Synergistic impacts of garlic and curcumin on growth performance, carcass characteristics, immunity, antioxidant status, and gut histology of broiler chickens

Abstract

This investigation estimated the synergistic influences of garlic (Ga) and curcumin (Cu) supplementation on the growth performance, carcass features, immunity, antioxidant capacity, and gut histology of broiler chickens. A total of 300 Cobb 500 chicks were assigned to five dietary treatments: T1 (control) fed only basal diet; T2 fed basal diet supplemented with 0.25% Ga+0.25% Cu, T3: fed basal diet supplemented with 0.25% Ga+0.50% Cu, T4: fed basal diet supplemented with 0.50% Ga+0.25% Cu, and T5: fed basal diet supplemented with 0.50% Ga+0.50% Cu. The maximum inclusion level (0.50% Ga + 0.50% Cu, equivalent to 5 g/kg diet each) produced the greatest final body weight, weight gain and feed conversion ratio despite no change in feed intake according to the results which demonstrated a significant enhancement in growth performance with supplementation. While intramuscular fat dropped in the supplemented groups carcass yield and breast protein content increased significantly suggesting improved nutrient utilization and lean tissue accretion. Furthermore, birds given garlic and curcumin had improved mineral content in their breast meat and higher serum calcium and phosphorus concentrations. As evidenced by increased albumin levels and decreased serum AST and creatinine supplementation improved liver and kidney function indicators. IgG and IgM concentrations were highest in T5 birds, indicating an improvement in immune status. Superoxide dismutase activity was higher and malondialdehyde levels were lower, indicating a reduction in oxidative stress and an improvement in antioxidant defenses. Histologically supplemented birds—especially those in T5—showed longer healthier intestinal villi and well-preserved bursal follicles suggesting enhanced immune organ development and gut integrity. T5 achieved the greatest net revenue and efficiency according to economic evaluation. The results showed that curcumin and garlic work in concert to improve broiler performance, health and profitability. This is a natural substitute for antibiotics.

Introduction

In recent decades, the demand for high-quality, affordable animal protein has precipitated a swift expansion of the global poultry business. Broiler chickens are among the most extensively produced livestock species worldwide. Maintaining optimal growth rates, feed efficiency, health, and product quality becomes increasingly challenging as production systems become more intricate (Dosoky et al., 2024; Hamouda et al., 2025). Antibiotic growth promoters (AGPs) were historically used in chicken diets to enhance feed efficiency, augment performance, and reduce mortality by suppressing pathogenic microorganisms (Youssef et al., 2023a; Ashour et al., 2024). Nevertheless, because of the growth of antimicrobial-resistant bacteria and the opportunity of antibiotic remains in poultry meat, the ongoing utilization of AGPs has created serious public health concerns (Mohamed et al., 2025; El-Abasy et al., 2025). Since various nations have prohibited or limited the utilization of AGPs in animal production (Kairalla et al., 2022a, b), there is a vital necessity for sustainable, safe, and efficient substitutes that can enhance output while preserving the health of both consumers and animals (Abd El-Hack et al., 2025; Reda et al., 2026). AGPs may be substituted by phytogenic feed additives (PFAs), especially herbs, spices, and their bioactive compounds (Kairalla et al., 2023; Deeb et al., 2024). Conferring to Abou-Kassem et al. (2025) and Kairalla and Alshelmani (2025), these natural compounds have a collection of biological activities, like antimicrobial, anti-inflammatory, antioxidant, immunomodulatory, and digestive- improving qualities.

Garlic (Allium sativum) and curcumin, the principal curcuminoid obtained from turmeric (Curcuma longa), have garnered significant attention among the several PFAs examined due to their potent and well-documented biological effects. Garlic comprises many sulfur-containing chemicals with potent antibacterial and immunostimulatory effects, including as allicin, ajoene, and diallyl sulfides (Abd El-Ghany, 2024). Research indicates that garlic decreases blood and liver cholesterol, mitigates oxidative stress, and suppresses the proliferation of bacteria, platelets, and other organisms (Prabayanti et al., 2024). Moreover, garlic has demonstrated significant antibacterial properties against bacterial diseases related to poultry (Ariza et al., 2024). Previous studies have demonstrated that garlic significantly enhances the growth performance and several biochemical traits of chickens (Kairalla et al., 2022a). Garlic, when incorporated into feed, has been shown to enhance growth and feed conversion ratio in broilers while decreasing mortality rates (Williams et al., 2024).

Curcumin is a naturally occurring polyphenol, also referred to as diferuloylmethane. It has been utilized as a customary spice in Middle Eastern and Asian cuisines for centuries (Xie et al., 2019). Curcumin is associated with various biological actions, including anti-inflammatory, antioxidant, antibacterial, anticoagulant, antidiabetic, and antiulcer properties (Urošević et al., 2022). Additionally, it improves metabolism and nutrition absorption while preventing anorexia and biliary disorders in livestock (Moniruzzaman and Min, 2020). Curcumin enhanced liver function, resulting in decreased blood glucose, LDL cholesterol, and triglycerides (Safari et al., 2023).

Garlic and curcumin have been the subject of much individual research, but their combined application as synergistic phytogenic additives in broiler diets is still largely unexplored. Garlic and curcumin's complementary modes of action point to a significant potential for synergistic effects. The antimicrobial properties of garlic may contribute to the maintenance of balanced gut microbiota, lowering the pathogenic load and improving the conditions for immune system and nutrient digestion (Abd El-Ghany, 2024). Because of its strong antioxidant properties, curcumin can protect tissues and promote metabolic efficiency by combating oxidative stress, which is a common problem in fast-growing broilers (Xie et al., 2019).

Considering the above factors, the present study was designed to evaluate the effects of dietary combination of garlic and curcumin, on growth performance, carcass traits, immune response, antioxidant status, and gut histology in broiler chickens. The working hypothesis was that simultaneous supplementation of garlic and curcumin, owing to their complementary biological activities, may enhance performance and health-related parameters compared with their individual inclusion. Accordingly, this study aimed to assess the potential of these phytogenic feed additives as natural growth-promoting strategies in broiler nutrition.

Materials and methods

This experiment was done at a private farm in New Salhia City, Sharqia Governorate, Egypt. All experimental procedures were revised and permitted by the Institutional Animal Care and Use Committee of the Faculty of Agriculture, Suez Canal University, Egypt (Approval No: SCU-Agr-REC 61/2025).

Birds, design, and management

A total of 300 one-day-old, unsexed Cobb 500 broiler chicks were obtained from a commercial hatchery. Upon arrival, each chick was separately weighed and randomly allotted into five experimental groups: T1 (control) fed only basal diet; T2 fed basal diet supplemented with 0.25% Ga+0.25% Cu (2.5 g/kg diet each), T3: fed basal diet supplemented with 0.25% Ga+0.50% Cu (2.5 and 5 g/kg diet, respectively), T4: fed basal diet supplemented with 0.50% Ga+0.25% Cu (5 and 2.5g/kg diet, respectively), and T5: fed basal diet supplemented with 0.50% Ga+0.50% Cu (5 g/kg diet each). Each treatment group included four replicates with 15 chicks per replicate, and the average initial body weight was 45.66±0.10 g. Garlic and curcumin powder were purchased from a commercial company (2 M Group, 10th of Ramadan in Sharqia, Egypt).

All diets were formulated in accordance with the NRC (1994) guidelines and provided in mash form across three feeding phases: starter (1–8 d), grower (9–18 d), and finisher (19–35 d). The formulations were designed to be iso-caloric and iso-nitrogenous. Chemical analyses of the experimental diets were carried out at the Department of Animal Production and Fish Resources, Faculty of Agriculture, Suez Canal University, Ismailia, Egypt, following the standard procedures of the AOAC (2002). Table 1 lists the components and approximate composition of the basal feed for each feeding period.

Table 1.

Formulation and chemical analysis (calculated and determined) of experimental basal diets.

Ingredient (%)	Starter (0-8D)	Grower (9-18D)	Finisher (19-35D)
Yellow corn	56.90	61.21	71.70
Soybean meal	30.05	26.00	18.23
Corn gluten meal 60%	6.75	5.05	1.00
Vegetable oil	1.82	3.01	4.00
Calcium carbonate	1.24	1.07	1.00
Di calcium phosphate	1.68	1.57	1.40
Mineral premix 1	0.25	0.30	0.35
Vitamin premix 2	0.25	0.30	0.35
NaCl	0.40	0.60	0.80
DL-Methionine	0.23	0.25	0.27
L-Lysine	0.33	0.44	0.60
Choline chloride	0.10	0.20	0.30
Total	100	100	100
Chemical calculated values %
Metabolizable energy (Kcal/kg)	3000	3104	3226
Crude protein (CP)	22.08	20.66	18.14
Lysine	1.323	1.307	1.227
Methionine	0.610	0.587	0.516
Methionine + Cystine	0.985	0.924	0.777
Calcium	0.940	0.929	0.908
A. Phosphorous	0.450	0.440	0.442
Chemical determined analysis%
Moisture	8.55	8.82	9.05
Crude protein	21.75	19.83	17.77
Crude fiber	3.40	3.73	3.96
Ether extract	5.35	5.74	6.89
Crude ash	5.83	5.22	5.11
Nitrogen free extract	55.12	56.66	57.22

¹Each 1 kg of vitamin mixture contained: 10.000.000 IU vit. A, 5.000.000 IU vit. D3, 80.000 mg vit. E, 3.000 mg vit. K3, 3.000 mg vit. B1, 9.000 mg vit. B2, 4.000 mg vit. B6, 20 mg vit. B12, 15.000 mg pantothenic acid, 60.000 mg Nicotinic acid, 2.000 mg Folic acid and 150 mg Biotin.

²Each 2 kg of minerals mixture contained: 500.000 mg choline chloride, 150.000 mg Cu, 1.000 mg I; 40.000 mg Fe, 100.000 mg Mn. and 350 mg Se.

The chicks were raised on an open-floor system with standardized management conditions; feed and water were offered ad libitum. Every replicate was accommodated in a floor pen bedded with cleaned wheat straw at stocking density of 10 birds/m². Artificial light was provided for 23 hours daily during the first week, followed by a gradual increase in the dark period to 4 hours per day for the remainder of the trial to support normal growth and welfare. Brooding temperature was maintained at 33–35°C during the first week and gradually reduced by 2–3°C weekly to reach 24°C by the end of the experiment. Relative humidity was maintained between 55–65%, and ventilation was ensured through natural air exchange.

All birds were raised in identical environmental, managerial, and hygienic conditions during the five-week trial. Every day, observations were made to document any indications of mortality and rickets. All birds were handled following institutional animal care and welfare guidelines.

Measurements

Growth performance and carcass features

Live body weight (LBW) in addition to feed intake (FI) were determined weekly (days 1, 7, 14, 21, 28, and 35) for each replicate using a digital precision scale to monitor growth trends accurately. Utilizing the data, body weight gain (BWG) and feed conversion ratio (FCR) were determined.

At the end of the experimental phase (5 weeks of age), 16 birds were randomly selected from each treatment group (4 birds/replicate) to represent the mean LBW at the time of slaughter. Birds were then made fast overnight, with water freely available. Birds selected for weighing were then humanely slaughtered using Islamic practices (Alshelmani et al., 2016), with subsequent defeathering, followed by careful removal of the head as close to the skull area as possible. Evisceration of the carcass was carried out via a posterior ventral incision, with subsequent removal of all the individual viscera. Non-edible portions such as the blood, feathers, legs, head, and viscera were disposed of, with subsequent weighing of the eviscerated carcass to obtain carcass dressing. Weighing of individual bird carcass components including proventriculus, intestine, Giblets (heart, liver, and gizzard), immune organs (spleen, bursa of Fabricius), as well as the abdominal fat, was carried out for each of the individual birds (Youssef et al., 2023b, c). carcass percentage was determined using the ratio for carcass weight including Giblets to live body weight, with individual carcass trait expressed as a percentage of live body weight for each treatment group (Alian et al., 2022).

Meat's chemical composition

A meat grinder was used to homogenize the gathered meat samples after each eviscerated carcass (from the same 16 slaughtered birds/treatment) was meticulously deboned. The minced samples were then promptly kept at –20°C until additional examination. Proximate chemical composition was determined using the standard procedures of the AOAC (2002). Dry matter content was ascertained by oven-drying the samples at 105°C for six hours or to reach a stable weight. Nitrogen content was ascertained using the Kjeldahl method and the crude protein content computed as nitrogen multiplied by a factor of 6.25. Crude fat was extracted utilizing Soxhlet apparatus with petroleum ether as solvent, while ash was verified by incinerating the samples in a muffle furnace at 550°C until a constant weight was obtained. Nitrogen-free extract (NFE) was estimated as 100% minus the combined percentages of moisture, crude protein, crude fat, and ash. Calcium and phosphorus concentration was analyzed using atomic absorption spectrophotometry according to Danilchenko et al. (2021).

Serum biochemical indices

At the end of the experimental interval (35 days), blood samples were gathered from the same slaughtered birds representing each treatment group. Serum was divided by centrifugation at 3000 rpm for 15 minutes and then kept at −20°C till further biochemical analysis. Serum concentrations of total protein, albumin, globulin, cholesterol, triglycerides, high-density lipoprotein (HDL), and low-density lipoprotein (LDL), creatinine, uric acid, calcium (Ca), phosphorus (P), aspartate aminotransferase (AST), alanine aminotransferase (ALT), and alkaline phosphatase (ALP) were verified colorimetrically utilizing commercial diagnostic kits (Egyptian Company for Biotechnology, S.A.E., and Diamond Diagnostics, D-P International) following the procedures described by Speicher (1990). Furthermore, immunological response immunoglobulins G and M (IgG, IgM) all procedures performed using commercially available test kits complied with the manufacturer’s instructions as found in Negm et al. (2025). Additionally, birds’ oxidative stress status was measured through superoxide dismutase (SOD) activity and malondialdehyde (MDA) concentration using commercially available kits in accordance with the guidance provided by the kit manufacturers (Spectrum Diagnostics, Egypt and Co. for Biotechnology, S.A.E).

Tibia ash

The right tibia from every carcass, acquired from the same slaughtered birds in every treatment group at the end of trail (35 days), was washed with adhering tissue with care and dried in a hot-air oven at 70°C for 24 hours or to a stable weight. Lipids were extracted from the dried tibiae using petroleum ether in a Soxhlet extractor, followed by re-drying and weighing to determine the defatted bone weight. The defatted tibiae were then ashed in a muffle furnace at 550°C for 24 hours or to a stable weight, and the resultant ash residues were weighed. The tibia ash percentage was determined from the weights of the defatted bone and ash. Atomic absorption spectrophotometry was employed to measure the amounts of calcium and phosphorus in the tibia ash using the Fodor et al. (1974) technique.

Histological status

Samples of the intestine (ileum), and bursa of Fabricius gland were gathered from the same slaughtered birds at the end of trail (35 days) in each treatment group and immediately fixed in 10% neutral-buffered formalin for 24 hours. The fixed tissues were then dehydrated through a graded series of ethanol (70–100%), cleared in xylene, and embedded in paraffin wax. Sections of 5 μm thickness were organized utilizing a rotary microtome (Leica RM 2155, England), stained with hematoxylin and eosin (H&E), and examined under a light microscope (Suvarna et al., 2018; Youssef et al., 2024a). All morphometric measurements were performed using image analysis software (Leica DM 750 Computerized Image Analyzer, Germany) on H&E-stained sections viewed under a light microscope equipped with an HD camera.

Economic Efficiency (EE)

Each treatment group's feed intake was multiplied by the associated cost per kilogram of diet to arrive at the final feed efficiency index. The difference between the money made from selling one kilogram of live broiler and the total amount spent on feed was then used to determine net revenue. To compare the profitability of different treatments, EE was estimated as the ratio of net revenue to total feed cost (Youssef et al., 2024b).

Statistical analysis

SPSS data procedure was examined by the technique of General Linear Model (GLM) (SPSS 2019). The experimental design consisted of multiple independent dietary treatments, each representing a specific combination of garlic and curcumin, in addition to a control group. Therefore, treatments were analyzed as one factor. The Duncan's multiple range test was used to evaluate the mean differences (Duncan, 1955). The model was utilized to do a one-way analysis of variance (ANOVA-test) in the following way:

$$Y_{ij}=\mu +T_i+e_{ij}$$

Where: Y_ij = the observation on the j_th individual from the ith treatments, μ = the overall mean, T_i = the fixed effect of the i_th treatments, and e_ij = the random error associated with the individual ij.

Results

Growth performance

Table 2 shows the influence of dietary supplements of garlic and curcumin on broiler performance. No significant difference in the initial body weights of the groups was seen (P>0.05). However, supplementation caused a significant enhancement in FBW and TBWG (P<0.001). The smallest values for weight were noted by the control group (T1) as 1436.1 g and 1390.6 g for FBW and TBWG, respectively, while the highest was recorded for birds fed the combined high level of garlic and curcumin T5: 0.50% each/kg diet-given FBW and TBWG of 1750 and 1704.6 g, respectively. Even though FI was not affected (P>0.05), the FCR of supplemented groups improved significantly, with T5 showing the most effective FCR at 1.68.

Table 2.

Influence of dietary garlic and curcumin supplementation on growth performance of broiler chickens.

Traits	Treatments					SEM	P value
	CONT	G0.25+C0.25	G0.25+C0.50	G0.50+C0.25	G0.50+C0.50
IBW (1 day)	45.77	45.72	45.60	45.59	45.63	0.05	0.755
FBW (35 day)	1436.11c	1627.78ab	1544.44bc	1616.67ab	1750.00a	2.55	<0.0001
Total FI (g/bird) (1-35 days)	3000.82	2965.56	2842.92	3001.52	2868.24	0.66	0.696
TBWG (1-35 days)	1390.56c	1582.28ab	1499.00bc	1571.28ab	1704.56a	2.54	<0.0001
FCR (1-35 days)	2.16a	1.87bc	1.90bc	1.91b	1.68c	0.04	0.008

^a,b,c Means in the same row with separate superscripts are significantly different at P < 0.05.

CONT: control group (basal diet without supplementation), G0.25+C0.25: basal diet supplemented with 0.25% Garlic+0.25% Curcumin, G0.25+C0.50: basal diet supplemented with 0.25% Garlic+0.50% Curcumin, G0.50+C0.25: basal diet supplemented with 0.50% Garlic+0.25% Curcumin, and G0.50+C0.50: basal diet supplemented with 0.50% Garlic+0.50% Curcumin.

IBW: Initial body weight, FBW: Final body weight at 5 Wks. of age, FI: Feed intake, TBWG: Total body weight gain, and FCR: Feed conversion ratio.

Carcass features

Table 3 displays the features of the carcass. Dietary supplementation resulted in a considerable (P<0.05) rise in both LBW and carcass percentage. In comparison with the control, birds in T2 (0.25% Garlic+0.25%) and T5 (0.50% Garlic+0.50%) had the highest carcass yield (72.45–73.08%). While bone percentage decreased (P=0.039), suggesting increased muscle deposition, meat percentage improved (P=0.05) in all supplemented groups. The percentages of abdominal fat, and giblets did not significantly change. All treated groups' intestinal length (gut cm) increased compared to the controls, indicating better intestinal development.

Table 3.

Influence of dietary garlic and curcumin supplementation on carcass traits of broiler chickens.

Traits	Treatments					SEM	P value
	CONT	G0.25+C0.25	G0.25+C0.50	G0.50+C0.25	G0.50+C0.50
LBW	1525.00b	1676.25a	1493.33b	1575.00b	1667.50a	1.90	<0.0001
Carcass %	70.49b	72.45a	72.32a	73.08a	72.50a	0.12	0.050
Giblets %	4.17	4.55	4.47	4.48	4.27	0.08	0.584
Abdominal Fat %	1.12	0.91	1.20	1.04	1.02	0.06	0.729
Bone %	9.11a	7.68b	8.08b	8.26b	7.64b	0.20	0.039
Meat %	61.38b	64.77a	64.24a	64.83a	64.86a	0.21	0.050
Dressing%	4.89	4.68	4.93	4.81	4.98	0.12	0.966
Gut %	198.75	219.25	223.33	222.00	228.25	1.12	0.181
Gut (cm)	65.55b	69.32a	68.72a	69.31a	69.13a	0.47	0.031

^a,b,c Means in the same row with separate superscripts are significantly different at P < 0.05.

CONT: control group (basal diet without supplementation), G0.25+C0.25: basal diet supplemented with 0.25% Garlic+0.25% Curcumin, G0.25+C0.50: basal diet supplemented with 0.25% Garlic+0.50% Curcumin, G0.50+C0.25: basal diet supplemented with 0.50% Garlic+0.25% Curcumin, and G0.50+C0.50: basal diet supplemented with 0.50% Garlic+0.50% Curcumin.

LBW: live body weight.

Giblets= Heat + Liver + Gizzard.

Meat composition and tibia mineralization

Table 4 illustrates that as supplementation boosted, the crude protein (CP) content of breast meat rose significantly (P<0.001), peaking in T5 (58.62%). Ether extract (EE), on the other hand, dropped dramatically (P<0.001) from 33.93% in T1 to 30.06% in T5. The percentages of moisture, ash, nitrogen-free extract (NFE), and tibia ash did not change (P>0.05).

Table 4.

Influence of dietary garlic and curcumin supplementation on meat chemical composition and tibia ash content of broiler chickens.

Traits	Treatments					SEM	P value
	CONT	G0.25+C0.25	G0.25+C0.50	G0.50+C0.25	G0.50+C0.50
Moisture %	6.83	6.61	7.02	6.72	6.51	0.07	0.183
Crude protein %	54.69d	55.71c	56.46bc	56.74b	58.62a	0.32	<0.0001
Ether extract %	33.93a	32.47b	31.75bc	31.23c	30.06d	0.31	<0.0001
Ash %	3.72	3.75	4.15	4.12	4.05	0.11	0.680
NFE %	0.83	1.47	0.64	1.19	0.76	0.11	0.147
Tibia ash %	34.40	35.54	35.89	35.37	36.19	0.37	0.664

^a,b,c Means in the same row with separate superscripts are significantly different at P < 0.05.

CONT: control group (basal diet without supplementation), G0.25+C0.25: basal diet supplemented with 0.25% Garlic+0.25% Curcumin, G0.25+C0.50: basal diet supplemented with 0.25% Garlic+0.50% Curcumin, G0.50+C0.25: basal diet supplemented with 0.50% Garlic+0.25% Curcumin, and G0.50+C0.50: basal diet supplemented with 0.50% Garlic+0.50% Curcumin.

NFE: Nitrogen Free Extract.

Meat, bone, and serum mineral profile

As shown in Table 5, dietary treatments significantly affected the calcium and phosphorus concentrations of meat and serum (P<0.05). Among these, T5 had higher contents of Ca⁺⁺, and P in meat, the values being 0.63% and 0.78%, respectively, while the lowest values were found in the control group. There was a comparable trend in serum calcium and phosphorus, which also suggested better mineral absorption and application. Nevertheless, there were no considerable variations in the tibia Ca⁺⁺, and P among treatments.

Table 5.

Influence of dietary garlic and curcumin supplementation on meat, bone, and serum mineral profile of broiler chickens.

Traits	Treatments					SEM	P value
	CONT	G0.25+C0.25	G0.25+C0.50	G0.50+C0.25	G0.50+C0.50
Meat
Calcium %	0.47e	0.50d	0.54c	0.58b	0.63a	0.01	<0.0001
Phosphorus %	0.67c	0.67c	0.73b	0.74b	0.78a	0.05	<0.0001
Tibia
Calcium %	32.42	32.63	31.88	31.67	33.07	0.25	0.426
Phosphorus %	13.08	13.19	13.51	13.20	13.57	0.16	0.873
Serum
Calcium (mg/dL)	8.75b	9.40ab	9.94a	10.36a	10.53a	0.18	0.011
Phosphorus (mg/dL)	5.00b	6.07a	5.61ab	6.23a	6.12a	0.15	0.050

^a,b,c Means in the same row with separate superscripts are significantly different at P < 0.05.

CONT: control group (basal diet without supplementation), G0.25+C0.25: basal diet supplemented with 0.25% Garlic+0.25% Curcumin, G0.25+C0.50: basal diet supplemented with 0.25% Garlic+0.50% Curcumin, G0.50+C0.25: basal diet supplemented with 0.50% Garlic+0.25% Curcumin, and G0.50+C0.50: basal diet supplemented with 0.50% Garlic+0.50% Curcumin.

Serum biochemical indices

Serum biochemical parameters are presented in Table 6. Supplementation with curcumin and garlic considerably increased the levels of Albumin (P=0.002) in the T4 and T5 groups. In addition, because of these same supplements, the A/G ratio also significantly increased. The activity of AST decreased (P=0.009) when comparing T5 to the control group, but the activity levels of both ALT and ALP remained statistically the same. Within each of the supplemented groups, the concentration of Creatinine significantly decreased (P=0.001), with the largest decrease occurring in groups T4 and T5, indicating that each group had improved renal function. With respect to the lipid profile, HDL considerably raised (P=0.014) within T5, but none of the other lipid profile measurements (TC, TG, and LDL) changed statistically.

Table 6.

Influence of dietary garlic and curcumin supplementation on serum biochemical parameters of broiler chickens.

Traits	Treatments					SEM	P value
	CONT	G0.25+C0.25	G0.25+C0.50	G0.50+C0.25	G0.50+C0.50
Liver and kidney functions
Total protein(g/dL)	3.52	3.70	3.61	3.84	3.76	0.04	0.095
Albumin (g/dL)	1.58c	1.62bc	1.53c	2.05a	1.90ab	0.05	0.002
Globulin (g/dL)	1.94	2.09	2.08	1.79	1.86	0.04	0.194
A/G	0.82bc	0.83bc	0.75c	1.19a	1.07ab	0.05	0.012
AST (U/l)	174.70a	173.31a	168.52ab	169.39ab	163.26b	1.14	0.009
ALT (U/l)	7.34	7.62	7.34	7.12	7.16	0.09	0.541
ALP (U/L)	332.74	333.30	327.28	320.49	320.73	1.23	0.184
Creatinine (mg/dL)	3.10a	2.98ab	2.82bc	2.59c	2.62c	0.04	0.001
Uric acid (mg/dL)	8.55	8.66	8.82	8.10	8.17	0.12	0.315
Lipid profile
Cholesterol (mg/dL)	161.23	163.13	157.60	158.99	158.82	0.44	0.776
Triglycerides (mg/dL)	70.49	66.41	69.62	65.71	67.66	0.74	0.202
HDL (mg/dL)	58.04b	56.44b	57.26b	60.25ab	65.02a	0.91	0.014
LDL (mg/dL)	44.97	44.37	44.93	44.58	44.33	0.50	0.992

^a,b,c Means in the same row with separate superscripts are significantly different at P < 0.05.

CONT: control group (basal diet without supplementation), G0.25+C0.25: basal diet supplemented with 0.25% Garlic+0.25% Curcumin, G0.25+C0.50: basal diet supplemented with 0.25% Garlic+0.50% Curcumin, G0.50+C0.25: basal diet supplemented with 0.50% Garlic+0.25% Curcumin, and G0.50+C0.50: basal diet supplemented with 0.50% Garlic+0.50% Curcumin.

AST: Aspartate aminotransferase, ALT: Alanine aminotransferase, ALP: Alkaline phosphatase, LDH: Lactate Dehydrogenase, HDL: High-density lipoprotein, and LDL: Low-density lipoprotein.

Immune response and antioxidant status

As revealed by Table 7, the combination of curcumin and garlic significantly improved antioxidant and immune responses. Serum IgG and IgM concentrations were significantly higher in all supplemented groups, with T5 having the highest at 501 ng/mL and 377 ng/mL, respectively (P<0.05). However, the percentages of spleen, and bursa did not significantly change between treatments.

Table 7.

Influence of dietary garlic and curcumin supplementation on immune response and antioxidant status of broiler chickens.

Traits	Treatments					SEM	P value
	CONT	G0.25+C0.25	G0.25+C0.50	G0.50+C0.25	G0.50+C0.50
Lymphoid organs
Spleen %	0.16	0.11	0.13	0.13	0.13	0.01	0.694
Bursa of Fabricius %	0.10	0.10	0.09	0.06	0.12	0.07	0.306
Immunoglobulins
IgG (ng/ml)	385d	432c	444c	475b	501a	0.85	0.004
IgM (ng/ml)	234d	286c	348bc	359b	377a	0.67	0.017
Antioxidant parameters
SOD (U/ml)	153.15b	158.88b	158.94b	168.35a	171.28a	1.64	0.001
MDA (nmol/ml)	3.02a	3.04a	2.91ab	2.72b	2.73b	0.04	0.021

a,b,c Means in the same row with separate superscripts are significantly different at P < 0.05.

CONT: control group (basal diet without supplementation), G0.25+C0.25: basal diet supplemented with 0.25% Garlic+0.25% Curcumin, G0.25+C0.50: basal diet supplemented with 0.25% Garlic+0.50% Curcumin, G0.50+C0.25: basal diet supplemented with 0.50% Garlic+0.25% Curcumin, and G0.50+C0.50: basal diet supplemented with 0.50% Garlic+0.50% Curcumin.

IgG: immunoglobulins Y, IgM: immunoglobulins M, SOD: superoxide dismutase activity, MDA: malondialdehyde.

SOD activity increased, while MDA concentration decreased in T4 and T5, suggesting an improvement in antioxidant defense and a decrease in lipid peroxidation, compared to other experimental groups.

Histopathological examination

Dietary supplementation with Ga and Cu significantly influenced ileal histomorphological traits in broiler chickens (Table 8). Ileal villus height (VH) was significantly increased in all supplemented groups compared to the control (P<0.0001). The highest VH value was noted in T2: 0.25% Ga+0.25% Cu (917.33 µm), followed by T5: 0.50% Ga+0.50% CU group (767.25 µm) and T3: 0.25% Ga+0.50% Cu (748.68 µm). The lowest villus height was noted in the control group (492.33 µm). Crypt depth (CD) was significantly decreased due to dietary treatments (P=0.003). The highest value of CD was noted in the control group (150.50 µm), while the lowest value was noted in T2: 0.25% Ga+0.25% Cu (119.25 µm).

Table 8.

Influence of dietary garlic and curcumin supplementation on histomorphology measurements (µm) of broiler chickens.

Traits	Treatments					SEM	P value
	CONT	G0.25+C0.25	G0.25+C0.50	G0.50+C0.25	G0.50+C0.50
Ileum VH.	492.33d	917.33a	748.68b	650.00c	767.25b	1.23	<0.0001
Ileum CD.	150.50a	119.25c	126.25bc	136.75ab	120.75bc	1.35	0.003
VH. - CD. Ratio	3.30d	7.69a	5.99b	4.75c	6.39b	0.35	<0.0001

^a,b,c Means in the same row with separate superscripts are significantly different at P < 0.05.

CONT: control group (basal diet without supplementation), G0.25+C0.25: basal diet supplemented with 0.25% Garlic+0.25% Curcumin, G0.25+C0.50: basal diet supplemented with 0.25% Garlic+0.50% Curcumin, G0.50+C0.25: basal diet supplemented with 0.50% Garlic+0.25% Curcumin, and G0.50+C0.50: basal diet supplemented with 0.50% Garlic+0.50% Curcumin.

VH.: Villi Height, CD.: Crypt Depth.

As a result, the VH:CD ratio significantly improved for all supplemented groups over the control (P<0.0001). The highest ratio was obtained in T2 with a value of 7.69, followed by T5 and T3, which were 6.39 and 5.99, respectively. The lowest VH:CD ratio was obtained in the control group with a value of 3.30, indicating poorer intestinal absorptive capacity. Generally, the combined supplementation of garlic and curcumin improved ileal mucosal architecture by increasing villus height and reducing crypt depth, thereby improving the VH:CD ratio, with the most intense effect at the 0.25% garlic + 0.25% curcumin level (T2).

Intestinal histology (Fig. 1, Fig. 2) illustrated that whereas control birds, T1, exhibited moderate crypt hyperplasia and focal mucosal erosion, birds in T2 and T5 presented with uniform villi and crypts, with only mild inflammation of the mucosa. Whereas T5 exhibited regular follicular architecture with mild hyperplasia, indicative of better lymphoid integrity and immune competence, sections of bursa of Fabricius from the control group presented marked lymphoid hyperplasia with some necrotic follicles.

Fig. 1.

Histopathological evaluation of the intestinal villi in broilers supplemented with garlic and curcumin.

Fig. 2.

Histopathological evaluation of the Bursa of Fabricius in broilers supplemented with garlic and curcumin.

Economic efficiency

Economic valuation revealed that dietary supplementation with garlic and curcumin increased profitability (Table 9). T5 achieved the greatest net revenue value of 85.81 L.E. and relative efficiency of 106.96%, whereas the control group had a net revenue value of 75.78 L.E. and 100%, respectively. Overall, results indicated that adding 0.50 g of garlic and 0.50 g of curcumin to each kilogram of broiler chicken feed improved growth performance, quality of the meat, immunity, antioxidant status, and financial returns.

Table 9.

Influence of dietary garlic and curcumin supplementation on economic efficiency of broiler chickens.

Items	CONT	G0.25+C0.25	G0.25+C0.50	G0.50+C0.25	G0.50+C0.50
Average feed intake (Kg/bird) Total =a	3000.82	2965.56	2842.92	3001.52	2868.24
Price / Kg feed (L.E.) b	18.600	19.600	20.200	20.000	20.600
Total feed cost (L.E.) = (a × b) =c	55.815	58.125	57.427	60.030	59.086
Average LBW (Kg) = d	1462.17	1556.88	1498.55	1607.00	1609.92
Price of LBW / bird (L.E.) = e	90.00	90.00	90.00	90.00	90.00
Total revenue (L.E.) =d × e = f	131.60	140.12	134.87	144.63	144.89
Net revenue (L.E.) = f - c = g	75.78	81.99	77.44	84.60	85.81
Economic Efficiency = (g/c)	1.358	1.411	1.349	1.409	1.452
Relative Efficiency	100.00	103.90	99.33	103.80	106.96

CONT: control group (basal diet without supplementation), G0.25+C0.25: basal diet supplemented with 0.25% Garlic+0.25% Curcumin, G0.25+C0.50: basal diet supplemented with 0.25% Garlic+0.50% Curcumin, G0.50+C0.25: basal diet supplemented with 0.50% Garlic+0.25% Curcumin, and G0.50+C0.50: basal diet supplemented with 0.50% Garlic+0.50% Curcumin.

Discussion

Growth performance was greatly enhanced by dietary supplementation with garlic and curcumin, particularly at the highest dose level of T5 (0.50% Ga + 0.50% Cu), when compared to controls, even though feed intake did not change. Rather than increasing appetite, this can be explained by improved nutrient utilization (Pan et al., 2022; Xu et al., 2024). Both feed additives' antimicrobial, digestive enzyme, and antioxidant properties support improved intestinal digestion and absorption, which is confirmed by the higher FCR. Besides their suppressive effects on pathogens like Salmonella, E. coli, and Clostridium spp., the organosulfur compounds from garlic, like allicin, diallyl sulfide, and S-allyl cysteine, also reduce the competition of gut microbes for nutrients, which can result in enhanced nutrient assimilation (Guillamon et al., 2021; Deeb et al., 2025). Curcumin exerts positive stimulation on secretion of intestinal digestive enzymes, bile, and activation of the Nrf2 antioxidant pathway, which reduces the intestinal oxidative stress in cells and helps in villus health (Chen et al., 2024).

The synergistic impact in T5 probably indicates the advantageous biological functions of both phytogenics. Curcumin regulates inflammation and safeguards intestinal tissues from oxidative damage, whereas garlic reduces pathogenic load and enhances gut microbial balance. This form of synergy aligns with the findings of Saleh et al. (2018) and Abou-Kassem et al. (2025), who indicated that a blend of phytogenic extracts enhanced nutrient digestibility and weight growth more effectively than individual additions. The observed increase in FBW and BWG in this study parallels the findings of Prasad et al. (2009) and Munir (2015), who reported significant performance enhancement in broilers treated with garlic powder at similar concentrations. Conversely, curcumin administration has enhanced feed conversion ratio and elevated final body weight by improving gut architecture and diminishing inflammatory cytokines. Comparable results have been disclosed in Xie et al. (2019) and Zhang et al. (2024). The current findings suggest that curcumin and garlic, particularly in combination, may serve as effective natural growth promoters capable of substituting antibiotic growth promoters. Enhanced intestinal health, increased antioxidant defense, and modified gut microbial ecology seem to be the mechanisms involved, all of which contribute to improved growth response and nutrient utilization, as noted by Urban et al. (2025).

Supplementing garlic and curcumin considerably raised intestinal length and enhanced carcass traits like meat and overall carcass percentages, while reducing bone percentage insignificantly. These improvements indicate better growth performance and protein accretion, probably due to improved nutrient digestibility and preferential nutrient partitioning toward lean tissue. Curcumin promotes muscle protein synthesis by modulating insulin-like growth factor (IGF-1) and reducing myofibrillar damage due to oxidative stress (Sureshbabu et al., 2023). Garlic bioactives exert hypolipidemic effects through the inhibition of hepatic ATP citrate lyase and HMG-CoA reductase, which inhibits fat deposition and diverts metabolism toward protein accumulation (Ahmed and Wang, 2021; Ahmad et al., 2022). The rise in meat percentage within treated groups agrees with Sharma et al. (2019), who detected an improvement in carcass yield in response to phytogenic supplementation in broilers. Slight reductions in bone percentage suggest increased muscle accretion relative to skeletal growth-a pattern consistent with Irshad et al. (2013)-even though tibia ash was not different among groups. Similarly, unaltered giblets, spleen, bursa, and abdominal fat are suggestive that the supplementation of both garlic and curcumin has neither induced organ hypertrophy nor pathological changes, as evidenced in a previous safety study investigating both compounds in poultry (Fan et al., 2018; Onibi et al., 2009). Though non-significant, abdominal fat exhibited a slight decrease, supporting the lipotropic effect of curcumin and the cholesterol-lowering properties of garlic. Noticeably higher intestinal length in T2–T5 suggests improved gut development, as curcumin stimulates villus growth and intestinal stem-cell activity (Xun et al., 2015), and garlic decrease inflammation and improves microbial balance, promoting deeper crypts and longer villi (Abd El-Ghany, 2024). These intestinal improvements increase absorptive capacity and, therefore, partly explain higher carcass yield. Overall, results indicated that the supplementation of garlic combined with curcumin increases muscle deposition, reduces fat synthesis, and improves intestinal morphometry, thereby enhancing carcass composition.

Garlic and curcumin supplementation significantly enhanced the chemical composition of broiler breast meat. In this context, crude protein was elevated while ether extract decreased, however moisture, ash, nitrogen-free extract, and tibia ash remained unchanged. The elevated CP noted in T5 elucidates an augmented protein synthesis and reduced muscle proteolysis by curcumin, attributed to its activation of the Nrf2 pathway, which safeguards muscle cells from oxidative stress (Sahin et al., 2016) and enhances IGF-1 and mTOR signaling, thereby facilitating muscle growth (Taengthong et al., 2022). The organosulfur compounds in garlic enhance hepatic protein synthesis and improve amino acid digestibility by reducing microbial competition for nutrients in the gut (Bhatwalkar et al., 2021). The augmentation in CP can therefore be elucidated by the collective supplementing. Likewise, the decrease in EE highlights the lipotropic properties of both compounds. Curcumin reduces intramuscular fat by inhibiting adipogenesis via downregulation of FASN mRNA and alteration of PPARγ expression (Pan et al., 2021), whereas garlic inhibits hepatic HMG-CoA reductase and ATP citrate lyase, thereby decreasing lipid synthesis and enhancing fat metabolism (Alam et al., 2018). Consequently, T5 exhibited the lowest levels of EE, supporting prior research indicating a reduction in breast fat of broilers when their diet was supplemented with curcumin and garlic (Brzóska et al., 2015). Consistent levels of hydration and ash indicate that these phytogenics serve as beneficial supplements for enhancing muscle metabolism without jeopardizing water retention or mineral composition. Despite elevated serum and meat mineral concentrations, tibia ash remained unaffected, suggesting that minerals were preferentially allocated to soft tissue rather than bone. This rationale aligns with the assertion of Li et al. (2025) that curcumin enhances calcium absorption without influencing bone ash. This study corroborates previous findings: curcumin enhances meat protein and diminishes fat (Pornanek and Phoemchalard, 2020), while garlic similarly inhibits lipid buildup (Onibi et al., 2009).

Garlic and curcumin supplementation significantly improved Ca⁺⁺ and P in meat and serum without altering the concentrations of tibia Ca⁺⁺ and P, thus indicating improved intestinal absorption and systemic utilization rather than increased deposition into bone. Curcumin can support mineral bioavailability by upregulating calcium transporters such as TRPV6 and PMCA1b (Areco et al., 2015) and enhancing transcellular Ca⁺⁺ movement through calbindin-D9k (Haussler et al., 2013). This is further supported by garlic for better absorption due to prebiotic-like consequences through the enhancement of organic acid production and improvement in mineral solubility (Pacyga et al., 2025). These are the mechanistic justifications for the reasons higher levels of minerals were obtained in meat and serum from T5. In fact, the higher levels of Ca⁺⁺ and P in muscle reflect better mineral deposition in muscles, thereby improving muscle metabolism that supports growth, as calcium is important for mitochondrial activity and muscle contraction (Terrell et al., 2023).The improved serum mineral profile also agrees with that observed by Qasem et al. (2016), where higher serum minerals were recorded with turmeric due to better gut health and antioxidant status, and with Gomaa et al. (2018), where garlic enhanced mineral metabolism by improving renal filtration and reducing oxidative stress. The lack of changes in tibia minerals agrees with Abdel-Moneim et al. (2020), who noted that improvement in serum minerals does not always result in higher tibia ash during rapid growth of muscles.

Supplementing garlic and curcumin significantly affected several serum biochemical indices like albumin, A/G ratio, AST, and creatinine. The enhanced liver function and increased hepatic protein synthesis are reflected in the increase of albumin levels in T4 and T5. Curcumin possesses hepatoprotective properties that help maintain normal hepatic function through the decrease of oxidative stress and inflammation by suppressing NF-κB and activating Nrf2 (Cui et al., 2025). Garlic also presents similar protective effects, as allicin has the potential to scavenge free radicals and enhance glutathione peroxidase activity (Gambari and Finotti, 2025). The lower levels of AST found in the treated groups, particularly in the T5 group, also supports the preventative properties found by Abdel-Moneim et al. (2020). This was due to adding turmeric and garlic to the diets of the broilers, which resulted in a reduction in liver enzyme leakage. Lower creatinine levels indicate less breakdown of protein and improved kidney function. Curcumin inhibits pro-inflammatory substances like TNF-α and IL-6, which reduces the oxidative damage to kidney tissues (Ofori-Attah et al., 2025). On the other hand, garlic decreases the plasma creatinine levels and enhances the perfusion of the kidneys (Abd El-Ghany, 2024).

The lipid profile results indicate a significant increase in HDL in T5, consistent with curcumin's capacity to enhance reverse cholesterol transport via ApoA1 induction (Tian et al., 2013) and the established effects of garlic on cholesterol metabolism by inhibiting HMG-CoA reductase activity (Deeb et al., 2025). The steady levels of triglycerides, LDL, and total cholesterol indicate a balance in lipid metabolism and supplementation, resulting in elevated protective lipid fractions without disrupting lipid homeostasis (Boren et al., 2022). The reduction in triglycerides, LDL, and total cholesterol in T5 may be attributed to the substantial quantities of organic tellurium compounds in garlic bulbs, which block various enzymes involved in cholesterol synthesis (Moses et al., 2024). Abd El-Ghany (2024) asserts that allicin derived from garlic can diminish fatty acid levels in broilers and impede hepatic fat and total cholesterol synthesis. Garlic possesses enzymes that may participate in the regulatory pathways of lipid metabolism, enhancing biliary cholesterol production and reducing the absorption rate of dietary cholesterol (Suleria et al., 2015). A further method for lowering cholesterol involves inhibiting the enzymes 3-hydroxyl-3-methylglutaryl-CoA reductase and acetyl CoA synthetase, which are essential for cholesterogenesis and fatty acid production. Similarly, garlic may influence lipid metabolism by exerting a depressive effect on lipogenic and cholesterogenic activities of certain hepatic enzymes, such as fatty acid synthase, glucose 6-phosphate dehydrogenase, and malic enzyme (Abd El-Ghany, 2024). Our data exhibit comparable trends to previous studies. A study by Molani-Gol et al. (2024) demonstrated that turmeric supplementation enhanced lipid metabolism and decreased liver enzyme levels. Broilers periodically administered garlic exhibit enhanced lipid profiles and reduced AST levels (Lim et al., 2023).

The supplementation of garlic and curcumin significantly improved antioxidant status and immune function, as seen by elevated SOD activity and increased levels of IgG and IgM, alongside diminished MDA levels. The potent immunostimulant and antioxidant characteristics of curcumin and garlic suggest that the immune system will derive advantages from both substances. The immunostimulant effects of curcumin are facilitated by the stimulation of the NF-κB and MAPK signaling pathways, resulting in B cell activation and the synthesis of immunoglobulins, or antibodies (Fan et al., 2018). The sulfur compounds from garlic enhance humoral immunity by mediating cytokine production, activating macrophages, and promoting lymphocyte proliferation (Rodrigues and Percival, 2019). The heightened concentrations of IgG and IgM observed in T4 and T5 indicate augmented primary and secondary immunological responses, corroborated by the findings of Allegra et al. (2022) and Mufungwe et al. (2024). Furthermore, enhancements in antioxidant activity were evidenced by increased SOD enzyme activity in all treated groups relative to the untreated controls. Curcumin is believed to stimulate the production of SOD, catalase, and glutathione peroxidase through the activation of the Nrf2–ARE pathway (Shahcheraghi et al., 2021); furthermore, thiols from garlic have been demonstrated to enhance glutathione synthesis (Rakshit et al., 2023). Curcumin and garlic have demonstrated a significant reduction in MDA levels in T4 and T5 compared to the control groups. Additional research has demonstrated that garlic enhances immunological response (Pourali et al., 2010) and that curcumin elevates antioxidant enzyme activity (Zhang et al., 2018).

The current results confirmed that dietary supplementation with garlic and curcumin markedly improved ileal histomorphology in broiler chickens, as evidenced by increased villus height, reduced crypt depth, and a higher villus height-to-crypt depth (VH:CD) ratio, particularly in T2 and T5. These structural changes indicate enhanced intestinal integrity and absorptive efficiency compared with the control group. Moreover, supplementation with curcumin and garlic clearly enhanced intestinal villus morphology, characterized by more homogeneous, elongated villi and well-organized crypts, especially in the T2 and T5 groups. The synergistic influences of curcumin and garlic on gut health regulation, inflammation reduction, microbial balance improvement, and promotion of epithelial regeneration account for the improvement observed in the supplemented groups. The substantial rise in VH noted in supplemented groups indicates enhanced mucosal development and an expanded absorptive surface area, thereby optimizing nutrient utilization and facilitating growth performance. Numerous studies have documented analogous enhancements in intestinal morphology after phytogenic supplementation, wherein plant-derived bioactive compounds improved villus architecture and the VH:CD ratio in broilers, signifying enhanced gut health and nutrient absorption efficacy (Obianwuna et al., 2024). The decrease in crypt depth seen in treated groups implies diminished epithelial turnover and reduced energy expenditure for tissue renewal, facilitating the allocation of more nutrients towards growth and production. Deep crypts are frequently linked to intestinal stress, inflammation, or accelerated epithelial turnover, whereas shallower crypts signify enhanced mucosal stability and health (Mounia et al., 2018). The higher VH:CD ratio in T2 and T5 confirms that garlic and curcumin work together. It is known that combinations of phytogenic compounds can have additive or synergistic effects on the shape of the intestines by speeding up the activity of digestive enzymes, improving the balance of microbes, and increasing the growth of epithelial cells (Obianwuna et al., 2024). Furthermore, curcumin inhibits NF-κB signaling, reduces pro-inflammatory cytokines such as IL-1β and TNF-α, and increases the expression of tight-junction proteins (occludin, claudin-1), thus improving intestinal integrity and reducing mucosal damage (Chen et al., 2024). Organosulfur compounds present in garlic, such as allicin and diallyl sulfide, are bioactive molecules able to support the growth of beneficial microbiota like Lactobacillus and Bifidobacterium and exert antimicrobial activity against pathogenic bacteria, thus reducing intestinal inflammation and improving villi regeneration (Guillamon et al., 2021). The modulation applied by curcumin on the TLR4 signaling pathway, as well as the capacity to dampen mucosal immune overactivation, is consistent with the finding of lower inflammatory infiltrates in T3–T5, thereby indicating increased gut immune tolerance (Burge et al., 2019). Furthermore, the prebiotic effect of garlic might enhance the production of short-chain fatty acids, including butyrate, which is utilized by colonocytes as energy source and supports villus elongation (Paliwal et al., 2022). The combined use of garlic and curcumin has likely created a gut environment featured by low oxidative stress and improved epithelial turnover, as mirrored by a healthier villus architecture. These findings are consistent with Feng (2025), who reported curcumin-induced improvement of intestinal mucosa, and Abdullah et al. (2010), who found that supplementation of broilers with garlic resulted in an improved goblet cells distribution and increased villus height.

Birds supplemented with garlic and curcumin, especially in T5, exhibited normal lymphoid follicular architecture with low necrosis and distinct follicular borders, indicating enhanced immunocompetence and reduced inflammatory damage. The bursa, as the principal lymphoid organ in birds, is essential for B-cell maturation, and its structural integrity indicates systemic immune activity. Curcumin enhances lymphoid tissue health by blocking pro-inflammatory signaling pathways such as NF-κB and JAK-STAT, and by mitigating the tissue-damaging effects of cytokines (Fan et al., 2018). Thiosulfinates in garlic enhance follicular growth by augmenting the phagocytic activity of macrophages and the proliferative action of lymphocytes (Jafari et al., 2023). The antioxidant efficacy of both phytogenics is further evidenced by a reduced occurrence of necrotic follicles in T3–T5. Curcumin stimulates Nrf2, augmenting endogenous antioxidant enzymes such as SOD and GPx, hence protecting lymphoid tissues from apoptosis generated by free radicals (Das and Vinayak, 2015). Garlic sustains lymphocyte viability by enhancing glutathione synthesis and reducing oxidative DNA damage (Rodrigues and Percival, 2019). The combined supplementation likely enhanced follicular density and averted necrosis by fortifying the antioxidant barriers encasing the bursal follicles.

Dietary supplementation of garlic and curcumin showed marked improvement in economic efficiency, with T5 having the highest net revenue and relative efficiency. While supplementation increased the cost of feeding, gains in body weight and FCR translated to higher income per head. Such results agree with the established phenomenon of improved profitability through enhanced nutrient utilization brought about by phytogenic additives. In like manner, Yang et al. (2015) reported that phytogenics improve economic efficiency because of growth increase and reduction of medical costs. Such superior performance from T5 was underpinned by lowered oxidative stress, strengthened immunity, and increased nutrient digestibility, which lessened losses due to subclinical disease. Garlic's antimicrobial properties contribute to lowered pathogen load and lessen medical interventions (El-Azzouny et al., 2018), while curcumin is anti-inflammatory and antioxidant in the gut, reducing mortality-related losses (Fessler et al., 2023). These consequences are in tandem with Metwally (2023), who, during herbal blends supplementation, observed higher profitability on the part of broilers, and those of Oleforuh-Okoleh et al. (2014), who were able to demonstrate that supplementation with garlic improved carcass yield and reduced feed cost per kg gain.

Conclusions

The supplementation of broiler diets with garlic and curcumin, particularly at 0.50% of each additive, caused considerable synergistic benefits. Combined additives enhanced LBW, FCR, carcass yield, and breast meat protein; advanced mineral utilization and organ function; and offered stronger immunity, greater antioxidant protection, and healthier intestinal and bursal histology that reflects advanced physiological resilience. Such improvements translated into superior economic efficiency. Overall, garlic and curcumin represent an effective, natural alternative to antibiotic growth promoters and support sustainable broiler production through improved performance, health, and profitability.

CRediT authorship contribution statement

Hamada S. Saber: Writing – review & editing, Writing – original draft, Visualization, Formal analysis, Data curation, Conceptualization. Hassan A. Khalil: Writing – review & editing, Writing – original draft, Visualization, Validation, Methodology, Investigation. Mohamed M.A. El-kashef: Writing – review & editing, Visualization, Software, Formal analysis, Data curation. Dalia A.A. Elsayed: Writing – review & editing, Writing – original draft, Visualization, Investigation, Formal analysis, Data curation. Hitham Anas: Writing – original draft, Visualization, Methodology, Investigation, Formal analysis, Data curation. Hanan M. Alharbi: Writing – review & editing, Writing – original draft, Visualization, Validation, Supervision, Funding acquisition, Formal analysis, Data curation. Khairiah M. Alwutayd: Writing – review & editing, Writing – original draft, Software, Resources, Formal analysis, Data curation. Mohammad M.H. Khan: Writing – review & editing, Writing – original draft, Methodology, Formal analysis, Data curation, Conceptualization. Mohamed E. Abd El-Hack: Writing – review & editing, Writing – original draft, Visualization, Methodology, Investigation, Data curation, Conceptualization. Islam M. Youssef: Writing – review & editing, Writing – original draft, Methodology, Investigation, Data curation.

Disclosures

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.