improved the antioxidant capacity of sows and colostrum composition, thereby enhancing antioxidant status and the growth performance of piglets. This study provides the possibility of maternal amino acid mixtures to improve the productivity of the swine industry.

Nutritional stimulation by in-ovo feeding modulates cellular proliferation and differentiation in the small intestinal epithelium of chicks

Nutritional stimulation of the developing small intestine of chick embryos can be conducted by in-ovo feeding (IOF). We hypothesized that IOF of glutamine and leucine can enhance small intestinal development by promoting proliferation and differentiation of multipotent small intestinal epithelial cells. Broiler embryos (n = 128) were subject to IOF of glutamine (IOF-Gln), leucine (IOF-Leu), NaCl (IOF-NaCl) or no injection (control) at embryonic d 17 (E 17). Multipotent, progenitor and differentiated cells were located and quantified in the small intestinal epithelium between E 17 and d 7 after hatch (D 7) in all treatment groups by immunofluorescence of SRY-box transcription factor 9 (Sox9) and proliferating cell nuclear antigen (PCNA), in-situ hybridization of leucine-rich repeat containing G-protein coupled receptor 5 (Lgr5) and peptide transporter 1 (PepT1) and histochemical goblet cell staining. The effects of IOF treatments at E 19 (48 h post-IOF), in comparison to control embryos, were as follows: total cell counts increased by 40%, 33% and 19%, and multipotent cell counts increased by 52%, 50% and 38%, in IOF-Gln, IOF-Leu and IOF-NaCl embryos, respectively. Only IOF-Gln embryos exhibited a significance, 36% increase in progenitor cell counts. All IOF treatments shifted Lgr5+ stem cell localizations to villus bottoms. The differentiated, PepT1+ region of the villi was 1.9 and 1.3-fold longer in IOF-Gln and IOF-Leu embryos, respectively, while goblet cell densities decreased by 20% in IOF-Gln embryos. Post–hatch, crypt and villi epithelial cell counts were significantly higher IOF-Gln chicks, compared to control chicks (P < 0.05). We conclude IOF of glutamine stimulates small intestinal maturation and functionality during the peri-hatch period by promoting multipotent cell proliferation and differentiation, resulting in enhanced compartmentalization of multipotent and differentiated cell niches and expansions of the absorptive surface area.

Functional role of branched chain amino acids in poultry: a review

This review provides insight into the effects of the branched-chain amino acids (BCAA: leucine, isoleucine, and valine) on the growth, production performance, immunity, and intestinal health of poultry. Besides providing nitrogen substrates and carbon framework for energy homeostasis and transamination, BCAA also function as signaling molecules in the regulation of glucose, lipid, and protein synthesis via protein kinase B and as a mechanistic target of the rapamycin (AKT-mTOR) signaling pathway that is important for muscle accretion. The level of leucine is generally high in cereals and an imbalance in the ratio among the 3 BCAA in a low protein diet would produce a negative effect on poultry growth performance. This occurs due to the structural similarity of the 3 BCAA, which leads to metabolic competition and interference with the enzymatic degradation pathway. Emerging evidence shows that the inclusion of BCAA is essential for the proper functioning of the innate and adaptive immune system and the maintenance of intestinal mucosal integrity. The recommended levels of BCAA for poultry are outlined by NRC (1994), but commercial broilers and laying hen breed standards also determine their own recommended levels. In this review, it has been noted that the requirement for BCAA is influenced by the diet type, breed, and age of the birds. Additionally, several studies focused on the effects of BCAA in low protein diets as a strategy to reduce nitrogen excretion. Notably, there is limited research on the inclusion ratio of BCAA in a supplemental form as compared to the ingredient-bound form which would affect the dynamics of utilization in different disease-challenged conditions, especially those affecting digesta passage ratio. In summary, this review encompasses the role of BCAA as functional AA and discusses their physiological effects on the productivity and health of poultry. The observations and interpretations of this review can guide future research to adjust the recommended levels of BCAA in feeding programs in the absence of subtherapeutic antibiotics in poultry.

Clostridium butyricum Alleviates Enterotoxigenic Escherichia coli K88-Induced Oxidative Damage Through Regulating the p62-Keap1-Nrf2 Signaling Pathway and Remodeling the Cecal Microbial Community

Clostridium butyricum (CB) can enhance antioxidant capacity and alleviate oxidative damage, but the molecular mechanism by which this occurs remains unclear. This study used enterotoxigenic Escherichia coli (ETEC) K88 as a pathogenic model, and the p62-Keap1-Nrf2 signaling pathway and intestinal microbiota as the starting point to explore the mechanism through which CB alleviates oxidative damage. After pretreatment with CB for 15 d, mice were challenged with ETEC K88 for 24 h. The results suggest that CB pretreatment can dramatically reduce crypt depth (CD) and significantly increase villus height (VH) and VH/CD in the jejunum of ETEC K88-infected mice and relieve morphological lesions of the liver and jejunum. Additionally, compared with ETEC-infected group, pretreatment with 4.4×10⁶ CFU/mL CB can significantly reduce malondialdehyde (MDA) level and dramatically increase superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) levels in the serum. This pretreatment can also greatly increase the mRNA expression levels of tight junction proteins and genes related to the p62-Keap1-Nrf2 signaling pathway in the liver and jejunum in ETEC K88-infected mice. Meanwhile, 16S rDNA amplicon sequencing revealed that Clostridium disporicum was significantly enriched after ETEC K88 challenge relative to the control group, while Lactobacillus was significantly enriched after 4.4×10⁶ CFU/mL CB treatment. Furthermore, 4.4×10⁶ CFU/mL CB pretreatment increased the short-chain fatty acid (SCFA) contents in the cecum of ETEC K88-infected mice. Moreover, we found that Lachnoclostridium, Roseburia, Lactobacillus, Terrisporobacter, Akkermansia, and Bacteroides are closely related to SCFA contents and oxidative indicators. Taken together, 4.4×10⁶ CFU/mL CB pretreatment can alleviate ETEC K88-induced oxidative damage through activating the p62-Keap1-Nrf2 signaling pathway and remodeling the cecal microbiota community in mice.

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.

Maternal Folic Acid Supplementation Differently Affects the Small Intestinal Phenotype and Gene Expression of Newborn Lambs from Differing Litter Sizes

The purpose of this study was to investigate the effect of maternal dietary folic acid (FA) supplementation during gestation on small intestinal development of newborn lambs of different litter sizes, focusing on the intestinal morphology and development-, apoptosis- and digestion-related genes expression. One hundred and twenty Hu ewes (Ovis aries) were inseminated and randomly allotted to three groups. One group received a control diet [without FA supplementation, control (CON)] and the other two groups received control diets supplemented with different amount of FA [16 or 32 mg FA per kg dry matter (DM), i.e., F16 and F32] during pregnancy. After lambing, according to the dietary FA levels and litter size (twins, TW; triplets, TR), the neonatal lambs were divided into 6 (TW-CON, TW-F16, TW-F32, TR-CON, TR-F16, TR-F32) treatment groups. The results showed that the ratio of small intestinal weight to live body weight and the thickness of the intestinal muscle layer in the offspring was enhanced significantly with increasing maternal FA supplementation (p < 0.05). Meanwhile, the expression levels of insulin-like growth factor I (IGF-I), B-cell lymphoma-2 (BCL-2) and sodium/glucose co-transporter-1 (SGLT1) in the small intestines of the newborn lambs were increased, while the opposite was true for Bcl2-associated × (BAX) in response to FA supplementation (p < 0.05). Moreover, the small intestinal weights of twins were significantly higher than those of triplets (p < 0.01), and the expression levels of IGF-I (p < 0.05), sucrase-isomaltase (SI) (p < 0.05) and solute carrier family 2 member 5 (SLC2A5) (p < 0.01) were significantly lower than those in triplets. These findings suggest that maternal FA supplementation could improve the offspring's small intestinal phenotype and the expression of development-, apoptosis- and digestion-related genes, so it could promote the small intestinal development of newborn lambs. Furthermore, the small intestine phenotypic development of twins was generally better than that of triplets, while the expression levels of the above genes of twins were lower than those of triplets.

High leucine levels affecting valine and isoleucine recommendations in low-protein diets for broiler chickens

Four experiments were conducted to estimate the optimal standardized ileal digestible (SID) level of branched-chain amino acids in low-protein diets during the starter, grower, and finisher periods, using the response surface methodology, and to study their effects on performance and mRNA expression of genes involved in the mechanistic target of rapamycin (mTOR) pathway of broiler chickens from 8 to 21 D of age. In experiments 1, 2, and 3, a total of 1,500 Cobb male broiler chickens were assigned to 15 diets of a central composite rotatable design (CCD) of response surface methodology containing 5 levels of SID Leu, Val, and Ile with 5 replicate pens of 20 birds each. A 3-factor, 5-level CCD platform was used to fit the second-order polynomial equation of broiler performance. In experiment 4, a total of 540 8-day-old Cobb male broiler chickens were distributed in a completely randomized 2 x 3 x 3 factorial arrangement with 2 SID Leu levels (1.28 or 1.83%), 3 SID Val levels (0.65, 0.90, or 1.20%), and 3 SID Ile levels (0.54, 0.79, or 1.09%) for a total of 18 treatments with 5 replicate cages of 6 birds each. High Leu levels impaired (P < 0.05) gain:feed when birds were fed marginal Val or Ile diets. However, gain:feed was restored when both Val and Ile were supplemented to reach adequate or high levels. High Leu levels increased (P < 0.05) mRNA expression of S6K1 and eEF2 genes only in birds fed high Ile levels. Dietary SID Leu, Val, and Ile levels required for gain:feed optimization in low-protein diets were estimated at 1.37, 0.94, and 0.87% during the starter period; 1.23, 0.82, and 0.75% during the grower period; and 1.15, 0.77, and 0.70% during the finisher phase, respectively. Higher Val and Ile levels are required to optimize the effect of Leu supplementation on mRNA expression of mTOR pathway genes in the pectoralis major muscle of broilers from day 1 to 21 after hatch.

Dietary valine levels affect growth, protein utilisation, immunity and antioxidant status in juvenile hybrid grouper (Epinephelus fuscoguttatus ♀ × Epinephelus lanceolatus ♂)

A 6-week growth trial was conducted to evaluate the influences of dietary valine (Val) levels on growth, protein utilisation, immunity, antioxidant status and gut micromorphology of juvenile hybrid groupers. Seven isoenergetic, isoproteic and isolipidic diets were formulated to contain graded Val levels (1·21, 1·32, 1·45, 1·58, 1·69, 1·82 and 1·94 %, DM basis). Each experimental diet was hand-fed to triplicate groups of twelve hybrid grouper juveniles. Results showed that weight gain percentage (WG%), protein productive value, protein efficiency ratio, and feed efficiency were increased as dietary Val level increased, reaching a peak value at 1·58 % dietary Val. The quadratic regression analysis of WG% against dietary Val levels indicated that the optimum dietary Val requirement for hybrid groupers was estimated to be 1·56 %. Gut micromorphology and expression of growth hormone in pituitary, insulin-like growth factor 1, target of rapamycin and S6 kinase 1 in liver were significantly affected by dietary Val levels. In serum, fish fed 1·58 % dietary Val had higher superoxide dismutase, catalase, lysozyme activities and IgM concentrations than fish fed other dietary Val levels. Fish fed 1·58 % dietary Val had higher expression of NF-E2-related factor 2 in head kidney than fish fed other dietary Val levels. Generally, the optimum dietary Val requirement for maximal growth of hybrid groupers was estimated to be 1·56 % of DM, corresponding to 3·16 % of dietary protein, and dietary Val levels affected growth, protein utilisation, immunity and antioxidant status in hybrid groupers.

Growth performance, carcass traits and digestive function of broiler chickens fed diets with graded levels of corn resistant starch

1. This study was conducted to assess the effects of graded levels of dietary corn resistant starch (RS) on growth performance, carcass traits, nutrient retention, digestive organ index, intestinal morphology, digestive enzyme activities, and mRNA expression of certain nutrient transporters in broiler chickens.2. A total of 320, 1-d-old Arbor Acres broiler chickens were randomly assigned to five dietary treatments, with eight replicates of eight birds in each. These treatments included one corn-soybean control diet, a corn-soybean based diet containing 20% corn starch, and three diets supplemented with 4%, 8% and 12% RS by replacing corn starch with 6.67%, 13.33% and 20% of Hi-Maize 260® (identified as control, RS1, RS2, RS3 and RS4, respectively). The feeding period lasted 42 days.3. Performance parameters including feed consumption, feed conversion, body weight gain and percentage of abdominal fat at d 42 of age, nutrient retention (including dry matter, fat, total starch and nitrogen free extract), and apparent metabolisable energy was measured from d 18 to 20 and d 39 to 41 and showed negative linear responses to increasing dietary RS level (P < 0.05). Birds fed the RS3 and RS4 diets showed higher relative weight of duodenum, jejunum and ileum, as well as lower villus height and villus height/crypt depth compared to the control (P < 0.05). The activity of pancreatic trypsin of birds at d 21 and 42 of age decreased linearly in response to the increase of dietary RS level (P < 0.01). There were linear changes in up-regulated mRNA expression of SGLT-1 and down-regulated mRNA expression of GLUT-2 with increasing proportion of RS at d 21 and 42 of age (P < 0.05), respectively.4. It was concluded that feeding broilers with diets containing higher concentrations of RS impaired the development of small intestine, which resulted in lower apparent total tract retention of nutrients and poorer body weight gain, feed efficiency and carcass traits of broiler chickens.

Dietary leucine supplementation improves intestinal health of mice through intestinal SIgA secretion

AIMS

Leucine supplementation promotes intestinal health, but the mechanism is largely unknown. This study aimed to elucidate the mechanisms underlying the beneficial effects of leucine on intestinal homeostasis.

METHODS AND RESULTS

Female ICR mice (6-week-old) were randomly assigned into three groups: (i) mice received a basal diet; (ii) mice received a dietary 0·5% crystalline l-leucine supplementation; and (iii) mice received a dietary 1·0% crystalline l-leucine supplementation. Our results showed that leucine supplementation stimulated the secretion of SIgA in mice ileum and expression of cytokines related to SIgA production. Moreover, leucine supplementation improved the expression of mTOR and p70S6K1 expression. Further study showed that leucine supplementation markedly decreased microbiota richness and induced a shift in the Firmicutes : Bacteroidetes ratio in favour of Firmicutes.

CONCLUSIONS

Therefore, our data suggested that leucine supplementation could enhance intestinal health through the regulation of mTOR pathway and promoting SIgA secretion in the mouse intestine, which might be associated with intestinal microbiota.

SIGNIFICANCE AND IMPACT OF THE STUDY

The present study found that dietary leucine supplementation of mice could improve intestinal health by enhancing intestinal SIgA secretion via a nonexclusive mechanism, which might include T cell-dependent pathway, T cell-independent pathway and gut microbiota.

Recent Progress on Branched-Chain Amino Acids in Obesity, Diabetes, and Beyond

Branched-chain amino acids (BCAAs) are essential amino acids that are not synthesized in our body; thus, they need to be obtained from food. They have shown to provide many physiological and metabolic benefits such as stimulation of pancreatic insulin secretion, milk production, adipogenesis, and enhanced immune function, among others, mainly mediated by mammalian target of rapamycin (mTOR) signaling pathway. After identified as a reliable marker of obesity and type 2 diabetes in recent years, an increasing number of studies have surfaced implicating BCAAs in the pathophysiology of other diseases such as cancers, cardiovascular diseases, and even neurodegenerative disorders like Alzheimer's disease. Here we discuss the most recent progress and review studies highlighting both correlational and potentially causative role of BCAAs in the development of these disorders. Although we are just beginning to understand the intricate relationships between BCAAs and some of the most prevalent chronic diseases, current findings raise a possibility that they are linked by a similar putative mechanism.

Amino Acids Influencing Intestinal Development and Health of the Piglets

Simple Summary

The health of piglets is an important issue in pig production. Nutritional support for intestinal development is a significant component of piglet care, and amino acids are essential for intestinal growth and development. For suckling piglets, the sows’ milk and the maternal environment shape the structure and support the function of the intestinal tract. The composition of milk affects intestinal morphology and the digestive, absorption and barrier function. After weaning, the optimal nutritional strategies of their diet are necessary to guarantee the piglets’ intestinal development and growth performance. Amino acids are the most important ingredient in piglet diets. The aim of this review is to collect and analyze the relationship between amino acid nutrition and intestinal development of piglets, and elucidate the impacts on piglet health.

Abstract

The amino acids and other components of diet provide nourishment for piglet intestinal development and maturation. However, early-weaned piglets struggle with tremendous stress, impairing normal intestinal health and leading to intestinal dysfunction and even death. The high prevalence worldwide of post-weaning diarrhoea syndrome (PWDS) in piglets has led to much interest in understanding the important role of nutrients in the establishment and maintenance of a functional intestinal tract. In particular, the impacts of amino acids on these functions must be considered. Amino acid levels greatly influence intestinal development in weaning piglets. The lack of amino acids can cause marked structural and functional changes in the intestine. Therefore, a comprehensive understanding of the functions of amino acids is necessary to optimize amino acid requirements of the developing intestinal tract to maximize piglet health and growth performance. This review summarizes the role of specific amino acids (arginine, glutamate, threonine, sulphur-containing amino acids (SCAAs), and branched-chain amino acids (BCAAs)) that have been proven to be beneficial for the intestinal health of weaned piglets.

In ovo injection of branched-chain amino acids: Embryonic development, hatchability and hatching quality of turkey poults

In this study, the influence of a branched-chain amino acid blend (BCAA composed of 3 l-leucine:1 l-valine:2 l-isoleucine) injected into the amniotic fluid was evaluated for embryonic growth, yolk-sac (YS) utilization and development of gastrointestinal tract (GIT) and skeletal muscles of turkey embryos from day 24 of incubation (24E) to hatching, together with hatchability, poult quality and liver L* (lightness), a* (redness) and b* (yellowness) values at hatch. At day 22 of incubation, embryonated eggs (n = 240) were assigned to three treatments, that is, eggs were not injected (control, NC) or injected with 1.5 ml sterile solution with 0.9% salt (SA) or 0.2% BCAA blend (BCAAb). These solutions were injected manually into the amniotic fluid of the embryonated eggs. To determine weights and lengths (where appropriate) of the studied organs and tissues, four embryonated eggs and poults per treatment were selected at 24E and at hatch. While the BCAAb decreased the YS and embryo weight, hatchability and the liver L* value, it increased the weight and quality of poults and the weights of breast and thigh muscles at hatch. In conclusion, the in ovo feeding of the BCAA blend negatively affected hatchability but positively affected hatching weight and poult quality by improving development of skeletal muscles and by regulating energy metabolism.

In ovo feeding of l-arginine regulates intestinal barrier functions of posthatch broilers by activating the mTOR signaling pathway

BACKGROUND

During the last phase of incubation, dramatic physiological and metabolic changes occur in chick embryos, and supplies of nutrients and energy are always insufficient. This study investigated the effects of in ovo feeding (IOF) of l-arginine (Arg) on the hatchability, growth performance, intestinal development and functions of posthatch broilers.

RESULTS

The IOF of Arg increased (P < 0.05) the feed intake and body weight gain during 1-21 days and 1-42 days, and the intestinal weight of 7- and 21-day-old broilers, compared with non-injected control and diluent-injected groups. The IOF of Arg increased (P < 0.05) villus height (VH), ratio of VH to crypt depth (CD) and density of goblet cells, and decreased (P < 0.05) the CD in jejunum of 1-, 7- and 21-day-old broilers. The IOF of Arg also increased (P < 0.05) the percentage of proliferating cell nuclear antigen positive cells of villus, and the mRNA expressions of mucin-2, claudin-1, zonula occludens-1 and -2 in jejunal mucosa of 21-day-old broilers. Meanwhile, IOF of Arg increased (P < 0.05) the protein abundance of phosphorylated mechanistic target of rapamycin (mTOR), ribosomal protein S6 kinase 1 and eukaryotic initiation factor 4E binding protein 1 in jejunal mucosa.

CONCLUSION

The IOF of Arg improved the development and barrier functions of small intestine, which might be associated with activating the mTOR pathway. In addition, the improved intestinal development might explain the improvement in feed intake and consequently the growth performance of broilers. Therefore, IOF of Arg solution could be an effective technology for regulating early nutrition supply and subsequent growth development in the poultry industry. © 2017 Society of Chemical Industry.

Regulation of intestinal health by branched-chain amino acids

Besides its primary role in the digestion and absorption of nutrients, the intestine also interacts with a complex external milieu, and is the first defense line against noxious pathogens and antigens. Dysfunction of the intestinal barrier is associated with enhanced intestinal permeability and development of various gastrointestinal diseases. The branched-chain amino acids (BCAAs) are important nutrients, which are the essential substrates for protein biosynthesis. Recently, emerging evidence showed that BCAAs are involved in maintaining intestinal barrier function. It has been reported that dietary supplementation with BCAAs promotes intestinal development, enhances enterocyte proliferation, increases intestinal absorption of amino acids (AA) and glucose, and improves the immune defenses of piglets. The underlying mechanism of these effects is mediated by regulating expression of genes and proteins associate with various signaling pathways. In addition, BCAAs promote the production of beneficial bacteria in the intestine of mice. Compelling evidence supports the notion that BCAAs play important roles in both nutrition and intestinal health. Therefore, as functional amino acids with various physiological effects, BCAAs hold key roles in promoting intestinal development and health in animals and humans.

Spinosad induces autophagy of Spodoptera frugiperda Sf9 cells and the activation of AMPK/mTOR signaling pathway

Spinosad, a high-selectivity neural toxin, has been widely used in agricultural production. However, the mode of action of spinosad on insect non-neural cells is not yet clear and hence requires further investigation. Therefore, to reveal the cytotoxic mechanisms of spinosad, we investigated whether and how it can induce autophagic cell death. After treating Sf9 cells with spinosad, the resulting autophagosome was observed by transmission electron microscopy and monodansylcadaverine staining. Interestingly, spinosad induced the accumulation of Beclin-1, degradation of p62, and intensification of LC3-B formation and translocation and thus autophagy, whereas, 3-MA treatment reverted the phenotype. Under ATP depletion conditions, spinosad induced autophagy of Sf9 cells and activation of the AMPK/mTOR signaling pathway.

Novel metabolic and physiological functions of branched chain amino acids: a review

It is widely known that branched chain amino acids (BCAA) are not only elementary components for building muscle tissue but also participate in increasing protein synthesis in animals and humans. BCAA (isoleucine, leucine and valine) regulate many key signaling pathways, the most classic of which is the activation of the mTOR signaling pathway. This signaling pathway connects many diverse physiological and metabolic roles. Recent years have witnessed many striking developments in determining the novel functions of BCAA including: (1) Insufficient or excessive levels of BCAA in the diet enhances lipolysis. (2) BCAA, especially isoleucine, play a major role in enhancing glucose consumption and utilization by up-regulating intestinal and muscular glucose transporters. (3) Supplementation of leucine in the diet enhances meat quality in finishing pigs. (4) BCAA are beneficial for mammary health, milk quality and embryo growth. (5) BCAA enhance intestinal development, intestinal amino acid transportation and mucin production. (6) BCAA participate in up-regulating innate and adaptive immune responses. In addition, abnormally elevated BCAA levels in the blood (decreased BCAA catabolism) are a good biomarker for the early detection of obesity, diabetes and other metabolic diseases. This review will provide some insights into these novel metabolic and physiological functions of BCAA.