Exploring the Role of Edible Dock Powder (Rumex K-1) in Enhancing Growth Performance, Organ Health, and Cecal Microbiota in Sanhua Goslings

Abstract

This study investigated the effects of dietary Edible Dock Powder (EDP) on growth performance, organ development, serum biochemistry, and cecal microbiota in Sanhua goslings. A total of 240 goslings were randomly allocated into four groups: one control group (Group A) and three experimental groups supplemented with EDP at concentrations of 1.00% (Group B), 2.50% (Group C), and 4.00% (Group D). Group B showed a significantly decreased feed-to-gain ratio (F/G) compared to the control group (p < 0.05). Organ analysis indicated an increase in liver and glandular stomach weights in Groups B and C (p < 0.05). Serum aspartate transaminase (AST) levels were significantly decreased in the EDP groups (p < 0.05), and glucose (GLU) levels were notably lower in Groups C and D compared to the control group (p < 0.05). Cecal microbiota analysis revealed that Group B was enriched in Prevotella and Streptococcaceae, while Cyanobacteria and Alistipes were higher in Group C. Additionally, Desulfovibrio was positively correlated with glandular stomach weight, and Oxalobacter with ADG (p < 0.05). These findings suggest that 1.00–2.50% EDP supplementation supports growth, enhances liver and gut health, and optimizes microbiota composition, providing a viable functional feed strategy for goslings.

1. Introduction

In recent years, global demands for food safety and environmental sustainability have increased. Developing efficient and eco-friendly feed additives has emerged as a key research focus in waterfowl production. Natural plant-based feed additives have garnered attention due to their rich nutritional profiles and diverse health benefits [1,2,3].

Edible Dock (Rumex patientia L. × Rumex tianschanicus cv. Rumex K-1) is a perennial herbaceous plant from the Polygonaceae family, widely distributed across Europe, North America, and Asia, and valued for its high adaptability and ecological flexibility [4]. Unlike many other plant-based feed additives, Edible Dock is notably rich in high-quality protein and amino acids, as well as polyphenols and flavonoids like quercetin and kaempferol, along with dietary fiber and essential minerals. These components give Edible Dock significant antioxidant, antibacterial, and anti-inflammatory properties, making it a promising natural feed additive for poultry [5]. Additionally, its high fiber content serves as a crucial substrate for cecal microbiota, supporting the growth of beneficial microbial communities and promoting gut health [6]. Recent studies have shown that Edible Dock leaf powder supplementation can enhance growth performance, boost antioxidant enzyme activity, and encourage a beneficial cecal microbiota composition in broilers [7]. Another study demonstrated that dietary supplementation of Rumex nepalensis leaf powder increased production performance and improved immune antioxidant status in broiler chickens [8]. This unique combination of protein-rich nutrition and broad health benefits positions Edible Dock as a sustainable and effective feed additive for poultry.

Sanhua Goose, a herbivorous poultry breed widely reared in southern China, is highly regarded by farmers for its excellent growth performance and adaptability [9]. The juvenile stage of Sanhua goslings is crucial for determining their future growth potential and health status, making it imperative to optimize their growth and health through scientifically managed nutrition during this period. Herbivorous poultry have a digestive system particularly adapted to plant-based diets, efficiently utilizing cellulose and other complex carbohydrates, which positions Edible Dock Powder as a uniquely advantageous supplement in Sanhua goose nutrition [10]. The cecum, a crucial part of the digestive system, contains a rich microbial population that is vital for cellulose breakdown, short-chain fatty acid production, and nutrient absorption [11]. Thus, incorporating Edible Dock Powder, which is rich in functional components, into the diets of Sanhua goslings may help regulate the cecal microbiota’s structure and function, leading to improved growth performance and overall health.

Although research on Edible Dock has been increasing, its practical application in waterfowl nutrition remains relatively limited. Therefore, this research seeks to thoroughly evaluate the effects of Edible Dock Powder on growth performance, organ health, serum biochemistry, and cecal microbiota in Sanhua goslings. We hypothesize that the appropriate inclusion of Edible Dock Powder will optimize the cecal microbiota, thereby significantly improving the growth performance and health status of the goslings. This research will offer new scientific insights into the use of plant-based feed additives in herbivorous poultry production and supply theoretical support for enhancing nutrition strategies for Sanhua goslings.

2. Research Methods and Materials

2.1. Animal Ethics Guidelines

The animal study was conducted following approval from the Animal Care and Use Committee of the Shanghai Academy of Agricultural Sciences (Approval No. SAASPZ0522050). The experimental procedures adhered to the ‘Guidelines for Welfare of Experimental Animals’ (GB/T 42011-2022) [12]. All necessary measures were taken to ensure the geese experienced minimal distress during this study.

2.2. Goslings and Housing

A total of 240 three-day-old Sanhua goslings were selected for this study. The goslings were housed in raised enclosures positioned 50–60 cm above the ground. Each enclosure was 2.5 m long, 1.5 m wide, and 1 m high, equipped with plastic mesh mats featuring 1 cm × 1 cm openings to prevent the goslings’ feet from becoming trapped. Each enclosure was equipped with feeders and waterers, providing the goslings with unrestricted access to food and water. A heat lamp was centrally installed in each enclosure for localized heating, while the overall barn temperature was regulated using a warm-air heater. In the first week, the barn’s ambient temperature was kept at around 20 °C, with the temperature directly under the heat lamp at 30 °C. As the study progressed, the barn temperature was gradually reduced to 15 °C, with the temperature under the heat lamp decreasing to 21 °C. Humidity levels were controlled between 60% and 65% to create an optimal environment for gosling growth. The light program was also carefully managed throughout the 28-day experimental period. From 1 to 7 days of age, goslings were exposed to 23 h of light and 1 h of darkness daily, with a light intensity of 25 lux. From 8 to 28 days, the light duration was reduced to 16 h daily, with an intensity of 15 lux. This light program was designed to optimize feed intake during the early phase and simulate natural conditions during the later phase, promoting healthy growth and development.

The amounts of Edible Dock Powder (EDP), premix, and feed ingredients were precisely calculated based on the experimental design. EDP was provided by Shanxi Sinuote Biotechnology Co., Ltd. (Xi’an, China). It was first thoroughly mixed with the premix in the specified proportions and then combined with the feed ingredients in a mechanical feed mixer (Model YS-B20101401, Weifang Youshun Environmental Technology Co., Ltd., Qingzhou, China) to ensure homogeneity. To maintain experimental reproducibility and data reliability, all feeds were freshly prepared on a weekly basis according to the experimental requirements.

The experiment was conducted in the brooding house at the Zhuanghang Base of the Shanghai Academy of Agricultural Sciences, over a period of four weeks. All vaccination protocols and health assessments were conducted in accordance with the relevant standards of the facility.

2.3. Experiment Design and Management

For this experiment, 240 Sanhua goslings were sourced from Xiangtian Ge Family Farm, (Ma’anshan, China) Anhui Province. Before the experiment started, all goslings were weighed and randomly divided into four treatment groups, each containing six replicates with 10 geese per replicate. The dietary treatments were defined as follows: Group A (control) was fed a diet without EDP supplementation, Group B was provided with a diet containing 1.00% EDP, Group C was provided with a diet containing 2.50% EDP, and Group D was provided with a diet containing 4.00% EDP. The diet formulations for each group were carefully designed based on the nutritional standards for commercial meat geese as recommended by DB37/T 2784-2016 [13], taking into account the specific nutritional properties of EDP.

2.4. Determination of Nutritional Composition

The crude protein (CP) content was measured following the methods established by the AOAC, 2005 [14]. Metabolizable energy (ME) was determined as the as-received lower heating value (LHV) using an oxygen bomb calorimeter (U-THERM, YXZR9302, Changsha, China) following Miller and Judd [15]. Oven-dried samples (105 °C) were ground, combusted (1.0 g, 2.5–3.0 MPa oxygen), and tested in triplicate. Results were reported as mean ± standard deviation. The crude fiber (CF) content was analyzed following the AOAC (2000) procedures [16], while the crude fat (EE) content was assessed in accordance with AOAC (1930) guidelines [17]. Calcium (Ca) levels were analyzed using the procedure detailed in AOAC (1985a) [18], and phosphorus (P) levels were determined following the method described in AOAC (1985b) [19]. The amino acid profile of the Edible Dock Powder (EDP) was determined by Engel Testing Services (Shanghai) Co., Ltd. (Shanghai, China), using methods specified by the Chinese National Standard (GB/T 18246-2019) [20]. The diet composition and nutritional values for each treatment group are provided in

Table 1. Ingredients and nutrient compositions of experimental diets (air-dry basis).

Ingredient, %	Diet Treatment
	A	B	C	D
Corn	55.58	56.45	55.78	55.25
Soybean (43% protein)	27.17	26.84	25.53	24.59
Husks	0.68	0.46	0.13	0.00
Edible Dock Powder (EDP)	0.00	1.00	2.50	4.00
Sprouting Corn Bran	9.26	7.93	9.00	9.00
Limestone	1.00	1.00	1.00	0.10
Dicalcium Phosphate	1.72	1.73	1.74	1.77
Premix 2	3.00	3.00	3.00	3.00
Soybean Oil	1.24	1.24	1.25	1.24
Salt	0.35	0.35	0.35	0.35
Nutritional Level 1
Metabolizable Energy, MJ/kg	11.71	11.71	11.71	11.71
Crude Protein, %	18.00	18.00	18.00	18.00
Crude Fiber, %	3.30	3.30	3.30	3.30
Ether Extract, %	3.79	3.79	3.79	3.81
Lysine, %	1.01	1.00	0.99	0.99
Methionine + Cystine, %	0.69	0.69	0.68	0.67
Arginine, %	1.15	1.15	1.14	1.16
Tryptophan, %	0.24	0.23	0.22	0.21
Threonine, %	0.89	0.87	0.84	0.79
Valine, %	0.70	0.70	0.70	0.71
Calcium, %	1.00	1.00	1.00	1.00
Non-Phytate Phosphorus, %	0.45	0.45	0.45	0.45

¹ Calculated nutrient concentration: Dietary nutrient composition is calculated values. ² The premix provides per kilogram of feed: Vitamin A 7500 IU, Vitamin B1 1.0 mg, Vitamin B2 6 mg, Pantothenic acid 9.2 mg, Vitamin B6 1.8 mg, Vitamin B12 0.10 mg, Vitamin D3 1600 IU, Vitamin E 13.5 IU, Vitamin K3 2 mg, Biotin 0.1 mg, Folic Acid 0.4 mg, Niacin 60 mg, Choline 1400 mg, Copper 6 mg, Iron 80 mg, Manganese 100 mg, Zinc 80 mg, Iodine 0.42 mg, Selenium 0.3 mg, Calcium 3 g, and Phosphorus 0.99 g.

, while the nutrient profile of EDP is presented in

Table 2. Nutrient composition of EDP.

Nutritional Level 1	Nutrients
Crude Protein, %	28.59 ± 1.23
Calorific Value, MJ/kg	14.54 ± 0.09
Ca, %	1.25 ± 0.17
P, %	0.50 ± 0.06
Ether Extract, %	0.50 ± 0.01
Crude Fiber, %	17.86 ± 1.31
Lysine, %	1.30 ± 0.43
Methionine + Cystine, %	0.52 ± 0.17
Arginine, %	1.31 ± 0.30
Threonine, %	1.15 ± 0.13
Valine, %	1.48 ± 0.25

¹ The components of EDP are analytical values. Each sample was analyzed in triplicate (n = 3), and the results are presented as mean ± standard deviation (SD).

.

2.5. Growth Performance Evaluation

At the start of the experiment, each Sanhua gosling was weighed after a 12 h fast to measure the initial body weight (IBW). The same procedure was repeated in the 4th week of the experiment to record the FBW of each gosling at the end of the brooding period. The data were utilized to calculate the ADG for each gosling. Throughout the experiment, feed intake for each replicate was carefully tracked to calculate the ADFI and F/G. Additionally, the mortality and culling rate for each replicate were monitored and recorded throughout the experiment.

The formulas used to evaluate growth performance are as follows:

ADG = (FBW − IBW)/Duration of the Experiment (days)

F/G = Total Feed Intake/Total Weight Gain

ADFI = F/G × ADG

Mortality and Culling Rate = (Number of Mortalities and Cullings in Each Replicate/Total Number of Individuals in Each Replicate) × 100%

2.6. Relative Organ Weight Measurement

During the 4th week of the experiment, two goslings with comparable body weights were chosen from each replicate group, with six replicates per treatment group, resulting in a total of 12 goslings sampled per treatment group. These selected goslings underwent a 12 h fasting period. Anesthesia was administered through the wing vein using 30 mg/kg of sodium pentobarbital. Once full anesthesia was achieved, a professional slaughterer performed exsanguination by severing the carotid artery. After confirming the absence of vital signs, samples were collected. Post-slaughter, the heart, liver, spleen, proventriculus, thymus, duodenum, jejunum, and ileum were meticulously separated and weighed. Prior to weighing, the entire intestinal tract was flushed with physiological saline to remove any internal contents.

The formula for determining relative organ weight is as follows:

Relative Organ Weight = (Organ Weight/Body Weight) × 100%

2.7. Blood Biochemical Analysis

During the exsanguination process performed by professional slaughter personnel via the carotid artery, a pro-coagulation blood collection tube was used to collect 5 mL of blood from each gosling. After the blood was left undisturbed for 1 h, the serum was separated by centrifuging at 4000 rpm for 8 min. The collected serum was used for biochemical analysis and sent to Shanghai Pinyi Biotechnology Co., Ltd. (Shanghai, China) for further testing. The biochemical parameters assessed included alanine aminotransferase (ALT), aspartate aminotransferase (AST), total protein (TP), albumin (ALB), globulin (GLB), blood urea nitrogen (BUN), glucose (GLU), total cholesterol (CHOL), total triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C). All biochemical parameters were analyzed using an automated biochemical analyzer (HITACHI 7180, HITACHI, Tokyo, Japan) according to the manufacturer’s guidelines.

2.8. Cecal Content 16S rRNA Sequencing

During the slaughter process, cecal contents were collected from each gosling and immediately placed into cryogenic tubes, which were preserved in liquid nitrogen to ensure sample integrity. The samples were then sent to Suzhou PANOMICS Biomedical Technology Co., Ltd. (Suzhou, China) for 16S rRNA sequencing. Microbial DNA was extracted from the cecal contents using the Tianamp Stool DNA Kit (Tiangen Biotech Co., Ltd., Beijing, China) according to the manufacturer’s instructions. After quality assessment, the DNA underwent PCR amplification using primers specific to the V3-V4 region of the 16S rRNA gene (F: ACTCCTACGGGAGGCAGCA; R: GGACTACHVGGGTWTCTAAT). The amplified products were then purified, quantified, and sequenced using the Illumina high-throughput sequencing platform. The obtained sequence data were subjected to bioinformatics analysis, including sequence assembly, quality control, denoising, and operational taxonomic unit (OTU) classification. Finally, these analyses were used to assess the diversity, composition, and relative abundance of the cecal microbial communities in the goslings.

3. Statistic and Analysis

The data collected from the experiment were initially processed using Microsoft Excel 2007, followed by further statistical analysis with SPSS 19.0. A one-way analysis of variance (ANOVA) was performed to evaluate the effects of different levels of EDP supplementation on the measured parameters. Descriptive statistics were performed for each treatment group, calculating the mean and SEM, and data normality was assessed using the Shapiro–Wilk test, while variance homogeneity was confirmed with the Levene test. If ANOVA revealed significant differences among groups (p < 0.05), Duncan’s multiple range test was applied for post hoc analysis to identify specific group differences. Results were reported as mean ± SEM, and a p value below 0.05 was regarded as statistically significant. Data analysis was performed using the following model:

$${\mathrm{Y}}_{\mathrm{i}\mathrm{j}}=\mathsf{\mu }+{\alpha }_{\mathrm{j}}+{ϵ}_{\mathrm{i}\mathrm{j}}.$$

where

${\mathrm{Y}}_{\mathrm{i}\mathrm{j}}$ = dependent variable,

$\mathsf{\mu }$ = overall mean,

${\alpha }_{\mathrm{j}}$ = fixed effect of the jth factor,

${ϵ}_{\mathrm{i}\mathrm{j}}$ = residual value due to random error.

4. Results

4.1. Growth Performance

The growth performance results are presented in

Table 3. Effects of dietary supplementation with EDP on the growth performance of Sanhua goslings.

Item	Diet Treatment				SEM	p-Value
	A	B	C	D
IBW, g	198.94 ± 4.85	198.17 ± 3.14	201.58 ± 3.29	202.61 ± 2.69	1.81	0.800
FBW, g	1366.25 ± 31.91	1452.30 ± 28.10	1417.20 ± 26.43	1381.56 ± 29.49	14.71	0.163
ADG, g	55.58 ± 1.40	60.33 ± 1.28	58.03 ± 1.24	56.29 ± 1.35	0.67	0.062
F/G	1.84 ± 0.02 a	1.68 ± 0.05 b	1.75 ± 0.05 ab	1.69 ± 0.03 b	0.02	0.042
ADFI, g	101.41 ± 99.03	99.03 ± 2.62	99.54 ± 2.53	94.16 ± 2.63	1.30	0.223
Mortality and Culling Rate, %	18.83 ± 4.22	5.81 ± 2.83	11.99 ± 5.60	12.75 ± 3.64	1.91	0.207

Notes: IBW: initial body weight, FBW: final body weight, ADG: average daily weight gain, ADFI: average daily feed intake, F/G: feed-to-gain ratio; ^a,b means with different superscript letters in the same row differ significantly (p < 0.05).

. There were no significant differences in IBW among the treatment groups (p > 0.05), indicating that the baseline conditions were consistent with the experimental design. The F/G ratio in Groups B and D were significantly lower compared to the control group (p < 0.05). Although no statistically significant differences in mortality and culling rates were observed among the treatment groups (p = 0.207), Groups B, C, and D exhibited a decreasing trend, with reductions of 13.02%, 6.84%, and 6.08%, respectively, compared to the control group.

4.2. Relative Organ Weight

The results for relative organ weights are presented in

Table 4. Effects of dietary supplementation with EDP on the relative organ weight of Sanhua goslings.

Items	Diet Treatment				SEM	p-Value
	A	B	C	D
Heart yield, %	0.70 ± 0.03	0.75 ± 0.01	0.71 ± 0.02	0.74 ± 0.02	0.01	0.363
Liver yield, %	3.18 ± 0.10 b	4.13 ± 0.26 a	3.72 ± 0.11 ab	3.57 ± 0.22 ab	0.11	0.011
Spleen yield, %	0.15 ± 0.01	0.17 ± 0.01	0.15 ± 0.02	0.14 ± 0.01	0.00	0.606
Glandular stomach yield, %	0.58 ± 0.02 b	0.63 ± 0.02 ab	0.69 ± 0.02 a	0.66 ± 0.03 a	0.04	0.029
Thymus yield, %	0.18 ± 0.02	0.22 ± 0.03	0.29 ± 0.04	0.26 ± 0.03	0.01	0.108
Duodenum yield, %	1.58 ± 0.10	1.61 ± 0.07	1.69 ± 0.11	1.55 ± 0.07	0.04	0.75
Jejunum yield, %	2.12 ± 0.22	2.11 ± 0.41	2.59 ± 0.11	2.26 ± 0.17	0.12	0.519
Ileum yield, %	1.94 ± 0.16	2.19 ± 0.12	2.35 ± 0.14	2.25 ± 0.21	0.08	0.341

^a,b Means with different superscript letters in the same row differ significantly (p < 0.05).

. Group B exhibited a significantly higher relative liver weight compared to the control group (p < 0.05), while Groups C and D showed significantly higher relative glandular stomach weights (p < 0.05). There were no significant differences in the other parameters (p > 0.05).

4.3. Serum Biochemical Parameters

The serum biochemical parameters are summarized in

Table 5. Effects of dietary supplementation with EDP on the blood biochemical of Sanhua goslings.

Items	Diet Treatment				SEM	p-Value
	A	B	C	D
ALT, U/L	12.17 ± 2.00	13.00 ± 1.98	10.83 ± 0.95	10.33 ± 0.84	0.75	0.608
AST, U/L	29.17 ± 4.47 a	17.17 ± 1.73 b	21.17 ± 1.42 b	18.00 ± 1.75 b	1.57	0.021
TP, g/L	41.67 ± 1.48	43.45 ± 1.03	40.40 ± 1.66	43.20 ± 1.00	0.67	0.350
ALB, g/L	15.27 ± 0.94	15.67 ± 0.74	14.27 ± 1.55	15.25 ± 0.69	0.23	0.151
GLB, g/L	26.40 ± 1.12	27.78 ± 0.78	26.13 ± 1.07	27.95 ± 0.72	0.47	0.418
BUN, mmol/L	0.28 ± 0.11	0.23 ± 0.06	0.18 ± 0.04	0.35 ± 0.08	0.04	0.477
GLU, mmol/L	10.87 ± 0.49 a	9.62 ± 0.17 ab	9.23 ± 0.61 b	9.23 ± 0.41 b	0.25	0.050
CHOL, mmol/L	4.55 ± 0.34	4.56 ± 0.21	4.09 ± 0.35	4.56 ± 0.25	0.14	0.599
TG, mmol/L	2.13 ± 0.19	1.69 ± 0.18	2.15 ± 0.41	1.84 ± 0.35	0.15	0.650
HDL-c, mmol/L	2.35 ± 0.18	2.41 ± 0.17	2.10 ± 0.18	2.39 ± 0.13	0.08	0.512
LDL-c, mmol/L	0.85 ± 0.05	0.80 ± 0.04	0.85 ± 0.07	0.79 ± 0.09	0.03	0.862

Notes: ALT: alanine transaminase; AST: aspartate transaminase; TP: total protein; ALB: albumin; GLB: globulin; BUN: blood urea nitrogen; GLU: glucose; CHOL: total cholesterol; TG: total triglycerides; HDL-c: high-density lipoprotein cholesterol; LDL-c: low-density lipoprotein cholesterol; ^a,b means with different superscript letters in the same row differ significantly (p < 0.05).

. AST levels were significantly lower in Groups B, C, and D compared to the control group (p < 0.05). However, no significant differences were observed among the groups for ALT, TP, ALB, GLB, BUN, CHOL, TG, HDL-c, and LDL-c levels (p > 0.05). Furthermore, GLU levels in Groups C and D were significantly reduced compared to the control group (p < 0.05).

4.4. Cecal Microbial Community Structure and Diversity

The results of cecal microbial community structure and diversity are shown in Figure 1. Both Principal Coordinates Analysis (PCoA) and non-metric multidimensional scaling (NMDS) demonstrated significant differences in the cecal microbial community structures among the treatment groups (Figure 1A,B). The PCoA analysis demonstrated a clear separation of the microbial community in Group A from those in Groups B, C, and D, suggesting notable intergroup differences (p < 0.05). The NMDS analysis further supported this finding, revealing a clear separation between Group A and the other groups. The Venn diagram analysis showed that Groups A, B, C, and D had 4570, 4513, 3817, and 3417 unique OTUs, respectively, with only 109 OTUs shared among all four groups (Figure 1C). These results indicate that while there are some common microbial species across the groups, each treatment group also harbored a large number of unique microbial communities. The alpha diversity results (Figure 1D) showed that the Chao1 index and observed species counts in Groups A and B were significantly lower than in Group D (p < 0.05), while the Simpson and Shannon indices showed no significant differences across the groups (p > 0.05).

4.5. Abundance and Taxonomic Structure of Cecal Microbial Communities

Figure 2 displays the composition and relative proportions of the cecal microbial communities. The cecal microbial composition at the phylum level was similar across all treatment groups, with the top ten phyla being Bacteroidetes, Firmicutes, Proteobacteria, Verrucomicrobia, Actinobacteria, Deferribacteres, Tenericutes, Elusimicrobia, Lentisphaerae, and Cyanobacteria (Figure 2A). At the genus level, the cecal microbiota composition was also similar across the groups, with the top 20 genera being Bacteroides, Desulfovibrio, Faecalibacterium, Barnesiella, Streptococcus, Helicobacter, Oscillospira, Odoribacter, Phascolarctobacterium, [Ruminococcus], YRC22, Prevotella, Parabacteroides, Akkermansia, Subdoligranulum, Ruminococcus, Rikenella, Megamonas, Alistipes, and Mucispirillum (Figure 2B). To better assess the variations in species composition between samples, visualize species abundance trends, and identify key marker species across groups, LEfSe cladograms were created (Figure 3). In Group A, the significantly enriched phylum was Deferribacteres, with the genus Mucispirillum being prominently enriched. In Group B, the significantly enriched genera and taxa were Prevotella and Streptococcaceae. In Group C, the enriched taxa included Desulfovibrio, Dehalobacterium, and Enterococcus. In Group D, the significantly enriched phylum was Cyanobacteria, with the genus Alistipes being notably enriched.

4.6. Analysis of Relative Abundance of Differential Phyla and Genera

Figure 4(A1,A2) display the phyla with notable differences in relative abundance among the treatment groups at the phylum level. Group D had a significantly higher relative abundance of Cyanobacteria compared to the other groups (p < 0.05) (Figure 4(A1)), whereas Deferribacteres showed significantly greater relative abundance in Group A compared to the rest (p < 0.05) (Figure 4(A2)). Figure 4(B1–B6) display genera with significant differences in relative abundance across the treatment groups at the genus level. Alistipes and Oxalobacter had significantly higher relative abundance in Groups C and D compared to Group A (p < 0.01) (Figure 4(B1,B6)). Desulfovibrio, Dehalobacterium, and Enterococcus showed significantly higher relative abundance in Group C compared to the control group (p < 0.05) (Figure 4(B2,B4,B5)). The relative abundance of Mucispirillum was significantly greater in Group A compared to the other treatment groups (p < 0.05) (Figure 4(B3)).

4.7. Spearman Correlation Analysis

The findings from the correlation analysis are displayed in Figure 5. Desulfovibrio exhibited a significant positive correlation with the relative weight of the glandular stomach (p < 0.05). Alistipes demonstrated a significant positive association with the relative weights of the liver, thymus, and jejunum (p < 0.05). Dehalobacterium showed a significant positive correlation with the relative weights of the jejunum and ileum (p < 0.05). Enterococcus exhibited a significant positive association with the relative weight of the duodenum and a negative correlation with serum CHOL levels (p < 0.05). Mucispirillum exhibited a significant negative correlation with ADG, ADFI, and LDL-C levels, as well as with the relative weights of the liver, thymus, and jejunum (p < 0.05). Oxalobacter exhibited a strong positive correlation with ADG and an inverse correlation with serum GLU levels (p < 0.05).

5. Discussion

In recent years, with the advancement of research in poultry nutrition, the potential of natural plant-based additives in improving production performance has attracted widespread attention [21,22]. Edible Dock Powder, as a natural additive, has demonstrated significant application value in this study. The results showed that EDP supplementation effectively improved feed conversion efficiency, particularly in certain treatment groups where the feed-to-gain ratio was markedly reduced, indicating enhanced feed utilization. While differences in mortality and culling rates among treatment groups were not statistically significant, a downward trend was observed in EDP-treated groups, suggesting its potential role in improving survival rates and health. Furthermore, EDP showed a positive impact on organ development, with increased relative weights of the liver and glandular stomach in some groups, indicating its potential to enhance nutrient absorption and metabolic functions through improved digestive organ development. These findings suggest that appropriate levels of EDP not only improve growth performance but also promote organ health, contributing to the overall well-being of waterfowl.

EDP contains abundant essential amino acids, including methionine, lysine, tryptophan, and valine, offering high-quality nitrogen sources that enhance nitrogen deposition and promote accelerated growth in geese [23]. In addition, EDP is rich in polyphenols and flavonoids, known for their antioxidant, anti-inflammatory, and immunomodulatory effects. These substances likely reduce oxidative stress, shield cells from free radical damage, and thus help maintain the health of geese [24].

Regarding organ development, EDP supplementation resulted in a marked increase in the relative weights of the liver and glandular stomach, indicating that EDP positively influences the growth and function of these organs. As the liver is a key metabolic organ, EDP’s rich antioxidant components, such as quercetin and kaempferol, may reduce oxidative stress, thus protecting liver cells and enhancing lipid and carbohydrate metabolism to provide more energy for growth [25]. Additionally, EDP’s high-quality protein and amino acid content may support liver and glandular stomach development by supplying essential nutrients needed for their growth and activity. The development of the glandular stomach may also be associated with EDP’s high dietary fiber content, which promotes gastrointestinal motility and stimulates digestive fluid secretion, thereby improving nutrient digestibility and utilization in the upper digestive tract [26]. These combined effects suggest that EDP’s diverse bioactive compounds enhance both digestive and metabolic functions in these organs.

In this study, supplementation with EDP significantly reduced serum AST and Glu levels in goslings, indicating that EDP positively influences hepatic and energy metabolism. As an important enzymatic marker of liver function, elevated AST levels are typically associated with liver cell damage. Therefore, a decrease in AST levels usually suggests the protection of liver cells and reduced hepatic damage, which correlates with improved liver function [27]. The decrease in AST levels could be due to the antioxidant properties of the polyphenols and flavonoids present in EDP. These compounds are well documented for their potent antioxidant capacity, which allows them to effectively scavenge free radicals and reduce oxidative stress-induced liver cell damage. Oxidative stress is a key factor leading to lipid peroxidation and protein degradation in liver cells. By mitigating this process through its antioxidant mechanisms, EDP helps preserve the integrity of liver cells [28]. This observation aligns with the observed increase in the relative liver weight of the goslings, suggesting that EDP not only protects liver function but also promotes structural growth in the organ. Furthermore, the significant reduction in serum GLU levels indicates that EDP also plays a role in regulating glucose metabolism in goslings. Maintaining appropriate blood glucose levels is essential for normal physiological functions and growth in poultry. Glucose regulation depends not only on insulin secretion but also on insulin sensitivity. The polyphenolic compounds in EDP may enhance insulin receptor sensitivity, facilitating more efficient glucose uptake by peripheral tissues, thereby aiding in the effective regulation of blood glucose levels [29]. In rapidly growing goslings, this improved glucose metabolism provides a stable and continuous energy supply, ensuring that the high energy demands during growth are met. While no statistically significant differences in growth (ADG or FBW) were observed among the groups, the improved feed efficiency (F/G) in EDP-supplemented groups may indicate a potential trend toward the better utilization of dietary nutrients, which warrants further investigation.

This study thoroughly assessed the effects of EDP on the structure and diversity of cecal microbiota in Sanhua goslings using 16S rRNA sequencing analysis. The results showed that EDP supplementation significantly altered the composition of the cecal microbiota. PCoA and NMDS revealed clear separations between the control and EDP-treated groups, suggesting that EDP notably changed the overall structure within the cecal microbiota. These changes may be attributed to the functional components of EDP, particularly quercetin and kaempferol, which could selectively promote the growth of specific bacterial groups by modifying the gut environment and nutrient availability [30]. This is further supported by the Venn diagram, which shows that there were relatively few shared OTUs between the groups, while a substantial number of unique OTUs were present in each group. This suggests that EDP fosters the formation of specific microbial communities that may play crucial roles in digestion and health maintenance in goslings. Additionally, the Alpha diversity analysis revealed that higher doses of EDP significantly increased species richness and microbial diversity in the cecum. Increased species diversity is typically associated with improved gut health, as higher diversity can enhance the stability of the microbial community, aiding the host in resisting pathogen invasion and maintaining gut function [31].

EDP supplementation significantly changed the taxonomic composition of the cecal microbiota in Sanhua goslings. Results indicated a significant increase in the relative abundance of Cyanobacteria in the high-dose EDP group, which may be linked to the dietary fiber content of EDP. Cyanobacteria likely utilize the dietary fiber in EDP as a fermentation substrate, breaking it down into short-chain fatty acids (SCFAs), which are crucial for maintaining gut health and optimizing host energy metabolism [32,33]. EDP also notably increased the abundance of the genera Alistipes and Oxalobacter. Alistipes is associated with dietary fiber levels and gut health, efficiently metabolizing complex carbohydrates and producing SCFAs, which improve the host’s gut environment [34]. Oxalobacter, on the other hand, plays a crucial role in oxalate metabolism, reducing oxalate accumulation and mitigating its negative impact on gut health. The increase in Oxalobacter may be linked to the oxalates found in EDP [35]. Additionally, the relative abundance of Desulfovibrio and Enterococcus also increased in the EDP-treated groups. Desulfovibrio modulates gut pH through sulfate reduction, inhibiting the growth of harmful bacteria [36]. Enterococcus primarily participates in lactic acid fermentation, helping maintain a low pH in the gut, and also produces bacteriocins—antimicrobial peptides that inhibit pathogenic bacteria, thereby enhancing gut barrier function [37]. In contrast, EDP supplementation significantly reduced the relative abundance of the phylum Deferribacteres and the genus Mucispirillum. High levels of Deferribacteres in the gut have been linked to inflammatory responses, potentially exacerbating pathological conditions through its metabolic byproducts [38]. The bioactive compounds in EDP, such as quercetin and kaempferol, possess potent anti-inflammatory and antioxidant properties, which likely modulate gut microbial composition by suppressing the growth of Deferribacteres, thus reducing inflammation. Mucispirillum is often associated with gut inflammation and pathology, with its increased abundance commonly seen as a marker of dysbiosis or inflammatory responses in the gut [39]. The reduction in Mucispirillum abundance following EDP supplementation suggests that EDP may have potential in alleviating or preventing gut inflammation-related pathologies.

The impact of EDP on gut microbiota is reflected not only in changes in microbial abundance but also in the significant correlations between specific microbes and various physiological indicators, revealing potential mechanisms behind growth, development, and overall health. The correlation analysis highlights the critical roles of these differentially abundant genera in physiological metabolism. The association between Desulfovibrio and glandular stomach function may stem from its involvement in sulfate reduction and SCFA production. Sulfate-reducing bacteria are known to participate in metabolic activities within the gut, particularly by generating hydrogen sulfide, which helps regulate digestive function and maintain an acidic environment conducive to nutrient absorption [40]. The increase in Desulfovibrio suggests that EDP may support gastrointestinal health by enhancing digestive functions and optimizing microbial communities. The significant correlation between Alistipes and organ development underscores its essential role in immune regulation and liver metabolism. Alistipes produces SCFAs such as propionate and butyrate, which not only provide energy for intestinal epithelial cells but also maintain gut barrier integrity through anti-inflammatory effects, supporting both liver and immune system health [41]. The increased abundance of Alistipes likely reflects EDP’s ability to promote gut health and organ functionality through the modulation of microbial metabolic pathways. Enterococcus is closely linked to lipid metabolism. Studies have shown that Enterococcus species possess probiotic properties that reduce cholesterol absorption, thereby lowering serum total cholesterol levels and improving lipid metabolism [42]. By increasing the abundance of Enterococcus, EDP may enhance lipid metabolism in goslings, leading to improved overall health. Conversely, the negative correlation between Mucispirillum and growth performance, along with health status, suggests its association with gut dysbiosis or inflammation. This genus is often enriched during inflammatory conditions, and its reduction may indicate an improvement in gut health, particularly through reduced inflammation and enhanced liver, thymus, and gut function [43]. The supplementation of EDP could suppress the overgrowth of harmful bacteria like Mucispirillum, significantly enhancing overall health in goslings. The increase in Oxalobacter is linked to its role in oxalate metabolism. The accumulation of oxalates can impair mineral absorption, but Oxalobacter effectively metabolizes oxalates, reducing their accumulation and helping to maintain mineral balance and gut health [44]. This mechanism likely explains the improved ADG and reduced serum GLU levels observed in the EDP group.

6. Conclusions

In conclusion, adding EDP to gosling diets can improve the feed conversion ratio and shows a potential trend toward reducing mortality and culling rates, contributing to overall health and production performance. EDP regulates liver function and glucose metabolism, ensuring a stable energy supply that promotes growth. Additionally, EDP significantly alters the cecal microbiota, encouraging the growth of beneficial bacteria (such as Alistipes and Oxalobacter) while inhibiting harmful bacteria (such as Mucispirillum), thereby enhancing gut health and supporting physiological development. As a functional plant-based feed additive, this study preliminarily verified EDP’s supportive effects on growth performance and gut health in Sanhua goslings.

To further validate these findings, future research should explore the applicability of EDP in other goose breeds and farming conditions. Multi-omics approaches, including metabolomics, microbiomics, and transcriptomics, could provide deeper insights into its mechanisms by identifying metabolic changes, analyzing gut microbiota dynamics, and revealing gene expression alterations in key tissues such as the liver and gut. Based on the results of this study, a dietary inclusion level of 1.00–2.50% EDP is recommended during the gosling rearing period to optimize growth performance and health outcomes.