Interactions between the cecal microbiota and non-alcoholic steatohepatitis using laying hens as the model

Multiomics Reveal the Effects and Regulatory Mechanism of Naringin on Metabolic Dysfunction-Associated Fatty Liver Disease of Laying Hens

This study aimed to utilize aged laying hens as a model to investigate the effects of naringin on the occurrence and progression of metabolic dysfunction-associated fatty liver disease (MAFLD), along with its underlying regulatory mechanisms. A total of 288 aged laying hens, 50-week-old, were divided into four groups: a normal diet (ND) group, and three naringin groups receiving 200 mg/kg (N1), 400 mg/kg (N2), and 600 mg/kg (N3). The experiment lasted for 10 weeks, after which serum, liver, and cecal contents were collected from the hens. Results indicated that dietary naringin supplementation reduced hepatic lipid deposition, lowered blood lipid levels, improved antioxidant capacity, and promoted estradiol secretion. Additionally, 16S rDNA analysis revealed that naringin enhanced microbial diversity in the cecum and regulated the abundance of gut microbes associated with fatty liver. Untargeted metabolomics of blood demonstrated that naringin decreased the concentration of glycerophospholipid and sterol lipid metabolites while increasing levels of pantothenic acids and amino acid metabolites. Furthermore, liver transcriptome analysis indicated that naringin interfered with fatty acid synthesis and transport processes while enhancing fatty acid oxidation. Dietary naringin supplementation can mitigate the occurrence of MAFLD by regulating the gut-liver axis and estrogen signaling, particularly in postmenopausal women.

Gut-testis axis in roosters: Lactiplantibacillus plantarum supplementation improves reproductive performance

Probiotics are widely used in poultry farming and industry, as they offer numerous health and performance benefits for birds. Probiotic Lactobacilli maintain gut microbiota balance, aid nutrient utilization, boost the immune system, increase stress resistance and serve as antibiotic alternatives. However, their impact on male reproductive function is not yet fully understood. This study investigated the effect of a novel probiotic strain, Lactiplantibacillus plantarum SNI3 (LbSNI3), on the reproductive performance of roosters. Twenty adult roosters were used. LbSNI3 was administered orally (dose: 2 × 107 CFU/animal/day) for 7 weeks to half of the animals. Control birds (10) received sterile tap water vehicle. Ejaculate volume, sperm concentration, sperm motility, number of IPVL penetration holes and testosterone plasma concentration have been measured weekly. Testis weight, dimensions and histology have been determined at the end of the experiment. mRNA levels of select genes, involved in spermatogenesis and sperm motility, oxidative and steroid synthesis have been measured in the testis samples by qRT-PCR. Total antioxidant capacity, superoxide dismutase (SOD) enzyme activity and malondialdehyde (MDA) levels were also analyzed. LbSNI3 administration increased the ejaculate volume, sperm concentration and the number of penetration holes, resulting in a significant improvement in the reproductivity index. In contrast, testosterone levels were not statistically different in control versus LbSNI3-treated groups. At the end of the experiment, testis size, the area, and the lumen of seminiferous tubuli were increased in LbSNI3-treated roosters. The testicular expression of Gpx1, Sepw1, Dio2, Birc5 and Rec8 genes was elevated following oral administration of LbSNI3. Total antioxidant activity, SOD activity significantly increased, while MDA concentration decreased, indicating enhanced antioxidant capacity in the testis. LbSNI3 produces a bacterial metabolite, γ-glutamyl-glutamate, which enters the glutathione cycle and strengthens the testicular defense mechanisms against oxidative stress. In conclusion, oral administration of probiotic LbSNI3 enhances antioxidant defense mechanisms in the testis, leading to increased reproductive index in adult roosters. This effect may be mediated through the gut-testis axis and could be utilized to improve productivity in the livestock industry.

How molting of laying hens influences body composition and blood parameters

The physiological and metabolic changes laying hens undergo during molt are poorly understood, but could aid in understanding why hens stop egg production during the first cycle of lay. We therefore induced a molt and studied how this influenced body composition, blood parameters and production performance. Additionally, four diets postmolt were fed in a 2 × 2 factorial design with two levels of metabolisable energy lay (ME Lay; low = 11.0 MJ and high = 11.9 MJ) and two apparent faecal digestible lysine levels (AFD; low = 0.58% and high = 0.72%). Data were subjected to mixed model analyses. A molt was successfully induced at 58 weeks of age, during which hens stopped consuming feed and producing eggs, and lost on average 21% BW. Most of this BW loss was due to body breast weight loss (-56 g, time effect P < 0.05) and ovary loss (-33.6 g, time effect P < 0.05) and to a lesser extent due to fat pad loss (-7.1 g, time effect P > 0.05). Early laying rate and egg mass production of hens fed the high AFD Lys diets postmolt were significantly higher compared to hens fed the low AFD Lys diet. Egg weights of hens fed high AFD Lys diets were lower. Both effects were only short-term in weeks 59-62 and indicated that high amino acid intake is important for early laying rate in the second cycle of lay, potentially related to feather growth and restoration of body protein. Hens fed low ME Lay diets increased average daily feed intake (ADFI) in weeks 62-65, compared to hens fed high ME Lay diets (P < 0.05). This resulted in higher ME Lay and AFD Lys intake (P < 0.05). Hens fed these low ME Lay diets had a higher egg mass production in weeks 62-65 (P < 0.05), due to higher egg weights (P < 0.05), without a difference in laying rate (P > 0.05). Average daily gain was also significantly higher, mostly due to higher breast percentage (P < 0.05). Hens fed low ME Lay diets probably needed a higher lipoprotein production in the liver to meet the egg production demand, indicated by higher plasma cholesterol (P = 0.07) and triglyceride (P < 0.05) levels, and heavier liver weights (P < 0.05). In conclusion, molting significantly influenced the body composition of laying hens, with reduced breast, liver and ovary weights. Lower postmolt ME Lay diets increased breast, liver and ovary weights and increased egg weights and egg mass production. High AFD Lys diets only showed a short-term positive effect on the laying rate.

Improving fatty liver hemorrhagic syndrome in laying hens through gut microbiota and oxylipin metabolism by Bacteroides fragilis: A potential involvement of arachidonic acid

Bacteroides fragilis (B. fragilis), a crucial commensal bacterium within the gut, has shown connections with hepatic lipid metabolism and inflammation regulation. Nonetheless, the role of B. fragilis in the progression of fatty liver hemorrhagic syndrome (FLHS) remains unknown. This study aims to explore the ameliorative effects of B. fragilis on FLHS in laying hens, as well as its underlying mechanisms. This is the first study to employ a chicken FLHS model, combining microbiomics and oxylipin metabolomics to investigate the mechanism of action of intestinal symbiotic bacteria. Exp. 1: 40 laying hens at 25 weeks old were randomly divided into five treatment groups (eight replicates per group and one hen per replicate), including the control group (basal diet), the high-energy and low-protein (HELP) group, and the HELP group with three different levels (108, 109, and 1010 CFU) of B. fragilis. Exp. 2: 18 chickens at 25 weeks old were randomly divided into three treatment groups (six replicates per group and one hen per replicate) including the control group (basal diet), the model group (HELP diet), and the arachidonic acid (AA) group (HELP diet with 0.3% AA). The experiment period of Exp. 1 and Exp. 2 were 8 weeks. B. fragilis significantly improved body weight of seventh week (P = 0.006), liver lipid degeneration, blood lipid levels (triglycerides, cholesterol, and low-density lipoprotein cholesterol; P < 0.05), and liver function (alanine aminotransferase and aminotransferase; P < 0.05) in laying hens. B. fragilis downregulated the expression of lipid synthesis-related genes fatty acid synthase, acetyl-CoA carboxylase, and liver X receptor α, and inflammation-related genes tumor necrosis factor α, interleukin (IL)-1β, IL-6, and IL-8 in the liver of FLHS-affected hens (P < 0.05), while upregulating the expression of lipid oxidation-related genes carnitine palmitoyl transferase-1, peroxisome proliferator activated receptor (PPAR) α, and PPARγ (P < 0.05). The in-depth analysis indicated alterations in oxylipin pathways triggered by B. fragilis, as evidenced by changes in the expression of pivotal genes arachidonate 15-lipoxygenase, arachidonate 5-lipoxygenase (P < 0.05), subsequently causing modifications in relevant metabolites. This included a decrease in pro-inflammatory substances such as 15-oxoETE (P = 0.004), accompanied by an increase in AA (P = 0.008). B. fragilis regulated the homeostasis of intestinal flora by increasing the abundance of Bacteroides and decreasing the abundance of Succinatimonas and Faecalicoccus (P < 0.05). The integrated analysis revealed a robust positive correlation between Bacteroides abundance and AA levels (P = 0.007). This relationship was corroborated through in vitro experiments. Subsequently, the beneficial effect of AA in mitigating FLHS was confirmed in laying hens with FLHS, further supported by reverse transcription-polymerase chain reaction analysis demonstrating gene expression patterns akin to B. fragilis intervention. This study demonstrated that B. fragilis exerts an anti-FLHS effect through modulation of oxylipin metabolism and gut microbiota stability, with a pivotal role played by AA.

Probiotic Supplementation Alleviates Corticosterone-Induced Fatty Liver Disease by Regulating Hepatic Lipogenesis and Increasing Gut Microbiota Diversity in Broilers

Emerging evidence indicates a close relationship between gut microbiota and fatty liver disease. It has been suggested that gut microbiota modulation with probiotics ameliorates fatty liver disease in rodents and humans, yet it remains unclear whether the same results will also be obtained in poultry. The aim of this study was to investigate whether a mixture of probiotics supplemented after hatching can prevent CORT-induced fatty liver disease in broilers, and to determine how such effects, if any, are associated with hepatic de novo lipogenesis and gut microbiota composition. Ninety-six one-day-old green-legged chickens were divided into a control group (CON) and probiotic group (PB). At 28 days of age, fatty liver was induced in 16 broilers that were randomly selected from the CON or PB group. At the end of the experiment, broilers from four groups, (i) the control group (CON), (ii) corticosterone group (CORT), (iii) probiotic group (PB), and (iv) PB plus CORT group (CORT&PB), were slaughtered for sampling and analysis. The results showed that probiotic administration significantly prevented CORT-induced body weight loss (p < 0.05) but did not alleviate the weight loss of immune organs caused by CORT. Compared to CON, the broilers in the CORT group exhibited a significant increase in triglyceride (TG) levels in plasma and liver (p < 0.01), as well as severe hepatocytic steatosis and hepatocellular ballooning, which was accompanied by the upregulation of hepatic lipogenesis gene expression. However, probiotic supplementation markedly decreased the intrahepatic lipid accumulation and steatosis histological score, which was associated with the downregulation of sterol regulatory element-binding protein-1 (SREBP1) and acetyl-CoA carboxylase (ACC) mRNA (p < 0.05) and the expression of its protein (p = 0.06). The cecal microbiota composition was determined by 16S rRNA high-throughput sequencing. The results showed that CORT treatment induced distinct gut microbiota alterations with a decrease in microbial diversity and an increase in Proteobacteria abundance (p < 0.05). In contrast, probiotic supplementation increased the beta diversity, the community richness, and the diversity index (p > 0.05), as well as the abundance of Intestinimonas (p < 0.05). Our results indicate that CORT treatment induced severe fatty liver disease and altered the gut microbiota composition in broilers. However, post-hatching probiotic supplementation had a beneficial effect on alleviating fatty liver disease by regulating lipogenic gene expression and increasing gut microbiota diversity and the abundance of beneficial bacteria. We demonstrate for the first time that the supplementation of probiotics to chicks had a beneficial effect on preventing fatty liver disease through regulating lipogenic gene expression and improving the gut microbial balance. Thus, our results indicate that probiotics are a potential nutritional agent for preventing fatty liver disease in chickens.

Targeting gut microbiota and metabolism profiles with coated sodium butyrate to ameliorate high-energy and low-protein diet-induced intestinal barrier dysfunction in laying hens

High energy diets are a risk factor for intestinal barrier damage. Butyrate, a major energy source for intestinal epithelial cells, has been shown to improve barrier dysfunction and modulate the gut microbiota. In this trial, we examined the preventative effect of coated sodium butyrate (CSB) on high-energy and low-protein (HELP)-induced intestinal barrier injury in laying hens, and also worked to determine the underlying mechanisms by an integrative analysis of gut microbiota and the metabolome. A total of 216 healthy 28-week-old Huafeng laying hens were randomly assigned to 3 groups with 6 replicates each: the CON group (normal diet), HELP group (HELP diet) and CH500 group (500 mg/kg CSB added to HELP diet). The duration of the trial encompassed a period of 10 weeks. The results revealed that CSB treatment improved the laying rate and mitigated the detrimental effects on intestinal barrier function and the inflammatory response induced by the HELP diet in laying hens (P < 0.05). Microbial profiling analysis revealed that the CSB treatment reshaped the HELP-perturbed gut microbiota and promoted the growth of beneficial bacteria (P < 0.05). Untargeted metabolomics analysis revealed that CSB reduced the metabolites associated with intestinal inflammation (P < 0.05). In conclusion, CSB did not merely modulate alterations in the gut microbiota composition and microbial metabolites but also yielded increased egg production, while mitigating intestinal barrier dysfunction and inflammatory responses induced by HELP in laying hens.

Dietary supplementation of poly-dihydromyricetin-fused zinc nanoparticles alleviates fatty liver hemorrhagic syndrome by improving antioxidant capacity, intestinal health and lipid metabolism of laying hens

Fatty liver hemorrhagic syndrome is the main cause of noninfectious death of laying hens and results in substantial economic losses to the poultry industry. This study focused on evaluating the effects of Poly-dihydromyricetin-fused zinc nanoparticles (PDMY-Zn NPs) on antioxidant capacity, liver lipid metabolism, and intestinal health in laying hens. A total of 288 Jingfen laying hens (52 wk old) with similar body weights were randomly divided into 4 dietary groups with 6 replicates in each group for 8 wk. The control group received a basal diet, while the treatment groups were supplemented with PDMY-Zn NPs at levels of 200, 400, and 600 mg/kg, respectively. The results indicate that PDMY-Zn NPs supplementation can enhance antioxidant parameters (P < 0.05) in the blood and liver of laying hens. Simultaneously, it can mitigate vacuolar degeneration and inflammatory necrosis in hepatocytes, improve the relative expression level of related parameters associated with liver lipid metabolism and key regulatory genes (P < 0.05). Furthermore, it has been observed to reshape the composition and diversity of cecum microbes by increasing beneficial probiotics such as Lactobacillus and Prevotella, while also enhancing villi height and villi/crypt ratio in the duodenum and ileum (P < 0.05). Additionally, it elevates liver bile acid content along with the relative expression of key genes involved in liver synthesis (P < 0.05). In summary, PDMY-Zn NPs showed potential to alleviate fatty liver hemorrhagic syndrome by enhancing antioxidant capacity, regulating liver lipid metabolism, and maintaining intestinal health.

Bile acid disorders and intestinal barrier dysfunction are involved in the development of fatty liver in laying hens

The pathogenesis of fatty liver is highly intricate. The role of the gut-liver axis in the development of fatty liver has gained increasing recognition in recent years. This study was conducted to explore the role of bile acid signaling and gut barrier in the pathogenesis of fatty liver. A total of 100 "Jing Tint 6" laying hens, 56-week-old, were used and fed basal diets until 60 weeks of age. At the end of the experiment, thirty individuals were selected based on the degree of hepatic steatosis. The hens with minimal hepatic steatosis (< 5 %) were chosen as healthy controls, while those with severe steatosis (> 33 %) in the liver were classified as the fatty liver group. Laying hens with fatty liver and healthy controls showed significant differences in body weight, liver index, abdominal fat ratio, feed conversion ratio (FCR), albumin height, Haugh unit, and biochemical indexes. The results of bile acid metabolomics revealed a clear separation in hepatic bile acid profiles between the fatty liver group and healthy controls, and multiple secondary bile acids were decreased in the fatty liver group, indicating disordered bile acid metabolism. Additionally, the mRNA levels of farnesoid X receptor (FXR) and genes related to bile acid transport were significantly decreased in both the liver and terminal ileum of hens with fatty liver. Moreover, the laying hens with fatty liver exhibited significant decreases in ileal crypt depth, the number of goblet cells, and the mRNA expression of tight junction-related proteins, alongside a significant increase in ileal permeability. Collectively, these findings suggest that disordered bile acids, suppressed FXR-mediated signaling, and impaired intestinal barrier function are potential factors promoting the development of fatty liver. These insights indicate that regulating bile acids and enhancing intestinal barrier function may become new preventive and therapeutic strategies for fatty liver in the near future.

Hepatoprotective effects of magnolol in fatty liver hemorrhagic syndrome hens through shaping gut microbiota and tryptophan metabolic profile

BACKGROUND

Magnolol (MAG) exhibits hepatoprotective activity, however, whether and how MAG regulates the gut microbiota to alleviate fatty liver hemorrhagic syndrome (FLHS) remains unclear. Therefore, we investigated the mechanism of MAG in FLHS laying hens with an emphasis on alterations in the gut-liver axis. We randomly divided 540 56-week-old Hy-line white laying hens with FLSH into 4 groups. The birds were fed a high-fat low-protein (HFLP) diet (CON) or HELP diets supplemented with 200, 400, and 600 mg/kg of MAG (M1, M2, and M3, respectively) for 9 weeks.

RESULTS

Magnolol supplementation increased the laying rate and ameliorated hepatic damage and dysfunction by regulating lipid metabolism, improving intestinal barrier function, and shaping the gut microbiota and tryptophan metabolic profiles. Dietary MAG supplementation downregulated the expression of lipid synthesis genes and upregulated the expression of lipid transport genes at varying degrees. The intestinal barrier function was improved by 200 and 400 mg/kg of MAG supplementation, as evidenced by the increased villus height and mRNA expression of tight junction related genes. Microbiological profile information revealed that MAG changed the gut microbiota, especially by elevating the abundances of Lactobacillus, Faecalibacterium, and Butyricicoccus. Moreover, non-targeted metabolomic analysis showed that MAG significantly promoted tryptophan metabolites, which was positively correlated with the MAG-enriched gut microbiota. The increased tryptophan metabolites could activate aryl hydrocarbon receptor (AhR) and relieved hepatic inflammation and immune response evidenced by the downregulated the gene expression levels of pro-inflammatory cytokines such as interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) in the liver. The fecal microbiota transplantation (FMT) experiments further confirmed that the hepatoprotective effect is likely mediated by MAG-altered gut microbiota and their metabolites.

CONCLUSIONS

Magnolol can be an outstanding supplement for the prevention and mitigation of FLHS in laying hens by positively regulating lipid synthesis and transport metabolism, improving the intestinal barrier function, and relieving hepatic inflammation by reshaping the gut microbiota and metabolite profiles through gut microbiota-indole metabolite-hepatic AhR crosstalk. These findings elucidate the mechanisms by which MAG alleviates FLHS and provide a promising method for preventing liver diseases by modulating gut microbiota and their metabolites.

Positive effects and mechanism of mulberry leaf extract on alleviating fatty liver hemorrhagic syndrome in laying hens

This experiment was conducted to investigate the effects of mulberry leaf extract (MLE) on alleviating fatty liver hemorrhagic syndrome (FLHS) in laying hens. The 576 Jing Fen laying hens of 56 weeks of age with good health and similar weights (1.76 ± 0.17 kg) were randomly divided into 6 groups, with 8 replicates in each group and 12 chickens in each replicate. The experiment lasted 56 d. The control group was fed a corn-soybean meal diet. The FLHS group was fed a high energy-low protein (HELP) diet, and the other four experimental groups were fed HELP diets supplemented with 0.04, 0.40, 0.80, and 1.20% MLE, respectively. The results showed that HELP treatment significantly induced liver injury, which indicated that the FLHS model was successfully established. MLE supplementation could alleviate the FLHS by reducing the liver index, abdominal fat percentage, total cholesterol (TC), triglyceride (TG), low-density lipoprotein (LDL), and very low-density lipoprotein (VLDL) in the serum (P < 0.05), and subsequently increase the egg production rate (P < 0.05). The laying hens fed 0.8% MLE exhibited the greatest production performance (P < 0.05) and could improve serum lipid levels. In addition, the genes associated with fatty acid synthesis (ACC, HMGR and SREBP-1C) were downregulated (P < 0.05), and genes related to fatty acid oxidation (CPT1A, AMPK, and ATGL) were found to be upregulated (P < 0.05). Supplementation with 1.2% MLE significantly reduced the relative abundance of Firmicutes and Desulfurized Bacillus (P < 0.05) and significantly increased the relative abundance of Fecal Bacillus (P < 0.05). In conclusion, MLE may regulate the mRNA expression of lipid metabolism-related genes through the AMPK signaling pathway and improve cecal microbiota balance and serum lipid levels to alleviate FLHS in laying hens and subsequently improve egg production performance.

Effect of High Dietary Iron on Fat Deposition and Gut Microbiota in Chickens

To meet the demand of consumers for chicken products, poultry breeders have made improvements to chickens. However, this has led to a new problem in the modern poultry industry, namely excessive fat deposition. This study aims to understand the effects of dietary iron supplementation on fat deposition and gut microbiota in chickens. In this study, we investigated the effects of iron on the growth performance, fat deposition, and gut microbiota of silky fowl black-bone chickens. A total of 75 7-week-old silky fowl black-bone chickens were randomly divided into three groups (five replicates per group, five chickens per replicate) and fed them for 28 days using a growing diet (control group), a growing diet + 10% tallow (high-fat diet group, HFD group), and a growing diet + 10% tallow + 500 mg/kg iron (HFDFe500 group), respectively. We detected the effects of iron on the growth performance, fat deposition, and gut microbiota of silky fowl black-bone chickens using the growth performance index test, oil red O staining, and HE staining, and found that the high-fat diet significantly increased liver and serum fat deposition and liver injury, while the addition of iron to the diet could reduce the fat deposition caused by the high-fat diet and alleviate liver injury. In addition, 16S rDNA sequencing was used to compare the relative abundance of gut microbiota in the cecal contents in different feeding groups. The results showed that the high-fat diet could induce gut microbiota imbalance in chickens, while the high-iron diet reversed the gut microbiota imbalance. PICRUSt functional prediction analysis showed that dietary iron supplementation affected amino acid metabolism, energy metabolism, cofactors, and vitamin metabolism pathways. In addition, correlation analysis showed that TG was significantly associated with Firmicutes and Actinobacteriota (p < 0.05). Overall, these results revealed high dietary iron (500 mg/kg) could reduce fat deposition and affect the gut microbiota of silky fowl black-bone chickens, suggesting that iron may regulate fat deposition by influencing the gut microbiota of chickens and provides a potential avenue that prevents excessive fat deposition in chickens by adding iron to the diet.

Establishment of a Steatosis Model in LMH Cells, Chicken Embryo Hepatocytes, and Liver Tissues Based on a Mixture of Sodium Oleate and Palmitic Acid

Research on hepatic steatosis in animal husbandry has been a prominent area of study. Developing an appropriate in vitro cellular steatosis model is crucial for comprehensively investigating the mechanisms involved in liver lipid deposition in poultry and for identifying potential interventions to address abnormalities in lipid metabolism. The research on the methods of in vitro liver steatosis in chickens, particularly the effects of different fat mixtures, is still lacking. In this study, LMH cells were utilized to investigate the effects of OA, SO, PA, SP, and their pairwise combinations on steatosis development, with the aim of identifying the optimal conditions for inducing steatosis. Analysis of triglyceride (TG) content in LMH cells revealed that OA and SP had limited efficacy in increasing TG content, while a combination of SO and PA in a 1:2 ratio exhibited the highest TG content. Moreover, Oil Red O staining results in LMH cells demonstrated that the combination treatment had a more pronounced induction effect compared to 0.375 mM SO. Additionally, RNA-seq analysis showed that 0.375 mM SO significantly influenced the expression of genes associated with fatty acid metabolism compared to the control group, whereas the combination of SO and PA led to an enrichment of key GO terms associated with programmed cell death. These findings suggest that varying conditions of cellular steatosis could lead to distinct disruptions in gene expression. The optimal conditions for inducing steatosis in LMH cells were also tested on chicken embryonic liver cells and embryos. TG detection and Oil Red O staining assays showed that the combination of SO and PA successfully induced steatosis. However, the gene expression pattern differed from that of LMH cells. This study lays the foundations for further investigations into avian hepatic steatosis.

Hericium erinaceus polysaccharides ameliorate nonalcoholic fatty liver disease via gut microbiota and tryptophan metabolism regulation in an aged laying hen model

Polysaccharides extracted from Hericium erinaceus (HEP) exhibit hepatoprotective activity in the alleviation of non-alcoholic fatty liver disease (NAFLD); however, the mechanisms underlying whether and how HEP regulation of the gut microbiota to alleviate liver-associated metabolic disorders are not well understood. This study used an aged laying hen model to explore the mechanisms through which HEP alleviates NAFLD, with a focus on regulatory function of HEP in the gut microbiome. The results showed that HEP ameliorated hepatic damage and metabolic disorders by improving intestinal barrier function and shaping the gut microbiota and tryptophan metabolic profiles. HEP increased the abundance of Lactobacillus and certain tryptophan metabolites, including indole-3-carboxylic acid, kynurenic acid, and tryptamine in the cecum. These metabolites upregulated the expression of ZO-1 and Occludin by activating the AhR and restoring the intestinal barrier integrity. The increased intestinal barrier functions decreased LPS transferring from the intestine to the liver, inhibited hepatic LPS/TLR4/MyD88/NF-κB pathway activation, and reduced hepatic inflammatory response and apoptosis. Fecal microbiota transplantation experiments further confirmed that the hepatoprotective effect is likely mediated by HEP-altered gut microbiota and their metabolites. Overall, dietary HEP could ameliorate the hepatic damage and metabolic disorders of NAFLD through regulating the "gut-liver" axis.

Effect of Bile Acids Supplementation in Fatty Liver Hemorrhagic Syndrome, Production Performance, Physiological and Quality Characteristics of Laying Hen Eggs

This study aimed to investigate the effects of bile acids (BAs) supplementation on fatty liver hemorrhagic syndrome (FLHS), production performance, and physiological and quality characteristics of laying hen eggs. Sixty Sanhuang laying hens, aged 28 weeks, were randomly allocated to six dietary treatments over a 4-week period, including the control (CON) group (feeding basal diet), the high-fat diet (HFD)-treated group (basal diet containing 10% soybean oil), and HFD supplemented with 0.01% and 0.02% of chenodeoxycholic acid (CDCA) or hyodeoxycholic acid (HDCA) groups. Production performance, egg quality, liver morphology, serum biochemical indexes, antioxidant capacity, proinflammatory cytokines, and intestinal microbiota were evaluated. The average body weight in 0.01% CDCA was larger than in the HFD group (p < 0.05). Eggshell Thickness in the CON group was greater than in the HFD, 0.01% CDCA, and HDCA groups (p < 0.05). Albumen height in the 0.02% HDCA group was higher than the HFD group (p < 0.05). Eggshell weight in the HFD group was less than the CON group (p < 0.05). Haugh unit (HU) in the HDCA group was larger than the HFD group (p < 0.05). Albumen weight in the 0.02% HDCA group was greater than the CON and HFD groups (p < 0.05). In the HFD group, the levels of triglyceride (TG), total cholesterol (TC), and low-density lipo-protein cholesterol (LDL-C) were surpassing the other groups (p < 0.05). The levels of catalase (CAT) and total superoxide dismutase (T-SOD) in the HFD group was smaller than the other groups (p < 0.05). The level of malondialdehyde (MDA) in the HFD group was higher than in the other groups (p < 0.05). Tumor necrosis factor-α (TNF-α) levels were larger in the HFD group than in the other groups (p < 0.05). The 16S rRNA sequencing analysis indicated significant variations in the relative abundance of specific bacterial populations among the different treatment groups. The treatment and CON groups exhibited a higher presence of bacteria that inhibit host energy absorption or promote intestinal health such as Firmicutes, Bacteroidetes, and Ruminococcus, whereas the HFD group showed an increased prevalence of potentially pathogenic or deleterious bacteria, such as Desulfovibrio spp. In conclusion, the supplementation of BAs in poultry feed has been demonstrated to effectively mitigate the detrimental effects of FLHS in laying hens. This intervention regulates lipid metabolism, bolsters antioxidant defenses, reduces inflammation, and modulates the gut microbiota, offering a novel perspective on the application of BAs in the poultry industry.

Effects of Yeast Culture on Laying Performance, Antioxidant Properties, Intestinal Morphology, and Intestinal Flora of Laying Hens

Yeast culture (YC) plays a significant role in enhancing the performance and health of poultry breeding. This study investigated the impact of different YC supplementation concentrations (basal diet with 1.0 g/kg and 2.0 g/kg of YC, YC1.0, and YC2.0) on egg production performance, egg quality, antioxidant properties, intestinal mucosal structure, and intestinal flora of laying hens. Both YC1.0 and YC2.0 groups significantly enhanced the egg protein height, Haugh unit, and crude protein content of egg yolks compared to the control group (p < 0.05). The supplementation with YC2.0 notably increased the egg production rate, reduced feed-to-egg ratio, and decreased the broken egg rate compared to the control group (p < 0.05). Additionally, YC supplementation enhanced serum total antioxidant capacity (T-AOC) and glutathione peroxidase (GSH-PX) activity while reducing malondialdehyde (MDA) content (p < 0.05). Moreover, YC supplementation promoted duodenal villus height and villus ratio in the duodenum and jejunum (p < 0.05). Analysis of cecal microorganisms indicated a decrease in Simpson and Shannon indices with YC supplementation (p < 0.05). YC1.0 reduced the abundance of Proteobacteria, while YC2.0 increased the abundance of Bacteroidales (p < 0.05). Overall, supplementation with YC improved egg production, quality, antioxidant capacity, intestinal morphology, and cecal microbial composition in laying hens, with significant benefits observed at the 2.0 g/kg supplementation level.

Reorganization of 3D genome architecture provides insights into pathogenesis of early fatty liver disease in laying hens

BACKGROUND

Fatty liver disease causes huge economic losses in the poultry industry due to its high occurrence and lethality rate. Three-dimensional (3D) chromatin architecture takes part in disease processing by regulating transcriptional reprogramming. The study is carried out to investigate the alterations of hepatic 3D genome and H3K27ac profiling in early fatty liver (FLS) and reveal their effect on hepatic transcriptional reprogramming in laying hens.

RESULTS

Results show that FLS model is constructed with obvious phenotypes including hepatic visible lipid deposition as well as higher total triglyceride and cholesterol in serum. A/B compartment switching, topologically associating domain (TAD) and chromatin loop changes are identified by high-throughput/resolution chromosome conformation capture (HiC) technology. Targeted genes of these alternations in hepatic 3D genome organization significantly enrich pathways related to lipid metabolism and hepatic damage. H3K27ac differential peaks and differential expression genes (DEGs) identified through RNA-seq analysis are also enriched in these pathways. Notably, certain DEGs are found to correspond with changes in 3D chromatin structure and H3K27ac binding in their promoters. DNA motif analysis reveals that candidate transcription factors are implicated in regulating transcriptional reprogramming. Furthermore, disturbed folate metabolism is observed, as evidenced by lower folate levels and altered enzyme expression.

CONCLUSION

Our findings establish a link between transcriptional reprogramming changes and 3D chromatin structure variations during early FLS formation, which provides candidate transcription factors and folate as targets for FLS prevention or treatment.

Prevotella and succinate treatments altered gut microbiota, increased laying performance, and suppressed hepatic lipid accumulation in laying hens

BACKGROUND

This work aimed to investigate the potential benefits of administering Prevotella and its primary metabolite succinate on performance, hepatic lipid accumulation and gut microbiota in laying hens.

RESULTS

One hundred and fifty 58-week-old Hyline Brown laying hens, with laying rate below 80% and plasma triglyceride (TG) exceeding 5 mmol/L, were used in this study. The hens were randomly allocated into 5 groups and subjected to one of the following treatments: fed with a basal diet (negative control, NC), oral gavage of 3 mL/hen saline every other day (positive control, PC), gavage of 3 mL/hen Prevotella melaninogenica (107 CFU/mL, PM) or 3 mL/hen Prevotella copri (107 CFU/mL, P. copri) every other day, and basal diet supplemented with 0.25% sodium succinate (Succinate). The results showed that PM and P. copri treatments significantly improved laying rate compared to the PC (P < 0.05). The amount of lipid droplet was notably decreased by PM, P. copri, and Succinate treatments at week 4 and decreased by P. copri at week 8 (P < 0.05). Correspondingly, the plasma TG level in Succinate group was lower than that of PC (P < 0.05). Hepatic TG content, however, was not significantly influenced at week 4 and 8 (P > 0.05). PM treatment increased (P < 0.05) the mRNA levels of genes PGC-1β and APB-5B at week 4, and ACC and CPT-1 at week 8. The results indicated enhanced antioxidant activities at week 8, as evidenced by reduced hepatic malondialdehyde (MDA) level and improved antioxidant enzymes activities in PM and Succinate groups (P < 0.05). Supplementing with Prevotella or succinate can alter the cecal microbiota. Specifically, the abundance of Prevotella in the Succinate group was significantly higher than that in the other 4 groups at the family and genus levels (P < 0.05).

CONCLUSIONS

Oral intake of Prevotella and dietary supplementation of succinate can ameliorate lipid metabolism of laying hens. The beneficial effect of Prevotella is consistent across different species. The finding highlights that succinate, the primary metabolite of Prevotella, represents a more feasible feed additive for alleviating fatty liver in laying hens.

Comparative Lipidomics and Metabolomics Reveal the Underlying Mechanisms of Taurine in the Alleviation of Nonalcoholic Fatty Liver Disease Using the Aged Laying Hen Model

SCOPE

Aged laying hen is recently suggested as a more attractive animal model than rodent for studying nonalcoholic fatty liver disease (NAFLD) of humans. This study aims to reveal effects and metabolic regulation mechanisms of taurine alleviating NAFLD by using the aged laying hen model.

METHODS AND RESULTS

Liver histomorphology and biochemical indices show 0.02% taurine effectively alleviated fat deposition and liver damage. Comparative liver lipidomics and gene expressions analyses reveal taurine promoted lipolysis, fatty acids oxidation, lipids transport, and reduced oxidative stress in liver. Furthermore, comparative serum metabolomics screen six core metabolites negatively correlated with NAFLD, including linoleic acid, gamma-linolenic acid, pantothenate, L-methionine, 2-methylbutyroylcarnitine, L-carnitine; and two core metabolites positively correlated with NAFLD, including lysophosphatidylcholine (14:0/0:0) and lysophosphatidylcholine (16:0/0:0). Metabolic pathway analysis reveals taurine mainly regulated linoleic acid metabolism, cysteine and methionine metabolism, carnitine metabolism, pantothenic acid and coenzyme A biosynthesis metabolism, and glycerophospholipid metabolism to up-adjust levels of six negatively correlated metabolites and down-adjust two positively correlated metabolites for alleviating NAFLD of aged hens.

CONCLUSION

This study firstly reveals underlying metabolic mechanisms of taurine alleviating NAFLD using the aged hen model, thereby laying the foundation for taurine's application in the prevention of NAFLD in both human and poultry.

Inulin-enriched Megamonas funiformis ameliorates metabolic dysfunction-associated fatty liver disease by producing propionic acid

Accumulated evidence supports the beneficial role of inulin in alleviating metabolic dysfunction-associated fatty liver disease (MAFLD) by modulating gut microbiota. However, the underlying mechanisms are not fully understood. Here we used high-fat diet (HFD)-induced laying hen model of MAFLD to investigate the effect of inulin on ameliorating MAFLD and found that the inulin-enriched Megamonas genus was inversely correlated with hepatic steatosis-related parameters. Oral administration of a newly isolated commensal bacterium by culturomics, M. funiformis CML154, to HFD-fed hens and mice ameliorated MAFLD, changed liver gene expression profiles, and increased intestinal propionate concentration. Further evidence demonstrated that the anti-MAFLD effect of M. funiformis CML154 is attributed to propionate-mediated activation of the APN-AMPK-PPARα signaling pathway, thereby inhibiting fatty acid de novo synthesis and promoting β-oxidation. These findings establish the causal relationships among inulin, M. funiformis, and MAFLD, and suggest that M. funiformis CML154 is a probiotic candidate for preventative or therapeutic intervention of MAFLD.

G protein-coupled estrogen receptor activation by bisphenol-A disrupts lipid metabolism and induces ferroptosis in the liver

As a metabolic disruptor, bisphenol A (BPA) has been widely reported to disrupt lipid balance. Moreover, BPA has gained significant attention due to its estrogenic activity. While both ferroptosis and the G-protein-coupled estrogen receptor (GPER) have been implicated in lipid metabolism, their link to BPA-induced lipid accumulation remains unclear. In this study, chickens were randomly assigned to three groups and housed them for 4 weeks: a control group (0 μg/L BPA), a low dose group (50 μg/L BPA) and a high dose group (5000 μg/L BPA) to investigate the underlying mechanism of BPA-induced hepatotoxicity. Our results showed that BPA exposure significantly increased the contents of TG, TC, and LDL-C while decreasing HDL-C levels. We also found that BPA treatment altered the levels of genes involved in fatty acid β-oxidation (ampkα, cpt-1, and ppaα), synthesis (acc, fas, scd-1, and srebp-1) and absorption (lpl and cd36). Moreover, the results showed that the BPA group had higher levels of IL-1β, IL-18 and TNF-α. These results indicated that BPA exposure disrupted lipid metabolism and induced inflammation in the liver. We also demonstrated that BPA caused hepatic ferroptosis by raising iron content and the expression of genes related to lipid peroxidation (lpcat3, acsl4 and alox15), while reducing the expression of antioxidant system-associated genes (gpx4, slc7a11 and slc3a2). Importantly, BPA remarkably activated GPER expression in the liver. Interestingly, inhibition of GPER remarkably ameliorated BPA-induced lipid metabolism disorder, inflammatory response, and ferroptosis, indicating the crucial role of GPER in BPA-induced liver abnormalities. These findings highlight the link between GPER and ferroptosis in BPA-induced hepatotoxicity, providing new insights into the potential hazard of BPA.

Age-associated changes in the growth development of abdominal fat and their correlations with cecal gut microbiota in broiler chickens

Excess abdominal fat is a common phenomenon in broiler chickens. Gut microbiota could regulate lipid metabolism through their effects on short-chain fatty acids (SCFAs) production. This study was conducted to investigate the potential relationship between abdominal fat development and cecal microorganism populations. Abdominal fat and cecum contents were collected at 3, 7, 14, 21, 28, 35, and 42 d of age. The results showed that abdominal fat weight increased with age. The abdominal fat percentage was higher between 7 and 21 d of age than at 3 d (P < 0.05), and it increased again at 28 to 42 d (P < 0.05). Morphological analysis showed that adipocyte diameter and cross-sectional area (CSA) increased significantly after 14 d of age (P < 0.05). Moreover, gut microbiota analysis indicated that the Chao1 and Shannon indices were higher between 14 and 28 d than at 3 d of age (P < 0.05). Furthermore, LEfse analysis revealed that Faecalibacterium, Anaerotruncus, Anaeroplasma, Subdoligranulum, and Clostridium emerged to become dominant at 14 d. A greater abundance of Bacteroides, Ruminococcus, Dehalobacterium, and Lactobacillus were determined at 28 d when compared with 14 d of age. Parabacteroides, Ochrobactrum, Lactobacillus, Blautia, Alistipes, Dehalobacterium, Odoribacter, and Suuterella were found to be predominant at 42 d. PICRUSt analysis revealed that amino acid metabolism, lipid metabolism, and terpenoids and polyketides metabolism were elevated at 14 d; the immune and digestive systems were significantly developed at 28 d. In addition, cecum propionic acid and butyric acid contents gradually increased (P < 0.05), while the isobutyric acid contents gradually decreased with advancing age (P < 0.05). Correlation analysis among SCFAs, differential genera and abdominal fat suggested that Coprobacillus, Shigella, and Butyricicoccus had negative correlations with propionic acid, butyric acid, and abdominal fat weight, but positive correlations with isobutyric acid. Isobutyric acid was identified as being negatively associated with abdominal fat weight, while the reverse was found for propionic acid and butyric acid. In conclusion, abdominal fat development is correlated with the emergence of specific microbes and d 14 may be a pivotal age for establishing this relationship.

Ginkgo biloba extract alleviates fatty liver hemorrhagic syndrome in laying hens via reshaping gut microbiota

BACKGROUND

Ginkgo biloba extract (GBE) is evidenced to be effective in the prevention and alleviation of metabolic disorders, including obesity, diabetes and fatty liver disease. However, the role of GBE in alleviating fatty liver hemorrhagic syndrome (FLHS) in laying hens and the underlying mechanisms remain to be elucidated. Here, we investigated the effects of GBE on relieving FLHS with an emphasis on the modulatory role of GBE in chicken gut microbiota.

RESULTS

The results showed that GBE treatment ameliorated biochemical blood indicators in high-fat diet (HFD)-induced FLHS laying hen model by decreasing the levels of TG, TC, ALT and ALP. The lipid accumulation and pathological score of liver were also relieved after GBE treatment. Moreover, GBE treatment enhanced the antioxidant activity of liver and serum by increasing GSH, SOD, T-AOC, GSH-PX and reducing MDA, and downregulated the expression of genes related to lipid synthesis (FAS, LXRα, GPAT1, PPARγ and ChREBP1) and inflammatory cytokines (TNF-α, IL-6, TLR4 and NF-κB) in the liver. Microbial profiling analysis revealed that GBE treatment reshaped the HFD-perturbed gut microbiota, particularly elevated the abundance of Megasphaera in the cecum. Meanwhile, targeted metabolomic analysis of SCFAs revealed that GBE treatment significantly promoted the production of total SCFAs, acetate and propionate, which were positively correlated with the GBE-enriched gut microbiota. Finally, we confirmed that the GBE-altered gut microbiota was sufficient to alleviate FLHS by fecal microbiota transplantation (FMT).

CONCLUSIONS

We provided evidence that GBE alleviated FLHS in HFD-induced laying hens through reshaping the composition of gut microbiota. Our findings shed light on mechanism underlying the anti-FLHS efficacy of GBE and lay foundations for future use of GBE as additive to prevent and control FLHS in laying hen industry.

Probiotics and vitamins modulate the cecal microbiota of laying hens submitted to induced molting

Induced molting enables laying hens to relax, restore energy and prolong the laying hen cycle, resolving problems such as poor egg quality and minimizing economic losses caused by rising global feeding costs. However, traditional molting methods may disrupt gut microflora and promote potential pathogens infections. This study used a customized additive with a mixture of probiotics and vitamins to induce molting and examine the cecal microbiota post molting. A total of two hundred 377 day-of-ISA Brown laying hens were randomly assigned to four groups: non-molt with basal diet (C), 12-day feeding restriction (FR) in earlier-molting (B), feed again to 27.12% egg production in middle-molting (A) and reach second peak of egg production over 81.36% in post-molting (D). Sequencing 16S rRNA to analyze cecal microbial composition revealed that there is no significant change in bacterial community abundance post-molting. In contrast to group C, the number of potentially harmful bacteria such as E. coli and Enterococcus was not found to increase in groups B, A, or D. This additive keeps cecal microbiota diversity and community richness steady. In cecal contents, hens in group B had lower Lactobacillus, Lachnospiraceae and Prevotellaceae (vsC, A, and D), no significant differences were found between post-molting and the non-molting. Furthermore, cecal microbiota and other chemicals (antibodies, hormones, and enzymes, etc.) strongly affect immunological function and health. Most biochemical indicators are significantly positively correlated with Prevotellaceae, Ruminococcaceae and Subdoligranulum, while negatively with Phascolarctobacterium and Desulfovibrio. In conclusion, the additive of probiotics and vitamins improved the cecal microbiota composition, no increase in the associated pathogenic microbial community due to traditional molting methods, and enhances hepatic lipid metabolism and adaptive immunological function, supporting their application and induced molting technology in the poultry breeding industry.

Osteocalcin and Its Potential Functions for Preventing Fatty Liver Hemorrhagic Syndrome in Poultry

Osteocalcin (OCN) is synthesized and secreted by differentiating osteoblasts. In addition to its role in bone, OCN acts as a hormone in the pancreas, liver, muscle, fat, and other organs to regulate multiple pathophysiological processes including glucose homeostasis and adipic acid metabolism. Fat metabolic disorder, such as excessive fat buildup, is related to non-alcoholic fatty liver disease (NAFLD) in humans. Similarly, fatty liver hemorrhage syndrome (FLHS) is a metabolic disease in laying hens, resulting from lipid accumulation in hepatocytes. FLHS affects hen health with significant impact on poultry egg production. Many studies have proposed that OCN has protective function in mammalian NAFLD, but its function in chicken FLHS and related mechanism have not been completely clarified. Recently, we have revealed that OCN prevents laying hens from FLHS through regulating the JNK pathway, and some pathways related to the disease progression have been identified through both in vivo and vitro investigations. In this view, we discussed the current findings for predicting the strategy for using OCN to prevent or reduce FLHS impact on poultry production.

Alterations in hepatic transcriptome and cecum microbiota underlying potential ways to prevent early fatty liver in laying hens

Fatty liver syndrome (FLS) is a kind of nutritional metabolic disease in laying hens. Revealing FLS pathogenesis during the early period is what really makes sense for the prevention or nutritional regulation strategies. In the study, 9 healthy or naturally occurring early FLS birds were screened based on visual inspection, liver index and morphologic analysis. Liver and fresh cecal content samples were collected. Then transcriptomic and 16S rRNA technologies are applied to investigate hepatic transcriptome and cecum microbiota composition. Unpaired Student t test and some omics methods were used for statistical analysis. Results showed higher liver weight and index were found in FLS group; morphologic analysis indicated that there existed more lipid droplets in the liver of birds with FLS. Based on DESeq2 analysis, there were 229 up- and 487 down-regulated genes in the FLS group, among which most genes related to de novo fatty acid synthesis were up-regulated such as acetyl-CoA carboxylase, fatty acid synthase, stearoyl-CoA desaturase, and ELOVL fatty acid elongase 6 (ELOVL6). Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis indicated that pathways associated with lipid metabolism and liver damage were affected. 16S rRNA sequencing analysis of cecum microbiota showed that there was a significant difference between the Con and FLS groups. LEfSe analysis revealed that the relative abundance of Coprococcus, Odoribacter, Collinsella, Turicibacter, YRC22, Enterococcus, Shigella, and Bifidobacterium were down-regulated in the FLS group, whereas the abundance of Bacteroides, Mucispirillum, Butyricicoccus, Campylobacter, Akkermansia, and Clostridium were up-regulated. The KEGG enrichment from differential microbiota suggested that some metabolism-related functions were altered to some extent. Taken together, during the developmental of early fatty liver of laying hens, lipogenesis was enhanced, whereas abnormal metabolism occurs not only in lipid transportation but also in hydrolysis, which caused structural damage to the liver organ. Moreover, the dysbiosis of the cecum microbiota occurred. All of these serve as targets or provide theoretical references for the development of probiotics for fatty liver prevention in laying hens.

Genome analysis reveals hepatic transcriptional reprogramming changes mediated by enhancers during chick embryonic development

The liver undergoes a slow process for lipid deposition during chick embryonic period. However, the underlying physiological and molecular mechanisms are still unclear. Therefore, the aim of the current study was to reveal the epigenetic mechanism of hepatic transcriptional reprogramming changes based on the integration analysis of RNA-seq and H3K27ac labeled CUT&Tag. Results showed that lipid contents increased gradually with the embryonic age (E) 11, E15, and E19 based on morphological analysis of Hematoxylin-eosin and Oil Red O staining as well as total triglyceride and cholesterol detection. The hepatic protein level of SREBP-1c was higher in E19 when compared with that in E11 and E15, while H3K27ac and H3K4me2 levels declined from E11 to E19. Differential expression genes (DEGs) among these 3 embryonic ages were determined by transcriptome analysis. A total of 107 and 46 genes were gradually upregulated and downregulated respectively with the embryonic age. Meanwhile, differential H3K27ac occupancy in chromatin was investigated. But the integration analysis of RNA-seq and CUT&Tag data showed that the overlap genes were less between DEGs and target genes of differential peaks in the promoter regions. Further, some KEGG pathways enriched from target genes of typical enhancer were overlapped with those from DEGs in transcriptome analysis such as insulin, FoxO, MAPK signaling pathways which were related to lipid metabolism. DNA motif analysis identify 8 and 10 transcription factors (TFs) based on up and down differential peaks individually among E11, E15, and E19 stages where 7 TFs were overlapped including COUP-TFII, FOXM1, FOXA1, HNF4A, RXR, ERRA, FOXA2. These results indicated that H3K27ac histone modification is involved in the transcriptional reprogramming regulation during embryonic development, which could recruit TFs binding to mediate differential enhancer activation. Differential activated enhancer impels dynamic transcriptional reprogramming towards lipid metabolism to promote the occurrence of special phenotype of hepatic lipid deposition.

Effect of exogenous bile salts supplementation on the performance and hepatic lipid metabolism of aged laying hens

Bile acids (BA), a series of hydroxylated steroids secreted by the liver, are involved in the digestion and absorption of dietary fats. In the present study, the effect of exogenous BAs on the performance and liver lipid metabolism of laying hens was investigated. Three hundred and sixty 50-wk-old Hy-line Brown hens were randomly allocated into three groups and subjected to one of the following treatments: fed with the basal diet (control, Con), the basal diet supplemented with 0.1 g/kg (0.1 g/kg BAs), or 0.2 g/kg (0.2 g/kg BAs) porcine BAs. Laying performance, egg quality, and blood parameters were measured during the 8-wk experimental period. The expression of genes related to hepatic lipid metabolism was determined at the end of experiment. The results showed that BAs treatments had no influence (P > 0.05) on laying rate, egg weight, and feed efficiency. BAs treatment, however, significantly decreased mortality of hens (P = 0.006). BAs treatment showed a transient negative influence on eggshell quality at week 4 but not at week 8. The yolk color on week 8 was increased by BAs treatments (P < 0.0001) compared to control. The duodenum index showed a tendency to be increased (P = 0.053) and jejunum index were increased (P = 0.007) by BAs treatment. Compared to control, BAs treatments decreased lipid droplet content (P < 0.0001) and TG content (P = 0.002) of liver. Fatty acid synthase activity was also decreased as an effect of BAs dietary supplementation. Compared to the control group, 0.1 g/kg BAs treatment increased (P < 0.05) the mRNA expression of genes Farnesoid X receptor (FXR) (P = 0.042), cytochrome P450 family 7 subfamily A member 1 (CYP7A1) (P = 0.002), and cytochrome P450 family 8 subfamily B member 1 (CYP8B1) (P = 0.017), fatty acid synthase (FAS) (P = 0.020), acetyl-CoA carboxylase (ACC) (P = 0.032), sterol regulatory element binding protein-1c (SREBP-1c) (P = 0.037), proliferator-activated receptor gamma (PPARγ) (P = 0.002), apolipoprotein B (APO-B) (P = 0.020), and very low density lipoprotein receptor (VLDLR) (P = 0.024). In conclusion, the addition of exogenous BAs reduces lipid accumulation in liver. BA supplementation reduces the mortality of hens and improves egg yolk color, with no unfavorable effect on laying performance. The result suggests that suppressed FAS activity is involved in the reduced hepatic lipid accumulation by BAs treatment.

The gut microbiota metabolite glycochenodeoxycholate activates TFR-ACSL4-mediated ferroptosis to promote the development of environmental toxin-linked MAFLD

Metabolic dysfunction-associated fatty liver disease (MAFLD) has become the most common chronic liver disorders in the world, and yet has no approved pharmacotherapy due to the etiology is complex. In the last ten years, increasing evidence have identified the environmental pollutants as risk factors for MAFLD. However, the underlying mechanism remains unclear. Our study found that bromoacetic acid (BAA, a typical kind of environmental toxin) increased triglycerides and total cholesterol levels as well as induced obvious hepatic steatosis and inflammation. The lipidomics showed that ferroptosis was implicated in the environmental toxin-linked MAFLD. Besides, the analysis of microbial metabolomics showed significant change of gut microbiome in BAA groups and the content of gut microbiota metabolite (glycochenodeoxycholate, GCDCA) increased sharply. In vitro study, we observed features of ferroptotic cells by transmission electron microscopy after BAA/GCDCA treatment. Besides, we demonstrated that BAA/GCDCA significantly increased iron contents, with upregulating transferrin receptor (TFR) and acyl-CoA synthetase long-chain family 4 (ACSL4) expression levels. By contrast, iron chelator or silencing TFR relieved BAA/GCDCA-induced lipid metabolism disorder and inflammation. What's more, the interaction between TFR and ACSL4 was also identified. Taken together, we found that, in response to environmental toxin, gut microbiota metabolite GCDCA activates TFR-ACSL4-mediated ferroptosis, which triggered subsequent lipid metabolism disorder and inflammation. Moreover, these findings firstly highlighted the functional relevance among ferroptosis, lipid metabolism and gut microbiota metabolite during environmental pollutant exposure, which shed light on the deep mechanism of environmental toxin-related MAFLD, providing potential targets for the prevention of MAFLD.

Regulation of the cecal microbiota community and the fatty liver deposition by the addition of brewers’ spent grain to feed of Landes geese

The effects of brewers’ spent grain (BSG) diets on the fatty liver deposition and the cecal microbial community were investigated in a total of 320 healthy 5-day-old Landes geese. These geese were randomly and evenly divided into 4 groups each containing 8 replicates and 10 geese per replicate. These four groups of geese were fed from the rearing stage (days 5–60) to the overfeeding stage (days 61–90). The Landes geese in group C (control) were fed with basal diet (days 5–90); group B fed first with basal diet in the rearing stage and then basal diet + 4% BSG in the overfeeding stage; group F first with basal diet + 4% BSG during the rearing stage and then basal diet in the overfeeding stage; and group W with basal diet + 4% BSG (days 5–90). The results showed that during the rearing stage, the body weight (BW) and the average daily gain (ADG) of Landes geese were significantly increased in groups F and W, while during the overfeeding stage, the liver weights of groups W and B were significantly higher than that of group C. The taxonomic structure of the intestinal microbiota revealed that during the overfeeding period, the relative abundance of Bacteroides in group W was increased compared to group C, while the relative abundances of Escherichia–Shigella and prevotellaceae_Ga6A1_group were decreased. Results of the transcriptomics analysis showed that addition of BSG to Landes geese diets altered the expression of genes involved in PI3K-Akt signaling pathway and sphingolipid metabolism in the liver. Our study provided novel experimental evidence based on the cecal microbiota to support the application of BSG in the regulation of fatty liver deposition by modulating the gut microbiota in Landes geese.

Dehydroepiandrosterone activates the GPER-mediated AMPK signaling pathway to alleviate the oxidative stress and inflammatory response in laying hens fed with high-energy and low-protein diets

Fatty liver hemorrhagic syndrome (FLHS) seriously threatens the layer industry due to it can cause a sudden decline in egg production and acute death, and dietary supplement with bioactive substance is considered an effective way to prevent the FLHS occurrence. Dehydroepiandrosterone (DHEA) is a popular dietary supplement and it possesses anti-oxidative and anti-inflammatory functions; however, the effect and underlying mechanism about DHEA in protecting against the occurrence and development of FLHS remain elucidated. The current results showed that DHEA relieved HELP-induced decrease of egg productivity and liver injury in laying hens. Meanwhile, DHEA markedly enhanced the antioxidant capacity and then alleviated oxidative stress via activation of nuclear factor (erythroid-derived 2)-like 2 (NRF-2) signal in laying hens fed with HELP diets. In addition, DHEA significantly alleviated HELP-stimulated systemic inflammatory response by suppressing the overproduction of hepatic pro-inflammatory factors in laying hens, and further found this beneficial effect was achieved by blocking the activation of NF-κB pathway. Furthermore, we found that DHEA promoted the AMP-activated protein kinase α (AMPKα) activation and increased the G-protein-coupled estrogen receptor (GPER) expression level in laying hens fed with HELP diets. In summary, our data demonstrated that DHEA attenuates oxidative stress and inflammation through the activation of GPER-AMPK signal axis in laying hens fed with HELP diets. These results might facilitate an understanding of the benefits and mechanism of DHEA on the development of FLHS, and provide sufficient data to support it as a dietary supplement to control the FLHS-related metabolic diseases in chickens.

Akkermansia muciniphila Enhances Egg Quality and the Lipid Profile of Egg Yolk by Improving Lipid Metabolism

Akkermansia muciniphila (A. muciniphila) has shown potential as a probiotic for the prevention and treatment of non-alcoholic fatty liver disease in both humans and mice. However, relatively little is known about the effects of A. muciniphila on lipid metabolism, productivity, and product quality in laying hens. In this study, we explored whether A. muciniphila supplementation could improve lipid metabolism and egg quality in laying hens and sought to identify the underlying mechanism. In the first experiment, 80 Hy-Line Brown laying hens were divided into four groups, one of which was fed a normal diet (control group), while the other three groups were administered a high-energy, low-protein diet to induce fatty liver hemorrhagic syndrome (FLHS). Among the three FLHS groups, one was treated with phosphate-buffered saline, one with live A. muciniphila, and one with pasteurized A. muciniphila. In the second experiment, 140 Hy-Line Brown laying hens were divided into two groups and respectively fed a basal diet supplemented or not with A. muciniphila lyophilized powder. The results showed that, in laying hens with FLHS, treatment with either live or pasteurized A. muciniphila efficiently decreased body weight, abdominal fat deposition, and lipid content in both serum and the liver; downregulated the mRNA expression of lipid synthesis-related genes and upregulated that of lipid transport-related genes in the liver; promoted the growth of short-chain fatty acids (SCFAs)-producing microorganisms and increased the cecal SCFAs content; and improved the yolk lipid profile. Additionally, the supplementation of lyophilized powder of A. muciniphila to aged laying hens reduced abdominal fat deposition and total cholesterol (TC) levels in both serum and the liver, suppressed the mRNA expression of cholesterol synthesis-related genes in the liver, reduced TC content in the yolk, increased eggshell thickness, and reshaped the composition of the gut microbiota. Collectively, our findings demonstrated that A. muciniphila can modulate lipid metabolism, thereby, promoting laying hen health as well as egg quality and nutritive value. Live, pasteurized, and lyophilized A. muciniphila preparations all have the potential for use as additives for improving laying hen production.

Influence of fermented feed additive on gut morphology, immune status, and microbiota in broilers

BACKGROUND

This study examined the effects of a solid-state fermented feed additive (FFA) on the small intestine histology/morphology, immunity and microbiota of broilers. Two hundred eighty-eight day-old Arbor Acre chicks, were randomly assigned to one of four groups (each group has 6 replicates, with each replicate containing 12 chickens). The negative control (NC; basal diet), the positive control (PC; basal diet +antibiotic 15 ppm), the fermented feed additive low dose (FFL; basal diet + 0.3 kg/t FFA), and the fermented feed additive high dose (FFH; 3 kg/t FFA) with Lactobacillus casei (L.casei).

RESULTS

The study found that the FFH and FFL groups gained more weight (1-21d) and the FFL and PC diets had better feed conversion ratio (P < 0.05) than the NC from 0-42d. The FFH group had higher villus height (P < 0.05) in the duodenum than the PC and villus height to crypt depth ratio VH/CD compared to PC and FFL groups. The FFL chickens had greater (P < 0.05) jejunal and ileal villus height than PC and NC groups respectively. The FFL group had a higher ileal VH/CD ratio (P < 0.05). Jejunum VH/CD was higher in FFL and FFH (P < 0.05) than PC (P < 0.05). FFH had a smaller thymus than NC (P < 0.05). FFA diets also increased IL-10 expression (P < 0.05). While IL-1 and TLR4 mRNA expression decreased (P < 0.05) compared to NC. The microbiota analysis showed that the microorganisms that have pathogenic properties such as phylum Delsulfobacterota and class Desulfovibriona and Negativicutes was also significantly reduced in the group treated with FFH and PC while microorganisms having beneficial properties like Lactobacillaceae family, Lactobacillus aviarus genus and Lactobacillus spp were also tended to increase in the FFH and FFL fermented feed groups compared to the PC and NC groups.

CONCLUSION

These findings suggested that the FFA diet may modulate cecal microbiota by reducing pathogenic microorganisms such as phylum Delsulfobacterota and class Desulfovibriona and Negativicutes improve beneficial microorganisms like Lactobacillaceae family, Lactobacillus aviarus genus and Lactobacillus spp. While FFA diet also affect immunity, and gene expression related to immunity.

Osteocalcin reduces fat accumulation and inflammatory reaction by inhibiting ROS-JNK signal pathway in chicken embryonic hepatocytes

Osteocalcin (OCN) has a function in preventing fatty liver hemorrhagic syndrome (FLHS) in poultry. The aim of this study was to investigate the effects of OCN on fat emulsion stimulated chicken embryonic hepatocytes and related signaling pathways. The primary chicken embryonic hepatocytes were isolated from the incubated 15-day (E15) pathogen free eggs and cultured with dulbecco's modified eagle medium (DMEM). After the hepatocyte density reached 80%, the cells were divided into 5 groups: control group (CONT), fat emulsion group (FE, 10% FE, v/v), FE with ucOCN at 1 ng/mL (FE-LOCN), 3 ng/mL (FE-MOCN), and 9 ng/mL (FE-HOCN). In addition, 2 mM N-Acetyl-L-cysteine (NAC) a reactive oxygen species (ROS) scavenger, and 5 μM SP600125, a Jun N-terminal kinase (JNK) inhibitor, were added separately in to the DMEM with 10% FE to test effects of FE on the function of ROS-JNK signal pathway. The number of hepatocytes, cell ultra-microstructure, viability, and apoptosis were detected after 48 h treatment, and the protein expressions and enzyme concentrations were detected after 72 h treatment. The results showed that, compared to the control group, FE increased the triglyceride (TG) concentration and lipid droplets (LDs) in chicken embryonic hepatocytes (P < 0.05), and induced hepatocytic edema with obviously mitochondrial swelling, membrane damage, and cristae rupture. FE also decreased ATP concentration, increased ROS concentrations and mitochondrial DNA (mtDNA) copy number, promoted inflammatory interleukin-1 (IL-1), IL-6, tumor necrosis factor-alpha (TNF-α) concentrations and hepatocytic apoptosis rate, and raised phospho-c-Jun N-terminal kinase (p-JNK) protein expressions. Compared to the FE group, ucOCN significantly increased hepatocyte viability, reduced hepatocytic TG concentrations and LDs numbers, and alleviated hepatocytic edema and mitochondrial swelling. Furthermore, ucOCN significantly decreased ROS concentrations, increased ATP concentrations, reduced IL-1, IL-6, TNF-α concentrations and hepatocytic apoptosis rate, and inhibited p-JNK protein expressions (P < 0.05). NAC had the similar functions of ucOCN reduced the ROS concentration and inhibited the TNF-α protein expression and p-JNK/JNK ration. Similarly, SP600125 reduced p-JNK/JNK protein expression, IL-1, IL-6, TNF-α, and TG concentrations without effects on ROS concentration and hepatocytic apoptosis. These results suggest that ucOCN alleviates FE-induced mitochondrial damage, cellular edema, and apoptosis of hepatocytes. These results reveal that the functions of ucOCN in reducing fat accumulation and inflammatory reaction in chicken embryonic hepatocytes are mostly via inhibiting the ROS-JNK signal pathway.

Intestinal microbiota of layer hens and its association with egg quality and safety

The intestinal microbiota has attracted tremendous attention in the field of the poultry industry due to its critical role in the modulation of nutrient utilization, immune system, and consequently the improvement of the host health and production performance. Accumulating evidence implies intestinal microbiota of laying hens is a potential mediator to improve the prevalent issues in terms of egg quality decline in the late phase of laying production. However, the regulatory effect of intestinal microbiota on egg quality in laying hens remains elusive, which requires consideration of microbial baseline composition and succession during their long lifespans. Notable, although Firmicutes, Bacteroidetes, and Proteobacteria form the vast majority of intestinal microbiota in layer hens, dynamic intestinal microbiota succession occurs throughout all laying periods. In addition to the direct effects on egg safety, intestinal microbiota and its metabolites such as short-chain fatty acids, bile acids, and tryptophan derivatives, are suggested to indirectly modulate egg quality through the microbiota-gut-liver/brain-reproductive tract axis. These findings can extend our understanding of the crosstalk between intestinal microbiota and the host to improve egg quality and safety. This paper reviews the compositions of intestinal microbiota in different physiological stages of laying hens and their effects on egg quality and proposes that intestinal microbiota may become a potential target for modulating egg quality and safety by nutritional strategies in the future.

The miR-216/miR-217 Cluster Regulates Lipid Metabolism in Laying Hens With Fatty Liver Syndrome via PPAR/SREBP Signaling Pathway

Fatty liver syndrome (FLS), a common metabolic disease in laying hens, caused by excessive hepatic fat deposition is a bottleneck in the poultry industry. However, no specific therapeutic methods have been developed. Evidence suggests that microRNAs (miRNAs) are essential for liver lipid metabolism and homeostasis, providing strong evidence for targeting miRNAs as a potential treatment option for liver diseases. However, the roles of miRNAs in the pathogenesis of FLS remain unclear. In present study, RNA-sequencing was performed to discern the expression patterns of miRNAs in normal and fatty livers of laying hens. In total, 12 dysregulated miRNAs (2 down-regulated and 10 up-regulated) were detected between the normal and fatty livers. Functional enrichment analysis showed the potential impacts of the dysregulated miRNAs on lipid metabolism. Notably, miR-216a/b and miR-217-5p, which belong to the miR-216/miR-217 cluster, were up-regulated in the sera and livers of FLS chickens, as well as free fatty acid (FFA)-induced LMH cells. Oil-red O staining revealed that up-regulation of the miR-216/miR-217 cluster induced lipid accumulation in FFA-induced LMH cells. Furthermore, the dual luciferase gene reporter assay and RT-qPCR analysis demonstrated that 3-hydroxyacyl-CoA dehydratase 2, F-box protein 8, and transmembrane 9 superfamily member 3 (TM9SF3) were directly targeted by miR-216a/b and miR-217-5p, respectively, and suppressed in the fatty livers of laying hens. Moreover, overexpression of the miR-216/miR-217 cluster or reduction in TM9SF3 levels led to activation of the proliferator-activated receptor/sterol regulatory-element binding protein (PPAR/SREBP) pathway. Overall, these results demonstrate that the miR-216/miR-217 cluster regulates lipid metabolism in laying hens with FLS, which should prove helpful in the development of new interventional strategies.

Protective Effects of Abrus cantoniensis Hance on the Fatty Liver Hemorrhagic Syndrome in Laying Hens Based on Liver Metabolomics and Gut Microbiota

As a metabolic disease, fatty liver hemorrhagic syndrome (FLHS) has become a serious concern in laying hens worldwide. Abrus cantoniensis Hance (AC) is a commonly used plant in traditional medicine for liver disease treatment. Nevertheless, the effect and mechanism of the decoction of AC (ACD) on FLHS remain unclear. In this study, ultra-high performance liquid chromatography analysis was used to identify the main phytochemicals in ACD. FLHS model of laying hens was induced by a high-energy low-protein (HELP) diet, and ACD (0.5, 1, 2 g ACD/hen per day) was given to the hens in drinking water at the same time for 48 days. Biochemical blood indicators and histopathological analysis of the liver were detected and observed to evaluate the therapeutic effect of ACD. Moreover, the effects of ACD on liver metabolomics and gut microbiota in laying hens with FLHS were investigated. The results showed that four phytochemicals, including abrine, hypaphorine, vicenin-2, and schaftoside, were identified in ACD. ACD treatment ameliorated biochemical blood indicators in laying hens with FLHS by decreasing aspartate aminotransferase, alanine aminotransferase, triglycerides, low-density lipoprotein cholesterol, and total cholesterol, and increasing high-density lipoprotein cholesterol. In addition, lipid accumulation in the liver and pathological damages were relieved in ACD treatment groups. Moreover, distinct changes in liver metabolic profile after ACD treatment were observed, 17 endogenous liver metabolites mainly associated with the metabolism of arachidonic acid, histidine, tyrosine, and tryptophan were reversed by ACD. Gut microbiota analysis revealed that ACD treatment significantly increased bacterial richness (Chao 1, P < 0.05; Ace, P < 0.01), and upregulated the relative abundance of Bacteroidetes and downregulated Proteobacteria, improving the negative effects caused by HELP diet in laying hens. Taken together, ACD had a protective effect on FLHS by regulating blood lipids, reducing liver lipid accumulation, and improving the dysbiosis of liver metabolomics and gut microbiota.

Effects of phenylpyruvate on the growth performance and intestinal microbiota in broiler chicken

1. The purpose of this study was to see how dietary supplementation with phenylpyruvate affected broiler growth, slaughter performance, gut health microbiota and immunity. This information can be used to develop alternative approaches to antibiotic replacement in modern poultry production and health.2. A total of 288, one-day-old broiler chickens were randomly assigned to one of four groups (six replicates each replicate has 12 chickens). A control basal diet (NC), basal diet plus antibiotic virginiamycin 15ppm (PC), basal diet plus phenylpyruvate 1 kg/t or 2 kg/t, respectively (LCP and HCP).3. Results showed that the birds in the PC group had higher ADFI during the first 21 d, and better FCR than the NC group. Feeding LCP and HCP improved broilers' FCR by 0.001 and 0.037% compared to the NC group respectively. The HCP-fed group has a higher all-eviscerated ratio than the NC group and less abdominal fat than the birds fed LCP. The birds fed HCP has increased villus length and crypt depth in the ileum compared to the NC group.4. The bursa index was lower in the HCP group whereas the thymus index was lower in LCP and PC groups. In contrast, birds fed HCP has lower pro-inflammatory cytokine IL-1, as well as lower TLR4. Phenylpyruvate improved number in the Selenomonadaceae, genus Megamonas bacteroides spp., which are known for their beneficial effects on the maintenance of the cell surface structure, regulating aromatic amino acids and Clostridia jejuni-suppressive treatment respectively.5. It was concluded that phenylpyruvate can be utilised in feed to improve growth performance and positively modulate gut microbiota. However, this was less efficient than antibiotics in improving growth performance, although more efficient in improving productive performance and gut morphology. Moreover, a high dose of phenylpyruvate is more effective than a low dose.

Dietary hawthorn-leaves flavonoids improves ovarian function and liver lipid metabolism in aged breeder hens

Hawthorn-leaves flavonoids (HF), extracted from hawthorn leaves, were reported to exert antioxidant, anti-inflammatory and hypolipidemic properties. The aim of our study was to investigate the effects of dietary HF on the reproduction performance and liver lipid metabolism of aged breeder hens. A total of 270 aged Qiling breeder hens (60-wk-old) were randomly divided into 3 treatments: 1) basic corn-soybean diet (CON); 2) basic corn-soybean diet supplemented with 30 mg/kg HF (LHF); 3) basic corn-soybean diet supplemented with 60 mg/kg HF (HHF). The results showed that supplemented HF significantly improved the egg-laying rate and hatching rate of aged breeder hens (P < 0.05). HF treatment reduced the serum TG, T-CHO and L-LDL levels (P < 0.05), and upregulated the mRNA expressions of ESR1, ESR2, VTGⅡ, ApoB, and ApoVI in the liver (P < 0.05). Serum estrogen levels in HF treated groups were elevated compared with the CON group (P < 0.05). In the HHF group, the number of the primordial follicles was higher in comparison with the CON group (P < 0.05). Furthermore, dietary supplementation with HF improved the activity of antioxidant enzymes (T-AOC, GSH-Pχ) (P < 0.05), following with the reversed ovarian apoptosis and morphological damage. In addition, 60 mg/kg dietary HF upregulated the protein expression of PCNA and Nrf2 in the ovary (P < 0.05). In summary, dietary supplementation with HF could improve the reproduction performance through regulating liver lipid metabolism and improving ovarian function in aged breeder hens.

Comparative effects of genistein and bisphenol A on non-alcoholic fatty liver disease in laying hens

Bisphenol A (BPA) and genistein (GEN) are selective estrogen receptor modulators, which are involved in the occurrence and development of metabolic syndrome. However, their roles in non-alcoholic fatty liver disease (NAFLD) of laying hens have not been reported. Here, we investigated the effects of different concentrations of GEN and BPA on the NAFLD of laying hens. Results showed that GEN ameliorated the high-energy and low-protein diet (HELP)-induced NAFLD by improving pathological damage, hepatic steatosis, and insulin resistance and blocking the expression of NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome-related factors. By contrast, high dose of BPA could aggravate these changes with serious symptom of NAFLD and suppress the level of ERα in the liver considerably, while GEN could reverse this phenomenon in a dose-dependent manner. In general, our research shows that the protective effect of GEN on NAFLD aims to improve the metabolic disorders and inflammation closely connected to ERα, while BPA can inhibit the expression of ERα and exacerbate the symptom of NAFLD. In conclusion, we elucidate the opposing effects of GEN and BPA in NAFLD of laying hens, thus providing a potential mechanism related to ERα and inflammation.

Untargeted and targeted metabolomics profiling reveals the underlying pathogenesis and abnormal arachidonic acid metabolism in laying hens with fatty liver hemorrhagic syndrome

As a metabolic disease, fatty liver hemorrhagic syndrome (FLHS) has become the major factor responsible for the noninfectious cause of mortality in laying hens, which lead to huge economic losses to poultry industry. However, the pathogenesis of FLHS remains unclear. The aim of present study was to identify novel liver metabolites associated with FLHS. Twenty healthy Chinese commercial Jing Fen laying hens aged 90 d were used in present study. After acclimatization for 2 wk, the hens were divided into 2 treatments (n = 10): control group (normal diet) and FLHS group (high-energy low-protein diet). The experiment lasted for 48 d, and the laying hens were killed for blood and liver sampling at the end of the experiment. Blood biochemical indicators and liver pathological changes were examined. Meanwhile, the changes in liver metabolic profile were investigated with the application of metabolomics approach. Significant increased levels of alanine aminotransferase, aspartate aminotransferase, low density lipoprotein, total cholesterol and triglycerides, decreased high density lipoprotein (P < 0.01), and hepatic steatosis were observed in hens of FLHS group, which suggested FLHS was successfully established in this study. Distinct changes in metabolite patterns in liver between control and FLHS group were observed by partial least-squares discriminant analysis. In total, 42 liver metabolites including tyrosine, glutathione, carnitine, linoleic acid, uric acid, arachidonic acid (ARA), lactate and lysophosphatidylcholine (14: 0) were identified and considered to be related with pathogenesis of FLHS. Pathway analysis revealed that these metabolites were mainly involved in amino acid metabolism, fatty acid metabolism, ARA metabolism, glucose metabolism and glycerophospholipid metabolism. Furthermore, targeted metabolomics found that ARA metabolites such as prostaglandins and hydroxyeicosatetraenoic acids were significantly increased in FLHS group (P < 0.05). In conclusion, our data showed that liver metabolites and ARA metabolism were linked to the pathophysiology of FLHS, which provided a basis for understanding the pathogenesis of FLHS in laying hens.

Alterations and Correlations of the Gut Microbiome, Performance, Egg Quality, and Serum Biochemical Indexes in Laying Hens with Low-Protein Amino Acid-Deficient Diets

The present study was carried out to investigate the effects of methionine (Met), lysine (Lys), isoleucine (Ile), and threonine (Thr) deficiency in a low-protein diet on laying performance, egg quality, serum biochemical indices, and the gut microbiota in laying hens. A total of 300 Peking Pink laying hens, at 38 weeks of age, were randomly allocated to five dietary treatments, each of which included six replicates of ten hens. Hens were fed an amino acid-balanced diet (Met: 0.46%; Lys: 0.76%; Ile: 0.72%; Thr: 0.56%; positive control, PC), Met deficiency diet (Met-, 0.25%), Lys deficiency diet (Lys-, 0.56%), Ile deficiency diet (Ile-, 0.54%), and Thr deficiency diet (Thr-, 0.46%) for 12 weeks. Hens were housed in pairs in 45 × 45 × 45 cm wire cages with three ladders and three birds per cage. Feed and water were provided ad libitum during the entire experimental period. All data were analyzed using one-way ANOVA with Turkey's multiple range test. Here, compared to the PC group, final body weight (FBW), average daily gain (ADG), egg production (EP), egg weight (EW), average daily egg mass (EM), average daily feed intake (ADFI), and yield of abdominal fat (AFY) in the Met-group were lower, while EW and EM were higher in the Lys-group. The feed egg ratio (FER) was increased in the Met- and Lys-groups, and EW and AFY were decreased in the Ile-group compared to the controls. Meanwhile, ADG, EP, EM, and ADFI were lower in the Thr group than the PC group. The level of triglycerides (TGs) in the four groups was lower and the concentrations of uric acid (UA) in the Met-group were higher than those in the PC group. The shell color in the Thr group was lower than the PC group. Of note, amino acid deficiency altered the gut microbial structure (e.g., increasing the level of Parabacteroides and decreasing the abundance of Lactobacillus) in hens. The correlation analysis showed that amino acid deficiency-induced gut microbiota alteration is closely associated with the change in key parameters: FER, UA, AFY, EW, EM, TG, FBW, EP, and ADFI. Collectively, our results highlight the role of adequate amino acid ratio supplementation in the low-crude-protein diet structure for laying hens.

Effects of Pyrroloquinoline Quinone on Lipid Metabolism and Anti-Oxidative Capacity in a High-Fat-Diet Metabolic Dysfunction-Associated Fatty Liver Disease Chick Model

Metabolic dysfunction-associated fatty liver disease (MAFLD) and its interaction with many metabolic pathways raises global public health concerns. This study aimed to determine the therapeutic effects of Pyrroloquinoline quinone (PQQ, provided by PQQ.Na₂) on MAFLD in a chick model and primary chicken hepatocytes with a focus on lipid metabolism, anti-oxidative capacity, and mitochondrial biogenesis. The MAFLD chick model was established on laying hens by feeding them a high-energy low-protein (HELP) diet. Primary hepatocytes isolated from the liver of laying hens were induced for steatosis by free fatty acids (FFA) and for oxidative stress by hydrogen peroxide (H₂O₂). In the MAFLD chick model, the dietary supplementation of PQQ conspicuously ameliorated the negative effects of the HELP diet on liver biological functions, suppressed the progression of MAFLD mainly through enhanced lipid metabolism and protection of liver from oxidative injury. In the steatosis and oxidative stress cell models, PQQ functions in the improvement of the lipid metabolism and hepatocytes tolerance to fatty degradation and oxidative damage by enhancing mitochondrial biogenesis and then increasing the anti-oxidative activity and anti-apoptosis capacity. At both the cellular and individual levels, PQQ was demonstrated to exert protective effects of hepatocyte and liver from fat accumulation through the improvement of mitochondrial biogenesis and maintenance of redox homeostasis. The key findings of the present study provide an in-depth knowledge on the ameliorative effects of PQQ on the progression of fatty liver and its mechanism of action, thus providing a theoretical basis for the application of PQQ, as an effective nutrient, into the prevention of MAFLD.

The intestinal microbial composition in Greylag geese differs with steatosis induction mode: spontaneous or induced by overfeeding

Background

Relationships between microbial composition and steatosis are being extensively studied in mammals, and causal relations have been evidenced. In migratory birds the liver can transiently store lipids during pre-migratory and migratory phases, but little is known about the implications of the digestive microbiota in those mechanisms. The Landaise greylag goose (Anser anser) is a good model to study steatosis in migratory birds as it is domesticated, but is still, from a genetic point of view, close to its wild migratory ancestor. It also has a great ingestion capacity and a good predisposition for hepatic steatosis, whether spontaneous or induced by conventional overfeeding. The conventional (overfeeding) and alternative (spontaneous steatosis induction) systems differ considerably in duration and feed intake level and previous studies have shown that aptitudes to spontaneous steatosis are very variable. The present study thus aimed to address two issues: (i) evaluate whether microbial composition differs with steatosis-inducing mode; (ii) elucidate whether a digestive microbial signature could be associated with variable aptitudes to spontaneous liver steatosis.

Results

Performances, biochemical composition of the livers and microbiota differed considerably in response to steatosis stimulation. We namely identified the genus Romboutsia to be overrepresented in birds developing a spontaneous steatosis in comparison to those submitted to conventional overfeeding while the genera Ralstonia, Variovorax and Sphingomonas were underrepresented only in birds that did not develop a spontaneous steatosis compared to conventionally overfed ones, birds developing a spontaneous steatosis having intermediate values. Secondly, no overall differences in microbial composition were evidenced in association with variable aptitudes to spontaneous steatosis, although one OTU, belonging to the Lactobacillus genus, was overrepresented in birds having developed a spontaneous steatosis compared to those that had not.

Conclusions

Our study is the first to evaluate the intestinal microbial composition in association with steatosis, whether spontaneous or induced by overfeeding, in geese. Steatosis induction modes were associated with distinct digestive microbial compositions. However, unlike what can be observed in mammals, no clear microbial signature associated with spontaneous steatosis level was identified.

Research Note: Increase of bad bacteria and decrease of good bacteria in the gut of layers with vs. without hepatic steatosis

Fatty liver hemorrhagic syndrome (FLHS), usually occurring in hens in the late laying period, can lower egg yield and even cause death. Similar to nonalcoholic fatty liver disease in humans, FLHS may begin with simple hepatic steatosis. It is known that gut microbiota is important to the development of nonalcoholic fatty liver disease, but the relationship between FLHS and gut bacteria remains unclear. In this study, bacteria compositions in the ileum and cecum were determined by 16S rDNA sequencing analysis in the groups of hens with vs. without hepatic steatosis (average liver fat contents were 0.34 mmol/g protein or 2.6% vs. 0.84 mmol/g protein or 6.0%). These hens were in the 2 tails of the liver fat content distribution with each tail accounting for 10% of the test population containing 90 66-wk-old healthy Rhode Island Red laying hens raised under routine feeding regimen. The results showed that liver weight but not the weights of the body, heart and abdominal fat were significantly different between the groups. Moreover, bacterial diversity was not significantly different between the groups, but bacterial diversity in the cecum was higher than that in the ileum. Proteobacteria was the most dominant phylum in the ileum, whereas Proteobacteria, Firmicutes, and Bacteroidetes were the most dominant phyla in the cecum. Some bacteria were common to the ileum and cecum, but some were unique. Furthermore, some bacteria were significantly different in abundance between the groups, that is the group without hepatic steatosis had more bacteria inhibiting host energy absorption or benefiting intestinal health, whereas the group with hepatic steatosis had more conditionally pathogenic or harmful bacteria. In conclusion, hepatic steatosis in laying hens is associated with intestinal bacterial composition (bacterial abundance) but not bacterial diversity. The identified common and unique bacteria are related to the functional characteristics of the ileum and cecum. The decrease of beneficial bacteria and the increase of harmful bacteria in the intestine of laying hens may increase FLHS incidence by promoting hepatic steatosis.

Alpha-lipoic acid improves the reproduction performance of breeder hens during the late egg-laying period

Alpha-lipoic acid (ALA), a multifunctional antioxidant, can promote fatty acid mobilization, energy expenditure and scavenge free radicals. The effects of dietary ALA on the reproductive performance of breeder hens were investigated in the current study. In the 5-week experiment, 180 54-week-old Qiling breeder hens were randomly divided into three treatments with five replicates and supplemented with three levels of ALA (0, 300 and 600 mg/kg) in the basic corn-soya bean meal diets. 600 mg/kg ALA treatment group (HLA) significantly improved the eggshell thickness and strength (p < .05). ALA-treated groups improved egg-laying rate compared with the CON group, but with no statistically significant difference (p > .05). The levels of HDL-C, ALB and estradiol (E2) of the serum in the HLA group were elevated compared with the CON group (p < .05). In addition, ALA (600 mg/kg) treatment exhibited a reduced level of serum AST and TG (p < .05). Dietary ALA increased the activity of hepatic lipase in liver (p < .05). Supplemental 600 mg/kg ALA also improved the SOD activity and total antioxidant capacity level, along with a decreased MDA in ovarian tissue (p < .05). Furthermore, the mRNA expressions of ESR1, ESR2, VTG2 and ApoB in the liver and FSHR in follicles were upregulated in the HLA group (p < .05). In conclusion, dietary supplementation with 600 mg/kg ALA during the late egg-laying period could improve lipid metabolism and reproductive performance of breeder hens.

Analysis of excreta bacterial community after forced molting in aged laying hens

Objective

As laying hens become aged, laying performance and egg quality are generally impaired. One of the practical methods to rejuvenate production and egg quality of aged laying hens with decreasing productivity is a forced molting. However, the changes in intestinal microbiota after forced molting of aged hens are not clearly known. The aim of the present study was to analyze the changes in excreta bacterial communities after forced molting of aged laying hens.

Methods

A total of one hundred 66-wk-old Hy-Line Brown laying hens were induced to molt by a 2-d water removal and an 11-d fasting until egg production completely ceased. The excreta samples of 16 hens with similar body weight were collected before and immediately after molting. Excreta bacterial communities were analyzed by high-throughput sequencing of bacterial 16S rRNA genes.

Results

Bacteroidetes, Firmicutes, and Proteobacteria were the three major bacterial phyla in pre-molting and immediate post-molting hens, accounting for more than 98.0%. Lactobacillus genus had relatively high abundance in both group, but decreased by molting (62.3% in pre-molting and 24.9% in post-molting hens). Moreover, pathogenic bacteria such as Enterococcus cecorum and Escherichia coli were more abundant in immediate post-molting hens than in pre-molting hens. Forced molting influenced the alpha diversity, with higher Chao1 (p = 0.012), phylogenetic diversity whole tree (p = 0.014), observed operational taxonomic unit indices (p = 0.006), and Simpson indices (p<0.001), which indicated that forced molting increased excreta bacterial richness of aged laying hens.

Conclusion

This study improves the current knowledge of bacterial community alterations in the excreta by forced molting in aged laying hens, which can provide increasing opportunity to develop novel dietary and management skills for improving the gastrointestinal health of aged laying hens after molting.