Open Veterinary Journal, (2026), Vol. 16(6): 3357-3366

Research Article

10.5455/OVJ.2026.v16.i6.7

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Effectiveness of Ketapang (Terminalia cattapa Linn.) extract as a feed additive on performance, erythrocyte and hemoglobin levels in broiler chickens

Kadek Rachmawati^1*, Kuncoro Puguh Santoso¹, Emy Koestanti Sabdoningrum², Rochmah Kurnijasanti¹, Aswin Rafif Khairullah³ and Nanik Hidayatik¹

¹Department of Basic Veterinary Medicine, Faculty of Veterinary Medicine, Universitas Airlangga, Surabaya, Indonesia

²Department of Animal Husbandry, Faculty of Veterinary Medicine, Universitas Airlangga, Surabaya, Indonesia

³Research Center for Veterinary Science, National Research and Innovation Agency (BRIN), Bogor, Indonesia

*Corresponding Author: Kadek Rachmawati. Department of Basic Veterinary Medicine, Faculty of Veterinary Medicine, Universitas Airlangga, Surabaya, Indonesia. Email: kadek-r [at] fkh.unair.ac.id

Submitted: 17/01/2026 Revised: 22/04/2026 Accepted: 04/05/2026 Published: 05/06/2026

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Abstract

Background: Ketapang (Terminalia catappa Linn.) leaves contain bioactive compounds, such as flavonoids, tannins, and saponins, which act as antioxidants, antimicrobials, and immunostimulants. These compounds may serve as an ecofriendly alternative to antibiotic growth promoters in broilers. Previous studies focused mainly on growth, leaving a gap in additional growth indices and hematological assessments.

Aim: This study evaluated the effects of 5%, 10%, and 15% Ketapang leaves (KL) extract administered orally as a supplement (w/v of dosing solution) on growth performance [percent daily gain, protein efficiency ratio, feed conversion ratio (FCR), and survival rate] and blood parameters (erythrocyte count and hemoglobin concentration) in broilers.

Methods: Twenty male broilers (21 days old, n=5 per group) were assigned to four groups: control (P0) and KL extract doses of 5% (P1), 10% (P2), and 15% (P3) orally for 14 days. Data were analyzed using one-way analysis of variance with Tukey’s honest significant difference post-hoc test.

Results: The KL extract significantly (p < 0.05) improved the measured growth and hematological parameters, with highly significant effects observed for weight gain, FCR, erythrocyte count, and hemoglobin concentration (p < 0.01). The FCR values were 1.78 (P0), 1.61 (P1), 1.52 (P2), and 1.67 (P3). The weight gain increased by 14%, 18%, and 10% for P1, P2, and P3, respectively, relative to the control. Erythrocyte counts increased from 2.22 × 10⁶/mm³ (P0) to 2.50 × 10⁶/mm³ (P1), 2.96 × 10⁶/mm³ (P2), and 2.37 × 10⁶/mm³ (P3), while hemoglobin increased from 7.28 g/dl (P0) to 8.07 g/dl (P1), 9.05 g/dl (P2), and 7.87 g/dl (P3). Regression and correlation analyses confirmed that 10% KL extract (P2) was the optimal dose.

Conclusion: The 10% KL extract was well tolerated under the conditions of this short-term 14-day study and was associated with improved growth performance and hematological parameters. Further studies with larger sample sizes and extended observation periods are needed to confirm the long-term efficacy and safety of this drug.

Keywords: Blood, Broiler, Feed additive, Performance of chicken, Terminalia cantata Linn.

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Introduction

In Indonesia, the poultry industry is a crucial sector in providing fast and efficient animal protein (Lokapirnasari et al., 2024). Broiler chickens are a leading commodity due to their rapid growth, efficient feed conversion, and high market demand (Riber and Wurtz, 2024). However, maintaining optimal growth performance amidst stress factors, feed quality, and potential pathogen infection is the main challenge in broiler farming (Oke et al., 2024). Therefore, strategies to increase broiler productivity rely not only on conventional feed formulations but also on natural feed additives that function as immunostimulants, antioxidants, and metabolism boosters (Obianwuna et al., 2024).

Antibiotic growth promoters (AGPs) have been widely used as feed additives to improve broiler performance (Paul et al., 2022). However, their use has been restricted or banned in several countries, including Indonesia, due to their potential to trigger antimicrobial resistance (AMR) and leave harmful residues in livestock products (Pasaribu et al., 2024). Recent surveillance data from Nigeria have reported an increasing prevalence of multidrug-resistant Escherichia coli and Salmonella spp. isolated from poultry farms, highlighting the contribution of antimicrobial misuse in livestock production to AMR emergence (Ajibola et al., 2025). This has prompted the search for safe, effective, and sustainable natural alternatives, particularly following the European Union ban on AGPs in 2006 and increasing reports of AMR bacteria in poultry (WHO, 2017). The extract of Ketapang leaves (KL) (Terminalia catappa Linn.), a tropical plant widely grown in Southeast Asia, is one potential candidate (Ramanan S et al., 2025).

KL extract contains bioactive compounds, such as flavonoids (e.g., quercetin and kaempferol derivatives), hydrolyzable tannins (e.g., punicalagin and corilagin), saponins, and alkaloids, which act as antioxidants and immunomodulators relevant to blood health and growth performance in broilers (Mwangi et al., 2024; Gulcin, 2025). Antioxidant activity protects erythrocytes from oxidative damage, while tannins and flavonoids may improve nutrient absorption and intestinal health by modulating gut microbiota and digestive enzyme activity, supporting growth indices measured in this study (Xu et al., 2022).

Erythrocytes and hemoglobin are key indicators of broiler physiological status and health (Nwaigwe et al., 2020). Blood hematobiochemical parameters reveal immune-related conditions and overall wellness (Chaparro and Suchdev, 2019; Zálešáková et al., 2025). Evaluating these parameters provides an objective picture of the effects of feed additives on broiler physiology (Yuanita et al., 2023).

KL extract can improve performance and hematological status in other animals, such as tilapia and catfish, by increasing hemoglobin and erythrocyte levels and reducing oxidative stress (Sanda Lembang et al., 2023; Zarqa et al., 2023). Prior research examined Terminalia catappa Linn. leaves’ effects on growth performance in broilers, but primarily measured feed intake, body weight gain, and feed conversion ratio (FCR) without assessing additional growth indices [percent daily gain (PDG), protein efficiency ratio (PER), FCR, and survival rate] or evaluating hematological parameters beyond erythrocyte and hemoglobin values (Mirino et al., 2025). However, limited information is available regarding its effects on additional growth indices, including PDG, PER, FCR, and survival rate, as well as key hematological responses represented by erythrocyte count and hemoglobin concentration. Furthermore, the optimal oral dose and the relationship between broiler growth performance and hematological responses remain unclear (Suprijatna et al., 2025).

This gap highlights the novelty of the present study, which comprehensively evaluates graded doses of KL extract on both advanced growth performance indices and hematological profiles in broiler chickens, followed by correlation and regression analyses to determine the optimal dose-response relationship.

Therefore, this study was conducted to evaluate the effects of graded doses of KL extract on growth performance (% weight gain, PDG, PER, FCR, and survival rate) and hematological parameters (erythrocyte count and hemoglobin concentration) in broilers. Statistical, Pearson correlation, and regression analyses were performed to determine the optimum dose of aqueous solution.

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Materials and Methods

Place and time of the research

This research was conducted in the experimental animal cage of the Faculty of Veterinary Medicine, Airlangga University, and the Pharmacology Laboratory, Airlangga University, from October 2024 to December 2024. The environmental conditions were strictly controlled: temperature, 28°C–32°C; relative humidity, 55%–65%; and a 16 hours light:8 hours dark cycle. To maintain air circulation, the cages were ventilated using a mechanical forced-air system. The stocking density was 10 birds/m², and the battery cages measured 120 × 60 × 50 cm (length × width × height), providing adequate space per bird according to the National Research Council (NRC) standard guidelines (NRC, 1994). The environmental conditions were monitored daily using a digital thermometer and hygrometer.

Ketapang extract

5 kg of KL from Tawangmangu, Central Java, Indonesia were authenticated from the Center for Research and Development of Medical Plants and Traditional Medicines (voucher specimen: B2P2TOOT).

Fresh leaves (5 kg) were washed and oven-dried at 50°C (Memmert UN55, Germany) for 7 days until they reached a constant weight. Dry simplicia powder (0.5 kg) was obtained after drying, corresponding to a 10% dry weight yield relative to fresh leaves.

The dried material was ground into powder and soaked in 2 l of 96% ethanol for 3 days with occasional stirring (maceration method). The extract solution was filtered through a sterile muslin cloth followed by Whatman No. 1 filter paper and evaporated using a rotary evaporator at 50°C under reduced pressure to obtain a thick brown extract. The extract yield was 18% (w/w).

Phytochemical analysis revealed total phenolics (45 mg GAE/g extract), total flavonoids (22 mg QE/g extract), tannins (15 mg/g extract), and saponins (10 mg/g extract). The major bioactive compounds were further quantified using high-performance liquid chromatography (Shimadzu LC-20AT, C18 column, detection at 280 nm). Gas Chromatography–Mass Spectrometry analysis identified additional phenolic acids and terpenoid constituents. Quality control included duplicate extraction, yield calculation, and validation against reference standards. Doses (5%, 10%, and 15%) are expressed as w/v (g extract per 100 ml solution) (Harborne, 1998; Azwanida, 2015).

Monitoring of health and mortality

All birds were monitored daily for disease clinical signs, behavioral changes, and overall health status throughout the study. Body condition was scored weekly based on a scale of 1–5, where 1 indicates emaciated and 5 indicates obese, following standard guidelines (Kestin et al., 1992). Feed and water intake, activity levels, feather condition, and signs of distress (panting, lethargy, and abnormal posture) were recorded.

No mortality occurred in any group during the 14-day treatment period (days 21–35). All birds maintained normal body condition scores (3–4), were active, exhibited normal feeding behavior, and showed no clinical signs of disease, indicating that supplementation with 5%, 10%, and 15% KL extract was well tolerated.

Treatment of broiler chickens with

Day-old male broilers were kept in brooder cages until they were 14 days old and fed commercial starter feed ad libitum. All broilers were provided with a commercial basal diet consisting of starter feed from days 0–14 and finisher feed from days 15–35. Table 1 presents the detailed composition and nutrient content of both diets, including metabolizable energy, crude protein, amino acids, minerals, and vitamin premix. At 15 days of age, 20 birds were randomly assigned to four groups (n=5 per group). The birds were acclimated for 7 days before treatment.

Table 1. Composition and nutrient content of the basal diets (starter and finisher) used in the broiler study.

At 21 days of age, the KL extract was freshly prepared daily and dissolved in 1% Carboxymethyl Cellulose (CMC)-Na as a suspending agent. Dosing solutions were prepared at concentrations of 5 g/100 ml (5%), 10 g/100 ml (10%), and 15 g/100 ml (15%) w/v. Each bird received 1 ml of solution per 100-g body weight via oral gavage once daily at 08:00 AM for 14 consecutive days (days 21–35). Thus, the administered doses were equivalent to approximately 500 mg/kg body weight (BW) (P1), 1,000 mg/kg BW (P2), and 1,500 mg/kg BW (P3), adjusted weekly according to individual BW measurements to maintain accurate mg/kg BW dosing.

The control group (P0) received an equivalent volume of 1% CMC-Na without extract via oral gavage under identical handling conditions. Daily health monitoring was performed, and no mortality occurred (Siddik et al., 2022; Das et al., 2024; Nag et al., 2025).

Growth performance parameters

Calculated as previously described. The survival rate was 100% across all groups, consistent with the absence of morbidity or mortality (Li et al., 2024). The following parameters were calculated from feed consumption and weight gain:

• FCR=total feed intake (g)/total weight gain (g)
• DFI (g/day)=total feed intake (g)/number of days
• Percent daily gain (PDG, %/day)=[(Wt − W0) / (W0 × t)] × 100, where Wt is the final body weight (g), W0 is the initial body weight (g), and t is the time (days).
• PER=weight gain (g)/protein intake (g)
• Relative growth rate (RGR, %)=((Final Weight − Initial Weight) / Initial Weight) × 100
• Survival rate (%)=(Number of surviving chickens/Initial number of chickens) × 100

Hematological measurements

On day 35, the birds were fasted for 4 hours before blood collection to minimize postprandial variations. Blood samples were collected from the brachial vein between 08:00 and 09:00 using sterile syringes containing Ethylenediaminetetraacetic Acid as an anticoagulant. Immediately after collection, blood was gently mixed with the anticoagulant and stored at 4°C until analysis, which was performed within 2 hours of sampling.

Erythrocyte measurement

Erythrocyte counting was performed using a Neubauer hemocytometer after dilution according to standard procedures. Counting was performed in duplicate, and the results were expressed as × 10⁶/mm³ (MG Science Institute, 2021).

Hemoglobin measurement

The cyan-methemoglobin method (Drabkin’s reagent) is considered standard. Briefly, 5 ml of Drabkin’s reagent was prepared in a clean test tube, and 20 µl of whole blood was added and gently mixed to ensure complete hemolysis. The mixture was incubated at room temperature (25°C–27°C) for 5–10 minutes. A blank reagent (Drabkin’s reagent without blood) was prepared simultaneously. The absorbance of the sample and blank was measured at 540 nm using a UV–Vis spectrophotometer (Shimadzu UV-1800, Shimadzu Corporation, Kyoto, Japan).

A commercially prepared standard cyanmethemoglobin solution was used to generate a calibration curve. The standard solutions at 2, 4, 6, 8, and 10 g/dl were measured in triplicate, and a linear regression equation (y=m•x + b, where y=absorbance and x=hemoglobin concentration) was calculated for each assay. Quality control included duplicate measurements of all samples, periodic remeasurement of standards, and verification of linearity (R² > 0.99) before sample analysis. The hemoglobin concentration of each sample was calculated from the standard curve and expressed in g/dl. Analysis was completed within 2 hours of blood collection to ensure sample integrity (Whitehead RD Jr et al., 2019).

Statistical analysis

Data were analyzed using SPSS v25.0. The normality of the residuals was assessed using the Shapiro–Wilk test, and the variance homogeneity was tested using Levene’s test. One-way analysis of variance was applied for group comparisons; when significant (p < 0.05), Tukey’s honestly significant difference (HSD) post hoc test was used. Superscript letters (a, b, and c) indicate significant differences between treatment means at p < 0.05. Exact p-values are reported where appropriate, and 95% CIs are provided. The effect sizes (partial η²) were calculated to quantify the magnitude of the treatment effects. Pearson correlation and regression analyses were performed to determine the relationships and identify the optimal dose. Statistical power was considered limited due to the small sample size (n=5 per group), which is acknowledged as a limitation of the study.

Ethical approval

The Animal Care and Use Committee, Airlangga University, approved this study (Ethical number: 223/HRECC.FODM/III/2023). All experimental procedures, including animal housing and management, oral gavage administration of Ketapang extract, blood collection from the brachial vein, daily health monitoring, and implementation of humane endpoints to minimize distress, were reviewed and approved.

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Results

Growth performance

The effects of KL extract on broiler growth performance and hematological parameters are presented in Table 2. The initial body weight at day 21 was 520 ± 10 g/bird across all groups; the final body weight at day 35 ranged from 1,038 ± 15 g (P0) to 1,220 ± 12 g (P2).

Table 2. Growth performance and hematological parameters of broilers treated with KL extract (mean ± SD).

The highest feed consumption was observed in P2 (10% KL extract), followed by P1 (5%) and P3 (15%), whereas the control group (P0) had the lowest intake. Statistical analysis was performed using one-way analysis of variance followed by Tukey’s HSD post-hoc test. One-way ANOVA revealed significant treatment effects on feed consumption (p=0.0003), weight gain (p=0.0001), FCR (p=0.0002), PDG (p=0.0001), RGR (p=0.0001), and PER (p=0.0002). The superscript letters indicate significant pairwise differences.

Gain in body weight and growth efficiency

Weight gain, PDG, RGR, and protein efficiency ratio (PER) were calculated from feed intake and weight measurements. The P2 group exhibited the highest performance across all parameters. The FCR was lowest in P2 (1.52), indicating higher feed efficiency, while P0 had the highest FCR (1.78). The survival rate was 100% in all groups.

The CV% ranged from 0.56% to 3.05% for growth parameters, indicating low within-group variability and good experimental consistency.

Abbreviations: FCR=feed conversion ratio; PDG=percent daily gain; RGR=relative growth rate; PER=protein efficiency ratio; DFI=daily feed intake.

Hematological parameters

Blood parameters, including erythrocyte count and Hemoglobin (Hb) concentration, were analyzed. The erythrocyte and hemoglobin values remained within the reference ranges for broilers. P2 had the highest erythrocyte count and hemoglobin levels (2.963 × 10⁶/mm³ and 9.045 g/dl, respectively). One-way ANOVA demonstrated significant treatment effects for erythrocyte count (p=0.0014) and Hb concentration (p=0.0008). The erythrocyte and hemoglobin CV% values ranged from 4.1% to 14.9%, reflecting moderate biological variation.

Correlation and regression analysis results

Pearson’s correlation analysis revealed strong positive associations between weight gain, PDG, and hematological parameters. Regression analysis indicated that 10% KL extract (P2) was the optimal dose for maximal growth and hematological response. The Pearson’s correlation coefficients between growth performance and hematological parameters are presented in Table 3.

Table 3. Pearson correlation coefficients.

Pearson’s correlation analysis demonstrated strong positive correlations between weight gain and PDG (r=0.97, p < 0.001), hemoglobin (r=0.91, p=0.002), and erythrocyte count (r=0.88, p=0.004).

The FCR showed a strong negative correlation with weight gain (r=−0.93, p=0.001) and PDG (r=−0.95, p < 0.001), indicating improved feed efficiency at higher growth performance.

Linear regression analysis between KL extract dose and weight gain demonstrated a quadratic dose-response trend, with the optimal response observed at the 10% dose (P2). Figure 1 shows the quadratic regression analysis illustrating the effect of KL extract dose on broiler weight gain.

Fig. 1. Quadratic regression analysis showing the relationship between dose of KL extract (%) and weight gain (g/day) in broilers. The highest predicted growth response was observed at approximately 10% supplementation.

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Discussion

The administration of KL extract (Terminalia catappa Linn.) as a feed additive significantly affected the growth performance of broiler chickens, including feed consumption, weight gain, feed conversion, blood erythrocyte, and hemoglobin levels. The initial body weight at day 21 was 520 ± 10 g/bird, and the final body weight at day 35 was P0=1,038 ± 15 g, P1=1,180 ± 12 g, P2=1,220 ± 12 g, and P3=1,140 ± 15 g. The 10% dose (P2) showed the most favorable overall growth and hematological outcomes among the tested groups under the conditions of this 14-day study. All statistical comparisons were based on one-way analysis of variance followed by Tukey’s HSD post-hoc test.

Effect of ketapang extract on production performance

The significant increase in feed consumption in the treatment groups indicates that the KL extract was associated with higher voluntary feed intake than the control. Mechanistically, KL extract contains flavonoids, tannins, and saponins, which may modulate gut microbiota, stimulate digestive enzymes, and reduce oxidative stress, potentially improving nutrient absorption and metabolic efficiency. However, these mechanisms were not directly measured in this study and are discussed only as proposed mechanisms based on previous literature (Allyn et al., 2018; Chen et al., 2022; Lemoni et al., 2025). Low-dose tannins can further stimulate digestive enzyme secretion and improve microflora balance, supporting better feed use (Xu et al., 2022).

The P2 group showed the highest feed consumption, weight gain, PDG, RGR, and PER and the lowest FCR, indicating improved feed conversion efficiency and growth performance at this optimal dose. The slight decline in performance at the 15% dose (P3) may reflect reduced palatability and gut tolerance due to higher antinutrient content (tannins and saponins), which could manifest as lower feed intake and slower growth, although no clinical signs of physiological stress were observed during daily monitoring (Esenbuga and Ekinci, 2023; Sharma et al., 2023). However, specific digestive tolerance parameters were not evaluated and therefore cannot be interpreted conclusively. Regression analysis confirmed that 10% KL extract is the optimal supplementation level for maximizing growth and hematological outcomes.

Influence on erythrocyte levels

Erythrocyte levels are key indicators of oxygen transport capacity and overall blood health (Mairbäurl and weber, 2012; Paarvanova et al., 2023). P2 significantly increased erythrocyte counts (2.96 × 10⁶/mm³, p < 0.05), whereas P1 and P3 did not significantly differ from the control. Pearson’s correlation analysis showed positive correlations between erythrocyte counts and growth performance indices (weight gain, PDG, and FCR), indicating that improved hematological status contributes to enhanced productivity.

The flavonoids and tannins in KL extract may contribute to erythrocyte stability and support hemopoiesis, as proposed mechanisms reported in previous studies; however, this was not directly confirmed in the present study (Aimola et al., 2014; Zahra et al., 2024). Speculative mechanistic explanations regarding protection against oxidative damage or stimulation of hemopoiesis have been minimized because oxidative stress markers and bone marrow activity were not assessed in this study.

Effect on Hb levels

Hemoglobin levels, which are closely linked to erythrocyte counts, reflect oxygen-carrying capacity and tissue oxygenation (Jensen, 2009). The highest hemoglobin levels were observed in P2 (9.05 g/dl, p < 0.05), with all values remaining within the reference ranges, indicating that the condition was well tolerated during the short-term experimental period (Dasofunjo et al., 2023). Regression and correlation analyses confirmed the relationship between hemoglobin concentration, erythrocyte counts, and growth indices, reinforcing the optimal 10% dose recommendation.

Proposed mechanisms from previous literature suggest that flavonoids and polyphenols may support Hb synthesis and erythropoiesis through antioxidant activity; however, these pathways were not directly assessed in the present study and should not be interpreted as findings derived from our data (Adeneye, 2009; Liu et al., 2019).

Physiological and production implications

Higher erythrocyte and hemoglobin levels improve oxygen transport, supporting aerobic metabolism and protein synthesis, which aligns with lower FCR and higher growth efficiency in P2 (Prihambodo et al., 2021; Astuti et al., 2022). However, specific metabolic pathways were not directly examined in this study. This highlights the integrated effect of KL extract on both digestive and systemic physiological functions, contributing to broiler productivity.

Dose and safety evaluation

High concentrations of tannins and saponins can reduce digestibility and affect cell membranes (Özoğul et al., 2025). Within the parameters measured in this short-term study, the 10% KL extract dose was well tolerated and associated with no observable clinical signs of toxicity during the 14-day trial period. The results indicate that 10% was the most favorable dose among those tested under the present experimental conditions rather than indicating full “optimization.”

However, this study has some limitations, including a relatively small sample size (n=20) and a short trial duration (14 days), which may restrict the generalizability of the findings. In addition, only selected hematological parameters were measured. Multivariate analyses were not performed due to sample size limitations.

Economic considerations

Although the study primarily focused on growth performance and hematological parameters, the economic aspects of using KL extract as a feed additive were not formally assessed. The cost of extract production, including raw material collection, drying, ethanol extraction, and standardization, could influence the feasibility of commercial broiler production (Azwanida, 2015). A preliminary estimate suggests that KL extract can be produced at a moderate cost at a small scale. However, formal cost–benefit analysis and comparison with commercial feed additives are needed to evaluate the practical adoption of KL by farmers. Therefore, future studies should investigate the economic feasibility and scalability of KL supplementation.

Future directions

Future studies should explore optimal extraction methods (e.g., solvent type, temperature, and duration) to maximize bioactive compound yield to further develop KL extract as a practical feed additive. To ensure consistent efficacy, standardization procedures for extract composition and potency should be established. Investigations into commercial application pathways, including integration into feed formulations, shelf-life stability, and large-scale production feasibility, are recommended.

In addition, long-term feeding trials are necessary to assess chronic effects on growth performance, hematological health, and broader safety parameters, including liver and kidney function biomarkers, histopathology, and additional hematological indices, if prospective evaluation is intended. Such studies will provide robust data to validate the preliminary findings of this short-term trial and facilitate its translation into sustainable poultry production practices.

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Conclusion

This study fills a research gap by evaluating the detailed growth and hematological parameters of broilers fed with KL (Terminalia catappa Linn.) extract, which previous studies did not fully address. Among the tested treatments, the oral administration of 10% KL extract (P2) for 14 days showed the most favorable overall response, with improved feed consumption, weight gain, % weight gain, PDG, RGR, PER, FCE, and 100% survival rate. Erythrocyte and hemoglobin levels were also enhanced, indicating potential benefits for blood health and oxygen-carrying capacity. Regression and correlation analyses indicated that the optimal supplementation level under the present experimental conditions was 10% and was positively associated with improved growth performance and hematological status. Oral administration of high doses (15%) may reduce performance due to the antinutritional effects of phenolics, affecting palatability and nutrient use. However, these findings should be interpreted within the limitations of this pilot study, including the relatively small sample size and short experimental duration of 14 days. To confirm efficacy and tolerability, further long-term studies with larger sample sizes and dedicated toxicity assessments are needed. Overall, oral supplementation with 10% KL extract was well tolerated during the study period and may serve as a promising natural alternative to AGPs in broiler production.

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Acknowledgments

Thanks to Faculty of Veterinary Medicine, Institute for Research and Community Services Universitas Airlangga and Universitas Airlangga.

Conflict of interest

The authors declare no conflict of interest.

Funding

This research is supported by the Faculty of Veterinary Medicine and Research and Community Service Institute, contract number: 1506/UN3.FKH/PT.01.03/2024, Airlangga University, Indonesia.

Authors’ contributions

K.R. and N.H.: Conceived, designed, and coordinated the study. A.R.K.: Designed data collection tools, supervised field sample and data collection, and performed laboratory work and data entry. K.P.S.: Validation, supervision, and formal analysis of data. E.K.S.: Reagents, materials, and analysis tools were contributed. R.K.: performed statistical analysis and interpretation and participated in the preparation of the manuscript. All authors have read, reviewed, and approved the final version of the manuscript.

Data availability

All data are available in the revised manuscript.

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