Taurine Attenuates Oxidized Fish Oil-Induced Oxidative Stress and Lipid Metabolism Disorder in Mice.

The objective of this study was to determine the effect of dietary taurine on lipid metabolism and liver injury in mice fed a diet high in oxidized fish oil. The ICR mice (six weeks old) were randomly assigned to six groups and fed different diets for 10 weeks: control (CON), normal plus 15% fresh fish oil diet (FFO), normal plus 15% oxidized fish oil diet (OFO), or OFO plus 0.6% (TAU1), 0.9% (TAU2) or 1.2% (TAU3) taurine. Compared to the CON group, OFO mice showed increased liver index, aspartate aminotransferase (AST) and malondialdehyde (MDA) levels in serum (p < 0.05). In addition, OFO mice had increased cholesterol (CHOL)/high-density lipoprotein cholesterol (HDL-C) and decreased HDL-C/low-density lipoprotein cholesterol (LDL-C) and n-6/n-3 polyunsaturated fatty acid (PUFA) ratio in serum (p < 0.05) compared with CON mice. Notably, dietary taurine ameliorated the liver index and AST and MDA levels in serum and liver in a more dose-dependent manner than OFO mice. In addition, compared to OFO mice, decreased levels of CHOL and ratio of CHOL/HDL-C and n-6 PUFA/n-3 PUFA in serum were found in TAU3-fed mice. Supplementation with TAU2 and TAU3 increased the relative mRNA expression levels of peroxisome proliferator-activated receptor α, adipose triglyceride lipase, lipoprotein lipase, hormone-sensitive lipase and carnitine palmitoyl transferase 1 in liver compared with the OFO group (p < 0.05). Moreover, impaired autophagy flux was detected in mice fed with the OFO diet, and this was prevented by taurine. These findings suggested that dietary taurine might provide a potential therapeutic choice against oxidative stress and lipid metabolism disorder.

Spatiotemporal Regulation of Circular RNA Expression during Liver Development of Chinese Indigenous Ningxiang Pigs.

BACKGROUND: There have been many studies on the relationship between circRNAs and fat deposition. Although the liver is a central organ for fat metabolism, there are few reports on the relationship between circRNAs in the liver and fat deposition. METHODS: In this study, we systematically analyzed circular RNAs in the liver of Ningxiang pigs, at four time points after birth (30 days, 90 days, 150 days and 210 days). RESULTS: A total of 3705 circRNAs were coexpressed in four time periods were found, and KEGG analysis showed that the significantly upregulated pathways were mainly enriched in lipid metabolism and amino acid metabolism, while significantly downregulated pathways were mainly related to signal transduction, such as ECM-receptor interaction, MAPK signaling pathway, etc. Short time-series expression miner (STEM) analysis showed multiple model spectra that were significantly enriched over time in the liver. By constructing a competing endogenous RNA (ceRNA) regulatory network, 9187 pairs of networks related to the change in development time were screened. CONCLUSIONS: The expression profiles of circRNAs in Ningxiang pig liver were revealed at different development periods, and it was determined that there is differential coexpression. Through enrichment analysis of these circRNAs, it was revealed that host genes were involved in metabolism-related signaling pathways and fatty acid anabolism. Through STEM analysis, many circRNAs involved in fat metabolism, transport, and deposition pathways were screened, and the first circRNA-miRNA-mRNA regulation network map in Ningxiang pig liver was constructed. The highly expressed circRNAs related to fat deposition were verified and were consistent with RNA-Seq results.

Comparison of the Effects of Inorganic or Amino Acid-Chelated Zinc on Mouse Myoblast Growth in vitro and Growth Performance and Carcass Traits in Growing-Finishing Pigs.

This study aimed to investigate the effects of the supplementation of different sources of zinc on mouse myoblast growth in vitro and the growth performance and carcass traits in growing-finishing pigs. In the in vitro trial, 25 or 75 mM zinc sulfate (ZnSO4), methionine-chelated zinc (ZnMet), and glycine-chelated zinc (ZnGly) were co-cultured with the myoblast during proliferation and differentiation. The results showed that the amino acid-chelated zinc supplementation, especially ZnMet, enhances cell proliferation and differentiation in mouse myoblast, and regulates the distribution in S and G2/M phases (P < 0.05). Meanwhile, the protein expression levels of the mammalian target of rapamycin pathways were up-regulated after treatment with 25 µM ZnMet (P < 0.05), which is consistent with the results of the enriched Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway in the transcriptome analysis. In the in vivo trial, 27 Duroc × (Landrace × Large White) pigs with an initial average weight of 31.62 ± 0.36 kg were divided into three groups with nine replicates per treatment. The dietary treatment groups were as follows: (1) ZnSO4 group, basal diet +75 mg/kg ZnSO4; (2) ZnMet group, basal diet +75 mg/kg ZnMet; and (3) ZnGly group, basal diet +75 mg/kg ZnGly. The whole trial lasted for 75 days. Increased final body weight, average daily gain, and decreased F/G were noted in the ZnMet group (P < 0.05). Moreover, the ZnMet group had higher carcass weight and loin eye area (P = 0.05). The ZnMet and ZnGly group both had lower serum total protein (P < 0.05), while the ZnMet group had higher serum alkaline phosphatase (P < 0.05). Also, the addition of ZnMet showed higher concentrations of zinc and iron in muscle, kidney, and serum (P < 0.05), improving the deposition and availability of micronutrients. In conclusion, amino acid-chelated zinc, particularly ZnMet, had the best effect, which could improve growth in vitro and increase growth performance while boosting bioavailability in growing-finishing pigs, ultimately, enhancing muscle mass, providing a theoretical basis and guidance for the future use of amino acid-chelated zinc to effectively replenish energy in animal nutrition and production.

Effects of Dietary Chlorogenic Acid Supplementation Derived from Lonicera macranthoides Hand-Mazz on Growth Performance, Free Amino Acid Profile, and Muscle Protein Synthesis in a Finishing Pig Model.

Chlorogenic acid (CGA), as one of the richest polyphenol compounds in nature, has broad applications in many fields due to its various biological properties. However, initial data on the effects of dietary CGA on protein synthesis and related basal metabolic activity has rarely been reported. The current study is aimed at (1) determining whether dietary CGA supplementation improves the growth performance and carcass traits, (2) assessing whether dietary CGA alters the free amino acid profile, and (3) verifying whether dietary CGA promotes muscle protein synthesis in finishing pigs. Thirty-two (Large × White × Landrace) finishing barrows with an average initial body weight of 71.89 ± 0.92 kg were randomly allotted to 4 groups and fed diets supplemented with 0, 0.02%, 0.04%, and 0.08% CGA, respectively. The results indicated that, compared with the control group, dietary supplementation with 0.04% CGA slightly stimulated the growth performance of pigs, whereas no significant correlation was noted between the dietary CGA levels and animal growth (P > 0.05). Furthermore, the carcass traits of pigs were improved by 0.04% dietary CGA (P < 0.01). In addition, dietary CGA significantly improved the serum free amino acid profiles of pigs (P < 0.01), while 0.04% dietary CGA promoted more amino acids to translocate to skeletal muscles (P < 0.05). The relative mRNA expression levels of SNAT2 in both longissimus dorsi (LD) and biceps femoris (BF) muscles were augmented in the 0.02% and 0.04% groups (P < 0.05), and the LAT1 mRNA expression in the BF muscle was elevated in the 0.02% group (P < 0.05). We also found that dietary CGA supplementation at the levels of 0.04% or 0.08% promoted the expression of p-Akt and activated the mTOR-S6K1-4EBP1 axis in the LD muscle (P < 0.05). Besides, the MAFbx mRNA abundance in the 0.02% and 0.04% groups was significantly lower (P < 0.05). Our results revealed that dietary supplementation with CGA of 0.04% improved the free amino acid profile and enhanced muscle protein biosynthesis in the LD muscle in finishing pigs.

Balanced branched-chain amino acids modulate meat quality by adjusting muscle fiber type conversion and intramuscular fat deposition in finishing pigs.

BACKGROUND: Pork is an important food for humans and improving the quality of pork is closely related to human health. This study was designed to investigate the effects of balanced branched-chain amino acid (BCAA)-supplemented protein-restricted diets on meat quality, muscle fiber types, and intramuscular fat (IMF) in finishing pigs. RESULTS: The results showed that, compared with the normal protein diet (160 g kg-1 crude protein), the reduced-protein diet (120 g kg-1 crude protein) supplemented with BCAAs to the ratio of 2:1:2 not only had higher average daily gain (P < 0.05) and carcass weight (P < 0.05) but also improved meat tenderness and juiciness by decreasing shear force (P < 0.05) and increasing water-holding capacity (P < 0.05). In particular, this treatment showed higher (P < 0.05) levels of phospho-acetyl-CoA carboxylase (P-ACC) and peroxisome proliferation-activated receptor-γ (PPARγ), and lower (P < 0.05) levels of P-adenosine 5'-monophosphate (AMP)-activated protein kinase (P-AMPK), increasing the composition of IMF and MyHC I (P < 0.05) in the longissimus dorsi muscle (LDM). In terms of health, this group increased eicosapentaenoic acid (EPA) (P < 0.01) and desirable hypocholesterolemic fatty acids (DHFA) (P < 0.05), and decreased atherogenicity (AI) (P < 0.01) and hypercholesterolemic saturated fatty acids (HSFA) (P < 0.05). CONCLUSION: Our findings suggest a novel role for a balanced BCAA-supplemented restricted protein (RP) diet in the epigenetic regulation of more tender and healthier pork by increasing IMF deposition and fiber type conversion, providing a cross-regulatory molecular basis for revealing the nutritional regulation network of meat quality. © 2021 Society of Chemical Industry.

Plant Extracts in Obesity: A Role of Gut Microbiota.

Obesity has become one of the most serious chronic diseases threatening human health. Its occurrence and development are closely associated with gut microbiota since the disorders of gut microbiota can promote endotoxin production and induce inflammatory response. Recently, numerous plant extracts have been proven to mitigate lipid dysmetabolism and obesity syndrome by regulating the abundance and composition of gut microbiota. In this review, we summarize the potential roles of different plant extracts including mulberry leaf extract, policosanol, cortex moutan, green tea, honokiol, and capsaicin in regulating obesity via gut microbiota. Based on the current findings, plant extracts may be promising agents for the prevention and treatment of obesity and its related metabolic diseases, and the mechanisms might be associated with gut microbiota.

Different Proportions of Branched-Chain Amino Acids Modulate Lipid Metabolism in a Finishing Pig Model.

This study aimed to investigate the effect of the supplementation of branched-chain amino acids (BCAAs) at different ratios in protein restriction diets on lipid metabolism in a finishing pig model. The BCAA supplementation (leucine/isoleucine/valine = 2:1:1 and 2:1:2) ameliorated the poor growth performance and carcass characteristics, particularly high fat mass caused by a protein-restricted diet. Serum adiponectin increased while leptin decreased in BCAA diets in comparison to the 12% CP group. BCAA supplementation also increased the low-protein expression of AMPK and SIRT1 caused by protein restriction. The mRNA and protein levels of peroxisome proliferation-activated receptor-γ (PPARγ) and acetyl-CoA carboxylase (ACC) were highest in the protein-restricted group and lowered in the 2:1:1 or 2:1:2 group. In conclusion, BCAAs supplemented in an adequate ratio range of 2:1:1 to 2:1:2 (2:1:2 is recommended) in reduced protein diets could modulate lipid metabolism by accelerating the secretion of adipokines and fatty acid oxidation.

Dietary Beta-Hydroxy Beta-Methyl Butyrate Supplementation Alleviates Liver Injury in Lipopolysaccharide-Challenged Piglets.

The current study was performed to investigate whether dietary ß-hydroxy-ß-methylbutyrate (HMB) could regulate liver injury in a lipopolysaccharide- (LPS-) challenged piglet model and to determine the mechanisms involved. Thirty piglets (21 ± 2 days old, 5.86 ± 0.18 kg body weight) were randomly divided into the control (a basal diet, saline injection), LPS (a basal diet), or LPS+HMB (a basal diet + 0.60% HMB-Ca) group. After 15 d of treatment with LPS and/or HMB, blood and liver samples were obtained. The results showed that in LPS-injected piglets, HMB supplementation ameliorated liver histomorphological abnormalities induced by LPS challenge. Compared to the control group, the activities of serum aspartate aminotransferase and alkaline phosphatase were increased in the LPS-injected piglets (P < 0.05). The LPS challenge also downregulated the mRNA expression of L-PFK, ACO, L-CPT-1, ICDH ß, and AMPKα1/2 and upregulated the mRNA expression of PCNA, caspase 3, TNF-α, TLR4, MyD88, NOD1, and NF-κB p65 (P < 0.05). However, these adverse effects of the LPS challenge were reversed by HMB supplementation (P < 0.05). These results indicate that HMB may exert protective effects against LPS-induced liver injury, and the underlying mechanisms might involve the improvement of hepatic energy metabolism via regulating AMPK signaling pathway and the reduction of liver inflammation via modulating TLR4 and NOD signaling pathways.

Taurine Alleviates Intestinal Injury by Mediating Tight Junction Barriers in Diquat-Challenged Piglet Models.

Background: Intestinal barrier contributes as an important role in maintaining intestinal homeostasis. Oxidative stress can cause critical damages in intestinal integrity of animals. Objectives: This study was conducted to investigate the alleviated effect of taurine against small intestine (duodenum, jejunum, ileum) injury induced by oxidative stress. Methods: The piglet model of diquat-induced oxidative stress was employed. In addition, analysis of intestinal morphology, reverse transcription PCR (RT-PCR), and Western blot were used in this study. Results: Compared with the control group (CON), diquat-induced oxidative stress triggers immune response; the content of immunoglobulin M (IgM) and immunoglobulin G (IgG) was significantly changed, but 0.60% taurine supplementation could restore the level of serum immunoglobulin. Oxidative stress induces serious damage in intestinal morphology structure and tight junction barrier. Compared with the CON, the villus height of intestine was significantly decreased, the crypt depth and villus height/crypt depth (V/C) were also decreased, and 0.60% taurine supplementation could restore impaired morphology and even improve crypt depth and V/C of the jejunum and ileum. Compared with the CON, oxidative stress markedly increased the messenger RNA (mRNA) expression level of claudin-1 and occludin in the duodenum, and the value of occludin was significantly decreased in the jejunum of the diquat group (DIQ). Relative to the DIQ, 0.60% taurine supplementation increased the mRNA expression level of claudin-1, occludin, and ZO-1 in the ileum. Compared with the CON, the expression of claudin-1 protein was significantly upregulated, and occludin and ZO-1 protein were both downregulated in the small intestine of DIQ. Conclusion: Taurine exerts protective effects by regulating immune response and restores the intestinal tight junction barrier when piglets suffer from oxidative stress.

Protective effects of taurine against muscle damage induced by diquat in 35 days weaned piglets.

BACKGROUND: Oxidative stress is a key factor that influences piglets' health. Taurine plays an imperative role in keeping the biological system from damage. This study was conducted to investigate the protective effect of taurine against muscle injury due to the secondary effect of diquat toxicity. RESULTS: Our study found that taurine effectively and dose-dependently alleviated the diquat toxicity induced rise of feed/gain, with a concurrent improvement of carcass lean percentage. The plasma content of taurine was considerably increased in a dose-dependent manner. Consequently, dietary taurine efficiently improved the activity of plasma antioxidant enzymes. Furthermore, taurine attenuated muscle damage by restoring mitochondrial micromorphology, suppressing protein degradation and reducing the percentage of apoptotic cells in the skeletal muscle. Taurine supplementation also suppressed the genes expression levels of the antioxidant-, mitochondrial biogenesis-, and muscle atrophy-related genes in the skeletal muscle of piglets with oxidative stress. CONCLUSIONS: These results showed that the dose of 0.60% taurine supplementation in the diet could attenuate skeletal muscle injury induced by diquat toxicity. It is suggested that taurine could be a potential nutritional intervention strategy to improve growth performance.

Dietary ß-hydroxy-ß-methylbutyrate improves intestinal function in weaned piglets after lipopolysaccharide challenge.

OBJECTIVES: The aim of this study was to explore the effects of ß-hydroxy-ß-methylbutyrate (HMB) on intestinal function of lipopolysaccharide (LPS)-challenged piglets. METHODS: Forty weaned piglets were used in a 2 × 2 factorial design. The major factors were challenge (saline or LPS) and diet (basal diet or 0.6% HMB-Ca diet). After 15 d of treatment with LPS or HMB, blood and intestine samples were obtained. RESULTS: The results showed that in LPS-injected pigs, HMB supplementation significantly increased jejunal villus height and ileal villus height-to-crypt depth ratio and decreased ileal crypt depth (P < 0.05). HMB also improved intestinal function indicated by elevated activities of intestinal mucosal disaccharidase and tricarboxylic acid cycle key enzymes. Furthermore, HMB significantly downregulated mRNA expression of Sirt1 in jejunum and mRNA expression of AMPKα1 and Sirt1 in ileum (P < 0.05), with a concurrent decrease of AMPKα phosphorylation in jejunum and ileum. Microbiota analysis indicated that HMB supplementation significantly increased α-diversity and affected relative abundances of Romboutsia and Sarcina at the genus level, accompanied by increased concentrations of all short-chain fatty acids except propionate in the terminate ileum of LPS-injected piglets. CONCLUSION: Dietary HMB supplementation could improve intestinal integrity, function, microbiota communities, and short-chain fatty acid concentrations in LPS-challenged piglets, suggesting its potential usage as a feed additive in weaned piglets to alleviate intestinal dysfunction triggered by immune stress.

Leucine Supplementation: A Novel Strategy for Modulating Lipid Metabolism and Energy Homeostasis.

Lipid metabolism is an important and complex biochemical process involved in the storage of energy and maintenance of normal biological functions. Leucine, a branched amino acid, has anti-obesity effects on glucose tolerance, lipid metabolism, and insulin sensitivity. Leucine also modulates mitochondrial dysfunction, representing a new strategy to target aging, neurodegenerative disease, obesity, diabetes, and cardiovascular disease. Although various studies have been carried out, much uncertainty still exists and further studies are required to fully elucidate the relationship between leucine and lipid metabolism. This review offers an up-to-date report on leucine, as key roles in both lipid metabolism and energy homeostasis in vivo and in vitro by acceleration of fatty acid oxidation, lipolysis, activation of the adenosine 5'-monophosphate-activated protein kinase (AMPK)-silent information regulator of transcription 1 (SIRT1)-proliferator-activated receptor γ coactivator-1α (PGC-1α) pathway, synthesis, and/or secretion of adipokines and stability of the gut microbiota.

Oxidative stress, nutritional antioxidants and beyond.

Free radical-induced oxidative stress contributes to the development of metabolic syndromes (Mets), including overweight, hyperglycemia, insulin resistance and pro-inflammatory state. Most free radicals are generated from the mitochondrial electron transport chain; under physiological conditions, their levels are maintained by efficient antioxidant systems. A variety of transcription factors have been identified and characterized that control gene expression in response to oxidative stress status. Natural antioxidant compounds have been largely studied for their strong antioxidant capacities. This review discusses the recent progress in oxidative stress and mitochondrial dysfunction in Mets and highlights the anti-Mets, anti-oxidative, and anti-inflammatory effect of polyphenols as potential nutritional therapy.

Dietary supplementation with the extract from Eucommia ulmoides leaves changed epithelial restitution and gut microbial community and composition of weanling piglets.

This study was conducted to compare the effects of Eucommia ulmoides leaves (EL) in different forms (EL extract, fermented EL, and EL powder) with antibiotics on growth performance, intestinal morphology, and the microbiota composition and diversity of weanling piglets. Compared to the control group, the antibiotics and EL extract significantly increased the average daily gain and decreased the feed: gain ratio as well as the diarrhea rate (P < 0.05). The EL extract significantly decreased the crypt depth and increased the ratio of villus height to crypt depth (P < 0.05), while the fermented EL group did the opposite (P < 0.05). The crypt depth in the antibiotics group was of similar value to the EL extract group, and was lower than the fermented EL and EL powder groups (P < 0.05). Compared to the control and antibiotics groups, the jejunul claudin-3 mRNA expression and the concentrations of total VFA, Chao 1, and ACE were significantly augmented in the EL extract group of piglets (P < 0.05). The EL extract groups also showed elevated Shannon (P < 0.05) and Simpson (P = 0.07) values relative to the control and antibiotics groups. At the phylum level, the EL extract group exhibited a reduced abundance of Bacteroidetes and an enhanced abundance of Firmicutes. At the genus level, the abundance of Prevotella was augmented in the EL extract group. Moreover, compared with the antibiotic group, the acetate concentration was enhanced in the EL extract and fermented EL groups. Overall, dietary supplementation with the EL extract, but not the fermented EL or EL powder, improved growth performance, jejunul morphology and function, as well as changed colonic microbial composition and diversity, which might be an alternative to confer protection against weanling stress in weanling piglets.

Glutamic acid supplementation reduces body fat weight in finishing pigs when provided solely or in combination with arginine and it is associated with colonic propionate and butyrate concentrations.

Changes in the composition of gut microbiota have been proposed as possible causes of obesity. Our previous study showed that glutamic acid (Glu) alone or a combination of Glu and arginine (Arg) decreased backfat thickness in finishing pigs. Therefore, this study aimed to investigate the effects of dietary supplementation with Glu and/or Arg on body fat weight, composition of gut microbiota, and short-chain fatty acid concentrations in the colons of finishing pigs, and to elucidate whether body fat weight was associated with changes in the colonic microbial community and concentrations of colonic metabolites. Sixty Duroc × Large White × Landrace pigs with an average initial body weight of 77.1 ± 1.3 kg were randomly assigned to one of five treatment groups (12 pigs per group). The pigs in the control group were fed a basal diet (BD group), while those in the experimental groups were fed a basal diet supplemented with either 2.05% l-alanine (Isonitrogenous, IS group), 1.00% l-arginine (Arg group), 1.00% glutamate + 1.44% l-alanine (Glu group), or 1.00% l-arginine + 1.00% glutamate (Arg_Glu group). The results showed that dietary supplementation with alanine has no effect (P > 0.05) on body fat weight, while with both Glu and Arg + Glu decreased (P < 0.05) body fat weight and increased (P < 0.05) colonic concentrations of propionate, butyrate, and valerate relative to the BD group. Negative relationships (P < 0.05) were observed between body fat weight and colonic propionate and butyrate concentrations. Compared to the IS group, dietary supplementation with Arg or Arg + Glu decreased (P < 0.05) colonic tyramine concentration. Compared to the IS group, the butyrate concentration increased (P < 0.05) in the Arg_Glu group. Compared to the BD group, the relative colonic abundance of Actinobacteria was higher (P < 0.05) in the Arg_Glu group. The abundances of Lachnospiraceae_XPB1014_group, norank_f_Erysipelotrichaceae, and Roseburia sp. were negatively (P < 0.05) correlated with body fat weight, and the abundance of norank_f_Erysipelotrichaceae was also negatively (P < 0.05) correlated with colonic butyrate concentration. These findings suggest that decreased body fat weight in finishing pigs can be induced by Glu supplementation alone or in combination with Arg. Glu + Arg supplementation was also associated with increased colonic butyrate and propionate concentrations and increased colonic Actinobacteria abundance.

Dietary xylo-oligosaccharide improves intestinal functions in weaned piglets.

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

Leucine alone or in combination with glutamic acid, but not with arginine, increases biceps femoris muscle and alters muscle AA transport and concentrations in fattening pigs.

Forty-eight Duroc × Large White × Landrace pigs with an average initial body weight of 77.09 ± 1.37 kg were used to investigate the effects of combination of leucine (Leu) with arginine (Arg) or glutamic acid (Glu) on muscle growth, free amino acid profiles, expression levels of amino acid transporters and growth-related genes in skeletal muscle. The animals were randomly assigned to one of the four treatment groups (12 pigs/group, castrated male:female = 1:1). The pigs in the control group were fed a basal diet (13% Crude Protein), and those in the experimental groups were fed the basal diet supplemented with 1.00% Leu (L group), 1.00% Leu + 1.00% Arg (LA group) or 1.00% Leu + 1.00% Glu (LG group). The experiment lasted for 60 days. Results showed an increase (p < 0.05) in biceps femoris (BF) muscle weight in the L group and LG group relative to the basal diet group. In longissimus dorsi (LD) muscle, Lys, taurine and total essential amino acid concentration increased in the LG group relative to the basal diet group (p < 0.05). In LG group, Glu and carnosine concentrations increased (p < 0.05) in the BF muscle, when compared to the basal diet group. The Leu and Lys concentrations of BF muscle were lower in the LA group than that in the L group (p < 0.05). A positive association was found between BF muscle weight and Leu concentration (p < 0.05). The LG group presented higher (p < 0.05) mRNA levels of ASCT2, LAT1, PAT2, SANT2 and TAT1 in LD muscle than those in the basal diet group. The mRNA levels of PAT2 and MyoD in BF muscle were upregulated (p < 0.05) in the LG group, compared with those in the basal diet group. In conclusion, Leu alone or in combination with Glu is benefit for biceps femoris muscle growth in fattening pig.

α-Ketoisocaproate and ß-hydroxy-ß-methyl butyrate regulate fatty acid composition and lipid metabolism in skeletal muscle of growing pigs.

OBJECTIVES: This study aims to investigate the effects and roles of excess leucine (Leu) versus its metabolites α-ketoisocaproate (KIC) and ß-hydroxy-ß-methyl butyrate (HMB) on fatty acid composition and lipid metabolism in skeletal muscle of growing pigs. METHODS AND RESULTS: Thirty-two pigs with a similar initial weight (9.55 ± 0.19 kg) were fed one of the four diets (basal diet, L-Leu, KIC-Ca and HMB-Ca) for 45 days. Results indicated that dietary treatments did not affect the intramuscular fat (IMF) content (p > 0.05), but differently influenced the fatty acid composition of longissimus dorsi muscle (LM) and soleus muscle (SM). In particular, the proportion of N3 PUFA specifically in LM was significantly decreased in the Leu group and increased in both KIC and HMB group relative to the basal diet group (p < 0.05). Furthermore, pigs fed KIC-supplemented diets exhibited decreased expression of FATP-1, ACC, ATGL, C/EBPα, PPARγ and SREBP-1c in LM and increased expression of FATP-1, FAT/CD36, ATGL and M-CPT-1 in SM relative to the basal diet control (p < 0.05). CONCLUSIONS: These findings indicated that doubling dietary Leu content decreased the percentage of N3 PUFA mainly in glycolytic skeletal muscle, whereas KIC and HMB improved muscular fatty acid composition and altered lipid metabolism in skeletal muscle of growing pigs. The mechanism of action of KIC might be related to the TFs, and the mechanism of action of HMB might be associated with the AMPK-mTOR signalling pathway.

Taurine is Involved in Energy Metabolism in Muscles, Adipose Tissue, and the Liver.

Energy metabolism is a basic and general process, by which the body acquires and uses energy to maintain normal function, and taurine plays a vital role in energy metabolism. Taurine deficiency may cause a weak energy metabolism and energy metabolism dysfunction. Taurine biosynthetic ability is limited, and its supplementation in the diet can strengthen energy metabolism in muscle performance, cardiac function, liver activity, and adipose tissue. Combining taurine with other drugs may have a superior effect in energy metabolism. In many metabolic disorders, taurine, or the combination of taurine with other drugs, also functions as a repair treatment for damaged tissues, and acts as a promoter for the balance of energy metabolism. The present study discusses the potential roles of taurine in energy metabolism.

ß-hydroxy-ß-methyl butyrate promotes leucine metabolism and improves muscle fibre composition in growing pigs.

The aim of this study was to investigate the effects of excess leucine (Leu) vs. its metabolites α-ketoisocaproate (KIC) and ß-hydroxy-ß-methyl butyrate (HMB) on Leu metabolism, muscle fibre composition and muscle growth in growing pigs. Thirty-two pigs with a similar initial weight (9.55 ± 0.19 kg) were fed 1 of 4 diets for 45 days: basal diet, basal diet + 1.25% L-Leu, basal diet + 1.25% KIC-Ca, basal diet + 0.62% HMB-Ca. Results indicated that relative to the basal diet and HMB groups, Leu and KIC groups exhibited increased Leu concentrations and decreased concentrations of isoleucine, valine and EAAs in selected muscle (p < 0.05) and had lower mRNA levels of MyHC I and higher expression of MyHC IIx/IIb (p < 0.05), and there was no significant difference between the basal and HMB-supplemented groups. Moreover, the mRNA expression levels of AMPKα and UCP3 were higher but the myostatin mRNA levels were lower in the soleus muscle of the HMB group than those from other groups (p < 0.05). These findings demonstrated that doubling dietary Leu content exerted growth-depressing effects in growing pigs; dietary KIC supplementation induced muscular branched-chain amino acid imbalance and promoted muscle toward a more glycolytic phenotype; while dietary HMB supplementation promoted the generation of more oxidative muscle types and increased muscle growth specially in oxidative skeletal muscle, and these effects of HMB might be associated with the AMPKα-Sirt1-PGC-1α axis and mitochondrial biogenesis.