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  • Original article
  • Open Access

Fermented Astragalus in diet altered the composition of fecal microbiota in broiler chickens

AMB Express20188:151

https://doi.org/10.1186/s13568-018-0682-4

  • Received: 19 May 2018
  • Accepted: 21 September 2018
  • Published:

Abstract

The composition and function of the intestinal microbiota play important roles in digestion and degradation of herbal medicines (HMs). However, few studies have examined the relationship between the fecal microbiota and HMs. In this study the effect of unfermented Astragalus (UA) and fermented Astragalus (FA) on growth performance, serum biochemical parameters, and fecal microbiota was evaluated in broiler chickens. In total, 180 one-day-old broiler chickens (Avian breeds) were randomly assigned to a control (C) group fed a basal diet, an unfermented (U) group fed a basal diet containing 0.5% UA, or a fermented (F) group fed a basal diet containing 0.5% FA, for 42 days. The F/G ratio was lower in F and U groups than in C group from 22 to 42 days (P < 0.05). Glutathione superoxide dismutase, antioxidant capacity, and total superoxide dismutase were higher, whereas malondialdehyde was lower in F group than in C and U groups from 1 to 21 days and from 22 to 42 days (P < 0.05). Fecal microbiota were profiled on an Illumina MiSeq platform following PCR amplification of the V4 region of the 16S rRNA gene. At the genus level Lactobacillus was the most abundant genus on day 7 in F group. Importantly, a potentially pathogenic genus, Enterococcus, was less abundant in the U and F groups than in the C group on day 35 (P < 0.05). These results indicate that dietary supplementation with 0.5% FA has beneficial effects on growth performance, serum biochemical parameters and fecal microbiota of broiler chickens.

Keywords

  • Fermented Astragalus
  • Growth performance
  • Serum biochemical parameters
  • Microbiota
  • Broiler chickens
  • 16S rRNA sequencing

Introduction

Over the past decades, the application of antibiotics has improved growth rate and feed conversion efficiency in poultry production (Sugiharto 2014). However, increased use of antibiotics in livestock and poultry production has prompted widespread concern about the prevalence of antibiotic-resistant bacteria. In particular, the accumulation of antibiotic residue in chickens results in the contamination of meat and eggs (Suresh et al. 2018). Increasing consumer awareness of food safety and biosecurity concerns is driving the poultry industry to look for alternatives to feed additives (Yitbarek et al. 2015). Previous studies have shown that herbal feed additives promote growth performance, improve immune function, while exerting anti-bacterial, anti-viral, and anti-oxidative effects in livestock (Wang et al. 2014b; Hu et al. 2011).

The root of Astragalus membranaceus (Fisch.) Bge. var. mongholicus, a common herbal medicine, contains polysaccharides, saponins, flavonoids, anthraquinones, alkaloids, amino acids, β-sitosterol, and metallic elements and has long been used as a feed additive in the livestock and poultry industries in China (Ibrahim et al. 2013; Li et al. 2009). The major polysaccharides present in Astragalus are mannose, d-glucose, d-galactose, xylose, and l-arabinose (Kallon et al. 2013). The major flavonoids of Astragalus are 3-O-β-d-glucoside, 2′-hydroxy-3′,4′-dimethoxyisoflavane-7-O-β-d-glycoside, 7,3′-dihydroxy-4′-methoxyisoflavone, 7,3-dimer-capto-4,1-methoxyisoflavone, 3-dimercapto-7,4,1-methoxyisoflavone, and kumatakenin (Lv et al. 2011; Xiao et al. 2004). A recent study showed that crude extracts of Astragalus are anti-inflammatory (Kim et al. 2013), anti-viral (Zhang et al. 2018), immunostimulatory (Zhang et al. 2017), promote growth performance (Li et al. 2018) and affects fecal microbiota of young hens (Qiao et al. 2018a). In recent years, fermentation has become a powerful tool for producing biological materials, degrading macromolecular material into small molecules, reducing the side effects associated with herbs such as Aristolochia plants, and introducing medicinal effects through biological modification (Lin and Chiang. 2008; Zhou et al. 2015; Luciano and Perazella 2015). Chinese herbs have long been processed using microbial fermentation. Solid state fermentation (SSF) is known to reduce anti-nutritional factors and improve the nutritional quality of feedstuffs (Ahmed et al. 2017). The fermentation of Astragalus by Aspergillus oryzae M29 improves antioxidant activity and increases phenolic content (Sheih et al. 2011). We previously showed that Astragalus fermentation by Bacillus subtilis using liquid fermentation technology promotes Astragalus polysaccharide production (Qiao et al. 2017).

Many herbal supplements include carbohydrates, particularly polysaccharides and oligosaccharides, which promote pharmacological immunomodulatory, antitumor, antioxidant, hypoglycemic, and anti-inflammatory effects (Li et al. 2013). However, most herbal carbohydrates can not be digested and used by the host in the absence of microbial fermentation (Vrize et al. 2010). Polysaccharides fermented by intestinal microbiota can be converted into short-chain fatty acids (SCFAs), which are beneficial to the host (Lyu et al. 2017). Similarly, flavonoids are important polyphenolic compounds in these herbs that may be more easily absorbed in the intestines after fermentation (Izumi et al. 2000). Supplementation with fermented herbs can trigger secretion of digestive enzymes, enhance digestion of nutrients in the intestine (Yu et al. 2015), modulate the gut microbiota and increase the proportion of beneficial microbiota (Zhang et al. 2015).

In previous studies, fermented herbs, including Ginkgo biloba leaves, Pinus needles, reportedly improve growth performance, feed efficiency, meat quality, immune function, and blood parameters in livestock (Ahmed et al. 2016; Wu et al. 2015; Zhang et al. 2015). Fermented herbs such as Anoectochilus formosanus Hyata, Flos Lonicera, and Rhizoma Atractylodis Macrocephalae have antioxidant activity and modulate the intestinal microbiota of rats (Ng et al. 2011; Wang et al. 2014a, 2015). Astragalus membranaceus root improves growth performance, antioxidant status, and serum metabolites of broilers chickens (Zhang et al. 2013). Although Astragalus fermentation has been studied in the past, the effects of fermented Astragalus (FA) in broiler chickens have not been investigated.

In this study, we determine the effects of Astragalus fermented by Lactobacillus plantarum on growth performance, blood characteristics, and fecal microbiota of broiler chickens.

Materials and methods

Fermentation of Astragalus

The dried root of Astragalus membranaceus (Fisch.) Bge. var. mongholicus was obtained from Gansu Huisen Pharmaceutical Development Co., Ltd. (Minxian, Gansu, China) and verified by Dr. JingYu Zhang (Henan University of Traditional Chinese Medicine, Zhengzhou, Henan, China). The fermentation of Astragalus was performed following our laboratory-optimized procedure as follows: Briefly, Astragalus was ground into a powder using a 100-mesh screen. The dried powder (2500 g) was inoculated with 105 colony-forming units (CFU)/mL of L. plantarum (CGMCC 1.557), which was originally obtained from the China General Microbiological Culture Collection Center (CGMCC). We previously reported the production parameters for fermenting Astragalus with L. plantarum: acetic acid, methylacetic acid, aethyl acetic acid and lactic acid were 1723.01 mg/kg, 95.34 mg/kg, 397.22 mg/kg, and 1946.17 mg/kg on day 15, respectively. Other production were: polysaccharides 9.43% on day 10; saponins, 20.1761 mg/g on day 25, flavonoids 1.9153 mg/g on day 15 (Qiao et al. 2018b). The L. plantarum strain was cultured in de Man, Rogosa, and Sharpe (MRS) medium at 37 °C for 18 h. Fermentation was conducted in 35 × 45-mm plastic film bags (Zhejiang Jinhu Plastics Machinery Co., Zhejiang, China), which were vacuum-sealed. The mixture was then incubated for 96 h at 37 °C under anaerobic conditions. At the end of the fermentation process, optimal fermentation was confirmed by calculating the number of L. plantarum CFUs, and measuring the pH of the FA preparation (the pH of the fermented product should be between 4.0 and 4.5). Unfermented Astragalus (UA) was ground into a powder using a 100-mesh screen, inoculated into MRS medium without L. plantarum, and cultured for 96 h at 37 °C under anaerobic conditions. FA and UA samples were spread on a polythene sheet and dried for 4 days up to 90% of its dry weight at 30–40 °C, and then ground. The results of nutritional analyses of Astragalus before and after fermentation are shown in Table 1.
Table 1

Nutritional composition of Astragalus before and after fermentation

Items

Before fermentation

After fermentation

Polysaccharides (%)

4.21

7.43

Total flavonoids (mg/g)

28.25

26.15

Total saponins (mg/g)

4.0

5.0

Ferment cells number (CFU/g)

0

9.2 × 1010

Acetic acid (mg/kg)

0

421.14

Methylacetic acid (mg/kg)

0

805.29

Ethyl acetic acid (mg/kg)

0

31.25

Lactic acid (mg/kg)

0

92.44

Experimental design and broiler chicken housing

A total of 180 one-day-old broiler chickens (Avian breeds) with average initial body weight (BW) of 51.45 g were purchased from a local commercial hatchery (Xinzheng, Henan, China). Birds were randomly assigned to one of three groups comprising six pens, with each pen containing ten birds (50% male and 50% female) and provided with feed and water ad libitum according to their BW during the 45-day experimental period. Each group was housed in an individual house of > 30 m2 to avoid between-group interference. Broilers and environmental parameters were checked twice daily by trained staff. From day 1 to 21, the temperature and humidity were maintained at 33–35 °C and 60–70%, respectively. From day 22 to 42, the temperature and humidity were maintained at 24–28 °C and 50–60%, respectively. All procedures were performed in accordance with the guidelines of the Chinese Agricultural Ministry. Basal diets were administered as mash and nutrient levels for the starter phase from day 1 to 21 and grower phase from day 22 to 42 were formulated to meet the Feeding Standard of Chicken of the People’s Republic of China (NY/T 33–2004). One group served as the control (C) group and was fed only conventional feed, while the U and F groups were fed feed mixed with either UA (0.5%) or FA (0.5%), respectively, throughout the entire experimental period (Table 2). All animal experiments were conducted according to the Guidelines for the Care and Use of Experimental Animals established and approved by the Laboratory Animal Management Committee of Henan University of Animal Husbandry and Economy (HNMY 1606).
Table 2

Composition of the basic diet (as a percentage of dried weight)

Ingredient

1–21 days

22–45 days

C group

U group

F group

C group

U group

F group

Corn

60.35

59.85

59.85

62.55

62.05

62.05

Soybean meal

28.25

28.25

28.25

26.15

26.15

26.15

Flour

4.0

4.0

4.0

5.0

5.0

5.0

Corn gluten meal

3.0

3.0

3.0

2.5

2.5

2.5

Fishmeal

1.2

1.2

1.2

1.0

1.0

1.0

Dicalcium phosphate

1.4

1.4

1.4

1.2

1.2

1.2

Limestone

1.2

1.2

1.2

1.0

1.0

1.0

NaCl

0.3

0.3

0.3

0.3

0.3

0.3

Oil

0.3

0.3

0.3

0.3

0.3

0.3

Fermented Astraglus

0

0

0.5

0

0

0.5

Unfermented Astraglus

0

0.5

0

0

0.5

0

Total

100

100

100

100

100

100

C group basal diet, U group basal diet + 0.5% unfermented Astragalus, F group basal diet + 0.5% fermentedAstragalus

Sample collection and measurements

The body weight of individual broiler chickens (on days 1, 21, and 42, weighed in the morning before feeding) and the amount of feed consumed by each group were recorded weekly and used to calculate the average daily feed intake (ADFI), average daily gain (ADG), and feed to gain (F/G) ratio per cage. The ADFI, ADG, and F/G ratio were determined separately for the starter (1–21 days) and grower (22–42 days) phases.

Six broiler chickens from each treatment group were selected randomly in the morning of day 21 and 42 of the experiment and feed was removed for 12 h. The BW of each bird was measured after which blood samples (5.0 mL) were taken from the wing vein. Blood samples were incubated at 37 °C for 30 min and subsequently separated by centrifugation at 12,000×g for 10 min at 4 °C. Serum samples were frozen at − 20 °C prior to serum biochemical parameter measurements. Levels of serum catalase (CAT), glutathione superoxide dismutase (GSH-Px), malondialdehyde (MDA), superoxide dismutase (SOD), and antioxidant capacity (AOC) were analyzed by spectrophotometrical methods with ELISA assay kits (Nanjing Jiancheng Bioengineering Institute, Nanjing, China) according to the manufacturer’s instructions. These antioxidant enzymes play an important role in balancing redox status (Wu et al. 2015).

Forty-five fecal samples were chosen randomly (five samples per group on days 7, 21, and 35, respectively) and stored immediately at − 20 °C prior to DNA extraction. DNA was isolated from 200 mg of feces from each bird using a DNA isolation kit (TIANGEN, cat#DP328) according to the manufacturer’s instructions. The quality of the extracted DNA was assessed by 0.8% agarose gel electrophoresis and spectrophotometry (optical density at 260/280 nm). The extracted DNA was stored at − 20 °C until further analysis.

For library preparation, the V4 region of the 16S rRNA gene was amplified from 10 ng of DNA from each fecal sample. The V4 region of the bacterial 16S rRNA gene was amplified by polymerase chain reaction (PCR) (98 °C for 30 s, followed by 27 cycles at 98 °C for 15 s, 50 °C for 30 s, and 72 °C for 30 s, followed by a final extension at 72 °C for 5 min) using the primers 5′-barcode–AYT GGG YDT AAA GNG–3′ and 5′–TAC NVG GGT ATC TAA TCC–3′, where the bar code was a seven-base sequence unique to each sample. PCRs were performed in triplicate in a 20-μL mixture containing 5 μL of 5 × reaction buffer, 5 × High GC buffer, 0.25 μL of Q5 high-fidelity DNA polymerase, 1 μL of each primer (10 μM), 0.5 μL of dNTPs (10 μM), 1 μL of template DNA, and 11.25 μL of distilled water. The amplicons were extracted from 2% agarose gels and then purified using the Axygen® AP-GX-250 AxyPrep™ DNA Gel Extraction Kit (Corning Life Sciences, Corning, NY, USA) according to the manufacturer’s instructions. The library was prepared using the TruSeq Nano DNA LT Library Prep Kit (Illumina, San Diego, CA, USA) and quantified using the Quant-iT PicoGreen dsDNA Assay Kit (Invitrogen Corporation, Carlsbad, CA, USA). The qualified library was subsequently diluted to 2 nM before sequencing.

For the library, paired-end sequencing (2 × 300 bp) was performed on an Illumina MiSeq platform using the MiSeq Reagent Kit V3 (600-cycles-PE) (MS-102-3033). A pooled library (2 nM) was mixed with fresh 0.1 N NaOH and then sequenced. The molarity of the library was controlled to within 15 pM. Library preparation and sequencing was performed by Personal Biotechnology Co., Ltd. (Shanghai, China).

Raw reads were quality filtered to remove chimeric reads, reads < 150 bp, or with average phred scores < 20. The remaining high-quality reads were processed using the Quantitative Insights into Microbial Ecology (QIIME) package v1.8 (Caporaso et al. 2010), merged and clustered into operational taxonomic units (OTUs) based on a 97% sequence similarity threshold. Taxonomic assignment was performed against the Greengenes reference database [the Ribosomal Database Project (RDP) Gold database, 2.2]. Next, archaeal and eukaryotic reads were removed to minimize the effect of very low abundance OTUs (Bokulich et al. 2013). Alpha diversity was estimated using the Chao 1, ACE, Shannon and Simpson indices. Beta diversity was determined by principal coordinate analyses (PCoA) (Lozupone and Knight 2005) using weighted and unweighted UniFrac distance metrics. While both weighted and unweighted UniFrac take into account phylogenetic distances between OTUs, unweighted UniFrac distance is a qualitative measure and does not take into account OTU abundance, and only considers presence/absence (Lozupone and Knight 2005), while weighted UniFrac is a quantitative measure that takes into account OTU abundance (Lozupone et al. 2007). Raw sequence reads were deposited to the National Center for Biotechnology Information Short Read Archive (SRA) under the accession number SRP1040138.

Statistical analysis

Experimental results are shown as the mean of triplicate measurements. The data were represented as mean ± standard deviation using SPSS version 18.0 for Windows (SPSS Inc., Chicago, IL, USA). Differences were considered statistically significant if P < 0.05. Diversity index data were analyzed statistically using analysis of variance (ANOVA). Principal Coordinates Analysis (PCoA) was conducted using the QIIME package v1.8 (Caporaso et al. 2010).

Results

Growth performance

The effects of UA and FA on the growth performance of broiler chickens are presented in Table 3. The ADFI of F group broiler chickens were higher than those of C and U groups from 1 to 21 days, but lower than those of C group chickens from 22 to 42 days (P < 0.05). The ADG of F and C group broiler chickens were higher than those of U group broiler chickens from 22 to 42 days (P < 0.05), with no significant differences from 1 to 21 days (P > 0.05). The F/G ratio was lower in F and U groups broiler chickens than in C group broiler chickens from 22 to 42 days, with significant differences from days 1 through 22 (P < 0.05).
Table 3

Effects of fermented Astragalus on growth performance of broiler chickens

Item

Time period (days)

Dietary treatment

SEM2

P-values

C group

U group

F group

ADFI (g/days)

1–21

30.20 ± 2.26a

25.10 ± 0.22a

38.37 ± 1.21b

1.048

0.0001

22–42 

67.84 ± 9.32a

59.21 ± 1.11a

64.71 ± 0.69

3.843

0.224

ADG (g/days)

1–21 

12.45 ± 0.73

12.91 ± 0.17

13.37 ± 0.50

0.369

0.178

22–42

31.26 ± 2.22ab

29.79 ± 1.40a

34.58 ± 1.38b

1.209

0.035

F/G

1–21

2.43 ± 0.10b

1.94 ± 0.04a

2.87 ± 0.20c

0.045

0.000004

22–42

2.16 ± 0.16b

1.99 ± 0.13ab

1.87 ± 0.55a

0.084

0.066

C group = basal diet; U group = basal diet + 0.5% unfermented Astragalus; F group=basal diet + 0.5% fermented Astragalus

ADFI average daily feed intake, ADG average daily gain, F/G feed gain ratio

a,b,cMeans in the same row bearing different superscripts differ significantly (P ≤ 0.05)

Serum biochemical parameters

The results of serum biochemical analyses are presented in Table 4. GSH-Px, AOC, and SOD were significantly higher in F group broiler chickens than in C and U group broiler chickens from 1 to 42 days (P < 0.05). MDA levels were lower in U group broiler chickens than in C and F group broiler chickens from 1 to 42 days (P <0.05). These results indicate that FA supplementation increase AOC and reduce MDA in serum.
Table 4

Effects of fermented Astragalus on the serum biochemical parameters of broiler chickens

Item

Time period (days)

Dietary treatment

SEM2

P-values

C group

U group

F group

CAT (U/mL)

1–21

2.26 ± 0.32

2.49 ± 0.22

2.65 ± 0.24

0.186

0.264

22–42

5.72 ± 0.45

5.82 ± 0.52

6.01 ± 0.35

0.315

0.721

GSH-Px (U/mL)

1–21

1 127.61 ± 79.64a

1133.50 ± 74.79a

1374.21 ± 89.65b

57.695

0.016

22–42

1 329.20 ± 96.00a

1 378.68 ± 86.00a

1569.12 ± 91.77b

64.592

0.040

AOC (U/mL)

1–21

8.90 ± 1.09a

9.56 ± 1.31a

13.23 ± 0.80b

0.767

0.006

22–42

10.42 ± 0.77a

11.03 ± 1.25a

13.44 ± 1.33b

0.809

0.039

MDA (nmol/mL)

1–21

10.79 ± 1.27b

9.46 ± 1.10b

7.05 ± 0.85a

0.769

0.015

22–42

4.23 ± 0.66

4.21 ± 0.53

3.89 ± 0.46a

0.395

0.713

SOD (U/mL)

1–21

118.03 ± 10.26a

121.45 ± 13.94a

156.97 ± 12.12b

8.627

0.014

22–42

208.67 ± 14.06a

213.96 ± 16.32a

248.76 ± 11.85b

10.036

0.027

C group = basal diet; U group = basal diet + 0.5% unfermented Astragalus; F group=basal diet + 0.5% fermented Astragalus

CAT catalase, GSH-Px glutathione superoxide dismutase, AOC antioxidant capacity, MDA malondialdehyde, SOD suproxide dismutase

a,bMeans in the same row bearing different superscripts differ significantly (P ≤ 0.05)

Data acquisition and analysis

16S rRNA gene sequencing was performed for 45 fecal samples, resulting in 2,923,539 high-quality sequences, with an average of 64,968 reads per sample. A total of 7918 OTUs were detected based on a minimum nucleotide sequence identity of 97% for OTU clustering (Table 5). Per-sample microbial complexity was estimated with alpha-diversity indices (Chao1 and abundance-based coverage estimator (ACE) indices, Shannon and Simpson indices). The Chao1 index was used to estimate species richness and the ACE index was used to indicate the number of OTUs of the community. As shown in Table 5, the Chao1 and ACE indices were highest in the U group on day 35, followed by the C group on day 35, the C group on day 21, the F group on day 35, the U group on day 7, the U group on day 21, the C group on day 7, the F group on day 7, and the F group on day 21.The Shannon diversity index was used to evaluate the richness and evenness of the community and the Simpson diversity index was used to indicate community diversity. As shown in Table 5, the Shannon and Simpson index were highest in the C group on day 7, followed by the U group on day 21. However, the remaining groups were fairly similar. This result illustrates that fecal microbiota abundance and diversity differ by growth period.
Table 5

Fecal microbiota diversity estimates (N = 45)

Samples

Numbers of OTUs

Chao 1 index

ACE

Simpson index

Shannon index

C1 (7 days)

903

345.2 ± 40.92b

372.21 ± 55.45b

0.94 ± 0.04b

5.33 ± 0.39b

U1 (7 days)

946

359.6 ± 49.16b

394.66 ± 53.43b

0.90 ± 0.09b

5.20 ± 1.02b

F1 (7 days)

1162

251.8 ± 78.50a

277.40 ± 79.91a

0.71 ± 0.13a

3.17 ± 0.83a

C2 (21 days)

315

378 ± 115.16b

422.77 ± 117.45b

0.81 ± 0.13

3.95 ± 1.40

U2 (21 days)

1094

350 ± 89.34ab

391.33 ± 96.54ab

0.79 ± 0.07

3.62 ± 0.76

F2 (21 days)

1099

234 ± 75.64a

266.37 ± 83.81a

0.76 ± 0.03

2.91 ± 0.26

C3 (35 days)

1036

395.2 ± 114.48

451.65 ± 110.94

0.83 ± 0.09

3.95 ± 1.50

U3 (35 days)

1137

518.2 ± 82.16ab

555.51 ± 73.39ab

0.82 ± 0.20

4.91 ± 1.68

F3 (35 days)

1126

373.4 ± 155.75

417.11 ± 151.05

0.79 ± 0.12

3.68 ± 1.66

Means within the same column with different lowercase letters indicate significant differences (P ≤ 0.05). Means within the same column with the same lowercase letter or no letter indicate that the differences are not significant (P ≥ 0.05)

C1 samples of group C on day 7, C2 samples of group C on day 21, C3 samples of group C on day 35, U1 samples of group U on day 7, U2 samples of group U on day 21, U3 samples of group U on day 35, F1 samples of group F on day 7, F2 samples of group F on day 21, F3 samples of group F on day 35

Microbial beta diversity analysis

Beta diversity analysis for the 45 fecal samples are presented by PCoA of unweighted and weighted UniFrac distance matrices (Fig. 1a, b). For the unweighted UniFrac PCoA principal component PC1, PC2 and PC3 explained 25.49%, 20.11%, and 9.3% of the between-sample variation, respectively (P = 0.001); for unweighted UniFrac PCoA PC1, PC2 and PC3 explained 41.75%, 14.92%, and 10% of the between-sample variation, respectively (P = 0.001). Both weighted and unweighted UniFrac PCoAs demonstrate a separation of all samples taken on day 7, irrespective of group. However, there was no clear separation by Astragalus supplementation (either fermented or unfermented) status from samples collected on days 21 and 35.
Fig. 1
Fig. 1

Beta diversity analysis of the 45 fecal samples. a Unweighted and b weighted UniFrac PCoA of individual chickens in each group. Individual samples are represented as group C (C1 on day 7, C2 on day 21, and C3 on day 35), group U (U1 on day 7, U2 on day 21, and U3 on day 35), and group F (F1 on day 7, F2 on day 21, and F3 on day 35)

Fecal microbiota profiles

As shown in Fig. 2a, c, and e, a total of fifteen phyla were identified. Firmicutes was the most dominant phylum (79.1% in C, 83.9% in U and 82.2% in F), followed by Proteobacteria (11.1% in C, 7.5% in U and 15% in F) and Bacteroidetes (8.2% in C, 6.5% in U and 1.3% in F) (P < 0.05). On day 7 the abundance of Proteobacteria was significantly higher in the U and F groups than in the C group, yet significantly lower on day 35 (P < 0.05). The phyla Elusimicrobia, Euryarchaeota and Lentisphaerae were only detected on day 35 in fecal samples.
Fig. 2
Fig. 2

Phylum- and genus-level analysis of the 45 samples. a Overall fecal microbiota composition of samples at the phylum level on day 7. b Overall fecal microbiota composition of samples at the genus level on day 7. c Overall fecal microbiota composition of samples at the phylum level on day 21. d Overall fecal microbiota composition of samples at the genus level on day 21. e Overall fecal microbiota composition of samples at the phylum level on day 35. f Overall fecal microbiota composition of samples at the genus level on day 35

At genus level (Fig. 2b, d, and f) Lactobacillus, Enterococcus, Turicibacter and Bacteroides were the most abundant genera among the 45 samples. On day 7 Lactobacillus was present at 19.6%, 38.2% and 69.8% in C, U and F groups (P < 0.05), respectively; on day 21 Lactobacillus was present at 10.8%, 52.8% and 52.4% in C, U and F groups (P < 0.05), respectively; and on day 35 Lactobacillus was present at 19.2%, 28.4% and 56.6% in C, U and F groups (P < 0.05), respectively. This indicates that Lactobacillus was consistently higher in U and F groups than in the C group. On day 35, Enterococcus abundance was lower in the U and F groups than in the C group. The C group was dominated by Enterococcus at 54.4%. Turicibacter was higher on day 21 than on day 7 and 35 in the F group. The F group was dominated by Turicibacter on day 21 (33.5%). Bacteroides was highest in the U group on day 35 (17.8%), follow in the C group on day 21 and 35. other groups was lower.

Community composition heatmap and cluster analysis

As shown in Fig. 3, the top 50 most abundant genera were clustered and presented as a heatmap. Lactobacillus was the most abundant genus in all samples at all three time points, irrespective of supplementation with UA or FA. Moreover, its abundance was higher in the U and F groups than in the C group on days 7, 21 and had the highest abundance in F groups on days 7. The C and U groups had higher abundances of Oscillospira and Ruminococcus than the F group on day 7. Enterococcus was more abundant in group C than in groups U and F. Interestingly, Turicibacter was more abundant on day 21 in the C, U, and F groups, although its abundance was lower on days 7 and 35.
Fig. 3
Fig. 3

Heatmap of the top 50 most abundant genera summarized by group. The top 50 most abundant genera were clustered using R software. The genera with higher abundances in the corresponding samples are shown in red, while those with lower abundances are shown in green. Lactobacillus was the most abundant genus on day 7 in F group. Enterococcus were more abundant in group C than in groups U and F on day 35

In addition, the abundances of Allobaculum and Coprobacillus were higher in the C and U group on day 7, while the abundance of Coprococcus was higher only in the U group on day 7. Faecalibacterium had higher abundance in the U group on day 35. These results indicate that both unfermented and fermented dietary Astragalus alters the relative abundance of certain genera in the fecal microbiota of broiler chickens.

Discussion

It is becoming increasingly apparent that gut microbiota play an important role in maintaining host health (Yeoman et al. 2012). However, very few studies have assessed the interaction between fermented Astragalus and fecal microbiota of broiler chickens. The present study was designed to assess the potential of FA as a feed additive by evaluating its effects on growth performance, serum biochemical parameters, and fecal microbiota of broiler chickens. Astragalus is rich in polysaccharides, saponins, and flavonoids, which makes it amenable to fermentation by Aspergillus oryzae M29, which increases its bioactive substance content through bioconversion (Sheih et al. 2011). In this study we show that Astragalus fermentation with L. plantarum significantly increased the production of polysaccharides and organic acids. This may be due to degradation of cell wall cellulose by digestive enzymes, allowing the release of more polysaccharides and extracellular polysaccharides during the fermentation process (Timmerman et al. 2014).

Previous studies have reported that certain fermented herb additives, such as Ginkgo biloba leaves, red ginseng, and water-plantain improve growth performance and feed efficiency in livestock (Ao et al. 2011; Cao et al. 2012; Hossain and Yang 2014). In the present study, these parameters were evaluated in chickens fed diets supplemented with FA. We show significantly higher growth performance and lower F/G ratios relative to chickens fed UA or control diets. The reason for these improvements may be that fermentation improves the flavor and palatability of feed and increases the activity of digestive enzymes in the intestinal tracts of livestock (Czech et al. 2009). Such plant-based water-soluble polysaccharides could enhance intestinal function in a manner similar to prebiotics (Li et al. 2009).

During fermentation of Astragalus with L. plantarum, a large amount of organic acids are produced, including acetic acid, methylacetic acid, ethyl acetic acid and lactic acid. These organic acids could decrease the pH of fermented Astragalus (Qiao et al. 2018b), which may inhibit pathogenic bacteria and maintain the balance of the intestinal microbiota. Simultaneously, the results of this study suggest increased Astragalus polysaccharides yield using L. plantarum fermentation. This may promote gut microbial fermentation of herbal carbohydrates yielding short-chain fatty acids (n-butyrate, acetate, and propionate), which are either absorbed across the gut epithelium into the circulation or utilized by enterocytes and can have numerous host beneficial effects (Xu et al. 2017). The SCFA butyrate has been shown to improve growth performance (Panda et al. 2009).

Our results suggest that diets supplemented with FA positively affect serum biochemical parameters in broiler chickens. The antioxidant enzymes SOD, GSH-Px, and AOC play an important role in balancing redox status (Wu et al. 2015). In this study serum SOD, GSH-Px, and AOC were higher in broiler chickens fed FA, which is in agreement with a previous study demonstrating improved antioxidant status following addition of Astragalus powder to the feed of broiler chickens (Zhang et al. (2013). One possible explanation for this is that SOD and GSH-Px have antioxidant activity and protect cells from free radicals (Fridovich 1995); a second possibility is that lactic acid bacteria (LAB), which are widely used in fermentation, also have antioxidant properties (Liu and Pan 2010; Wang et al. 2009). In addition, we showed that the production of polysaccharides and flavonoids by Astragalus was increased by fermentation with LAB. Antioxidant properties may also be affected by polysaccharides, phenolics, and flavonoids (Wu et al. 2015). It has been reported that polysaccharides have antioxidant potential and can promote serum and hepatic antioxidant enzyme activity in chickens and rats (Deng and Hu 2011; Saleh et al. 2013; Sun and Wang. 2010; Yan et al. 2010).

We analyzed the fecal microbiota of broiler chickens fed with UA and FA. The alpha-diversity analyses showed that the three groups exhibited greater species richness and diversity on day 35 and U groups was highest, as indicated by the Chao 1 and ACE. Previous results suggest that the intestinal microbiota population of chickens becomes more diverse with aging (Shaufi et al. 2015), which is in agreement with our results. We report differences in beta-diversity between microbial communities of the C, U, and F groups on day 7. These results may be explained by the UA and FA feed additives, which had different pH values, contained the probiotic L. plantarum in FA, and microbial secondary metabolites that may have an effect on the fecal microbiota.

At the phylum-level, Firmicutes was the most dominant phylum, followed by Proteobacteria and Bacteroidetes, in all three groups on days 7, 21, and 35. In the F group on day 35, Firmicutes accounted for more than 90% of all bacterial sequences. These results are consistent with previous reports, where Firmicutes was the most dominant taxon in broiler chickens (Xu et al. 2016; Danzeisen et al. 2011; Qu et al. 2008; Yeoman et al. 2012). These results could be partially attributed to the effect of fermented Astragalus on some bacteria. It is believed that in the F group, fermented Astragalus played a role in the degradation of plant polysaccharides, promoted nutrient digestion and absorption, and maintained fecal microbial diversity. Future studies are needed to ascertain the underlying cause of these results.

At the genus-level, Lactobacillus had the highest abundance in F group on day 7 (Figs. 2, 3), which is in agreement with a previous report (Ding et al. 2017). However, the U and F groups had a higher proportion of Lactobacillus relative to controls (C group) across all three time points. Importantly, a potentially pathogenic genus Enterococcus (two species were common: E. faecalis and E. faecium) abundance was lower in the U and F groups than in the C group on day 35 (P < 0.05), which indicates that dietary supplementation with UA and FA effectively modulated the fecal microbiota in the later stage of broiler chickens. This may be the reason for later promotion of weight gain and antioxidant status in U and F groups relative to controls.

In this study, fermenting Astragalus resulted in an enrichment in polysaccharides, flavonoids, saponins and organic acids. The polysaccharide content may be influenced by intestinal microbiota and activate to generate enzymes resulting in higher abundance of Lactobacillus in chickens fed fermented Astragalus. Lactobacillus can complement other beneficial microbes to increase the efficiency of feed utilization in broiler chickens (Saito et al. 2003). Moreover, it is well documented that flavonoids maintain intestinal barrier integrity, modulate the secretion of gut hormones and shape microbiota composition and function (Oteiza et al. 2018). In addition, gut microbiota can hydrolyze absorbed saponins that may generate potential health benefits (Lim et al. 2015). Therefore, broiler chicken growth was improved in chickens receiving dietary fermented Astragalus due to an increase in available polysaccharides, flavonoids, saponins, and microbially-generated organic compounds.

Our results indicate that FA-supplemented diets improve growth performance and serum biochemical parameters in broiler chickens, and that both UA and FA modulate the fecal microbiota of broiler chickens. This is the first study to show that unfermented and fermented Astragalus affect fecal microbiota in broiler chickens. Recent studies have reported that gut microbiota can transform herbs into metabolites, which improve the composition of gut microbiota (Xu et al. 2017). Although the effects of herbs have been investigated on gut microbial populations of chickens and humans, the exact mechanisms remain unclear. We speculate that UA and FA alter fecal microbiota diversity because of their anti-inflammatory and antioxidative properties (Kim et al. 2013), which can adjust the immune balance and potentially reduce the need for antibiotics in chicken feed (Sanpha et al. 2013). Moreover, Astragalus is fermented by L. plantarum to produce large amounts of organic acids, such as lactic acid, methyl acetic acid, acetic acid, and ethyl acetic acid, which may be advantageous to the population of beneficial bacteria, while inhibiting the propagation of certain harmful bacteria, although further investigation is needed in this regard.

Despite their preliminary nature, our results indicate that the composition of fecal microbiota of broiler chickens fed UA and FA differed from that of broiler chickens fed a standard diet. This study provides a foundation for further studies on the interaction between microbiota and Astragalus.

Abbreviations

HMs: 

herbal medicines

FA: 

fermented Astragalus

SSF: 

solid state fermentation

CGMCC: 

China General Microbiological Culture Collection Center

MRS: 

de Man, Rogosa, and Sharpe

CFU: 

colony-forming units

BW: 

body weight

ADFI: 

average daily feed intake

ADG: 

average daily gain

F/G: 

feed to gain ratio

CAT: 

levels of serum catalase

GSH-Px: 

glutathione superoxide dismutase

MDA: 

malondialdehyde

SOD: 

superoxide dismutase

AOC: 

antioxidant capacity

RDP: 

Ribosomal Database Project

NGS: 

high-throughput, next-generation sequencing

OTUs: 

operational taxonomic units

PCR: 

polymerase chain reaction

PCoA: 

principal coordinate analysis

UA: 

unfermented Astragalus

ACE: 

abundance-based coverage estimator

LAB: 

lactic acid bacteria

Declarations

Authors’ contributions

Conceived and designed the experiment: HXQ, CZB. Performed the experiments: HXQ, YZS. Data analysis: HTS. Wrote the paper: HXQ. All authors read and approved the final manuscript.

Acknowledgements

Not applicable.

Competing interests

The authors declare no conflicts of interest.

Availability of data and materials

The data generated or analyzed during this study are included in this article.

Consent for publication

Not applicable.

Ethics approval and consent to participate

The protocols of the animal experiments were approved by the Laboratory Animal Management Committee of Henan University of Animal Husbandry and Economy and conducted in accordance with the Guidelines for the Care and Use of Experimental Animals.

Funding

This work was supported by the Henan Province Natural Science Planning Fund Projects [Grant no. 162300410128], by the Henan Province Science and Technology Open Cooperation Project [Grant no. 182106000042] and by the Veterinary Discipline Key Construction Project of Henan University of Animal Husbandry and Economy [Grant no. MXK2016102].

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Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

Authors’ Affiliations

(1)
College of Veterinary Medicine, Henan University of Animal Husbandry and Economy, Longzihu North road NO. 6, Zhengzhou, Henan, People’s Republic of China
(2)
Probiotics Bio-transformation Engineering Technology Research Center of Henan Province, Longzihu North road NO. 6, Zhengzhou, Henan, People’s Republic of China
(3)
Key Laboratory of Probiotics Fermentation Traditional Chinese Medicine of Zhengzhou city, Longzihu North road NO. 6, Zhengzhou, 450046, Henan, People’s Republic of China

References

  1. Ahmed ST, Mun HS, Islam MdM, Ko SY, Yang CJ (2016) Effects of dietary natural and fermented herb combination on growth performance, carcass traits and meat quality in grower-finisher pigs. Meat Sci 122:7–15View ArticleGoogle Scholar
  2. Ahmed A, Zulkifli I, Abdoreza FS, Norhani A, Liang JB (2017) Response of broiler chickens to dietary inclusion of fermented canola meal under heat stress condition. Ital J Anim Sci. 16(4):546–551View ArticleGoogle Scholar
  3. Ao X, Meng QW, Kim IH (2011) Effects of fermented red ginseng supplementation on growth performance, apparent nutrient digestibility, blood hematology and meat quality in finishing pigs. Asian-Australas J Anim Sci. 24(4):525–531View ArticleGoogle Scholar
  4. Bokulich NA, Subramanian S, Faith JJ, Gevers D, Gordon JI, Knight R, Mills DA, Caporaso JG (2013) Quality-filtering vastly improves diversity estimates from Illumina amplicon sequencing. Nat Methods 10(1):57–59View ArticleGoogle Scholar
  5. Cao FL, Zhang XH, Yu WW, Zhao LG, Wang T (2012) Effect of feeding fermented Ginkgo biloba leaves on growth performance meat quality, and lipid metabolism broilers. Poult Sci 91(5):1210–1221View ArticleGoogle Scholar
  6. Caporaso JG, Kuczynski J, Stombaugh J, Bittinger K, Bushman FD, Costello EK, Fierer N, Pena AG, Goodrich JK, Gordon JI, Huttley GA, Kelley ST, Knights D, Koenig JE, Ley RE, Lozupone CA, McDonald D, Muegge BD, Pirrung M, Reeder J, Sevinsky JR, Turnbaugh PJ, Walters WA, Widmann J, Yatsunenko T, Zaneveld J, Knight R (2010) QIIME allows analysis of high-throughput community sequencing data. Nat Methods 7(5):335–336View ArticleGoogle Scholar
  7. Czech E, Kowalczuk E, Grela R (2009) The effect of a herbal extract used in pig fattening on the animal’ performance and blood components. Ann UMCS. 27:25–33Google Scholar
  8. Danzeisen JK, Kim HB, Isaacson RE, Tu ZJ, Johnson TJ (2011) Modulation of the chicken cecal microbiome and metagenome in response to anticoccidial and growth promoter treatment. PLoS ONE 11:e27949View ArticleGoogle Scholar
  9. Deng ZH, Hu QL (2011) Effects of Astragalus membranaceus polysaccharides on oxidative damage in skeletal muscle of exhaustive rats. Afr J Agric Res. 6(17):4086–4090Google Scholar
  10. Ding JM, Dai RH, Yang LY, He C, Xu K, Liu SY, Zhao WJ, Xiao L, Luo LX, Zhang Y, Meng H (2017) Inheritance and establishment of gut microbiota in chickens. Front Microbiol. 10(8):1967View ArticleGoogle Scholar
  11. Fridovich I (1995) Superoxide radical and superoxide dismutases. Annu Rev Biochem 64:97–112View ArticleGoogle Scholar
  12. Hossain ME, Yang CJ (2014) Effect of fermented water plantain on growth performance, meat composition, oxidative stability, and fatty acid composition of broiler. Livest Sci. 162(4):168–177View ArticleGoogle Scholar
  13. Hu CH, Zuo AY, Wang DG, Pan HY, Zheng WB, Qiana ZC, Zou XT (2011) Effects of broccoli stems and leaves meal on production performance and egg quality of laying hens. Anim Feed Sci Tech. 170(1):117–121View ArticleGoogle Scholar
  14. Ibrahim LF, Marzouk MM, Hussein SR, Kauashty SA, Mahmoud K, Saleh NAM (2013) Flavonoid constitients and biological screening of Astragalus bombycinus Boiss. Nat Prod Res 27(4–5):386–393View ArticleGoogle Scholar
  15. Izumi T, Piskula MK, Osawa S, Obata A, Tobe K, Saito M, Kataoka S, Kubota Y, Kikuchi M (2000) Soy isoflvone aglycones are absorbed faster and in higher amounts than their glucosides in humans. J Nutr 130:1695–1699View ArticleGoogle Scholar
  16. Kallon S, Li X, Ji J, Chen C, Xi Q, Chang S, Xue C, Ma J, Xie Q, Zhang Y (2013) Astragalus polysaccharide enhances immunity and inhibits H9N2 avian influenza virus in vitro and in vivo. J Anim Sci Biotechnol. 4(1):22–37View ArticleGoogle Scholar
  17. Kim JH, Kim MH, Yang G, Huh Y, Kim SH, Yang WM (2013) Effects of topical application of Radix Astragaliceus on allergic dermatitis. Immunopharmacol Immunotoxicol 35:151–156View ArticleGoogle Scholar
  18. Li SP, Zhao XJ, Wang JY (2009) Synergy of Astragalus polysaccharides and probiotics (Lactobaciilus and Bacillus cereus) on immunity and intestinal microbiota in chicks. Poult Sci 88(3):519–525View ArticleGoogle Scholar
  19. Li SP, Wu DT, Lv GP, Zhao J (2013) Carbohydrates analysis in herbal glycomics. Trend Anal Chem. 52:155–169View ArticleGoogle Scholar
  20. Li Y, Lei X, Guo W, Wu S, Duan Y, Yang X, Yang X (2018) Transgenerational endotoxin tolerance-like effect caused by paternal dietary Astragalus polysaccharides in broilers’ jejunum. Int J Biol Macromol 111:769–779View ArticleGoogle Scholar
  21. Lim SM, Jeong JJ, Kang GD, Kim KA, Choi HS, Kim DH (2015) Timosaponin AIII and its metabolite sarsasapogenin ameliorate colitis in mice by inhibiting NF-kappaB and MAPK activation and restoring Th17/Treg cell balance. Int Immunopharmacol 25:493–503View ArticleGoogle Scholar
  22. Lin YW, Chiang BH (2008) Anti-tumor activity of the fermentation broth of Cordyceps militaris cultured in the medium of Radix astragali. Process Biochem 43(3):244–250View ArticleGoogle Scholar
  23. Liu CF, Pan TM (2010) In vitro effects of lactic acid bacteria on cancer cell viability and antioxidant activity. J Food Drug Anal. 18(2):77–86Google Scholar
  24. Lozupone CA, Knight R (2005) UniFrac: a new phylogenetic method for comparing microbial communities. Appl Environ Microbiol 71(12):8228–8235View ArticleGoogle Scholar
  25. Lozupone CA, Hamady M, Kelley ST, Knight R (2007) Quantitative and qualitative beta diversity measures lead to different insights into factors that structure microbial communities. Appl Environ Microbiol 73(5):1576–1585View ArticleGoogle Scholar
  26. Luciano RL, Perazella MA (2015) Aristolochi acid nephropathy: epidemiology, clinical presentation, and treatment. Drug Saf 38(1):55–64View ArticleGoogle Scholar
  27. Lv YW, Hu W, Wang YL, Huang LF, He YB, Xie XZ (2011) Identification and determination of flavonoida in astragali radix by high performance liquid chromatography coupled with DAD and ESI-MS detection. Molecules 16(3):2293–2303View ArticleGoogle Scholar
  28. Lyu M, Wang YF, Fan GW, Wang XY, Xu SY, Zhu Y (2017) Balancing herbal medicine and functional food for prevention and treatment of cardiometabolic diseases through modulationg gut microbiota. Front Microbiol. 8:2146View ArticleGoogle Scholar
  29. Ng CC, Wang CY, Wang YP, Tzeng WS, Shyu YT (2011) Lactic acid bacterial fermentation on the production of functional antioxidant herbal Anoectochilus formosanus Hayata. J Biosci Bioeng 111(3):289–293View ArticleGoogle Scholar
  30. Oteiza PI, Fraga CG, Mills DA, Taft DH (2018) Flavonoids and the gastrointestinal tract: local and systemic effects. Mol Aspects Med 61:41–49View ArticleGoogle Scholar
  31. Panda AK, Rama RS, Raju M, Shyam SG (2009) Effect of butyric acid on performance, gastrointestinal tract health and carcass characteristics in broiler chickens. Asian Australas J Anim. 22:1026–1031View ArticleGoogle Scholar
  32. Qiao HX, Shi HT, Zhang Z, Jiang YL, Bian CZ (2017) Characteristics of Bacillus subtilis HNMY-13 and HNMY-15 strains in aflatoxin B1 degradation and Astragalus bio-transformation. Afr J Biotechnol. 16(38):1882–1888View ArticleGoogle Scholar
  33. Qiao HX, Zhang LH, Shi HT, Song YZ, Bian CZ (2018a) Astragalus Affects Fecal Microbial Composition of Young Hens as Determined by 16S rRNA Sequencing. AMB Express. 8:70View ArticleGoogle Scholar
  34. Qiao HX, Zhang XJ, Shi HT, Song YZ, Bian CZ, Guo AZ (2018b) Assessment of the physicochemical properties and bacterial composition of Lactobacillus plantarum and Enterococcus faecium-fermented Astragalus membranaceus using single molecule, real-time sequencing technology. Sci Rep. 8:11862View ArticleGoogle Scholar
  35. Qu A, Brulc JM, Wilson MK, Law BF, Theoret JR, Joens LA, Konkel ME, Angly F, Dinsdale EA, Edwards RA, Nelson KE, White BA (2008) Comparative metagenomics reveals host specific metavirulomes and horizontal gene transfer element in the chicken cecum microbiome. PLoS ONE 8:e2945View ArticleGoogle Scholar
  36. Saito K, Kawamura Y, Oda Y (2003) Role of the pectinolytic enzyme in the lactic acid fermentation of potato pulp by Rhizopus oryzae. J Ind Mcicrobiol Biotechnol. 30:440–444View ArticleGoogle Scholar
  37. Saleh AA, Hayashi K, Ohtsuka A (2013) Synergistic effect of feeding Aspergillus Awamori and Saccharomyces Cerevisiae on growth performance in broiler chickens; promotion of protein metabolism and modification of fatty acid profile int the muscle. J Poult Sci. 50(3):242–250View ArticleGoogle Scholar
  38. Sanpha K, Li XY, Ji J, Chen CY, Xi QY, Chang S, Xue C, Ma J, Xie Q, Zhang Y (2013) Astragalus polysaccharide enhances immunity and inhibits H9N2 avian influenza virus in vitro and in vivo. J Anim Sci Biotechnol. 4:22–33View ArticleGoogle Scholar
  39. Shaufi MAM, Sieo CC, Chong CW, Gan HM, Ho YW (2015) Deciphering chicken gut microbial dyamics based on high-throughput 16S rRNA metagenomics analyses. Gut Pathog. 7:4View ArticleGoogle Scholar
  40. Sheih IC, Fang TJ, Wu TK, Chang CH, Chen RY (2011) Purification and properties of a novel phenolic antioxidant from Radix astragali fermented by Aspergillus oryzae M29. J Agric Food Chem 59(12):6520–6525View ArticleGoogle Scholar
  41. Sugiharto S (2014) Role of nutraceuticals in gut health and growth performance of poultry. J Saudi Soc Agric Sci. 15(2):99–111Google Scholar
  42. Sun H, Wang ZB (2010) Effects on exercise endurance capacity and antioxidant properties of Astragalus membranaceus polysaccharides (APS). J Med Plants Res. 4(10):982–986Google Scholar
  43. Suresh G, Das RK, Kaur BS, Rouissi T, Avalos RA, Chorfi Y, Godbout S (2018) Alternatives to antibiotics in poultry feed:molecular perspectives. Crit Rev Microbiol. 44(3):318–335View ArticleGoogle Scholar
  44. Timmerman HM, Koning C, Mulder JML, Rombouts FM, Beynen AC (2014) Monostrain, multistrain and multispecies probiotics–a comparison of functionality and efficacy. Int J Food Microbiol 96(3):219–233View ArticleGoogle Scholar
  45. Vrize A, Holleman F, Zoetenal EG, de Vos WM, Hoekstra JB, Nieuwdorp M (2010) The environment within: how gut microbiota may influence metabolism and body composition. Diabetologia 53(4):606–613View ArticleGoogle Scholar
  46. Wang CY, Ng CC, Shyu YT (2009) Probiotic potential of noni juice fermented with lactic acid bacteria and bifidobacteria. Int J Food Sci Nutr 60(6):98–106View ArticleGoogle Scholar
  47. Wang JH, Bose S, Kim GC, Hong SU, Kim JH, Kim JE (2014a) Flos lonicera ameliorates obesity and associated endotoxemia in rats through modulation of gut permeabilty and intestinal microbiota. PLoS ONE 1:e86117View ArticleGoogle Scholar
  48. Wang XF, Shen J, Li ZS, Zhi LH, Yang XJ, Yao JH (2014b) Sulfated Astragalus polysaccharide regulates the inflammatory reaction in LPS-infected broiler chicks. Int J Biol Macromol 69:146–150View ArticleGoogle Scholar
  49. Wang JH, Bose S, Kim HG, Han KS, Kim HJ (2015) Fermented Rhizoma Atractylodis Macrocephalae alleviates high fat diet-induced obestiy in association with regulation of intestinal permeability and microbiota in rats. Sci Rep. 5:8391View ArticleGoogle Scholar
  50. Wu QJ, Wang ZB, Wang GY, Li YX, Qi YX (2015) Effects of feed supplemented with fermented pine needles (Pinus ponderosa) on growth performance and antioxidant status in broilers. Poult Sci 94(6):1138–1144View ArticleGoogle Scholar
  51. Xiao HB, Krucker M, Albert K (1032) Liang XM (2004) Determination and identification of isoflavonoids in Radic astragali by matrix solidphase dispersion extraction and high-performance liquid chromatography with photodiode array and mass spectrometric detection. J Chromatogr A 1–2:117–124Google Scholar
  52. Xu YH, Yang HX, Zhang LL, Su YH, Shi DH, Xiao HD, Tian Y (2016) High-throughput sequencing technology to reveal the composition and function of cecal microbiota in Dagu chicken. BMC Microbiol 16(1):259–268View ArticleGoogle Scholar
  53. Xu J, Chen HB, Li SL (2017) Understanding the molecular mechanisms of the interplay between Herbal medicine and gut microbiota. Med Res Rev 37(5):1140–1185View ArticleGoogle Scholar
  54. Yan N, Xie YP, Sun SG, Sun XD, Ren FX, Shi QR, Wang SH, Zhang WD, Li XM, Zhang J (2010) Chemical analysis of Astragalus mongholicus polysaccharides and antioxidant activity of the polysaccharides. Carbohydr Polym 82(3):636–640View ArticleGoogle Scholar
  55. Yeoman CJ, Chia N, Jeraldo P, Sipos M, Goldenfeld ND, White BA (2012) The microbiome of the chicken gastrointestinal tract. Anim Health Res Rev. 13(1):89–99View ArticleGoogle Scholar
  56. Yitbarek A, Echeverry H, Munyaka P, Rodriguez-Lecompte JC (2015) Innate immune response of pullets fed diets supplemented with prebiotics and synbiotics. Poult Sci 94(8):1802–1811View ArticleGoogle Scholar
  57. Yu WW, Zhang XH, Ahmad H, Zhao LG, Wang T, Cao FL (2015) Intestinal absorption function of broiler chicks supplemented with Ginkgo leaves fermented with Bacillus species. Pakistan J Zool. 47(2):479–490Google Scholar
  58. Zhang GG, Yang ZB, Wang Y, Yang WR (2013) Effects of Astragalus membranaceus root processed to different particle sizes on growth performance, antioxidant status, and serum metabolites of broiler chickens. Poult Sci 92(1):178–183View ArticleGoogle Scholar
  59. Zhang XH, Sun ZY, Cao FL, Ahmad H, Yang X, Zhao LG, Wang T (2015) Effects of dietary supplementation with fermented Ginkgo biloba-leaves on antioxidant capacity, intestinal morphology and microbial ecology in broiler chickens. Br Poult Sci. 56(3):370–380View ArticleGoogle Scholar
  60. Zhang P, Wang J, Wang W, Liu X, Liu H, Li X, Wu X (2017) Astragalus polysaccharides enhance the immune response to avian infectious bronchitis virus vaccination in chickens. Microb Pathog 111:81–85View ArticleGoogle Scholar
  61. Zhang P, Liu X, Liu H, Wang W, Liu X, Wu X (2018) Astragalus polysaccharides inhibit avian infectious bronchitis virus infection by regulating viral replication. Microb Pathog 114:124–128View ArticleGoogle Scholar
  62. Zhou H, Wang CZ, Ye JZ, Chen HX, Tao R, Zhang YS (2015) Solid-state fermentation of Ginkgo biloba L. residue for optimal production of cellulase, protease and the simultaneous detoxification of Ginkgo biloba L. residue using Candida tropicalis and Aspergillus oryzae. Eur Food Res Technol 240(2):379–388View ArticleGoogle Scholar

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