Soya saponin improves egg-laying performance and immune function of laying hens

Ammonia negatively impacted egg production and altered the diversity of microbial communities in cage-reared Muscovy ducks

The aim of this study was to examine the effects of NH3 variations across different positions within a cage-reared duck house on the egg production performance and fecal microbiome in Muscovy ducks. Totals of 3,168 female Muscovy ducks (180 ± 2 d) were randomly assigned to 1,056 cages. From d 293 to 300, the egg production rate and levels of NH3, H2S, CO2, temperature, humidity, light intensity, and dust particles were recorded. Two spatial distribution-based experimental classification methods were applied, one grouping ducks into Front, Middle, and End categories, and the other into First, Second, and Third layers. On d 300, serum and feces samples were collected for further analysis. The result showed that both the egg production rate and serum PROG level in the Front were higher than End (P < 0.05). However, no significant differences were found among the First, Second, and Third groups. Among the environmental factors, ammonia (NH3) is a major harmful gas in cage-reared duck houses, with observed concentrations showing a gradient from lower levels in the Front group to higher levels in the Middle group (P < 0.05), and even higher levels in the End group (P < 0.05). Gene sequencing of the 16S rRNA gene revealed a higher relative abundance of Firmicutes in both the Front and Middle groups compared to the End group (P < 0.05). Specifically, within the Firmicutes phylum, the relative abundance of Lactobacillus and Romboutsia was notably higher in the Front group compared to both the Middle and End groups (P < 0.05). What's more, the abundance of Lactobacillus had a negative correlation with NH3 concentration and positive correlation with egg production rate. In conclusion, NH3 concentrations showed variations across different areas of the cage-reared duck house, with higher levels detected at the rear. The elevated NH3 level was identified as the main factor negatively impacting egg production in Muscovy ducks and contributing to a decline in the abundance of Firmicutes, specifically Lactobacillus.

Methionine Source and Level Modulate Gut pH, Amino Acid Transporters and Metabolism Related Genes in Broiler Chickens

This study determined the effects of two methionine (Met) sources at three total sulfur amino acids (TSAA) to lysine ratios (TSAA/Lys) on gut pH, digestive enzyme activity, amino acid transporter expression, and Met metabolism of broilers. The birds were randomly assigned to a 2 × 3 factorial arrangement with Met sources (dl-Met and dl-2-hydroxy-4-(methylthio)-butanoic acid (OH-Met)) and TSAA/Lys (0.58, 0.73, and 0.88) from 1 to 21 days. The results demonstrated that dl-Met and OH-Met supported the same growth performance, but high TSAA/Lys ratio reduced the feed intake and body weight (P < 0.05). OH-Met reduced the crop chyme pH and enhanced the jejunal lipase activity (P < 0.05). ATB0,+ expression decreased with increased dl-Met levels in the duodenum; the low TSAA/Lys ratio induced a stronger mRNA expression of basolateral Met transporters. OH-Met resulted in an increase of cystathionine β-synthase expression in the liver and a decrease in serum homocysteine levels at middle TSAA/Lys ratio compared with dl-Met treatment (P < 0.05). In conclusion, two Met sources support the same growth, but OH-Met acidified the crop chyme. The investigated transporter transcripts differed significantly along the small intestine. At the middle TSAA/Lys ratio, OH-Met showed a higher metabolic tendency of the trans-sulfuration pathway compared with dl-Met.

Dietary supplementation of osthole and icariin improves the production performance of laying hens by promoting follicular development

Osthole (Ost) and icariin (Ica) are extracted from traditional Chinese medicine Cnidium monnieri and Epimedii Folium, respectively, and both exhibit estrogen-like biological activity. This study aimed to determine the efficacy and safety of combining Ost with Ica on the production performance of laying hens and to explore their possible mechanisms. The production performance, egg quality, residues of Ost and Ica in eggs, serum reproductive hormone levels, expression of ovarian reproductive hormone receptor, proliferation of granulosa cells in small yellow follicles (SYF), and progesterone secretion in large yellow follicles (LYF) related genes and proteins expression were detected. The results showed that adding 2 mg/kg Ost + 2 mg/kg Ica to the feed increased the laying rate, average egg weight, Haugh unit, and protein height of laying hens. Serum follicle-stimulating hormone (FSH), luteinizing hormone (LH), and progesterone (P4) levels increased, and the expression of ovarian estrogen receptor (ER), follicle-stimulating hormone receptor (FSHR), and progesterone receptor (PGR) mRNA was up-regulated. Additionally, the mRNA and protein levels of steroidogenesis acute regulatory protein (StAR), cytochrome P450 side-chain cleavage (P450scc), and 3β-hydroxysteroid dehydrogenase (3β-HSD) increased in LYF. Furthermore, mRNA and protein levels of proliferating cell nuclear antigen (PCNA), cyclin E1, and cyclin A2 were up-regulated in SYF. The residues of Ost and Ica in egg samples were not detected by high-performance liquid chromatography (HPLC). In conclusion, dietary supplementation of Ost and Ica increased granulosa cells proliferation in SYF and increased P4 secretion in granulosa cells of LYF, ultimately improving the production performance of laying hens.

Quality characteristics, lysozyme activity, and albumen viscosity of fresh hatching duck eggs after a week's storage at various temperatures

The study aimed to analyze the qualitative features of Cherry Valley duck' hatching eggs during storage at different temperatures. Eggs were divided into 3 equal groups with 30 eggs each: fresh egg and stored at 7 °C and 17 °C within one week. Qualitative analyses of duck eggs were carried out, considering the morphological composition, physicochemical characteristics, lysozyme activity, and albumen viscosity. The highest weight of yolk and its percentage was found in the 17 °C group. The weight and percentage of albumen were significantly the highest in the group of fresh eggs. Higher egg weight loss was observed in the group stored at higher temperatures. Higher thick albumen height and Haugh units were found in fresh eggs and eggs stored at 7 °C. Different temperatures of egg storage did not affect lysozyme activity in thick and thin albumen. Stored eggs were characterized by lower albumen viscosity only at a shear rate of 10 rpm. The higher viscosity of thick albumen compared to thin ones was demonstrated at 10 and 20 rpm shear rates. The presented research results indicate a large diversity of selected qualitative indicators of hatching duck eggs, which may affect their storage and suitability for incubation.

Probiotic cocktails accelerate baicalin metabolism in the ileum to modulate intestinal health in broiler chickens

BACKGROUND

Baicalin and probiotic cocktails are promising feed additives with broad application prospects. While probiotic cocktails are known to enhance intestinal health, the potential synergistic impact of combining baicalin with probiotic cocktails on the gut health of broiler chickens remains largely unexplored. Therefore, this study aims to investigate the influence of the combined administration of baicalin and probiotic cocktails on the composition of ileal and cecal microbiota in broiler chickens to elucidate the underlying mechanisms responsible for the health-promoting effects.

RESULTS

A total of 320 1-day-old male Arbor Acres broilers were divided into 4 groups, each with 8 replicates of 10 chicks per replicate. Over a period of 42 d, the birds were fed a basal diet or the same diet supplemented with 37.5 g/t baicalin (BC), 1,000 g/t probiotic cocktails (PC), or a combination of both BC (37.5 g/t) and PC (1,000 g/t). The results demonstrated that BC + PC exhibited positive synergistic effects, enhancing intestinal morphology, immune function, and barrier function. This was evidenced by increased VH/CD ratio, sIgA levels, and upregulated expression of occludin and claudin-1 (P < 0.05). 16S rRNA analysis indicated that PC potentiated the effects of BC, particularly in the ileum, where BC + PC significantly increased the α-diversity of the ileal microbiota, altered its β-diversity, and increased the relative abundance of Flavonifractor (P < 0.05), a flavonoid-metabolizing bacterium. Furthermore, Flavonifractor positively correlated with chicken ileum crypt depth (P < 0.05). While BC + PC had a limited effect on cecal microbiota structure, the PC group had a very similar microbial composition to BC + PC, suggesting that the effect of PC at the distal end of the gut overshadowed those of BC.

CONCLUSIONS

We demonstrated the synergistic enhancement of gut health regulation in broiler chickens by combining baicalin and probiotic cocktails. Probiotic cocktails enhanced the effects of baicalin and accelerated its metabolism in the ileum, thereby influencing the ileal microbiota structure. This study elucidates the interaction mechanism between probiotic cocktails and plant extract additives within the host microbiota. These findings provide compelling evidence for the future development of feed additive combinations.

Effects of dietary supplementation with Radix Isatidis polysaccharide on egg quality, immune function, and intestinal health in hens

This study aimed to investigate the effects of supplementing laying hen diets with Radix Isatidis Polysaccharide (RIPS) on egg quality, immune function, and intestinal health. The research was conducted using 288 Hyland Brown hens, which were randomly assigned to four dietary treatments: control (without RIPS), low dose (200 g/t), medium dose (500 g/t), and high dose (1000 g/t) of RIPS. Each dietary treatment was administered to eight replicates of nine hens for nine weeks. The results revealed that RIPS inclusion in diets significantly improved egg quality parameters such as egg shape index, yolk color, haugh unit, and protein height (P < 0.05). Additionally, RIPS supplementation enhanced immune function as evidenced by an alteration in serum biochemical parameters, an increase in the spleen index, and a decrease in the liver index. Further, an evaluation of intestinal health showed that RIPS fortified the intestinal barrier, thus increasing the population of beneficial intestinal bacteria and reducing the abundance of harmful ones. Such mechanisms promoted intestinal health, digestion, and nutrient absorption, ultimately leading to enhanced egg quality. In conclusion, supplementing laying hen diets with RIPS has been demonstrated to improve egg quality by boosting immunity and optimizing intestinal digestion and absorption.

Potential Immunoregulatory Mechanism of Plant Saponins: A Review

Saponins are extracted from different parts of plants such as seeds, roots, stems, and leaves and have a variety of biological activities including immunomodulatory, anti-inflammatory effects, and hypoglycemic properties. They demonstrate inherent low immunogenicity and possess the capacity to effectively regulate both the innate and adaptive immune responses. Plant saponins can promote the growth and development of the body's immune organs through a variety of signaling pathways, regulate the activity of a variety of immune cells, and increase the secretion of immune-related cytokines and antigen-specific antibodies, thereby exerting the role of immune activity. However, the chemical structure of plant saponins determines its certain hemolytic and cytotoxicity. With the development of science and technology, these disadvantages can be avoided or reduced by certain technical means. In recent years, there has been a significant surge in interest surrounding the investigation of plant saponins as immunomodulators. Consequently, the objective of this review is to thoroughly examine the immunomodulatory properties of plant saponins and elucidate their potential mechanisms, with the intention of offering a valuable point of reference for subsequent research and advancement within this domain.

The effects of sodium butyrate (NaB) combination with soy saponin dietary supplementation on the growth parameters, intestinal performance and immune-related genes expression of hybrid grouper (Epinephelus fuscoguttatus♀ × E. lanceolatus♂)

Soy saponins are generally known to have negative effects on growth and the intestines of aquatic animals, and appropriate levels of sodium butyrate (NaB) may provide some mitigating effects. We investigated the effects of low and high levels of soy saponin and the protective effects of NaB (based on high level of soy saponin) on growth, serum cytokines, distal intestinal histopathology, and inflammation in hybrid grouper (Epinephelus fuscoguttatus ♀ × E. lanceolatus ♂). The experiment included four groups: fishmeal group (FM, 0.00% saponin and 0.00% NaB), low saponin group (SL, 0.30% saponin and 0.00% NaB), high saponin group (SH, 1.50% saponin and 0.00% NaB) and high saponin with NaB group (SH-NaB, 1.50% saponin and 0.13% NaB). The results showed compared to FM, the final body weight (FBW) and weight gain (WG) were significantly higher and lower in SL and SH, respectively (P < 0.05). Compared to SH, the FBW and WG were significant higher in SH-NaB (P < 0.05). In the serum, compared to FM, the interferon γ (IFN-γ) and interleukin-1β (IL-1β) levels in SH were significantly increased (P < 0.05). Compared to SH, the IFN-γ level was significantly decreased in SH-NaB (P < 0.05). In the distal intestine, based on Alcian Blue-Periodic Acid-Schiff (AB-PAS) observation, the goblet cell/μm was significantly increased and decreased in the SL and SH, respectively, compared to FM. The intestinal diameter/plica height ratio in the SH was significantly higher than those in the FM, SL and SH-NaB (P < 0.05). The NO and ONOO- levels in the SH were significantly higher than that in FM and SL (P < 0.05). At the transcriptional level in the distal intestine, compared to FM, the mRNA levels of tumor necrosis factor (tnfα), il1β, interleukin-8 (il8) and ifnγ were significantly up-regulated in the SH (P < 0.05). Compared to the SH, tnfα, il8 and ifnγ were significantly down-regulated in the SH-NaB (P < 0.05). Compared to the FM, the mRNA levels of claudin3, claudin15, zo2 and zo3 were significantly up-regulated in the SL (P < 0.05). The mRNA levels of occludin, claudin3, claudin12, claudin15, zo1, zo2 and zo3 were significantly down-regulated in the SH compared to the FM (P < 0.05). Additionally, compared to the SH, the mRNA levels of occludin, claudin3, claudin12, claudin15, zo1, zo2 and zo3 were significantly up-regulated in the SH-NaB (P < 0.05). After the 7-day Vibrio parahaemolyticus challenge test, the survival was significantly higher and lower in the SL and SH, respectively, compared to FM (P < 0.05). Overall, low and high levels of soy saponins had positive and negative effects on growth, disease resistance, serum cytokines, and distal intestinal development and anti-inflammation, respectively, in hybrid grouper. NaB effectively increased disease resistance and improved distal intestinal inflammation in hybrid grouper, but the effects of NaB were mainly observed in improving distal intestinal tight junctions.

Supplementing Genistein for Breeder Hens Alters the Growth Performance and Intestinal Health of Offspring

Recent research revealed that dietary genistein supplementation for breeder hens can improve the immune function of offspring chicks. However, it remains unknown whether this maternal effect could improve the intestinal health of offspring. This study was conducted to explore the mechanism involved in the maternal effect of genistein on the intestinal mucosa and microbial homeostasis of chicken offspring. A total of 120 Qiling breeder hens were fed a basal diet, a 20 mg/kg genistein-supplemented diet, or a 40 mg/kg genistein-supplemented diet for 4 weeks before collecting their eggs. After hatching, 180 male offspring (60 chickens from each group) were randomly selected and divided into three groups: (1) the offspring of hens fed a basal diet (CON); (2) the offspring of hens fed a low-dose genistein-supplemented diet (LGE); (3) the offspring of hens fed a high-dose genistein-supplemented diet (HGE). At 17 d, 72 male offspring (48 chickens from CON and 24 chickens from LGE) were divided into three groups: (1) the offspring of hens fed a basal diet (CON); (2) the CON group challenged with LPS (LPS); (3) the LGE group challenged with LPS (LPS + LGE). The results showed that maternal genistein supplementation increased the birth weight and serum level of total protein (TP), followed by improved intestinal villus morphology. Continuously, the maternal effect on the body weight of chicks lasted until 21 d. Additionally, it was observed that maternal genistein supplementation exhibited protective effects against LPS-induced morphological damage and intestinal mucosal barrier dysfunction by upregulating the expression of tight junction proteins, specifically ZO-1, Claudin1, E-cadherin, and Occludin, at 21 d. Using 16S rRNA gene sequencing, we demonstrated that maternal supplementation of genistein has the potential to facilitate the maturation of newly hatched chicken offspring by enhancing the abundance of Escherichia coli. Additionally, maternal genistein supplementation can effectively reduce the abundance of Gammaproteobacteria, thus mitigating the risk of bacterial diversity impairment of LPS. In light of these findings, maternal genistein supplementation holds promise as a potential strategy for ameliorating intestinal mucosal damage and modulating the microbiome in chicken offspring.

Effect of follicle-stimulating hormone and luteinizing hormone levels on egg-laying frequency in hens

Background and Aim

Gonadotropins, for example, follicle-stimulating hormone (FSH) and luteinizing hormone (LH), are hormones that affect the reproductive process. In hens, optimal levels of FSH and LH can stimulate follicle growth fairly rapidly and thereby increase egg production through follicle development and increased ovulation. Follicle-stimulating hormone acts in the early stages of follicular growth, whereas LH acts on pre-ovulatory follicles. Normal follicular growth is the result of the complementary action of FSH and LH. Low FSH and LH levels result in the formation of follicles but a lack of egg production in chickens. This study aimed to investigate FSH and LH hormone levels from layer chickens with different egg-laying frequencies.

Materials and Methods

Fifty blood serum samples were collected from 54-week-old ISA brown strain hens that were divided into five groups (with 10 hens per group) as follows: Hens that lay eggs (i) every day, (ii) once every 2 days, (iii) twice every 3 days, (iv) 3 times every 4 days, and (v) hens that do not lay eggs. Follicle-stimulating hormone and LH levels were measured in samples using an enzyme-linked immunosorbent assay, and the data were analyzed using multivariate analysis of variance.

Results

Follicle-stimulating hormone levels were significantly associated with the frequency of egg laying in ISA brown strain hens (p < 0.05); the highest FSH level (869.005 ± 149.194 pg/mL) was found in hens that lay eggs every day. In contrast, the highest LH level (51.386 ± 2.410 mIU/mL) was found in hens that lay eggs every 2 days.

Conclusion

High level of FSH (869.005 ± 149.194 pg/mL) was associated with a high frequency of egg laying (every day) in ISA brown strain hens, and LH level of around 30.406 pg/mL was associated with daily egg laying in these hens.

Soya saponin fails to improve the antioxidation and immune function of laying hens with antibiotics treated

Soya saponin (SS) helps to improve antioxidant and immune function of body, and intestinal bacteria might play an important role here. In the present study, the co-occurring network of the ileal flora was analyzed with 50 mg/kg SS supplemented to the diet, and Romboutsia was found to have evolved into a dominant flora. In addition, the co-occurring network of the flora was changed with the combined antibiotic treated, and the unidentified-cyanobacteria developed into the dominant flora, whereas the relative abundance of Romboutsia was dropped. Dietary SS failed to elevate the relative abundance of Romboutsia with antibiotics treated, at the same time, it was not helpful for the antioxidant and immune function of laying hens. While dietary SS had a little help on the egg-laying performance. Intestinal bacteria did play a key role in the biological functions of SS on laying hens. In conclusion, SS failed to improve the antioxidation and immune function of laying hens with antibiotics treated.

Fecal Microbiota Transplantation Reshapes the Physiological Function of the Intestine in Antibiotic-Treated Specific Pathogen-Free Birds

The topic about the interactions between host and intestinal microbiota has already caught the attention of many scholars. However, there is still a lack of systematic reports on the relationship between the intestinal flora and intestinal physiology of birds. Thus, this study was designed to investigate it. Antibiotic-treated specific pathogen-free (SPF) bird were used to construct an intestinal bacteria-free bird (IBF) model, and then, the differences in intestinal absorption, barrier, immune, antioxidant and metabolic functions between IBF and bacteria-bearing birds were studied. To gain further insight, the whole intestinal flora of bacteria-bearing birds was transplanted into the intestines of IBF birds to study the remodeling effect of fecal microbiota transplantation (FMT) on the intestinal physiology of IBF birds. The results showed that compared with bacteria-bearing birds, IBF birds had a lighter body weight and weaker intestinal absorption, antioxidant, barrier, immune and metabolic functions. Interestingly, FMT contributed to reshaping the abovementioned physiological functions of the intestines of IBF birds. In conclusion, the intestinal flora plays an important role in regulating the physiological functions of the intestine.

Dietary Saccharomyces cerevisiae improves intestinal flora structure and barrier function of Pekin ducks

This study aimed at investigating the effects of dietary Saccharomyces cerevisiae (SC) on the intestinal flora structure and barrier function of Pekin duck. A total of 180 1-day-old Pekin ducks were randomly divided into 3 groups with 6 replicates in each group and 10 birds per replicate. The birds in the control group (CON) were fed the basal diet, and those in the experimental group were fed the basal diets supplemented with 600 mg/kg SC (LSC) and 1,200 mg/kg (HSC), respectively. The trial lasted for 42 d. Results showed that LSC and HSC treatments tended to improve the feed conversion efficiency during the trial. The ileum length of birds in the LSC and HSC groups was elevated. Additionally, with 600mg/kg SC supplemented, the mRNA levels of villin, claudin3, and MUC 2 in d21 were up-regulated, as well as the mRNA levels of villin, claudin3, occludin, i-FABP, ZO-1, and MUC 2 in d42. In addition, dietary SC supplementation improved the α-diversity of the bacteria in cecal chyme and tended to increase the abundance (RA) of Bacteroidetes (P = 0.071). Besides, the RA of Ruminococcaceae_UCG-014 was raised in the LSC group. Beyond that, the RA of Proteobacteria was descended with two levels of SC added. In conclusion, dietary Saccharomyces cerevisiae, particularly at 600 mg/kg level, improved the intestinal flora structure and barrier function of Pekin duck.

Lipoamide Alleviates Oxidized Fish Oil-Induced Host Inflammatory Response and Oxidative Damage in the Oviduct of Laying Hens

Fish oil (FO) is an important source of lipid in functional food and aquafeeds. However, the harmful effects of oxidized fish oil (OFO) on host metabolism and reproductive health are not yet clear. In addition, lipoamide (LAM) has been widely studied as an agent for alleviating various diseases associated with oxidative disruption. Therefore, in the current study, to investigate the effects of LAM in alleviating OFO-induced decline in reproductive performance and oxidative damage to the oviduct in laying hens. We constructed a 1% fresh FO model, a 1% OFO model, and a LAM model with 1% OFO (OFO + LAM) added at 100 mg/kg to explore the antioxidant effect of LAM. Herein, these results were evaluated by breeding performance, immune responses, estrogen, and antioxidant indices of serum samples, as well as the number of follicles and antioxidant parameters of oviducts. From the results, compared with the FO group, OFO significantly decreased the egg-laying rate, increased the contents of total protein (TP) and inflammatory factors [tumor necrosis factor α (TNF-α), interleukin (IL)-6, IL-8, and interferon γ (INF-γ)], and reduced the concentrations of anti-oxidation [total antioxidant (T-AOC), total superoxide dismutase (T-SOD), glutathione peroxidase (GSH-Px), glutathione (GSH), glutathione reductase (GR), catalase (CAT), and hydroxyl radical scavenging activity (HRSA)] in serum samples, as well as reduced the levels of anti-oxidation indexes in oviduct tissues (p < 0.05). Of note, the supplementation of LAM could significantly increase the laying performance, improve the levels of serum immunoglobulins (IgA, IgG, and IgM), serum estrogen [progesterone (P) and estradiol (E2)], and serum antioxidant parameters (T-AOC, T-SOD, GSH-Px, GSH, GR, CAT, and HRSA) and decrease the concentrations of serum inflammatory cytokines (TNF-α, IL-6, IL-8, and INF-γ) in laying hens following OFO administration (p < 0.05). In addition, LAM could dramatically increase the contents of antioxidant factors (p < 0.05) in oviducts and enhance the secretion capacity of the uterine part. Taken together, OFO caused host metabolic dysfunction, oxidative damage, uterine morphological abnormalities, and alterations of ovarian function. These results suggested that LAM administration could alleviate host metabolic dysfunctions and inflammatory damage, and then ameliorate oxidative damage in the oviduct induced by OFO, ultimately improving reproductive function.

Dietary soya saponin improves the lipid metabolism and intestinal health of laying hens

Soya saponin (SS) is a natural active substance of leguminous plant, which could improve lipid metabolism and regulate immune function. Intestinal flora might play a key role in the biological functions of SS. The objective of this study was to measure the effects of dietary SS on immune function, lipid metabolism, and intestinal flora of laying hens with or without antibiotic treated. The experiment was designed as a factorial arrangement of 3 dietary SS treatments × 2 antibiotic treatments. Birds were fed a basal diet (CON) or a low-SS diet (50 SS) containing 50 mg/kg SS, or a high-SS diet (500 SS) containing 500 mg/kg SS. Birds were cofed with or without antibiotics. The growth experiment lasted for 10 wk. Results showed that birds fed the 50 mg/kg SS diet tended to have lower abdominal fat rate. The gene expression of liver X receptor-α (LxR-α) in liver and serum total cholesterol (TC) were dropped, and the gene expression of acyl-CoA thioesterase 8 (ACOT8) in liver were upregulated. Compared with CON group, the levels of lysozyme, IL-10, and transforming growth factor (TGF-β) in the serum were elevated as along with gene expression of IL-10, TGF-β, and LYZ in ileum of both 50 and 500 SS group. However, the level of secretory immunoglobulin A (sIgA) and Mucin-2 in the ileum were downregulated in the 500 SS group. Additionally, Lactobacillus and Lactobacillus gasseri were the dominant bacteria in the 50 SS group, whereas the relative abundance of Lactobacillus was dropped in the 500 SS group. With combined antibiotics treatment, the α-diversity of bacteria was reduced, and the biological effects of SS were eliminated. In conclusion, the lipid metabolism, immune function, and intestinal flora of the laying hens were improved with the dietary supplementation of 50 mg/kg SS. But dietary 500 mg/kg SS had negative effects on laying hens.