In modern intensive breeding system, broilers are exposed to various challenges, such as diet changes and pathological environment, which may cause the increase in the incidence rate and even death. It is necessary to take measures to prevent diseases and maintain optimal health and productivity of broilers. With the forbidden use of antibiotics in animal feed, polysaccharides from plants have attracted much attention owing to their lower toxicity, lower drug resistance, fewer side effects, and broad-spectrum antibacterial activity. It had been demonstrated that polysaccharides derived from plant exerted various functions, such as growth promotion, anti-inflammation, maintaining the integrity of intestinal mucosa, and regulation of intestinal microbiota. Therefore, the current review aimed to provide an overview of the recent advances in the impacts of plant-derived polysaccharides on anti-inflammation, gut health, and intestinal microbiota community of broilers in order to provide a reference for further study on maintaining the integrity of intestinal structure and function, and the related mechanism involved in the polysaccharide administration intervention.

The present study was conducted to investigate the effects of glutamine (Gln) supplementation on intestinal inflammatory reaction and mucosa barrier of broilers administrated with lipopolysaccharide (LPS) stimuli. A total of 120 1-d-old male broilers were randomly divided into four treatments in a 2 × 2 experimental arrangement, containing immune challenge (injected with LPS in a dose of 0 or 500 μg/kg of body weight) and dietary treatments (supplemented with 1.22% alanine or 1% Gln). The results showed that growth performance of broilers intra-abdominally injected with LPS was impaired, and Gln administration alleviated the adverse effects on growth performance induced by LPS challenge. Furthermore, Gln supplementation reduced the increased concentration of circulating tumor necrosis factor-α, interleukin-6 and interleukin-1β induced by LPS challenge. Meanwhile, D-lactic acid and diamine oxidase concentration in plasma were also decreased by Gln supplementation. In addition, the shorter villus height, deeper crypt depth and the lower ratio of villus height to crypt depth of duodenum, jejunum and ileum induced by LPS stimulation were reversed by Gln supplementation. Gln administration beneficially increased LPS-induced reduction in the expression of intestine tight junction proteins such as zonula occludens protein 1 (ZO-1), claudin-1 and occludin except for the ZO-1 in duodenum and occludin in ileum. Moreover, Gln supplementation downregulated the mRNA expression of toll-like receptor 4, focal adhesion kinase, myeloid differentiation factor 88 and IL-1R-associated kinase 4 in TLR4/FAK/MyD88 signaling pathway. Therefore, it can be concluded that Gln administration could attenuate LPS-induced inflammatory responses and improve intestinal barrier damage of LPS-challenged broilers.

Pre-slaughter transport stress could induce multiple comprehensive variations in physiological and metabolic parameters of broilers. However, the entire metabolomics of pre-slaughter transport stress and supplementation of exogenous energy regulatory substances on broilers is still poorly understood. The metabolome characteristics of broilers subjected to 3 h pre-slaughter transport stress combined with 1,200 mg/kg guanidinoacetic acid (GAA_1,200) supplementation were analyzed using gas chromatography-mass spectrometry (GC−MS) in this study. The results showed that, compared to the control group (no transport), 3 h pre-slaughter transport stress (T_3h) decreased creatine (Cr), phosphocreatine (PCr) and adenosine triphosphate (ATP), and increased adenosine diphosphate (ADP), adenosine monophosphate (AMP) and the ratio of AMP to ATP in pectoralis muscle (PM) of broilers by high performance liquid chromatography (HPLC) analysis. However, GAA_1,200 supplementation reversed the negative effects induced by 3 h pre-slaughter transport stress. Besides, GAA_1,200 supplementation elevated mRNA expression of creatine transporter in PM. Our metabolomics approaches demonstrated that 38 and 48 significant metabolites were separately identified between the control group and T_3h group, and T_3h group and 3 h pre-slaughter transport stress combined with GAA_1,200 supplementation group using the standard of variable importance in the projection values >1 and P < 0.05. Among these, the metabolites involved in amino acid metabolism (alanine, glycine, serine, threonine, cysteine , methionine, phenylalanine, tyrosine, and tryptophan), oxidative stress (3-methylhistidine, 1-methylhistidine and glutathione), non-protein amino acid (citrulline) metabolism, and energy metabolism (Cr, PCr, sarcosine, and glycocyamine) were confirmed through pathway enrichment analysis, which could be chosen as suitable candidate targets for further analysis of the effects of exogenous energy substances on broilers subjected to transport stress.

Objective: The present study was to evaluate the effects of different rapeseed meal substitution (RSM) and glutamine (Gln) supplementation on growth performance, intestine morphology, and intestinal mucosa barrier of broilers.Methods: Four hundred and twenty Qiandongnan Xiaoxiang Chicken at 1 day of age with similar weight were chosen and were randomly assigned into 7 groups, consisting of 10 replicates per group and 6 broilers per replicate. Three groups were provided with diets separately containing 0%, 10%, and 20% RSM, and the other four groups were fed with diets separately supplemented with 0.5% and 1% Gln based on the inclusion of 10% and 20% RSM. At 21 and 42 days of age, 10 broilers per group were chosen to collect plasma and intestinal samples for further analysis.Results: The results showed that 10% RSM decreased average daily feed intake (ADFI) and average daily weight gain (ADG) of broilers at 21 days of age (p<0.05). Furthermore, both ADFI and ADG of broilers at 21 and 42 days of age were decreased by 20% RSM, while feed conversion ratio (FCR) was increased (p<0.05). Besides, 10% RSM resulted in lower intestinal villus height and the ratio of villus height to crypt depth, deeper crypt depth (p<0.05), combined with the lower mRNA expressions of occludin, claudin-1, and zonula occludens-1 (ZO-1) in broilers at 21 days of age (p<0.05). Similar results were also observed in broilers at 21 and 42 days of age fed with 20% RSM. However, 1% Gln improved the growth performance of broilers fed with 10% and 20% RSM (p<0.05), ameliorated intestine morphology and elevated mRNA expressions of occludin, claudin-1 and ZO-1 (p<0.05).Conclusion: In conclusion, the increasing inclusion of RSM resulted in more serious effects on broilers, however, 1.0% Gln could reverse the negative effects induced by the inclusion of RSM.

The aim of our present study was to investigate the effects of Gln supplementation on liver inflammatory responses as well as protein synthesis and degradation in the muscle of LPS-challenged broilers. A total of 120 one-day-old male broiler chickens (Arbor Acres Plus) were randomly arranged in a 2 × 2 factorial design with five replicates per treatment and six broilers per replicate, containing two main factors: immune challenge (injected with LPS in a dose of 0 or 500 µg/kg of body weight) and dietary treatments (supplemented with 1.22% alanine or 1% Gln). After feeding with an alanine or Gln diet for 15 days, broilers were administrated an LPS or a saline injection at 16 and 21 days. The results showed that Gln supplementation alleviated the increased mRNA expressions of interleukin-6, interleukin-1β, and tumor necrosis factor-α induced by LPS in liver. Moreover, the increased activity of aspartate aminotransferase combined with the decreased expression of glutaminase in muscle were observed following Gln addition. In addition, in comparison with the saline treatment, LPS challenge altered the signaling molecules’ mRNA expressions associated with protein synthesis and degradation. However, Gln supplementation reversed the negative effects on protein synthesis and degradation in muscle of LPS-challenged broilers. Taken together, Gln supplementation had beneficial effects: alleviating inflammatory responses, promoting protein synthesis, and inhibiting protein degradation of LPS-challenged broilers.

Objective: Antemortem stress accelerated muscle energy consumption in postmortem muscle. The objective of our study was to investigate the regulation of guanidinoacetic acid (GAA) administration on the postmortem glycolysis and protein acetylation in postmortem muscle of antemortem stress.Methods: Forty C57BL/6 male mice were chosen and randomly assigned to four treatment groups (A, B, C and D), each treatment consisted of 10 replicates. Mice in group B, C and D were treated with 0.05% GAA oral administration for 6 days. On the 7th day of the experiment, the mice in group A and B were injected with saline, and mice in group C and D were injected with 5-aminoimidazole-4-carboxamide1-β-D-ribofuranoside (AICAR; 50 μg/g body weight) and a combined injection with AICAR (50 μg/g body weight) and histone acetylase inhibitor II (HAT II; 185 μg/g body weight), respectively.Results: The results showed that the values of pH45min and pH24h of postmortem muscle in GAA administration were higher than those in the control group. However, the opposite result was observed in AICAR group. Moreover, the activities of pyruvate kinase, hexokinase and fruc-tose-2,6-diphosphatase, combined with the protein abundance of phosphorylated liver kinase, phosphorylated AMPKα2 and total acetylated protein were all decreased by GAA administration and HAT II treatment.Conclusion: Taken together, adenosine 5'-monophosphate-activated protein kinase signaling and protein acetylation could mediate the regulation of GAA administration on postmortem glycolysis of antemortem stress-muscle.