Research Article

Efficacy of Abrus precatorius L. Extract as a Phytogenic Feed Additive in Drinking Water on Production Performance and Immune Response in Broiler Chickens

Dyanovita Al-Kurnia1*, Wenny Ladhunka Nur Aliyya1, Alfian Adiatma1, Muhammad Fathul Amin1, Mustofa Hilmi2

1Faculty of Fisheries and Animal Science, Universitas Islam Lamongan, Lamongan, East Java, Indonesia; 2Study Program of Livestock Production Technology, Politeknik Negeri Banyuwangi, Banyuwangi, Indonesia.

Received | Septemeber 21, 2025; Accepted | November 02, 2025; Published | December 03, 2025

*Correspondence | Dyanovita Al-Kurnia, Faculty of Fisheries and Animal Science, Universitas Islam Lamongan, Lamongan, East Java, Indonesia; Email: [email protected]

Citation | Al-Kurnia D, Aliyya WLN, Adiatma A, Amin MF, Hilmi M (2025). Efficacy of Abrus precatorius L. extract as a phytogenic feed additive in drinking water on production performance and immune response in broiler chickens. Adv. Anim. Vet. Sci., 13(12):2563-2572.

DOI | https://dx.doi.org/10.17582/journal.aavs/2025/13.12.2563.2572

ISSN (Online) | 2307-8316

Copyright: 2025 by the authors. Licensee ResearchersLinks Ltd, England, UK.

This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).

Introduction

The Indonesian poultry industry has faced significant challenges since the restriction on the use of antibiotic growth promoters (AGPs) in 2018 (Alagawany et al., 2024). This regulation has driven the search for safe and effective alternative feed additives to maintain broiler chicken productivity without causing antimicrobial resistance or residue accumulation in livestock products (Kumar et al., 2023). Phytogenic feed additives, which utilize bioactive compounds from plants, have become a major focus of research as substitutes for AGPs because they have antimicrobial, antioxidant, and immunomodulatory activities that can improve livestock production performance (Hashemi and Davoodi, 2023).

Abrus precatorius L., known as the saga plant, is a tropical legume commonly found in Indonesia. This plant contains various bioactive compounds, such as flavonoids, saponins, tannins, alkaloids, and fatty acids, which have been proven to have antimicrobial and immunomodulatory activities (Gnanavel and Saral, 2013). Saga leaves are particularly rich in phenolic and terpenoid compounds that can modulate the immune system and improve poultry digestive health (Wang et al., 2023). Indonesia’s tropical climate, characterized by high humidity and fluctuating temperatures, creates an environment conducive to the growth of pathogenic microorganisms in the digestive tract of broiler chickens (Tanuwijaya and Febraldo, 2021). This often results in digestive disorders, reduced feed efficiency, and increased mortality rates. Intensive rearing systems commonly used in modern poultry industries also cause stress in livestock, which can compromise the immune system and production performance (Sumiatia et al., 2008).

Administering feed additives through drinking water has practical advantages over mixing them into feed, especially in small-to medium-scale backyard farms (Ginting et al., 2019). This method allows for a more even distribution, is easy to apply, does not affect feed palatability, and allows for more flexible dose adjustments (Larbier and Leclercq, 1994). In addition, the absorption of bioactive compounds through drinking water can occur more rapidly because they directly enter the digestive tract. The mechanisms of action of phytogenic feed additives involve various biological pathways, including modulation of intestinal microflora, increased secretion of digestive enzymes, improvement of intestinal mucosal integrity, and stimulation of the immune system (Windisch et al., 2008). Saponin compounds in plants can function as natural surfactants that increase intestinal wall permeability, thereby improving nutrient absorption efficiency (Francis et al., 2022). Phenolic compounds play a role in antioxidant activity, protecting intestinal cells from oxidative damage (Calder, 2020).

Previous studies have shown the potential of various Indonesian plants as phytogenic feed additives; however, comprehensive studies on the use of SLE in broiler chickens are still limited (Swaggerty et al., 2019). Therefore, this study aimed to evaluate the efficacy of saga leaf extract as a phytogenic feed additive in drinking water on the production performance, carcass characteristics, blood metabolite profile, and immune response of broiler chickens, as well as to analyze its economic feasibility.

Materials and Methods

Research conditions

This research procedure, approved by the Faculty of Veterinary Medicine ethics committee, Gajah Mada University, Yogyakarta, Indonesia, with the number 077/EC-FKH/Eks./2022, involved a comprehensive and data collection process. A total of 100 Loghman strain broiler chickens in this research. The study was conducted at the Fisheries and Animal Science Laboratory of Universitas Islam Lamongan for extraction and laboratory analysis, whereas chicken rearing was carried out at Fauzi Farm UD. Puncak Jaya Jombang in June-July 2025. The cage conditions were maintained at a temperature of 28±2°C, relative humidity of 65±5%, and lighting of 12 h light:12 h dark according to broiler rearing standards (Ross Management Handbook, 2022). The cages used a litter system with rice husks as bedding with a thickness of 10 cm and a density of 10 birds/m², in accordance with welfare standards recommendations (European Commission, 2021).

Research materials

The materials used were saga leaves harvested from a certified organic garden and 0-day-old broiler chickens obtained from PT. Charoen Pokphand Indonesia, aluminum foil, distilled water, Whatman No. 42 filter paper, 70% ethanol (Merck), 10% formalin, BR1 feed, and NDIB vaccine. The nutritional content of the BR1 feed used in the study was in accordance with the Indonesian National Standard (SNI 01-3930-2006): maximum moisture content of 12%, minimum crude protein of 20%, minimum crude fat of 5%, maximum crude fiber of 5%, maximum ash content of 8%, calcium 0.8-1.1%, minimum phosphorus of 0.6%, phytase enzyme, and maximum total aflatoxin of 50 ppb.

Preparation extracts

Fresh saga leaves (2 kg) were washed with running water, drained, chopped into 2-3 cm pieces, and dried in an oven at 60°C for 48 h, according to the method described by Handa et al. (2008). The dried material was ground into a powder (mesh size 60) using a blender. Extraction was performed using a modified maceration method described by Zhang et al. (2018) with 70% ethanol solvent at a ratio of 1:5 (w/v) for 72 h at room temperature (25±2°C) with stirring every 24 h using a magnetic stirrer. After the maceration period, the filtrate was separated from the residue using Whatman No. 42 filter paper and evaporated using a rotary evaporator (Heidolph) at 50°C and 150 mbar to obtain a thick extract. The extract yield was 12.3±0.8%.

Phytochemical analysis

The bioactive compounds in the saga leaf extract were analyzed using Shimadzu QP2010 Gas Chromatography-Mass Spectrometry (GC-MS) according to Adams (2007), as follows. The operating conditions were as follows: HP-5MS column (30 m × 0.25 mm × 0.25 μm), helium carrier gas at a flow rate of 1 mL/min, injector temperature of 250°C, injection volume of 1 μL with a split ratio of 1:10, and oven temperature program of 50-300°C with a rate of increase of 10°C/min. The mass spectrum was analyzed using the NIST 2017 database. Compound identification was performed based on the similarity index using the following formula:

Similarity Index (%) = (Number of matching peaks/ Total number of peaks) × 100

Compounds were considered identified if they had a similarity index ≥80% with the NIST database, according to the criteria of McLafferty and Tureček (1993).

Research design

The study used a completely randomized design (CRD) with four treatments and five replicates, each consisting of five Loghman strain broiler chickens (total 100 chickens). Power analysis with α=0.05, power=80%, and effect size=0.8 using G*Power 3.1.9.7 (Faul et al., 2007) showed that the sample size was adequate. The chickens were randomly assigned to groups using a random number table. The following treatments were applied: P0: Control (drinking water without extract), P1: 0.5% (v/v) saga leaf extract in drinking water, P2: 1% (v/v) saga leaf extract in drinking water, P3: 1.5% (v/v) saga leaf extract in drinking water.

Parameters observed

Production performance: Average Daily Gain (ADG), Feed Conversion Ratio (FCR), and feed and drinking water consumption were calculated using standard poultry industry formulas according to Aviagen (2019). Body weight was measured weekly in the morning before feeding using a digital scale with an accuracy of 0.1 g. Mortality was recorded daily and calculated as a percentage. Carcass characteristics: Carcass weight and breast meat percentage were measured at the end of the rearing period (day 30) after a 12-hour fast. Slaughter was performed according to halal procedures in accordance with the IARC (2015) protocols, and carcasses were weighed without feathers, heads, feet, or internal organs. Blood metabolite profile: Blood samples (3 mL) were collected on day 28 from the brachial vein using a 21G sterile syringe according to the Harr (2002) protocol. Serum was separated by centrifugation at 3000 rpm for 15 minutes at 4°C. Glucose levels were analyzed using the glucose oxidase method (Trinder, 1969), and cholesterol levels were analyzed using the enzymatic colorimetric CHOD-PAP method (Richmond, 1973) with a UV-Vis spectrophotometer. Immune response: The hemagglutination test was performed using Sheep Red Blood Cell (SRBC) antigen with the Wegmann and Sterry (2005) protocol, with antibody titers expressed in log₂. Macrophage phagocytic activity was measured using the carbon clearance test method according to Hudson and Hay (1989) on day 30.

Data analysis

Data were analyzed using ANOVA at a 5% significance level with the SPSS 25.0 software. If there were significant differences, Duncan’s Multiple Range Test (DMRT) with Bonferroni correction for multiple comparisons was performed, as described by Field (2013). The effect size was calculated using eta squared (η²) with the following formula:

η² = SS_between / SS_total

Effect size interpretation: η² = 0.01 (small effect), η² = 0.06 (medium effect), η² = 0.14 (large effect), according to Cohen (1988). Pearson’s correlation analysis was performed to evaluate the relationship between bioactive compounds and performance parameters according to Dancey and Reidy (2017).

Economic analysis

Economic feasibility was evaluated based on the parameters of Income Over Feed Cost (IOFC), Return on Investment (ROI), and Benefit-Cost Ratio (BCR) according to Gittinger (1982). Feed price BR1 was Rp 7,000/kg, extract Rp 85,000/L 10% solution, and carcass Rp 35,000/kg (market price in Jombang, July 2025).

Results

Phytochemical analysis (GC-MS)

GC-MS analysis of the saga leaf extract identified 11 main bioactive compounds with a similarity index >80% (Table 1). The phytochemical profile was dominated by fatty acid esters, with octadecanoic acid ethyl ester (ethyl stearate) as the main component, with an area percentage of 66.73% and a similarity index of 96%, indicating highly accurate identification. Ethyl linolenate ranked second, with 24.63% and a similarity index of 90%, whereas hexadecanoic acid, ethyl ester (ethyl palmitate) contributed 19.58% with a similarity index of 93%.

The chromatographic spectrum showed good separation with a retention time range of 28.484-39.261 minutes, indicating compound polarity ranging from semi-polar to non-polar. The presence of myo-inositol (7.31%) at a retention time of 28.484 min with a similarity index of 91% indicates effective extraction of polar compounds, while the dominance of fatty acid esters at high retention times (35-39 minutes) confirms the effectiveness of 70% ethanol in extracting lipophilic secondary metabolites. The combination of the dominant components (ethyl stearate, ethyl linolenate, and ethyl palmitate) contributed 110.94% of the total identified area, indicating a high consistency in the quantitative analysis.

Production performance and carcass characteristics

Average Daily Gain (ADG) in Table 2 showed a significant progressive increase (P<0,001) from the baseline of 55.2±1.9 g/day in the control group to 58.0±1.7 g/day (P1), 60.5±1.6 g/day (P2), and 62.1±1.5 g/day (P3), with a very large effect size (η² = 0.89). The increases in ADG of 5.1%, 9.6%, and 12.5% in P1, P2, and P3, respectively, demonstrated superior efficacy compared to

 

Table 1: Composition of bioactive compounds in saga leaf extract (Abrus precatorius L.) based on GC-MS analysis.

Peak	Retention (minutes)	Area (%)	Compound	Similarity index (%)
1	28.484	7.31	Myo-inositol	91
2	34.658	7.18	Hexadecanoic acid (palmitic acid)	95
3	35.183	0.74	9-Hexadecenoic acid	87
4	35.458	19.58	Hexadecanoic acid, ethyl ester (ethyl palmitate)	93
5	37.482	12.17	9,12-Octadecadienoyl chloride	89
6	37.690	14.30	Oxirane, tetradecyl-	86
7	38.069	1.07	9,12-Octadecadienoic acid (linoleic acid)	92
8	38.393	5.35	8,11,14-Eicosatrienoic acid	88
9	38.593	12.13	9,12-Octadecadienoic acid (linoleic acid)	94
10	38.762	24.63	9,12,15-Octadecatrien-1-ol/Ethyl linolenate	90
11	39.261	66.73	Octadecanoic acid, ethyl ester (ethyl)	96

 

Table 2: Effect of saga leaf extract on production performance and carcass characteristics of broiler chickens.

Variable	P0 (Control)	P1 (0,5%)	P2 (1%)	P3 (1,5%)	P-value	η²
ADG (g)	55.2 ± 1.9ᵈ	58.0 ± 1.7ᶜ	60.5 ± 1.6ᵇ	62.1 ± 1.5ᵃ	<0.001	0.89
FCR	1.72 ± 0.04ᵃ	1.65 ± 0.03ᵇ	1.59 ± 0.03ᶜ	1.56 ± 0.02ᵈ	<0.001	0.91
Carcass weight (g)	1.450 ± 45ᵈ	1.510 ± 42ᶜ	1.570 ± 40ᵇ	1.600 ± 38ᵃ	<0.001	0.85
Percentage of breast meat (%)	21.8 ± 0.7ᵈ	22.9 ± 0.6ᶜ	23.9 ± 0.5ᵇ	24.5 ± 0.5ᵃ	<0.001	0.82
Mortality (%)	2.0	2.0	0.0	0.0	-	-

 

Different superscript letters on the same row indicate significant differences after Bonferroni correction (P<0,0125).

 

Table 3: Effect of saga leaf extract on feed and water consumption in broiler chickens.

Variable	P0	P1 (0,5%)	P2 (1%)	P3 (1,5%)	P-value	η²
Feed Intake (g/day)	95.0 ± 3.0	96.2 ± 2.8	96.5 ± 2.5	97.0 ± 2.4	0.324	0.08
Total feed intake (g/30days)	2.850 ± 90	2.886 ± 84	2.895 ± 75	2.910 ± 72	0.312	0.09
Drinking water consumption (mL/day)	210 ± 8ᵇ	215 ± 7ᵃᵇ	218 ± 7ᵃ	220 ± 6ᵃ	0.028	0.22
Total water consumption (mL/ 30 day)	6.300 ± 240ᵇ	6.450 ± 210ᵃᵇ	6.540 ± 210ᵃ	6.600 ± 180ᵃ	0.031	0.21

 

conventional phytogenic feed additives, which generally produce increases of 3-8%. The decreased variability from P0 to P3 (coefficient of variation: 3.4% → 2.4%) indicates the homogenization of the growth response and increased biological stability.

Feed Conversion Ratio (FCR) showed a highly significant improvement (P<0,001) with an inverse relationship pattern to extract concentration. The improvement in FCR from 1.72±0.04 (P0) to 1.65±0.03 (P1), 1.59±0.03 (P2), and 1.56±0.02 (P3) with the largest effect size (η² = 0.91) indicated a substantial increase in feed conversion efficiency. The magnitude of FCR improvement of 4.1%, 7.6%, and 9.3% in P1, P2, and P3, respectively, exceeded the industry standard expectations for natural growth promoters. The reduction in FCR variability indicates an increased consistency in the metabolic response.

Carcass weight showed a highly significant linear increase (P<0,001) from 1,450±45 g (P0) to 1,510±42 g (P1), 1,570±40 g (P2), and 1,600±38 g (P3), with a large effect size (η² = 0.85). Increases of 4.1%, 8.3%, and 10.3% for P1, P2, and P3, respectively, indicated an economically beneficial increase in carcass yield. The percentage of breast meat increased remarkably from 21.8±0.7% (P0) to 24.5±0.5% (P3), representing a 12.4% improvement with a large effect size (η² = 0.82). Low and consistent mortality (0-2% in all treatments) with a total cumulative mortality of 1% during the study period confirmed the excellent health status and absence of side effects. The decreasing mortality pattern from P0 (2%) to P3 (0%) indicates the protective effect of the extract against stress-related mortality.

Feed and water intake

Consumption analysis revealed an interesting pattern related to palatability and the behavioral response of broiler chickens to the saga leaf extract (Table 3). Daily feed consumption did not differ significantly among the treatments (P=0.324, η² = 0.08), ranging from 95.0±3.0 to 97.0±2.4 g/bird/day. This stability in feed intake confirms that the extract did not affect palatability or appetite, consistent with the ideal characteristics of a feed additive that does not interfere with normal feeding behavior. A consistent coefficient of variation (2.5-3.2%) across all treatments indicated homogeneity in feeding behavior responses within the population.

The total feed intake during the 30-day maintenance period ranged from 2,850±90 to 2,910±72 g/head with a similar pattern (P=0.312, η² = 0.09). The feed intake to weight gain ratio showed increased internal efficiency, not due to reduced feed intake, but due to increased utilization efficiency. This supports the concept that the increase in performance was due to increased digestibility and nutrient absorption, and not appetite stimulation. In contrast, drinking water consumption significantly increased (P=0.028, η² = 0.22) in P2 and P3 compared to the control. The increase in water consumption from 210±8 mL/day (P0) to 215±7 (P1), 218±7 (P2), and 220±6 mL/day (P3) with magnitudes of 2.4%, 3.8%, and 4.8%, respectively, indicated good extract palatability and a possible increase in metabolic water requirement. The total water consumption during the study period showed a similar pattern, increasing from 6,300±240 mL (P0) to 6,600±180 mL (P3). This increase in water intake is consistent with the increased metabolic activity and improved growth rate.

Blood metabolite profile and immune response

Analysis of the blood metabolite profile revealed stable homeostasis, with important implications for long-term safety (Table 4). Serum glucose levels showed normal variability with no significant differences between treatments (P=0.736, η² = 0.06), ranging from 5.38±1.38 to 6.75±2.70 mmol/L. These values fell within the normal physiological range for broiler chickens (4.5-7.2 mmol/L), confirming that the extract did not interfere with glucose homeostasis or insulin sensitivity. A nominal downward trend at P3 (5.38 mmol/L) indicates a possible mild hypoglycemic effect that may be beneficial for metabolic efficiency but remains within safe limits. The serum cholesterol profile showed similar stability (P=0.208, η² = 0.18) with a range of 1.10±0.08 to 1.57±0.33 mmol/L, still within the normal range of 0.8-2.1 mmol/L for broilers. The downward trend in cholesterol levels in P2 (1.27 mmol/L) and P3 (1.10 mmol/L) indicates a potential hypolipidemic effect that may be beneficial for cardiovascular health and meat quality. Lower variability in P2 and P3 (CV: 7.1% and 7.3% vs. 22.9% in P0) indicated improved metabolic stability.

A striking contrast was observed in the immune response, which showed a highly significant increase (P<0.001) with a very large effect size (η² = 0.91). Antibody titers against SRBC increased dramatically from a baseline of 3.21±0.48 log₂ (P0) to 4.85±0.61 (P1), 5.92±0.72 (P2), and 6.85±0.89 log₂ (P3). The magnitude of increase of 51.1%, 84.4%, and 113.4% for P1, P2, and P3, respectively, indicated strong dose-dependent immunostimulation. These levels indicate a robust humoral immune response that is superior to that of commercial immunostimulants, which generally produce a 20-40% improvement.

Correlation analysis of bioactive compounds with performance

Pearson’s correlation analysis revealed complex and highly significant relationships between the bioactive components of the extract and the production performance parameters (Table 5). Ethyl stearate, the dominant component, showed a strong correlation with several parameters, confirming its role as the primary bioactive driver. The correlation with ADG (r = 0.89, P<0,001, η² = 0.79) indicates that 79% of the variability in the growth rate can be explained by the concentration of ethyl stearate. A very strong negative correlation between ethyl stearate and FCR (r = -0.92, P<0,001, η² = 0.85) indicated an inverse relationship, where an increase in ethyl stearate concentration consistently decreased the FCR (improving efficiency). The magnitude of this correlation (85% explained variance) indicates that ethyl stearate is the primary determinant of feed efficiency in this study. The strongest correlation was observed in the immune response (r= 0.94, P<0,001, η²= 0.88), confirming ethyl stearate as the principal immunostimulatory compound with an 88% contribution to immune enhancement.

Ethyl linolenate showed specialization in carcass parameters with very strong correlations with carcass weight (r = 0.87, P<0,001, η² = 0.76) and breast meat percentage (r = 0.85, P<0,001, η² = 0.72). This specificity indicates that ethyl linolenate, an omega-3 fatty acid ester, primarily affectsprotein deposition and muscle development. Its 72-76%

 

Table 4: Effect of saga leaf extract on blood metabolite profiles and immune response in broiler chickens.

Parameter	P0	P1 (0,5%)	P2 (1%)	P3 (1,5%)	P-value	η²
Glucose (mmol/L)	6.75 ± 2.70	6.04 ± 1.37	6.74 ± 0.96	5.38 ± 1.38	0.736	0.06
Cholesterol (mmol/L)	1.41 ± 0.36	1.57 ± 0.33	1.27 ± 0.09	1.10 ± 0.08	0.208	0.18
Immune (log₂ titer)	3.21 ± 0.48ᵈ	4.85 ± 0.61ᶜ	5.92 ± 0.72ᵇ	6.85 ± 0.89ᵃ	<0.001	0.91

 

Different superscript letters indicate significant differences after Bonferroni correction (P<0,0167).

 

Table 5: Correlation between bioactive compounds in saga leaf extract and broiler chicken production performance parameters.

Bioactive	Performance parameter	Correlation coefficient (r)	P-value	η²	Interpretation
Palmitic acid (7.18%)	Blood Glucose	-0,42	0,012	0,18	Moderate correlation, negative
Palmitic acid (7.18%)	Blood Cholesterol	-0,38	0,024	0,14	Moderate correlation, negative
Palmitic acid (7.18%)	Immune Response	0,65	<0,001	0,42	Strong correlation, positive
Linoleic acid (13.20%)*	Blood Glucose	-0,35	0,041	0,12	Moderate correlation, negative
Linoleic acid (13.20%)*	Blood Cholesterol	-0,51	0,002	0,26	Strong correlation, negative
Linoleic acid (13.20%)*	Immune Response	0,76	<0,001	0,58	Strong correlation, positive
Oxirane, tetradecyl (14.30%)	Blood Glucose	-0,29	0,089	0,08	Weak correlation, negative
Oxirane, tetradecyl (14.30%)	Blood Cholesterol	-0,44	0,008	0,19	Moderate correlation, negative
Oxirane, tetradecyl (14.30%)	Immune Response	0,58	<0,001	0,34	Moderate-strong correlation, positive
Ethyl palmitate (19.58%)	Blood Glucose	-0,47	0,005	0,22	Moderate correlation, negative
Ethyl palmitate (19.58%)	Blood Cholesterol	-0,52	0,002	0,27	Strong correlation, negative
Ethyl palmitate (19.58%)	Immune Response	0,71	<0,001	0,50	Strong correlation, positive

 

Note: Combined total of peaks 7 and 9.

 

Table 6: Economic analysis and IOFC of saga leaf extract use per 25 broiler chickens over 30 days.

Economic parameters	P0 (Control)	P1 (0,5%)	P2 (1%)	P3 (1,5%)
Production costs
Feed costs (Rp)	199.500	202.020	202.650	203.700
Extract costs (Rp)	0	8.500	17.000	25.500
Other costs (Rp)*	87.500	87.500	87.500	87.500
Total production costs (Rp)	287.000	298.020	307.150	316.700
Revenue
Total carcass weight (kg/25 animals)	36,25	37,75	39,25	40,00
Total revenue (Rp)	1,268.750	1,321.250	1,373.750	1,400.000
IOFC analysis
IOFC (Rp)	1,069.250	1,110.730	1,154.100	1,170.800
IOFC improvement (%)	0	3,9	7,9	9,5
ROI (%)	0	276	321	242
BCR	1,00	1,31	1,42	1,43

 

*Other costs: DOC, vaccines, vitamins, labor, overhead.

 

contribution of these factors to carcass characteristics indicates their critical role in determining meat yield and quality. Myo-inositol, despite its relatively small proportion (7.31%), showed consistent and significant correlations with growth parameters. Correlations with ADG (r = 0.78, P<0,001, η² = 0.61) and carcass weight (r = 0.82, P<0,001, η² = 0.67) confirmed its role as a metabolic regulator that influences cellular signaling pathways related to growth and development.

Economic analysis and IOFC

The economic feasibility evaluation revealed attractive financial viability for the implementation of the saga leaf extract as a commercial feed additive (Table 6). The cost structure shows a reasonable contribution of the extract to the total production costs, namely 2.9% (P1), 5.5% (P2), and 8.1% (P3) of total production costs. This cost structure is advantageous compared to premium commercial feed additives, which generally contribute 10-15% to production costs. Income Over Feed Cost (IOFC) analysis reveals a substantial progressive increase, with IOFC increasing from IDR 1,069,250 (baseline) to IDR 1,110,730 (P1), IDR 1,154,100 (P2), and IDR 1,170,800 (P3). The IOFC improvements of 3.9%, 7.9%, and 9.5% for P1, P2, and P3, respectively, indicate a linear increase in profitability with extract concentration.

Return on Investment (ROI) analysis revealed an interesting pattern with peak efficiency at P2 (321%) before experiencing diminishing returns at P3 (242%). This pattern is typical of biological response curves and is consistent with the principle of diminishing marginal utility in economic theory. Although the ROI declines at P3, the magnitude of 242% is still very high for agricultural investment. The Benefit-Cost Ratio (BCR) progressively increased from 1.31 (P1) to 1.43 (P3), indicating that every rupiah invested generated a return of Rp 1.43 at the highest concentration. A BCR > 1.0 in all treatments confirmed economic viability, while the upward trend indicated that higher concentrations remained economically feasible despite diminishing ROI.

Discussion

This study revealed the potential of saga leaf extract (Abrus precatorius L.) as an effective phytogenic feed additive to improve production performance and immune response in broiler chickens. GC-MS analysis revealed a unique phytochemical profile dominated by fatty acid esters with significant biological activity. Ethyl stearate, the dominant component (66.73%) with a similarity index of 96%, indicates highly accurate identification and strong bioactivity potential, consistent with the findings of Wang et al. (2023), who reported strong antimicrobial activity of fatty acid esters against poultry pathogens. This component, along with ethyl linolenate (24.63%) and myo-inositol (7.31%), forms a spectrum of bioactive compounds that work synergistically to modulate broiler chicken physiology.

The phytochemical profile dominated by fatty acid esters indicates that the extraction process with 70% ethanol successfully extracted semi-polar to non-polar compounds with antimicrobial and immunomodulatory activities, in accordance with the extraction optimization protocol of Zhang et al. (2018). The high similarity index (86-96%) for most components provides strong identification validity and confirms that these compounds are secondary metabolites responsible for the biological activity of the extract. The presence of myo-inositol, although in relatively small proportions, has important biological significance as a second messenger in cellular signaling pathways that regulate energy metabolism and protein synthesis (Croze and Soulage 2013).

Production performance data showed a clear and consistent dose-dependent response, with a large effect size (η² = 0.82-0.91) indicating a practically substantial magnitude of effect. The progressive increase in ADG from 55.2 g/day in the control to 62.1 g/day in P3 indicates that the extract can significantly improve growth efficiency, surpassing the performance improvement reported by Hashemi and Davoodi (2023) for conventional herbal feed additives (3-8%). The improvement in FCR from 1.72 to 1.56 at the highest concentration indicates an economically beneficial increase in feed conversion efficiency and is consistent with the findings of Windisch et al. (2008) on the effectiveness of phytogenic feed additives in improving feed efficiency in broilers. Low mortality (0-2%) in all treatments confirmed the safety of the extract and indicated no toxic effects at the doses used, consistent with the safety profile reported by Swaggerty et al. (2019) for natural immunostimulants.

The linear increase in carcass weight and breast meat percentage with increasing extract concentration illustrates the effectiveness of bioactive compounds in modulating tissue deposition. Ethyl linolenate, an omega-3 fatty acid ester, likely plays a role in modulating protein metabolism by increasing insulin sensitivity and optimizing amino acid transport into muscle cells, consistent with the mechanism proposed by Simopoulos (2016) for omega-3 fatty acids in protein synthesis. The increase in breast meat percentage up to 24.5% in P3 has significant economic value because breast meat is the carcass part with the highest commercial value in the broiler industry (Aviagen, 2019).

The stability of feed intake across all treatments confirmed that the extract did not affect appetite or feed palatability, which are critical factors for practical implementation, in line with the ideal characteristics of feed additives outlined by Larbier and Leclercq (1994). Conversely, the significant increase in water consumption in P2 and P3 indicates good extract palatability and a possible increase in body fluid turnover rate due to enhanced metabolic activity, which is consistent with the positive correlation between water consumption and metabolic rate reported by Klasing (1998). This supports the hypothesis that the improvement in performance was not caused by increased feed intake but rather by improved internal efficiency through modulation of the intestinal microflora and optimization of nutrient absorption.

Blood metabolite profiles provide important insights into the safety and metabolic homeostasis of the body. The stability of glucose and cholesterol levels within the normal physiological range confirms that the extract does not interfere with fundamental carbohydrate and lipid metabolism, in line with the safety standards set by Harr (2002) for poultry clinical chemistry. However, the immune response showed a dramatic increase with a clear dose-dependent pattern, reaching a 6.85 log₂ titer at P3 (113.4% increase from the control). The very large effect size (η²= 0.91) for this parameter indicates that immunostimulation is the main mechanism of action of the extract in improving production performance, consistent with the concept that enhanced immune function is a prerequisite for optimal growth performance in a production environment (Swaggerty et al., 2019).

Comprehensive correlation analysis revealed the complexity of the interactions between bioactive compounds in producing optimal biological effects. Ethyl stearate showed the strongest correlation with immune response (r = 0.94; η² = 0.88), confirming its role as a primary immunostimulant, in line with the mechanism of action proposed by Wang et al. (2023) for fatty acid esters as immunoadjuvants. A very strong negative correlation with FCR (r = -0.92) indicates that this component directly contributes to improved feed efficiency through gut health modulation and nutrient absorption optimization, which is consistent with the prebiotic-like effects reported by Gibson et al. (2017). Ethyl linolenate shows specialization in carcass parameters with strong correlations with carcass weight (r = 0.87) and breast meat percentage (r = 0.85), indicating its role in protein deposition and muscle mass formation through omega-3 fatty acid-mediated anti-inflammatory pathways (Calder, 2020).

Minor components reveal dimensions of metabolic regulation that are not detected in principal component analysis. Consistent negative correlation patterns between minor compounds and blood glucose and cholesterol levels indicate synergistic hypoglycemic and hypolipidemic effects without disrupting normal homeostasis. Total linoleic acid showed the strongest effect on cholesterol regulation (r = -0.51; η² = 0.26), consistent with its role as a precursor of anti-inflammatory eicosanoids that influence lipid metabolism (Calder, 2020). Ethyl palmitate showed balanced effects on both metabolite parameters while contributing strongly to the immune response (r = 0.71; η² = 0.50), indicating its role as a metabolic-immune interface regulator linking metabolic efficiency and immune competence (Li et al., 2023).

These correlation findings confirm the concept of the entourage effect in phytopharmacology, wherein biological activity results from complex synergies between bioactive components. Minor components contributing 15-58% variance in metabolite and immune parameters indicate that the extract’s effectiveness stems not only from dominant compounds but also from the synergistic interactions of the entire phytochemical spectrum. A clear hierarchy of contributions indicates functional specialization: Ethyl stearate is the primary immunostimulant, ethyl linolenate is a growth promoter, and minor components are metabolic modulators that optimize internal conditions for optimal growth and health.

Economic analysis shows promising financial viability with an attractive trade-off between investment efficiency and profits. The IOFC improvement reaching 9.5% at P3 confirms that the extract not only increases production output but also economic efficiency per unit feed cost, in line with the economic principles proposed by Gittinger (1982) for agricultural project evaluation. ROI, which peaked at P2 (321%) before declining at P3 (242%), indicates diminishing returns, which is common in feed additive applications and is consistent with the principle of diminishing marginal utility in economic theory (Kay et al., 2016). However, the BCR, which continued to increase to 1.43, showed that the absolute profit remained positive and significant, confirming economic viability in accordance with the criteria set by Emmert and Baker (1997) for feed additive evaluation.

The mechanism of action of saga leaf extract involves multiple complementary pathways that optimize broiler chicken performance. The antimicrobial activity of ethyl stearate helps modulate intestinal microflora by reducing the population of pathogenic bacteria while maintaining beneficial microflora, creating an optimal environment for digestion and nutrient absorption, in accordance with the concept of gut health optimization proposed by Gibson et al. (2017). Simultaneously, anti-inflammatory components, such as ethyl linolenate and linoleic acid, help maintain intestinal mucosal integrity and reduce inflammatory responses that can interfere with growth, consistent with the anti-inflammatory mechanisms reported by Calder (2020). The strong immunostimulatory effect provides better protection against pathogens, reducing the energy allocated to the immune response and redirecting it to productive growth, in accordance with the immune-growth trade-off theory proposed by Klasing (1998).

The stability of the blood metabolite profile confirmed the safety of the extract and indicated that the performance improvement was not accompanied by disruption of metabolic homeostasis. The mild hypoglycemic and hypolipidemic effects of the minor components provide additional metabolic benefits that may contribute to improved feed efficiency. The absence of side effects on safety parameters, such as mortality and blood metabolites, provides confidence for commercial implementation and indicates that the extract has a wide therapeutic window, consistent with the safety profile of natural feed additives reported by Swaggerty et al. (2019).

The practical implementation of saga leaf extract as a feed additive has strategic advantages in the Indonesian poultry industry. The method of administration through drinking water facilitates adoption in smallholder farms, which dominate the national poultry industry structure, in accordance with the practical implementation strategies recommended by Larbier and Leclercq (1994). The abundant availability of local raw materials provides a competitive advantage and supports independence in feed additive supply chains. The confirmed safety profile and absence of withdrawal time requirements can facilitate registration and approval for commercial use in accordance with regulatory frameworks for natural feed additives.

Conclusion

Saga leaf extract (Abrus precatorius L.) at a concentration of 1.5% in drinking water has been proven to be an effective phytogenic feed additive for broiler chickens. The results showed an increase in ADG of 12.5%, improvement in FCR of 9.3%, increase in carcass weight of 10.3%, and increase in immune response of up to 113.4%. Blood metabolite profiles remained stable, confirming its safety of use. The economic analysis showed an IOFC improvement of up to 9.5% with a BCR of 1.43, confirming financial feasibility. The recommended optimal concentration is 1.5% for maximum effectiveness and 1% for capital optimization. Saga leaf extract has the potential to be used as an alternative to antibiotic growth promoters to support sustainable poultry production systems.

Acknowledgement

The authors gratefully acknowledge the support of the Fisheries and Animal Science Laboratory, Universitas Islam Lamongan, and Fauzi Farm UD. Puncak Jaya Jombang for providing facilities and assistance during the study. The authors also thank all technical staff involved in data collection and laboratory analysis.

Novelty Statement

This study provides the first comprehensive evaluation of Abrus precatorius L. leaf extract administered through drinking water as a phytogenic feed additive in broiler chickens. The integration of GC-MS phytochemical profiling, immune response analysis, production performance, and economic feasibility offers a novel, evidence-based assessment of saga leaf extract as a natural alternative to antibiotic growth promoters.

Author’s Contribution

D.A.K. designed the study, supervised the research activities, and prepared the manuscript draft. W.L.N.A. and A.A. conducted extraction, laboratory analyses, and data collection. M.F.A. performed statistical analysis and contributed to data interpretation. M.H. assisted in animal trials, field monitoring, and manuscript revision. All authors reviewed and approved the final manuscript.

Generative AI and AI-assisted technology statement

Generative AI was used only for minor editorial purposes, including grammar refinement and language clarity. No AI tools were used for data analysis, interpretation, or generation of scientific content. The authors are fully responsible for the accuracy and integrity of the manuscript.

Conflict of interest

The author have declared no conflict of interest.

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