Dietary date (Phoenix dactylifera) modulates antioxidant defenses, immune function, and cecal microbiota to improve performance in Muscovy ducks

Abstract

Phytogenic feed additives from agro-industrial byproducts are increasingly explored as antibiotic alternatives in poultry, yet their efficacy in Muscovy ducks remains poorly documented. This study investigated the effects of dietary date (Phoenix dactylifera) fruit supplementation at 0% (control), 5% (D1), and 10% (D2) on growth performance, blood biochemistry, antioxidant status, immune function, meat quality, intestinal morphology, and cecal microbiota in Muscovy ducks over a 42-day feeding trial. Date fruit supplementation dose-dependently improved final body weight, average daily gain, and feed conversion ratio (p < 0.05) without affecting feed intake. Serum antioxidant capacity was markedly enhanced, with elevated T-SOD, GSH-Px, and T-AOC alongside reduced MDA in both treated groups (p < 0.05). Immunologically, date significantly increased IgA and IgG while decreasing TNF-α and IL-6 (p < 0.05). Intestinal histomorphometry revealed improved ileal villus height, width, and crypt depth (p < 0.05). Cecal microbiome analysis showed increased alpha diversity, phylum-level shifts favoring Bacillota and Actinomycetota, and genus-level enrichments correlated with enhanced performance and immunity. Meat quality remained largely unaffected, with only reduced leg muscle redness. Correlation analyses linked specific beneficial genera to improved antioxidant and immune indices. Collectively, these findings provide the first systematic evidence that 10% whole date fruit inclusion is a safe, effective functional additive for Muscovy ducks, enhancing productivity through antioxidant, immunomodulatory, and microbiome-modulating mechanisms and offering a sustainable nutritional strategy to reduce reliance on synthetic additives in duck production systems.

Introduction

Intensified poultry production demands cost-effective, sustainable feed additives that enhance productivity while reducing reliance on synthetic growth promoters and antibiotics. With growing consumer awareness and regulatory restrictions on antimicrobial use in animal feed, phytogenic feed additives derived from agro-industrial byproducts have emerged as viable alternatives (Obianwuna et al., 2024; Wang, et al., 2025; Li et al., 2026). Among these, the date palm (Phoenix dactylifera) and its various derivatives, including date fruit, date pits (seeds), date palm pollen, and date processing wastes, have attracted considerable research interest (Raza, et al., 2023; Shah, et al., 2026). Global date production of date fruit reached approximately 9.93 million tons in 2024, with Saudi Arabia (1.93 million tons), Egypt (1.75 million tons) and Algeria (1.34 million tons) being the three leading producers and collectively accounting for approximately 50.6% of global production. China produced approximately 162,330 tons of dates in the same year, representing about 1.6% of global production (FAO, 2025). Nutritionally, date fruits are rich in carbohydrate (mainly glucose, fructose and sucrose), dietary fiber, essential minerals (potassium, magnesium, calcium, and iron), and vitamins (Attia, et al., 2021). More importantly, they contain an array of bioactive phytochemicals, notably phenolic compounds, flavonoids, tannins, and carotenoids, which are known to possess potent antioxidant, anti-inflammatory, and immune-modulatory properties (Al-Farsi and Lee, 2008; Vayalil, 2012). These attributes make date fruit products attractive candidates for inclusion in poultry diets, not only as energy sources but also as functional additives that can influence multiple physiological systems.

A growing body of evidence from studies in broiler chickens and Japanese quails has shown that dietary date fruit supplementation positively affects growth performance. Inclusion of date palm seeds at 2-4% levels in broilers significantly improved body weight gain and feed conversion ratio, attributed to their high metabolizable energy content and improved nutrient digestibility (El-Far, et al., 2016). Similarly, dried date waste meal incorporated at 9% in broilers' diets increased carcass weight and dressing percentage, confirming that date by-product can serve as an effective energy substitute without compromising growth (El Boushy, et al., 2000; Raza, Tahir, Naz, Alhidary, Khan, Losacco and Tufarelli, 2023). In quails, date palm pollen at 1-7 g/kg enhanced growth rates and feed efficiency (Lehmood, et al., 2017). Beyond energy provision, the bioactive constituents of date fruit may stimulate digestive enzyme secretion and improve intestinal morphology, facilitating better nutrient absorption (Alyileili, et al., 2020). Date fruit supplementation also improves blood biochemical parameters. Studies showed reductions in serum total cholesterol, triglycerides, and low-density lipoprotein cholesterol, alongside elevations in high-density lipoprotein cholesterol, in broilers and quails fed date fruit by-products (Itodo, et al., 2026). These hypolipidemic effects are likely mediated by soluble fiber and polyphenols that interfere with lipid absorption and enhance bile acid excretion (Attia, Reda, Patra, Elnesr, Attia and Alagawany, 2021). The antioxidant capacity of date fruit products has been extensively documented. Date pits, in particular, are exceptionally rich in phenolic compounds that function as potent free radical scavengers. In broiler chickens, dietary date seeds improved the antioxidant profile in serum, liver, and intestine (Attia and Al-Harthi, 2015). Similarly, supplementing quails with date palm pollen significantly increased total antioxidant capacity and reduced nitric oxide and MDA concentrations (Lehmood, Shawket and Al-Salhie, 2017). Dietary date seeds in broilers elevated serum interferon-gamma and interleukin-2 levels, indicating an enhanced cell-mediated immune response (Itodo, Kanayo, Joshua, Abel, Galadima, Ahmed, Kano, Samuel, Adah and Hassan, 2026).

The gut microbiota plays a pivotal role in nutrient metabolism and intestinal health (Kogut, 2022; Ma et al., 2026). date fruit contains fermentable fibers and oligosaccharides that exert prebiotic-like effects, selectively promoting beneficial bacteria such as Lactobacillus while suppressing pathogenic Escherichia coli and Staphylococcus aureus in broilers and quails (Attia and Al-Harthi, 2015; Raza, Tahir, Naz, Alhidary, Khan, Losacco and Tufarelli, 2023). A balanced gut microbiome enhances digestion, nutrient absorption, and mucosal immunity, indirectly contributing to better growth and meat quality (Kogut, 2019, 2022).

Despite extensive evidence in chicken and quails, comprehensive studies on the effects of date fruit products in Muscovy ducks are conspicuously lacking. This gap is particularly important because Muscovy ducks are economically important in many tropical and subtropical regions, valued for its lean, flavorful meat and adaptability to diverse rearing systems (Lionel, et al., 2026; Liu, et al., 2026). However, their nutritional responses to phytogenic feed additives remain under-explored. Although preliminary research with palm kernel cake (a related by-product) indicates that Muscovy ducks can tolerate up to 15% inclusion without adverse effects on performance, metabolism, antioxidant status, immunity, meat quality, and the effects on cecal microbiota have not been systematically evaluated in this species (Fadil, et al., 2014).

Therefore, the present study was designed to investigate the influence of dietary date fruit supplementation on growth performance, blood profile, antioxidant enzyme activities, immune parameters, meat quality attributes and cecal microbiota composition in Muscovy ducks. The findings are expected to provide a scientific rationale for using date byproducts as a sustainable and functional feed ingredient in ducks' diets, thereby contributing to more efficient and eco-friendly poultry production.

Materials and methods

Animal ethical approval and experimental site

The experiment was conducted at the Research Base, South China Agricultural University, China. All animal procedures were approved by the Institutional Animal Care and Use Committee of the College of Animal Science, South China Agricultural University (2026F190) and were carried out in accordance with relevant guidelines and regulations.

Experimental duck housing and diet

A total of 108 healthy, 1-day-old white-feathered Muscovy ducks with similar initial body weight 47.18±0.037 (g) were obtained from Wen’s Food group Co., LTD. Guangdong, China. Upon arrival, ducks were randomly assigned to three treatment groups, each with 6 replicate pens (6 ducks per replicate pen), for a total of 36 ducks per treatment.

The study employed a completely randomized design (CRD) with three dietary treatments. The treatments were as follows: the control group, which received the basal diet without supplementation; the D1 group, which received the basal diet supplemented with 5% date fruit; and the D2 group, which received the basal diet supplemented with 10% date fruit powder. The 5% and 10% inclusion levels were selected based on the previous studies showing improved growth performance, nutrient digestibility, and gut health in broilers fed up to 9% dried date meal (Raza, Tahir, Naz, Alhidary, Khan, Losacco and Tufarelli, 2023), and on the recommended 5-10% inclusion range for date fruit products in poultry diets (Attia, Reda, Patra, Elnesr, Attia and Alagawany, 2021). A higher level (e.g., 15%) was not tested because date fruit powder is rich in simple sugars and crude fiber; above 10% inclusion, dietary energy and protein dilution, and potential negative effects on nutrient balance and pellet quality, become difficult to control, and no dose-response data above 10% are available for ducks (Attia, Reda, Patra, Elnesr, Attia and Alagawany, 2021). Date fruit (Aseel Variety) were purchased from the local market of the Khairpur Mir's, Sindh Pakistan. The Aseel variety is a soft date cultivar widely grown in the Sindh province and is characterized by higher sugar content. The date fruit were pitted, oven-dried at 60°C until constant weight was achieved, and then ground to pass through a 1-mm sieve to produce a homogeneous dried date fruit powder. Oven-drying at 60°C was chosen because this temperature is generally considered safe for preserving most phenolic compounds and flavonoids in date fruit, although some thermolabile constituents may be partially degraded. The total phenolic content of the dried date fruit powder was 4.7 mg gallic acid equivalents (GAE)/g, and the total flavonoid content was 2.3 mg quercetin equivalents (QE)/g. Based on these values and the inclusion levels, the calculated total phenolic concentrations in the experimental diets were approximately 2.1 and 3.4 mg GAE/g for the 5% and 10% date fruit supplementation groups during the starter phase, and 1.9 and 3.1 mg GAE/g during the grower phase, respectively. These concentrations are within the range reported to exert antioxidant and immunomodulatory effects in poultry (Attia, Reda, Patra, Elnesr, Attia and Alagawany, 2021). This powder was incorporated into the experimental diets at the expense of corn and soybean meal to maintain isocaloric and isonitrogenous conditions. The proximate composition and total phenolic content of the dried date fruit powder were reported in our previous study (Shah, Xia, Wang, Yuan, Shah, Shah, Khan, Pan, Shi and Chen, 2026). The trial lasted for 42 days. The basal diet was formulated to meet the nutrient requirements according to the Chinese National Standard NY/T 2122-2012 for Muscovy ducks. The ingredient composition and analyzed nutrient levels of the experiment diets are presented in Table 1. Representative samples of each experimental diet were collected and analyzed for proximate composition (dry matter, crude protein, crude fat, crude fibre, and ash) and mineral content (calcium and total phosphorus) following AOAC (2005) methods (AOAC, 2005). The analyzed values are presented in Table 1. Ducks were housed in a cage-rearing system (70 cm × 70 cm) with ad libitum access to feed and fresh water throughout the experimental period. Room temperature was maintained at 33°C for the first 3 days and gradually reduced by 2-3°C per week until reaching 22-24°C. Relative humidity was kept at 55-65%, and a lighting schedule of 23 h light: 1 h dark during the first week, followed by 16 h light: 8 h dark for the remaining trial, was provided.

Table 1.

Diet composition and nutrient levels of experimental diets for Muscovy ducks (air-dry basis).

Items	Starter phase (1 to 21 d)			Grower phase (22 to 42 d)
	Control	D1 (5%)	D2 (10%)	Control	D1 (5%)	D2 (10%)
Ingredients (%)
Corn	62.12	57.12	52.12	70.9	65.9	60.9
Soybean meal (44% CP)	28	28.5	29	15.85	16.5	17
Dried date fruit powdera,d	0	5	10	0	5	10
Fish meal (65% CP)	3	3	3	2	2	2
Soybean oil	2.5	2	1.5	3	2.5	2
Wheat bran	0.08	0.08	0.08	4.05	4.05	4.05
Limestone	1.2	1.2	1.2	1.2	1.2	1.2
Dicalcium phosphate	1.5	1.5	1.5	1.5	1.5	1.5
Salt	0.3	0.3	0.3	0.3	0.3	0.3
DL-Methionine (99%)	0.2	0.2	0.2	0.15	0.15	0.15
L-Lysine·HCl (78%)	0.1	0.1	0.1	0.05	0.05	0.05
Vitamin-mineral premixb	1	1	1	1	1	1
Total	100	100	100	100	100	100
Analyzed nutrient levelsc
Crude protein (CP, %)	20	19.95	19.9	17.5	17.45	17.4
Calcium (Ca, %)	0.9	0.9	0.9	0.85	0.85	0.85
Crude fibre (%)	3.8	4.7	5.6	4.2	5.1	6
Metabolizable energy (ME, kcal/kg)	2900	2895	2890	2920	2915	2910
Available phosphorus (Avail. P, %)	0.4	0.4	0.4	0.4	0.4	0.4
Lysine (%)	1	1	1	0.85	0.85	0.85
Methionine + Cystine (%)	0.75	0.75	0.75	0.7	0.7	0.7

^aDried date fruit powder was prepared by pitting, oven-drying at 60°C until constant weight, and grinding to pass through a 1-mm sieve. Date fruit replaced corn and soybean oil to maintain isocaloric and isonitrogenous conditions.

^bPremix provided per kg diet: vitamin A 10,000 IU; D₃ 2,500 IU; E 30 IU; K₃ 2 mg; B₁ 2 mg; B₂ 6 mg; B₆ 4 mg; B₁₂ 0.02 mg; niacin 40 mg; pantothenic acid 12 mg; folic acid 1 mg; biotin 0.15 mg; choline chloride 600 mg; Cu 8 mg; Fe 80 mg; Zn 60 mg; Mn 60 mg; Se 0.3 mg; I 0.4 mg.

^cAnalyzed nutrient values. ME, metabolizable energy; CP, crude protein; Avail. P, available phosphorus. Diets met the requirements of NY/T 2122-2012.

^dProximate composition of dried date fruit powder: dry matter 925 g/kg, crude protein 68 g/kg, ether extract 12.1 g/kg, crude fibre 115 g/kg, neutral detergent fibre (NDF) 184 g/kg, acid detergent fibre (ADF) 123 g/kg, ash 31 g/kg, total sugars 685 g/kg, pH 5.8, total phenolics 4.7 mg gallic acid equivalents (GAE)/g, flavonoids 2.3 mg quercetin equivalents (QE)/g, and tannins 1.2 g/kg. Microbial load: lactic acid bacteria 3.2 log CFU/g, yeast 2.1 log CFU/g, and mold 1.5 log CFU/g. Aflatoxin B1 and ochratoxin were not detected (ND). Total phenolic and flavonoid contents were determined as described in the Materials and Methods.

Samples collection

On the first and last day of the research trial, the initial and final body weights of the ducks were measured, respectively. Feed was provided daily at 8.00 am, and leftovers were weighed for replicate. Average daily gain (ADG) and average daily feed intake (ADFI) were calculated for each replicate pen. Feed conversion ratio (FCR) was then calculated as ADFI divided by ADG (ADFI/ADG).

On the last day of the trial, one duck with average weight was selected from each replicate pen, and blood samples were collected through the jugular vein and left for 30 minutes before centrifugation at 2,000 × g for 15 minutes to obtain serum. The samples were frozen in liquid nitrogen and later stored in −20°C refrigerator until analysis. The same ducks were first anesthetized with sodium pentobarbital (30 mg/kg BW, IV) and then euthanized by exsanguination, which is a standard humane slaughter method for poultry. Organs such as the heart, liver, spleen, kidney, pancreas, gizzard, thymus, glandular stomach, intestine, and gall bladder were collected and weighed to determine organ index, as per the following formula.

Relative organ weight (g/kg) = Organ Weight (g)/ Final Body weight at slaughter (kg)

The final body weight was body weight recorded on day 42 immediately before slaughter was used for all organ index calculations. The chest and leg muscles were also collected from the slaughtered ducks for meat quality determination.

Biochemical parameters analysis

The automatic biochemical analyzer (Cobas C311, Roche Diagnostic, Basel, Switzerland) was used to measure the serum glucose, triglycerides, high-density lipoprotein (HDL-C), low-density lipoprotein (LDL-C), Alkaline phosphatase (ALP), globulin (GLB), and total cholesterol (CHO), at Guangzhou Daan Gene Biotechnology Co., LTD., Guangzhou, Guangdong, China. The serum antioxidant profile, including total Superoxide Dismutase (T-SOD) (Hydroxylamine method), Glutathione Peroxidase (GSH-Px) (Hydrogen peroxidase method), Malondialdehyde (MDA) (Thio-barbituric acid method), Total Antioxidant Capacity (T-AOC) (Ferric ion reduction method), and Catalase (CAT) (Ammonium molybdate method), was determined using kits from Nanjing Jiangcheng Bioengineering Institute (Nanjing, China) following the manufacturer’s instructions. The serum immunity profile of the Immunoglobulin A (IgA), Immunoglobulin G (IgG), Tumor Necrosis Factor-alpha (TNF-α), Interleukin-6 (IL-6) and Interleukin-1 beta (IL-1β) was determined by enzyme-linked immunosorbent assay (ELISA) kits (Jiangsu Meibiao Biotechnology Co., Ltd., Yancheng, Jiangsu, China) following the manufacturer’s instructions.

Histopathological analysis

Intestine (1 cm from the middle portion of the duodenum, jejunum and ileum) samples were collected and rinsed three times with phosphate-buffered saline (PBS) to remove the blood and intestinal contents. Each tissue was cut into small pieces (about 5 × 5 × 3 mm) and fixed in 4% formaldehyde solution. These fixed samples were subsequently processed by dehydration, paraffin embedding, sectioning, mounting, dewaxing, washing, and staining with hematoxylin and eosin (H&E), and sealing to produce H&E-stained sections for histological analysis. Intestinal villus height, villus width, and crypt depth were measured using ImageJ (v 1.8.0, National Institutes of Health, Bethesda, MD).

Meat quality analysis of the leg and chest muscles

The portable pH meter (Testo 205, Testo SE & Co. KGaA, Lenzkirch, BW, Germany) was used 45 minutes after slaughter to measure the pH of the leg and chest muscles. The pH meter electrode was inserted to a depth of 1 cm in three different muscle portions to obtain the results. After each measurement, the electrode tip was rinsed with distilled water and cleaned with neutral filter paper before analyzing the next sample. After 24 h, the samples were used again to determine the pH. Meat color (CIE, L*, a*, and b* representing lightness, redness, and yellowness, respectively) was measured using an automatic colorimeter (HunterLab, Reston, VA). Measurements were performed at 45 minutes and 24 h post-slaughter. Before each reading, the surface of the chest and leg muscles was gently blotted dry with neutral filter paper. Under ambient indoor lighting, color values were recorded from three different positions per sample after the instrument reading had stabilized. Following the initial 45-minute measurements, the samples were placed in resealable plastic bags and stored at 4°C until the second measurement at 24 h.

Cooking loss was determined for samples stored at 4°C immediately post-collection and analyzed 24 h later. For each replicate, approximately 30 g of muscle, carefully trimmed of visible fascia and adipose tissue, was weighed to record the initial weight (W1). The sample was then placed in a sealed bag and fully immersed in a water bath (PolyScience, Niles, IL) preheated to 75°C. Samples were cooked until the internal temperature reached 72°C, which was monitored with a digital probe thermometer (Maverick Industries, Inc., Edison, NJ). The samples were then removed, cooled to room temperature, and gently blotted dry before reweighing to obtain the final weight (W2). Cooking loss was calculated using the following formula:

Cooking loss (%) = [(W1-W2) / W1] × 100

Shear force was measured on the same cooked samples after they had cooled to room temperature. The samples were trimmed along the orientation of the muscle fibers to obtain long strips free of connective tissue and fat, each with a uniform cross-section of 0.5 cm × 0.5 cm. During measurement, each strip was positioned so that the muscle fiber direction was perpendicular to the shear blade of the texture analyzer (Stable Micro Systems, Godalming, Surrey, UK). Three replicate measurements were performed per sample, and the average shear force was recorded in Newtons (N).

16s rRNA sequencing and analysis

Genomic DNA was isolated from cecal contents using the E.Z.N.A Soil DNA kit (Omega Bio-tek, Norcross, GA). The integrity and purity of the extracted DNA were assessed via agarose gel electrophoresis and spectrophotometer (Thermo Fisher Scientific, Waltham, MA). The bacterial 16S rRNA V3-V4 hypervariable regions were amplified using the primer pair 338F (5′-ACTCTCTACGGGAGGCAGCAG-3′) and 806R (5′-GGACTACHVGGGTWTCTAAAT-3′), on an ABI GeneAmp® 9700 PCR thermocycler (Applied Biosystems, Foster City, CA). Following purification, the resulting amplicons were pooled in equimolar concentrations and subjected to paired-end sequencing (2 × 300 bp) on an Illumina MiSeq platform (Illumina, San Diego, CA) at Majorbio Bio-Pharm Technology Co., Ltd. (Shanghai, China). We initially processed the raw sequencing data using fastp (v0.20.0; https://github.com/OpenGene/fastp) for quality filtering, followed by paired-end assembly with FLASH (v1.2.7; http://www.cbcb.umd.edu/software/flash). Operational taxonomic units (OTUs) were subsequently clustered at a 97% similarity threshold using UPARSE (v7.1; http://drive5.com/uparse/), which also facilitates the removal of chimeric sequences. Taxonomic assignment of each OTU was conducted using the RDP classifier (v2.2; http://rdp.cme.msu.edu/) against the Silva 16S rRNA database (release 138) with a confidence threshold of 70%.

Alpha diversity indices (Sobs, Chao, Ace, Shannon and Simpson), the non-parametric Kruskal Wallis H test was employed, as microbiota diversity indices typically do not satisfy the assumption of normality and homoscedasticity required for parametric ANOVA. When significant overall differences were detected (p < 0.05), pairwise multiple comparison were performed using Dunn’s post-hoc test with Bonferroni correction for multiple testing.

Beta diversity of the cecal microbial community was assessed using PERMANOVA (permutational multivariate analysis of variance) with 999 permutations, based on Bray-Curtis distance matrices, and differences in community structure among groups were visualized using Principal coordinate analysis (PCoA). Linear discriminant analysis effect size (LEfSe) was employed to identify differentially abundant bacterial taxa among treatment groups, with a linear discriminant analysis (LDA) score threshold of > 2.0 considered significant.

Statistical analysis

All data were analyzed using SPSS software (version 20.0; IBM Corp., Armonk, NY). Before analysis, residual normality and homogeneity of variances were assessed using the Shapiro-Wilk test and Levene's test, respectively. Growth performance (final body weight, ADG, ADFI, and FCR), organ index, blood biochemistry, antioxidant indices, immune parameters, meat quality attributes, intestinal morphometric measurements were analyzed using one-way analysis of variance (ANOVA) with dietary treatment (Control, D1, D2) as the fixed factor. The experimental unit was the pen (n = 6) for growth performance and individual ducks (n = 6) for all other parameters. When significant overall differences were detected (p < 0.05), Tukey's honestly significant difference (HSD) post-hoc test was applied for pairwise comparisons.

Pearson's correlation analysis was performed to explore relationships between the top 30 most abundant cecal genera and key physiological parameters. All quantitative results are expressed as mean ± SEM, with significance at p < 0.05.

Results

Growth performance

Growth performance results are presented in Table 2. Date fruit supplementation significantly (p < 0.05) improved final body weight, ADG, and FCR. Specifically, the D2 group (10% date fruit) had significantly higher final body weight and ADG, and lower FCR, compared with control group (p < 0.05), while the D1 group (5% date fruit) showed intermediate values that did not differ significantly from either group. However, there was no significant (p > 0.05) effect on ADFI among the groups.

Table 2.

Effect of dietary date fruit supplementation on growth performance in Muscovy ducks.

Item	Treatments			SEM	P-value
	Control	D1	D2
BW (g) 0 d	47.00	47.36	47.18	0.112	0.458
BW (g) 42 d	3250.00b	3358.33ab	3441.67a	28.868	0.014
ADG (g)	77.38b	79.96ab	81.94a	0.687	0.014
ADFI (g)	127.02	125.27	126.73	0.378	0.128
FCR	1.64a	1.57ab	1.55b	0.015	0.011

BW= body weight, ADG= average daily gain, ADFI= average daily feed intake, FCR= feed conversion ratio (g feed consumed / g body weight gain), (n = 6 per treatment); C= control, D1=5% date fruit supplementation, D2 10% date fruit supplementation.

Organs index

Organs index results of the different groups are displayed in Table 3. We found no significant (p > 0.05) difference in the organ index in the organs, including the heart, liver, spleen, kidney, pancreas, gizzard, thymus, glandular stomach, intestine, and gall bladder, among all groups.

Table 3.

Effect of dietary date fruit supplementation on organs index (g/kg body weight) in Muscovy ducks.

Item	Treatments			SEM	P-value
	Control	D1	D2
Heart	5.30	5.43	5.23	0.115	0.786
Liver	20.71	21.45	20.18	0.530	0.538
Spleen	1.02	0.79	0.87	0.067	0.410
Kidney	7.05	6.93	6.24	0.222	0.295
Pancreas	2.58	2.15	2.29	0.091	0.136
Gizzard	24.44	21.80	21.28	0.790	0.224
Thymus	4.70	4.86	4.50	0.393	0.940
Glandular stomach	3.71	3.33	3.25	0.138	0.384
Intestine	37.36	44.02	40.64	1.375	0.140
Gall bladder	1.69	2.23	1.31	0.181	0.110

Relative organ weight (g/kg body weight). Data are presented as mean ± SEM (n = 6 per treatment). C = control, D1 = 5% date fruit supplementation, D2 = 10% date fruit supplementation. SEM, standard error of the mean.

Blood biochemistry

The results of the blood profile are presented in Table 4. Supplementation of date fruit in the diet of Muscovy ducks significantly (p < 0.05) increased total cholesterol and HDL-C levels in D1 and D2 groups compared to the control group, while LDL-C remained unchanged. In addition, date fruit supplementation did not significantly (p > 0.05) affect BUN, ALP, GLU, and TG levels among the groups.

Table 4.

Effect of dietary date fruit supplementation on blood profile in Muscovy ducks.

Item	Treatments			SEM	P-value
	Control	D1	D2
BUN (mmol/L)	0.70	0.59	0.71	0.024	0.068
ALP (U/L)	533.00	527.17	527.20	6.983	0.934
GLU (mmol/L)	12.90	13.44	12.35	0.212	0.105
TG (mmol/L)	2.27	1.58	1.57	0.167	0.143
CHO (mmol/L)	4.14b	4.94a	5.50a	0.175	0.001
HDL-C (mmol/L)	2.24b	2.58ab	2.61a	0.063	0.024
LDL-C (mmol/L)	1.62	1.70	1.58	0.041	0.566

BUN, Blood urea nitrogen; ALP, Alkaline phosphatase; GLU, Glucose; TG, Triglycerides; CHO, Cholesterol; HDL-C, High-density lipoprotein cholesterol; LDL-C, Low-density lipoprotein cholesterol. Data are presented as mean ± SEM (n = 6 per treatment). C = control, D1 = 5% date fruit supplementation, D2 = 10% date fruit supplementation. SEM, standard error of the mean. a,b superscripts within a row indicate significant differences (p < 0.05).

Antioxidant profile

The serum antioxidant profile results are presented in Table 5. The results showed that supplementing the diet of Muscovy ducks with date fruit significantly (p < 0.05) increased the concentrations of T-SOD, GSH-Px, and T-AOC in the D1 and D2 groups compared with the control group. In addition, these supplementations significantly (p < 0.05) reduced MDA levels in the D1 and D2 groups compared with the control group. However, no significant (p > 0.05) difference was observed in CAT levels among the groups.

Table 5.

Effect of dietary date fruit supplementation on serum antioxidant profile in Muscovy ducks.

Item	Treatments			SEM	P-value
	Control	D1	D2
T-SOD U/mL	183.61b	227.51a	230.72a	6.204	<0.001
GSH-Px U/L	267.57b	289.10ab	318.15a	6.696	0.002
MDA nmol/mL	6.69a	5.59b	5.40b	0.170	<0.001
T-AOC U/mL	7.06c	7.79b	8.37a	0.154	<0.001
CAT U/mL	5.38	5.70	5.88	0.098	0.095

T-SOD = total superoxide dismutase, GSH=glutathione peroxidase, MDA=Malondialdehyde, T-AOC = total antioxidant capacity, CAT= Catalase, SEM=Standard error of mean, (n = 6 per treatment); C= control, D1=5% date fruit supplementation, D2 10% date fruit supplementation, superscript letters indicate significant differences among treatment groups (p < 0.05).

Immunity profile

The results of the serum immunity profile are presented in Table 6. The results showed that supplementing the diet of Muscovy ducks with date fruit significantly (p < 0.05) increased IgA and IgG levels in the D1 and D2 groups compared with the control group. However, these supplementations significantly (p < 0.05) reduced TNF-α and IL-6 levels in the D1 and D2 groups compared with the control group, and no significant (p > 0.05) difference was observed in IL-1β levels among all groups.

Table 6.

Effect of dietary date fruit supplementation on serum immune profile in Muscovy ducks.

Item	Treatments			SEM	P-value
	Control	D1	D2
IgA μg/mL	24.11b	25.60b	37.21a	1.476	<0.001
IgG μg/mL	130.26b	143.52b	171.37a	4.634	<0.001
TNF-α ng/L	1464.69a	1341.33a	926.97b	74.131	0.002
IL-6 ng/L	59.32a	54.44a	35.86b	2.662	<0.001
IL-1β ng/L	56.99	50.77	52.75	1.226	0.100

IgA, Immunoglobulin A; IgG, Immunoglobulin G; TNF-α, Tumor Necrosis Factor-alpha; IL-6, Interleukin-6; IL-1β, Interleukin-1 beta. Data are presented as mean ± SEM (n = 6 per treatment). C = control, D1 = 5% date fruit supplementation, D2 = 10% date fruit supplementation. SEM, standard error of the mean. a,b superscripts within a row indicate significant differences (p < 0.05).

Intestinal morphology

The results of the intestinal morphology of different segments in the intestine, including duodenum, jejunum and ileum, are presented in Fig. 1 (A, B, C) & Table 7. Supplementation of the Date (D2) significantly increased the villus height (p < 0.01), villus width (p = 0.002) and crypt depth (p = 0.026) in the ileum. These supplements also significantly increased villus width in the duodenum (p = 0.043) and crypt depth in the jejunum (p < 0.01) in the D1 and D2 groups compared with the control group. However, no significant differences were observed in the villus height and crypt depth in the duodenum and villus height and villus width of the jejunum segments of the small intestine in ducks.

Fig. 1.

Effect of dietary date fruit supplementation on intestinal morphology of the Muscovy ducks. (A-C) Representative Hematoxylin and eosin (H&E) stained sections of (A) duodenum, (B) jejunum, and (C) ileum; scale bar = 100 µm.

Table 7.

Effect of dietary date fruit supplementation on intestinal morphology of the Muscovy ducks.

Item	Treatments			SEM	P-value
	Control	D1	D2
Duodenum
Villus Height	263.01	287.47	303.68	7.21	0.058
Villus Width	26.44b	30.20ab	34.42a	1.35	0.043
Crypt depth	38.90	39.54	43.95	1.58	0.389
Jejunum
Villus Height	242.20	246.57	266.00	5.44	0.166
Villus Width	31.30	32.97	32.65	1.59	0.912
Crypt depth	30.86c	42.43b	50.45a	2.24	<0.001
Ileum
Villus Height	894.57b	941.88b	1134.89a	30.81	<0.001
Villus Width	99.39b	143.84a	149.77a	7.21	0.002
Crypt depth	89.66b	92.24ab	116.00a	4.63	0.026

Data are presented as mean ± SEM (n = 6 per treatment). C = control, D1 = 5% date fruit supplementation, D2 = 10% date fruit supplementation. SEM, standard error of the mean. a,b,c superscripts within a row indicate significant differences (p < 0.05).

Meat quality

The results of the meat quality parameters are presented in Table 8. The results showed that Date fruit supplementation had no significant (p > 0.05) effect on pH, color (L*, b*), shear force, or cooking loss in both chest and leg muscles. However, leg muscle redness (a*) was significantly (p < 0.05) affected, with the control group showing higher a value than the D2 group (10% date fruit), while D1 (5% date fruit) was intermediate and did not differ from either group.

Table 8.

Effect of dietary date fruit supplementation on meat quality parameters of chest and leg muscles in Muscovy ducks.

Item	Treatments			SEM	P-value
	Control	D1	D2
Chest muscle
pH (45 min) pH (24 h)	6.33 5.83	6.21 5.87	6.28 5.88	0.055 0.018	0.682 0.475
L*	55.60	53.22	53.22	1.161	0.716
a*	14.64	17.00	16.05	1.129	0.717
b*	15.86	15.42	16.53	0.680	0.817
Shear force (N) Cooking loss (%)	25.15 25.40	24.37 24.10	23.88 24.52	0.895 0.479	0.859 0.552
Leg muscle
pH (45 min) pH (24 h)	6.07 5.78	5.97 5.81	6.06 5.83	0.07 0.032	0.831 0.832
L*	41.78	44.43	45.97	1.30	0.442
a*	22.73a	19.66ab	17.98b	0.78	0.034
b*	12.22	11.55	13.12	0.75	0.724
Shear force (N) Cooking loss (%)	31.42 15.43	29.27 14.52	30.32 14.09	0.90 0.578	0.651 0.658

pH was measured at 45 minutes and 24 hours post-slaughter, L, lightness; a, redness; b, yellowness. Data are presented as mean ± SEM (n = 6 per treatment). C = control, D1 = 5% date fruit supplementation, D2 = 10% date fruit supplementation. SEM, standard error of the mean. a,b superscripts within a row indicate significant differences (p < 0.05).

Cecal microbiota

The microbiota community composition in the cecum showed 10, 6, and 8 OTUs unique to groups C, D1, and D2, respectively, and 158 OTUs shared among all 3 groups, as shown in Fig. 2A. Fig. 2B, C, E and F showed the results of the Sobs, Chao, Ace, and Shannon index increased with date fruit supplementation (p < 0.05). However, the Simpson index was lower in date-supplemented groups than in the control group (p < 0.05; Fig. 2D, E).

Fig. 2.

Cecal microbial community composition and diversity indices. (A) Venn diagram showing the number of unique and shared bacterial OTUs (Operational Taxonomic Units) among groups. Alpha diversity indices: (B) Sobs index, (C) Chao index, (D) Simpson index, (E) Ace index, (F) Shannon index and (G) Principal Coordinate Analysis (PCoA) plot based on Bray-Curtis distance matrices showing beta diversity among groups. Data are presented as mean ± SEM (n = 6 per treatment). C = control, D1 = 5% date fruit supplementation, D2 = 10% date fruit supplementation. p < 0.05 indicates significant differences between groups.

Beta-diversity analysis was carried out to examine disparities in the cecal microbial community among groups (Fig. 2G). According to the PCoA plots derived from the Bray-Curtis distance matrix, the points representing cecal microbiota among the three groups were clearly separated along the coordinate axes. Next, we explored the relationship between the microbial communities of cecum samples from the control, D1, and D2 groups. The figure below shows the microbial composition of groups C, D1, and D2 at the phylum (Fig. 3A) and genus (Fig. 3F) levels. At the phylum level, the dominant species are Bacillota, Bacteroidota, and Thermodesulfobacteriota, accounting for 58.8-59.9%, 25.3-26% and 7.7-9% of the total bacterial abundance, respectively. At the genus level, the dominant species are Bacteroides, Desulfovibrio, and norank o_Clostridia_UCG-014, accounting for 11.3-13.2%, 7.5-9%, and 5.2-5.4% of the total bacterial abundance, respectively. The relative abundance of Bacillota and Actinomycetota was highest in the D2 group and lowest in the C group (p < 0.05; Fig. 3B, C). In contrast, the relative abundance of Bacteroidota (Fig. 3D) was highest in the control group compared with the D1 and D2 groups. These findings further indicate that supplementing the ducks' diet with date fruit can influence the composition of microbial communities in the cecum.

Fig. 3.

Cecal microbial composition at phylum and genus levels. (A) Relative abundance of the top 15 phyla across treatment groups. Relative abundance of individual phyla: (B) Bacillota (formerly Firmicutes), (C) Actinomycetota, (D) Bacteroidota (formerly Bacteroidetes), and (E) Patescibacteria. (F) Relative abundance of the top 30 genera. Data are presented as mean ± SEM (n = 6 per treatment). C = control, D1 = 5% date fruit supplementation, D2 = 10% date fruit supplementation. p < 0.05 indicates significant differences between groups.

To investigate changes in microbial community genera/species across groups C, D1, and D2, we compared differences among these groups. The differentially expressed genera/species likely represent microbial communities associated with different treatments. Inter-group difference analysis showed that, compared to the control group, several genera in D1 and D2 exhibited significant differences at the genus level, including CHKCI001, norank_f__F082, Paludicola, and Ruminococcus (Fig. 4A).

Fig. 4.

Differential abundance, biomarker identification, and correlation analysis of cecal microbiota. (A) Kruskal-Wallis H test bar plot showing the mean proportions (%) of significantly different bacterial taxa among groups. P-values are listed on the right. Colored bars represent the group with the highest abundance (blue = C; red = D1; green = D2). (B) Linear Discriminant Analysis Effect Size (LEfSe) analysis identifying biomarker taxa enriched in each group (LDA score threshold > 2.0). Colors correspond to the respective groups (blue = C; red = D1; green = D2). Prefixes indicate taxonomic ranks: p, phylum; c, class; o, order; f, family; g, genus. (C) Pearson's correlation heatmap between the top 30 most abundant cecal bacterial genera (y-axis) and key physiological parameters, including growth performance, antioxidant indices, immune markers, and intestinal morphology (x-axis). Red and blue indicate positive and negative correlations, respectively. Asterisks inside boxes indicate statistically significant correlations (*p < 0.05, **p < 0.01). Data are presented as mean ± SEM (n = 6 per treatment). C = control, D1 = 5% date fruit supplementation, D2 = 10% date fruit supplementation.

Furthermore, linear discriminant analysis (LEfSe) was used to identify differentially expressed bacterial genera and explore changes in biological community characteristics under different date fruit supplementation. The results showed that CHKCI001, Paludicola, and unclassified_Prevotellaceae were significantly enriched in group C; Clostridia, Actinomycetota, and unclassified_Tannerellaceae were significantly enriched in group D2; and norank_F082, F082, and Peptococcaceae were significantly enriched in group D1 (Fig. 4B).

Correlation analysis

The top 30 most abundant cecal bacterial genera were correlated with growth performance, antioxidant profiles, immune indices, and ileal morphology (Fig. 4C). Regarding growth performance, Ruminococcaceae, Thomasclavelia, Akkermansia, and CHKCI001 were negatively associated (p < 0.05) with final body weight (FBW), average daily gain (ADG), feed conversion ratio (FCR), and average daily feed intake (ADFI). In contrast, Desulfovibrio exhibited a positive correlation with ADFI. For antioxidant status, Oscillospira showed negative correlations with T‑SOD, GSH‑Px, T‑AOC, and CAT, while both Oscillospira and CHKCI001 were positively linked to MDA. Regarding immunity and ileal morphology, Clostridia_UCG‑014 displayed a positive correlation with IgG, and Lachnospiraceae was positively correlated with both IgA and IgG; additionally, Lachnospiraceae (villus height), Ruminococcaceae (villus width and crypt depth), Ruminococcus (villus width), and CHKCI001 (villus height) displayed significant positive correlation with intestinal structural integrity (p < 0.05).

Discussion

Dietary polyphenols-rich agro-industrial by-products are increasingly recognized as viable alternatives to in-feed antibiotics in poultry (Al-Farsi and Lee, 2008; Vayalil, 2012; Shah et al., 2025;). Yet, their efficacy in non-conventional species such as Muscovy ducks remains largely uncharacterized. This is the first systemic investigation of the effects of whole date fruit supplementation at 5% and 10% on performance, systemic physiology, meat quality, intestinal histomorphology, and cecal microbiota in Cairina moschata. Our results show that 10% date fruit consistently improve growth, antioxidant capacity, humoral immunity, and gut architecture, while 5% provides intermediate benefits. Notably, the positive responses occur without compromising meat quality, supporting date fruit as a functional, sustainable feed ingredient for duck production.

Date fruit inclusion significantly enhanced growth performance, with final body weight, ADG, and FCR improving in a dose-dependent manner, while ADFI remained unchanged. This pattern suggests improved nutrient utilization rather than increased intake. The findings echo earlier reports in broilers fed date seeds or dried date waste (Attia and Al-Harthi, 2015; El Boushy, Van der Poel and Poel, 2000), as well as in quails supplemented with date pollen (Lehmood, Shawket and Al-Salhie, 2017). The underlying mechanisms are likely dual: date fruit supply readily fermentable carbohydrates (glucose, fructose, sucrose) that provide metabolizable energy, and their phenolic-rich fraction may stimulate digestive enzyme secretion and improve absorptive capacity (Alyileili, El-Tarabily, Belal, Ibrahim, Sulaiman and Hussein, 2020; Shi, et al., 2023). The latter is substantiated by our intestinal morphometric data, where 10% date fruit significantly increased villus height, villus width, and crypt depth, especially in the ileum. Expanded villus surface area facilitates more efficient nutrient uptake, directly contributing to the superior FCR observed. Furthermore, unchanged organ indices across all treatments indicate that growth-promoting effects were not accompanied by organomegaly or pathological hypertrophy, confirming the safety of date fruit supplementation at these inclusion levels. No mortality or clinical health issues occurred during the study, further supporting the tolerability of date fruit at both 5% and 10% inclusion levels.

In contrast to the growth benefits, blood biochemical responses were divergent from typical hypolipidemic reports in chicken (Masoudi, et al., 2011). Date fruit supplementation at 10% raised serum total cholesterol and HDL-C, while LDL-C, triglycerides, glucose, BUN, and ALP remained unaffected. The elevation in HDL-C is particularly noteworthy, as this lipoprotein is associated with reverse cholesterol transport and reduced cardiovascular risk (Shah, Xia, Wang, Yuan, Shah, Shah, Khan, Pan, Shi and Chen, 2026). Previous studies in broilers and quails consistently reported a reduction in total cholesterol, triglycerides and LDL-C alongside increased HDL-C when feeding date seed or date pollen (Itodo, Kanayo, Joshua, Abel, Galadima, Ahmed, Kano, Samuel, Adah and Hassan, 2026; Lehmood, Shawket and Al-Salhie, 2017). However, those investigations primarily utilized date pits or pollen products low in sugar and rich in insoluble fiber and polyphenols, which interfere with lipid absorption and enhance bile acid excretion (Al-Farsi and Lee, 2008). In contrast, whole date fruit contains considerable amounts of simple sugars (∼70-80% dry matter) (Siddiq and Greiby, 2013), which, in a species with distinct lipid metabolism, may stimulate hepatic de novo lipogenesis. Interestingly, the selective increase in HDL-C without a concomitant rise in LDL-C suggests that the hypocholesterolemic effects of date fiber and polyphenols may partially counteract any potential LDL-C-elevating influence of the sugar fraction. High-sugar feed ingredients have been shown to modulate hepatic lipid metabolism in poultry, with some studies reporting hypocholesterolemic effects rather than increases (Hussein, et al., 2016). While we did not measure meat lipid content or fatty acid profiles in this study, the elevated HDL-C without a concomitant increase in LDL-C suggests that the additional cholesterol is primarily transported via the reverse cholesterol transport pathway, which may mitigate potential negative implications. This product- and species-specific response underscores the need to differentiate between date fractions and poultry species when evaluating metabolic outcomes. Importantly, the unchanged BUN and ALP levels indicate that hepatic and renal functions were not compromised, confirming that the observed hypercholesterolemic effect was not pathological but rather a physiological adaptation to the dietary carbohydrate and fiber composition. The overall metabolic profile remained within physiological acceptable ranges for ducks, and the elevated HDL-C may actually confer beneficial effects on systemic lipid transport and immune function, as HDL particles can bind and neutralize bacterial lipopolysaccharides, contributing to reduced systemic inflammation.

The most robust and consistent positive effect was observed in antioxidant status. Both 5% and 10% date fruit markedly elevated serum T-SOD, GSH-Px and T-AOC, while decreasing MDA, a hallmark of lipid peroxidation. Catalase activity was unchanged, suggesting that date polyphenols preferentially enhanced the glutathione-peroxidase and superoxide dismutase pathways. These results align perfectly with studies in broilers and quails, where date seed and pollen similarly amplified enzymatic antioxidant defenses (Alyileili, El-Tarabily, Belal, Ibrahim, Sulaiman and Hussein, 2020; Attia and Al-Harthi, 2015; Lehmood, Shawket and Al-Salhie, 2017). The phenolic compounds, especially flavonoids, tannins, and hydroxycinnamic acids, present in date fruit act as direct radical scavengers and also upregulate endogenous antioxidant enzymes (Al-Farsi and Lee, 2008; Vayalil, 2012). The reduction in MDA indicates diminished oxidative damage to cellular membranes, which is critical for maintaining enterocyte integrity, immune cell function and overall metabolic efficiency (Shah, et al., 2025). Enhanced antioxidant capacity likely constituents a central axis linking dietary supplementation to improved health and performance. The selective enhancement of specific parameters suggests a targeted, regulated response rather than a nonspecific stress reaction. This is particularly important in intensive production systems where oxidative stress from heat, density and dietary factors can compromise both welfare and productivity.

Regarding immune functions, date fruit significantly increased serum IgA and IgG concentrations and simultaneously reduced the pro-inflammatory cytokines TNF-α and IL-6, with IL-1β unaffected. This dual immunostimulatory and anti-inflammatory profile is consistent with previous chicken data, where date seeds elevated interferon-gamma and IL-2, indicating enhanced cell-mediated immune responses (Itodo, Kanayo, Joshua, Abel, Galadima, Ahmed, Kano, Samuel, Adah and Hassan, 2026). The rise in immunoglobulin suggests that date bioactives promote B-cell maturation and antibody secretion. At the same time, the suppression of TNF-α and IL-6 indicates attenuation of chronic low-grade inflammation, a common constraint on growth in intensive poultry systems. The anti-inflammatory effect is plausibly mediated by polyphenols that inhibit NF-κB translocation and downstream cytokine transcription (Vayalil, 2012). This immunomodulation, coupled with strengthened antioxidant defenses, created a physiological environment conducive to better disease resistance and nutrient repartitioning toward muscle accretion. The reduction in inflammatory markers without complete suppression of immunoglobulin production indicates a balanced, homeostasis immune modulation rather than generalized immunosuppression. The lack of effect on IL-1β suggests that date polyphenols may have selective inhibitory effects on specific inflammatory pathways, potentially through differential regulation of cytokine gene expression.

Intestinal morphology improved markedly, particularly in the distal small intestine. Supplementation with 10% date fruit increased villi height, villi width, and crypt depth in the ileum, and also enhanced duodenal villus width and jejunal crypt depth. These histomorphometric changes are classically associated with enhanced digestive and absorptive capacity, corroborating earlier work in which degraded date pits increased villi length and the villus/crypt ratio in broilers (Alyileili, El-Tarabily, Belal, Ibrahim, Sulaiman and Hussein, 2020). The trophic effect may arise from the fermentable fiber and oligosaccharide fraction of date fruit, which serve as substrates for beneficial microbial metabolites, chiefly short-chain fatty acids, that promote epithelial proliferation and differentiation (Alhomsi and Bayraktar, 2025). The decreased inflammatory cytokines further support improved intestinal barrier function, as a healthy mucosa reduces endotoxin translocation and systemic immune activation. The ileum, being the primary site of nutrient absorption in birds, showed the most pronounced improvements, suggesting that date fruit supplementation appears to enhance digestive capacity in the ileum, the primary site of nutrient absorption for efficient nutrient uptake. The increased crypt depth, indicative of enhanced cell turnover and renewal, suggests that date fruit supplementation promotes intestinal homeostasis and resilience against environmental challenges.

Meat quality parameters, pH, color (L*, b*), cooking loss and shear force were largely unaffected by date fruit supplementation. The ultimate pH values (24 h post-mortem) observed in this study ranged from 5.78 to 5.88, which falls within the normal physiological range for poultry meat (typically 5.7–6.0). This indicates that date fruit supplementation did not adversely affect muscle glycolysis or post-mortem metabolism. The only significant change was reduced redness (a*) in the leg muscle in the 10% group. This marginal effect may be attributed to polyphenol-mediated modulation of myoglobin redox states, but it does not translate into any particular sensory or technological defect. The absence of adverse effects on water-holding capacity and tenderness is reassuring, as it confirms that up to 10% date fruit can be safely included without compromising the commercial quality of the duck meat (El-Deek, et al., 2010). The maintenance of meat quality parameters despite significant changes in systemic metabolism and gut microbiota suggests that date fruit supplementation improves physiological function while preserving the meat's intrinsic quality attributes. Future research should examine the fatty acid profile of meat from date-supplemented duck, as polyphenolic compounds may influence lipid composition and oxidative stability during storage.

Cecal microbiota analysis revealed that date fruit supplementation reshaped microbial community composition and increased alpha diversity (Chao, Ace, Sobs, Shannon), indicating a more resilient and diverse ecosystem. Beta-diversity ordination showed clear separation among groups, confirming a treatment-specific shift. At the phylum level, Bacillota (Firmicutes) and Actinomycetota were enriched in the 10% group, while Bacteroidota were more abundant in the control group. This shift toward a higher Firmicutes/Bacteroidota ratio is often associated with enhanced energy harvest in other species and may partly explain the improved FCR observed here (Jumpertz, et al., 2011; Murphy, et al., 2010). However, causation cannot be established from the present correlation data. At the genus level, LEfSe identified Clostridia, Actinomycetota and unclassified Tannerellaceae as enriched in the D2 group, whereas control ducks harbored more CHKCI001, Paludicola and unclassified Prevotellaceae.

Correlation analysis further revealed that Ruminococcaceae, Thomasclavelia and Akkermansia were negatively associated with growth parameters, while Clostridia_UCG-014 and Lachnospiraceae correlated positively with IgG and IgA levels. Notably, Lachnospiraceae and Ruminococcaceae were positively linked to villus height and crypt depth, suggesting that specific fibre-degrading taxa contribute to the observed morphological improvements. These microbial modulations are consistent with the prebiotic action of date fibres and oligosaccharides, which selectively promote beneficial bacteria such as Bifidobacterium and Lactobacillus while suppressing pathogenic populations (Escherichia coli, Salmonella, and Shigella), as previously reported in broilers (Attia and Al-Harthi, 2015; Lehmood, Shawket and Al-Salhie, 2017). By favoring saccharolytic populations that produce butyrate and other short-chain fatty acids (SCFAs), date fruit may enhance gut health and systemic immunity through multiple interconnected mechanisms: direct energy supply to epithelial cells, regulation of intestinal barrier function, modulation of immune responses, and competitive exclusion of pathogens (Parada Venegas, et al., 2019; Rooks and Garrett, 2016). The negative correlation between certain genera (e.g., Akkermansia) and growth parameters is intriguing, as Akkermansia is typically considered beneficial in mammalian systems (Derrien, et al., 2004). This species-specific discrepancy highlights the need for poultry-focused microbiome research to fully understand host-microbe interactions in avian species, which may differ substantially from mammalian models due to differences in digestive anatomy and physiology (McWhorter, et al., 2009). Collectively, the improved growth performance, antioxidant status, immune function, and intestinal morphology observed in date-supplemented ducks appear to be mechanistically interconnected. The phenolic compounds and fermentable fibers in date fruit likely act synergistically: polyphenols directly scavenge free radicals and upregulate endogenous antioxidant enzymes, while fermentable fibers promote beneficial gut microbes that produce SCFAs, which in turn enhance epithelial integrity and modulate systemic immunity. This integrated gut-liver-immune axis may provide a coherent explanation for the dose- dependent improvement in productivity without compromising meat quality.

Several limitations of this study should be acknowledged. First, while correlation analysis revealed associations between specific bacterial genera and host physiological parameters, these findings are correlative and do not establish causation. Future studies employing metagenomic sequencing, gnotobiotic models, or fecal microbial translational research are warranted to confirm causal relationships. Second, the study was conducted over 42 days covering the grower-finisher phase; further research is needed to evaluate the effects of date fruit supplementation across the entire production cycle, including the starter phase. Third, although serum cholesterol increased, we did not measure cholesterol content in the meat or fatty acid profiles. Fourth, while this study focused on systemic antioxidant status, immune function, and gut microbiota, we did not measure tissue-specific antioxidant enzymes in meat or intestine, digestive enzyme activities (e.g., amylase, lipase, protease), or the expression of genes related to intestinal integrity (e.g., tight junction proteins and mucins). These additional analyses would provide deeper mechanistic insights into how date polyphenols and fermentable fibers exert their local effects on intestinal barrier function, digestive capacity, and muscle oxidative stability. Future molecular and biochemical studies are warranted to confirm these mechanisms. Fifth, we did not measure drip loss or water-holding capacity separately from cooking loss; future studies should include these parameters for a more comprehensive assessment of meat quality. Finally, generalizing these findings to other duck breeds or production systems requires validation.

Conclusion

This study showed that dietary date fruit at 10% inclusion is a safe and effective functional additive for Muscovy ducks, improving growth, antioxidant defenses, humoral immunity and intestinal integrity without compromising meat quality. These benefits are mediated through direct antioxidant effects, immunomodulation, enhanced intestinal morphology, and favorable shifts in cecal microbiota. The 5% level also confers benefits, though to a lesser degree. These findings provide a robust scientific foundation for valorizing date fruit as a sustainable feed ingredient in duck production, reducing reliance on synthetic additives. Future research should explore optimal inclusion levels across production phases, evaluate long-term safety and carcass fatty acid profiles, and examine potential synergies with other phytogenic compounds.

Author contributions

Ali Mujtaba Shah: Conceived and designed the study, acquired and analyzed the data, interpreted the results, wrote the manuscript, reviewed and edited the final version, and approved the final version. Zijie Li: Contributed to the study design, analyzed and interpreted the data, critically reviewed and edited the manuscript for important intellectual content, and approved the final version. Liuxiang Chen: Contributed to data acquisition and analysis, participated in the interpretation of results, critically reviewed the manuscript for important intellectual content, and approved the final version. Yue Zhao: Contributed to data acquisition and analysis, participated in the interpretation of results, critically reviewed the manuscript for important intellectual content, and approved the final version. Jihan Jiang: Contributed to data acquisition and analysis, participated in the interpretation of results, critically reviewed the manuscript for important intellectual content, and approved the final version. Yongsi Ma: Contributed to data acquisition and analysis, participated in the interpretation of results, critically reviewed the manuscript for important intellectual content, and approved the final version. Wence Wang: Conceived and designed the study, analyzed and interpreted the data, wrote and edited the manuscript, critically reviewed the final version for important intellectual content, and approved the final version.

All authors have read and approved the final manuscript and agree to be personally and publicly accountable for all aspects of the work, ensuring that any questions regarding the accuracy or integrity of the research are thoroughly investigated and resolved.

Informed consent statement

Not applicable.

Declaration of AI and AI-assisted technologies in the writing process

During the preparation of this work the author(s) used Grammarly tool to improve the grammar and clarity of English language. No other AI tools were used for content generation, data analysis, or figure creation. After using this tool, the author(s) reviewed and edited the content as needed and take (s) full responsibility for the content of the publication.

Ethics declaration

This study was conducted in accordance with the ARRIVE (Animal Research: Reporting of In Vivo Experiments) guidelines. This study was approved by the South China Agricultural University. (Approval No. 2026F190).

Disclosures

The authors declare no conflict of interest.

Data availability statement

The data presented in this study are available upon reasonable request from the corresponding author.