Differences in egg yolk precursor formation of Guangxi Ma chickens with dissimilar laying rate at the same or various ages

Lactiplantibacillus plantarum FRT4 protects against fatty liver hemorrhage syndrome: regulating gut microbiota and FoxO/TLR-4/NF-κB signaling pathway in laying hens

BACKGROUND

Fatty liver hemorrhage syndrome (FLHS) has become one of the major factors leading to the death of laying hen in caged egg production. FLHS is commonly associated with lipid peroxidation, hepatocyte injury, decreased antioxidant capacity, and inflammation. However, there are limited evidences regarding the preventive effect of Lactiplantibacillus plantarum on FLHS in laying hens and its mechanisms. Our previous results showed that Lp. plantarum FRT4 alleviated FLHS by regulating lipid metabolism, but did not focus on its antioxidant and anti-inflammatory functions and mechanisms. Therefore, this study aimed to investigate the preventive mechanisms of Lp. plantarum FRT4 in alleviating FLHS, with a focus on its role in antioxidant activity and inflammation regulation.

RESULTS

Supplementation with Lp. plantarum FRT4 enhanced the levels of T-AOC, T-SOD, and GSH-Px, while reducing the levels of TNF-α, IL-1β, IL-8, and NLRP3 in the liver and ovary of laying hens. Additionally, Lp. plantarum FRT4 upregulated the mRNA expressions of SOD1, SOD2, CAT, and GPX1, downregulated the mRNA expressions of pro-inflammatory factors IL-1β, IL-6, and NLRP3, and upregulated the mRNA expressions of anti-inflammatory factors IL-4 and IL-10. Lp. plantarum FRT4 improved the structure and metabolic functions of gut microbiota, and regulated the relative abundances of dominant phyla (Bacteroidetes, Firmicute, and Proteobacteria) and genera (Prevotella and Alistipes). Additionally, it influenced key KEGG pathways, including tryptophan metabolism, amino sugar and nucleotide sugar metabolism, insulin signaling pathway, FoxO signaling pathway. Spearman analysis revealed that the abundance of microbiota at different taxonomic levels was closely related to antioxidant enzymes and inflammatory factors. Furthermore, Lp. plantarum FRT4 modulated the mRNA expressions of related factors in the FoxO/TLR-4/NF-κB signaling pathway by regulating gut microbiota. Moreover, the levels of E2, FSH, and VTG were significantly increased in the ovary after Lp. plantarum FRT4 intervention.

CONCLUSIONS

Lp. plantarum FRT4 effectively ameliorates FLHS in laying hens. This efficacy is attributed to its antioxidant and anti-inflammatory properties, which are mediated by modulating the structure and function of gut microbiota, and further intervening in the FoxO/TLR-4/NF-κB signaling pathway. These actions enhance hepatic and ovarian function and increase estrogen levels. Video Abstract.

Integrated metabolome and transcriptome analysis reveals key genes and pathways associated with egg yolk percentage in chicken

Yolk percentage is a critical index in the egg product industry, reflecting both nutritional value and economic benefits. To elucidate the underlying mechanisms that contribute to variations in egg yolk percentage, we performed integrated transcriptome and metabolome analyses on the liver, ovary, and magnum tissues of Rhode Island Red chickens with high and low yolk percentages. A total of 322 differentially expressed genes (DEGs) and 128 significantly differential metabolites (SDMs) (VIP>1, P < 0.05) were identified in the liver, whereas 419 DEGs and 215 SDMs were detected in the ovary, and 238 DEGs along with 47 SDMs were found in the magnum. In the liver, genes such as HMGCR, DHCR7, MSMO1, and CYP7A1 were linked to cholesterol metabolism, essential for steroid hormone synthesis and yolk formation, while ACACB, ACSL1, ACSL4, LPL, and SGPP2 were involved in fatty acid biosynthesis, a key process for supplying energy and structural components of the yolk. In the ovary, COL6A6, COMP, CHAD, ITGA7, THBS2, and TNC contributed to extracellular matrix-receptor interactions, which are fundamental for follicle development and oocyte maturation. In the magnum, UGT1A1, MAOB, and ALDH3B2 participated in drug metabolism-cytochrome P450 and amino acid metabolism, ensuring a proper environment for egg white formation and potentially influencing nutrient allocation to the yolk. Metabolic pathway enrichment revealed that steroid hormone biosynthesis, glycerophospholipid metabolism, and betaine metabolism were predominant in the liver; pyruvate, taurine, and hypotaurine metabolism in the ovary; and phenylalanine metabolism in the magnum. Moreover, integrated analysis highlighted key metabolites and genes potentially regulating yolk deposition, including 7,8-dihydroneopterin and Pg 38:4 in the liver (related to immune modulation and lipid metabolism, respectively), thalsimine in the ovary, as well as DL-glutamine in the magnum, all of which may be crucial for maintaining metabolic homeostasis and supporting egg formation. Collectively, these findings deepen our understanding of how distinct molecular and metabolic pathways in the liver, ovary, and magnum orchestrate yolk proportion and deposition. Such insights may advance future strategies to improve egg quality and productivity in poultry breeding programs.

Effects supplementation of novel multi-enzyme on laying performance, egg quality, and intestinal health and digestive function of laying hens

This study investigated the effects of multi-enzyme supplementation on various aspects of laying hens, including laying performance, egg quality, intestinal health and digestive function. In total, 384 Jingfen No.6 laying hens at 65-week-age were randomly assigned to four distinct dietary treatments: a basal diet (CON), CON supplemented with 150 g/t multi-enzyme (T1), CON with 300 g/t multi-enzyme (T2), and 600 g/t multi-enzyme (T3). A significant linear (P = 0.044) and quadratic (P = 0.014) increase was observed in the laying rate, while the feed/egg ratio exhibited a linear (P = 0.001) and quadratic (P < 0.001) decrease with increasing multi-enzyme supplementation. Additionally, linear (P < 0.05) and quadratic (P < 0.05) increases were observed in yolk rate and haugh unit with increasing levels of multi-enzyme supplementation. The trypsin activity in the duodenum and crude protein digestibility showed linear (P < 0.05) and quadratic (P < 0.05) increase with the addition of multi-enzyme. Furthermore, lipase and amylase activities in the duodenum increased quadratically (P = 0.041) and linearly (P = 0.040), respectively. Both jejunal and ileal digesta viscosities showed linear (P < 0.05) and quadratic (P < 0.05) decrease with the increasing addition of multi-enzyme. Moreover, multi-enzyme supplementation significantly increased (P < 0.05) the number of goblet cells in the intestinal of the treatment groups. The mRNA expression of Occludin-1, mucin 2 (MUC-2), large neutral amino acids transporter small subunit 1 (LAT-1) in the jejunum were significantly increased (P < 0.05) in the treatment groups (T1, T2 and T3) compared to the CON group. Additionally, the mRNA expression of solute carrier family 6-member 19 (B0AT-1) and large neutral amino acids transporter small subunit 4 (LAT-4) were significantly evaluated (P < 0.05) in the T2 and T3 groups, respectively. In conclusion, multi-enzyme supplementation enhanced digestive enzyme activities and intestinal barrier function, reduced intestinal digesta viscosity, and regulated mRNA expression of intestinal amino acid and lipid transporter genes, thereby improving crude protein digestibility and positively affecting laying performance and egg quality in hens.

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.

Pterostilbene, a Resveratrol Derivative, Improves Ovary Function by Upregulating Antioxidant Defenses in the Aging Chickens via Increased SIRT1/Nrf2 Expression

Oxidative stress is recognized as a prominent factor contributing to follicular atresia and ovarian aging, which leads to decreased laying performance in hens. Reducing oxidative stress can improve ovarian function and prolong the laying period in poultry. This study investigates the impact of Pterostilbene (PTS), a natural antioxidant, on ovarian oxidative stress in low-laying chickens. Thirty-six Hy-Line White laying chickens were evenly divided into four groups and fed diets containing varying doses of PTS for 15 consecutive days. The results showed that dietary supplementation with PTS significantly increased the laying rate, with the most effective group exhibiting a remarkable 42.7% increase. Furthermore, PTS significantly enhanced the antioxidant capacity of aging laying hens, as evidenced by increased levels of glutathione, glutathione peroxidase, superoxide dismutase, catalase, and total antioxidant capacity in the ovaries, livers, and serum. Subsequent experiments revealed decreased expressions of Bax, Caspase-3, and γ-H2AX, along with an increased expression of BCL-2 in the ovaries and livers of laying hens. PTS supplementation also positively affects fat metabolism by reducing abdominal fat accumulation and promoting fat transfer from the liver to the ovary. To elucidate the mechanism underlying the effects of PTS on ovarian function, a series of in vitro experiments were conducted. These in vitro experiments revealed that PTS pretreatment restored the antioxidant capacity of D-galactose-induced small white follicles by upregulating SIRT1/Nrf2 expression. This protective effect was inhibited by EX-527, a specific inhibitor of SIRT1. These findings suggest that the natural antioxidant PTS has the potential to regulate cell apoptosis and fat metabolism in laying chickens by ameliorating oxidative stress, thereby enhancing laying performance.

High albumen height by expression of GALNT9 and thin eggshell by decreased Ca2+ transportation caused high hatchability in Huainan partridge chicken

Hatchability could be quite different among individuals of indigenous chicken breed which might be affected by the egg quality. In this study, hatchability was individually recorded among 800 forty-wk-old Huainan partridge chickens. The chickens were then divided into high and low hatchability groups (HH and LH group) with 50 birds in each group. Egg quality was further determined in the 2 groups. Eight birds from each group were selected for slaughtering and tissue, responsible for egg formation, collection for structure observation by staining and candidate gene expression by transcriptome analysis. The hatchability in HH was 100% and 61.18% in LH. The eggshell thickness and shell strength were significantly lower, while the albumen height and Haugh unit were significantly higher in HH group than those in LH group (P < 0.05). The magnum weight and index, and the expression of polypeptide N-acetylgalactosaminyltransferase 9 (GALNT9), which responsible for thick albumen synthesis, in HH group were also significantly higher than that of LH group (P < 0.05). Compared with the LH group, there were 702 differentially expressed genes (DEGs) in HH group, of which 402 were up-regulated and 300 were down-regulated. Candidate genes of calbindin 1 (CALB1) and solute carrier family 26 member 9 (SLC26A9), which regulate calcium signaling pathway so as to affect Ca2+ transportation, exhibited significant high and low expression, respectively, in HH group compared to those in LH group (P < 0.05). Therefore, indigenous chicken with high expression of GALNT9 in magnum to form thick albumen to provide more protein for embryo, while high CALB1 and low expression of SLC26A9 to decrease Ca2+ transportation so as to form a thinner eggshell and provide better gas exchange during embryo development.

Dynamic Changes in Intestinal Gene Expression and Microbiota across Chicken Egg-Laying Stages

Eggs are a vital dietary component for humans, and it is beneficial to increase egg production to support poultry farming. Initially, the egg production rate rises rapidly with young hens until it reaches its peak, and then it declines gradually. By extending the duration of peak egg production, the hens' performance can be enhanced significantly. Previous studies found dynamic changes in gut microbiota during egg-laying, and several species of microbiota isolated from the chicken gut improved egg-laying performance. However, the interaction between microbes and host gene expression is still unclear. This study provides a more comprehensive understanding of chicken egg-laying by examining dynamic alterations in the microbiota of the entire intestinal tract (i.e., duodenum, jejunum, and ileum) and gene expression. The microbial community in the intestine underwent significant changes during different egg-laying periods (i.e., pre-, peak-, and late-laying periods). Metagenomic functional analysis showed that the relative abundance of biosynthesis of amino acids, secondary metabolites, and cofactors decreased significantly in the duodenum, jejunum, and ileum of aging hens. The relative levels of aldosterone, GnRH, insulin, growth hormone, and other hormone-related pathways increased dramatically in the intestinal microbiota during egg-laying, but only in the microbiota located in the duodenum and ileum. Transcriptome analysis suggested that genes associated with various transport processes were upregulated consistently in the small intestine during egg-laying; genes involved in the development of intestinal structure were down-regulated; and genes involved in response to DNA damage and stress were consistent with changes in laying rate. The abundance of Lactobacillus was related to the expression of ANGPTRL1, ANGPTRL2, ANGPT1L, and NOXO1 in the duodenum; Muricomes was correlated significantly with NFKBIZ, LYG2, and IRG1L expression in the jejunum; and Campylobacter was correlated positively with the expression of KMT2A and USF3 in the ileum. These results indicated that the intestinal microbiota and host gene expression may influence egg production jointly.

Lactiplantibacillus plantarum FRT4 attenuates high-energy low-protein diet-induced fatty liver hemorrhage syndrome in laying hens through regulating gut-liver axis

BACKGROUND

Fatty liver hemorrhage syndrome (FLHS) becomes one of the most major factors resulting in the laying hen death for caged egg production. This study aimed to investigate the therapeutic effects of Lactiplantibacillus plantarum (Lp. plantarum) FRT4 on FLHS model in laying hen with a focus on liver lipid metabolism, and gut microbiota.

RESULTS

The FLHS model of laying hens was established by feeding a high-energy low-protein (HELP) diet, and the treatment groups were fed a HELP diet supplemented with differential proportions of Lp. plantarum FRT4. The results indicated that Lp. plantarum FRT4 increased laying rate, and reduced the liver lipid accumulation by regulating lipid metabolism (lipid synthesis and transport) and improving the gut microbiota composition. Moreover, Lp. plantarum FRT4 regulated the liver glycerophospholipid metabolism. Meanwhile, "gut-liver" axis analysis showed that there was a correlation between gut microbiota and lipid metabolites.

CONCLUSIONS

The results indicated that Lp. plantarum FRT4 improved the laying performance and alleviated FLHS in HELP diet-induced laying hens through regulating "gut-liver" axis. Our findings reveal that glycerophospholipid metabolism could be the underlying mechanism for the anti-FLHS effect of Lp. plantarum FRT4 and for future use of Lp. plantarum FRT4 as an excellent additive for the prevention and mitigation of FLHS in laying hens.

Dietary naringin supplementation on hepatic yolk precursors formation and antioxidant capacity of Three-Yellow breeder hens during the late laying period

In this study, the effects of naringin on hepatic yolk precursors formation and antioxidant capacity of Three-Yellow breeder hens during late laying period were evaluated. A total of 480 (54-wk-old) Three-Yellow breeder hens were randomly assigned to 4 groups (6 replicates of 20 hens): nonsupplemented control diet (C), and control diet supplemented with 0.1%, 0.2%, and 0.4% of naringin (N1, N2, and N3), respectively. Results showed that dietary supplemented with 0.1%, 0.2%, and 0.4% of naringin for 8 wk promoted the cell proliferation and attenuated the excessive fat accumulation in the liver. Compared with C group, increased concentrations of triglyceride (TG), total cholesterol (T-CHO), high-density lipoprotein cholesterol (HDL-C), and very low-density lipoprotein (VLDL), and decreased contents of low-density lipoprotein cholesterol (LDL-C) were detected in liver, serum and ovarian tissues (P < 0.05). After 8 wk of feeding with naringin (0.1%, 0.2%, and 0.4%), serum estrogen (E₂) level, expression levels of proteins and genes of estrogen receptors (ERs) increased significantly (P < 0.05). Meanwhile, naringin treatment regulated expression of genes related to yolk precursors formation (P < 0.05). Furthermore, dietary naringin addition increased the antioxidants, decreased the oxidation products, and up-regulated transcription levels of antioxidant genes in liver tissues (P < 0.05). These results indicated that dietary supplemented with naringin could improve hepatic yolk precursors formation and hepatic antioxidant capacity of Three-Yellow breeder hens during the late laying period. Doses of 0.2% and 0.4% are more effective than dose of 0.1%.

Egg Yolk Fat Deposition Is Regulated by Diacylglycerol and Ceramide Enriched by Adipocytokine Signaling Pathway in Laying Hens

The mechanism which regulates differential fat deposition in egg yolk from the indigenous breeds and commercial laying hens is still unclear. In this research, Chinese indigenous Huainan Partridge chickens and Nongda III commercial laying hens were used for egg collection and liver sampling. The weight of eggs and yolk were recorded. Yolk fatty acids were determined by gas chromatography-mass spectrometry. Lipid metabolites in the liver were detected by liquid chromatography-mass spectrometry. Yolk weight, yolk ratio and yolk fat ratio exhibited higher in the Huainan Partridge chicken than that of the Nongda III. Compared to the Nongda III, the content of total saturated fatty acid was lower, while the unsaturated fatty acid was higher in the yolk of the Huainan Partridge chicken. Metabolites of phosphatidylinositol and phosphatidylserine from glycerolphospholipids, and metabolites of diacylglycerol from glycerolipids showed higher enrichment in the Huainan Partridge chicken than that of the Nongda III, which promoted the activation of the adipocytokine signaling pathway. However, metabolites of phosphatidic acid, phosphatidylcholine, phosphatidylethanolamine and lysophosphatidylcholine from glycerol phospholipids, and metabolites of triacylglycerol from glycerolipids showed lower enrichment in the Huainan Partridge chicken than that of the Nongda III. The high level of yolk fat deposition in the Huainan Partridge chicken is regulated by the activation of the adipocytokine signaling pathway which can promote the accumulation of diacylglycerol and ceramide in the liver.

Effects of non-fasting molting on performance, oxidative stress, intestinal morphology, and liver health of laying hens

Animal welfare concerns in laying-hen production facilities have necessitated research on alternative strategies for improving egg production and hen health. At present, most laying-hen facilities in China use the fasting method, but with international emphasis on animal welfare, scholars have begun to find ways to improve production efficiency while ensuring animal welfare standards are adhered to. Therefore, this study investigated the effects of non-fasting molting on production performance, oxidative stress, intestinal morphology, and liver health of laying hens. A total of 180 healthy 90-week-old Dawu Jinfeng laying hens with similar body weights and laying rates (76 ± 2%) were randomly divided into three groups, with five replicates per group and 12 hens per replicate. The hens in the experimental group (NF) were molted using the non-fasting method, the negative control group (C) was not treated with centralized molting, and the positive control group (F) was molted using the fasting method. The results showed that: (1) During the molting period, the laying rate in the NF group (10.58%) decreased and was significantly lower than that in the other two groups (P < 0.05). During the secondary laying peak period, the laying rate in the NF group was highest (89.71%); significantly higher than that in the C group (P < 0.05). (2) During the molting period, compared to the C group, the NF group showed a significant decrease and increase in the total antioxidant capacity (T-AOC) and superoxide dismutase (T-SOD) activity, respectively (P < 0.05). During the secondary laying peak period, the T-SOD activity of the NF group was significantly lower than that of the C group (P < 0.05). (3) During the molting period, the villus height (VH) and the ratios of VH to crypt depth (V/C) of the duodenum, jejunum, and ileum in the NF group were significantly lower than those in the C group (P < 0.05). At the secondary laying peak period, the jejunum V/C was significantly higher than that in the C group (P < 0.05), whereas in the duodenum and ileum it increased but not significantly (P > 0.05). (4) During the molting period, serum glutathione transaminase (AST) and glutathione alanine transaminase (ALT) activities were significantly higher (P < 0.05), and very low-density lipoprotein (VLDL) content and liver weight were significantly lower (P < 0.05) in the non-fasted and fasted groups. However, there was a low degree of liver injury (cell boundary still visible) in the NF group. At the secondary laying peak period, there was no significant difference (P > 0.05) in the indices among the three groups and the liver returned to normal. In summary, non-fasting molting can improve the production performance of laying hens in the later stages, ensure the welfare and health of animals, and provide a theoretical basis for the efficient production of laying hens.

Research Note: Integrated transcriptomic and metabolomic analysis reveals potential candidate genes and regulatory pathways associated with egg weight in ducks

Egg weight is an important indicator of egg phenotypic traits, which directly affects the economic benefits of the poultry industry. In the present research, laying ducks were classified into high egg weight (HEW) and light egg weight (LEW) groups. To reveal the underlying mechanism that may be responsible for the egg weight difference, the integrated analysis of transcriptomes and serum metabolomics was performed between the two groups. The results showed extremely significant differences (P < 0.01) in the total egg weight at 300 d, and average egg weight between the HEW and LEW groups. 733, 591, 82, and 74 differentially expressed genes (DEGs) were identified in the liver, magnum, F1, and F5 (hierarchical follicles) follicle membrane, respectively. The candidate genes were screened further from the perspective of forming an egg. In terms of egg yolk formation, the functional analysis revealed fatty acid metabolism-related pathways account for 36% of the liver's top pathways, including fatty acid biosynthesis, folate biosynthesis, fatty acid metabolism, and glycerol lipid metabolism pathways. FASN gene was identified as the key candidate gene by comprehensive analysis of gene expression and protein-protein interaction (PPI) network. In the follicle membrane, the DEGs were mainly enriched in protein processing in the endoplasmic reticulum, and MAPK signaling pathway, and HSPA2, HSPA8, BAG3 genes were identified as crucial candidate genes. In terms of egg white formation, the functional analysis revealed protein metabolism-related pathways account for 40% of the magnum's top pathways, which includes protein processing in the endoplasmic reticulum pathway. HSP90AA1 and HSPA8 genes were identified as key candidate genes. In addition, the integrated transcriptomic and metabolomic analysis showed that arginine and proline metabolism pathways could contribute to differences in egg weight. Thus, we speculated that the potential candidate genes, regulatory pathways, and metabolic biomarkers mentioned above might be responsible for the egg weight difference. These findings might provide a theoretical basis for improving the egg weight of ducks.

Dietary naringin supplementation on laying performance and antioxidant capacity of Three-Yellow breeder hens during the late laying period

In this study, the effects of 3 graded dietary levels (0.1%, 0.2%, and 0.4%) of naringin were studied in Three-Yellow breeder hens during the late laying period (55-62 wk). A total of 480 Three-Yellow breeder hens (54-wk-old) were randomly divided into 4 groups (6 replicates of 20 hens): basal diet group (C), and basal diets supplemented with 0.1%, 0.2%, and 0.4% of naringin (N1, N2, and N3), respectively. Results showed that dietary supplementation with 0.1%, 0.2%, and 0.4% of naringin for 8 wk increased the laying rate and egg mass, enhanced egg yolk color, and decreased the feed egg ratio (P < 0.05). Meanwhile, compared with hens in C group, there were more preovulatory follicles and higher ovarian index as well as an enhanced ovarian somatic cell proliferation in hens of N2 and N3 groups (P < 0.05). With 0.2% and 0.4% naringin, glutathione concentration, the activity of catalase and total superoxide dismutase, and the total antioxidant capacity of ovarian tissues and serum increased (P < 0.05), while the contents of malondialdehyde and hydrogen peroxide decreased (P < 0.05). Moreover, compared to C group, the transcription levels of antioxidant genes in ovarian tissues increased in hens from N2 and N3 groups (P < 0.05). In conclusion, supplementation with 0.2% and 0.4% naringin both could improve the laying rate, ovarian and serum antioxidant capacity of Three-Yellow breeder hens during the late laying period.

Hepatic glycerolipid metabolism is critical to the egg laying rate of Guangxi Ma chickens

Yolk formation in liver is an important process for egg production in hens. The correlations between egg laying rate decline and liver function changes in Guangxi Ma chickens remain unclear. In this study, a total of 21,750 genes and 76,288 transcripts were identified in the RNA expression profiles isolated from liver tissues of 5 groups of Guangxi Ma chickens divided according to the age and egg laying rate. Numerous differential genes (DEGs) were identified after pairwise comparison among samples, and time series analysis categorization (age-related factors) revealed that down-regulated DEGs with aging were predominantly involved in lipid transportation and metabolic processes in the low egg laying rate groups. Notably, functional enrichment analysis confirmed that DGAT2, LIPG, PNPLA2, LPL, CEL, LIPC, DGKD, AGPAT2, AGPAT1 and AGPAT3 were highlighted as hub genes in glycerolipid metabolism pathway, which may be an essential non-age related factors of egg laying rate by regulating the synthesis of triacylglycerol (TAG) in liver. Finally, we categorized DEGs in Guangxi Ma chickens with different egg laying rate caused by age-related factors and found that DEGs with different expression patterns performing different biological functions. The analysis of DEGs with lower egg laying rate caused by non-age related factors and showed that the transportation of TAG was suppressed. Furthermore, critical genes and pathways involved in the synthesis of TAG in livers were identified, which dynamically regulated the formation of yolk precursors. Our results expanded the knowledge of the molecular mechanisms of the yolk precursor synthesis in chicken livers. The results will be helpful to explore the factors that affect egg laying rate from the perspective of yolk synthesis and provide a theoretical basis for improving the egg production of Guangxi Ma chickens.