JAHP_14_1_333-338

INTRODUCTION

Chicken meat is increasingly favored worldwide due to its high-quality protein, low fat content, and elevated levels of polyunsaturated fatty acids (PUFAs): Making it a healthier alternative to red meats such as beef and pork (Brenes and Roura, 2010; Ahmed et al., 2013; Suiryanrayna and Ramana, 2015). In the Philippines, poultry production remains a vital component of the livestock sector, contributing significantly to food security and the agricultural economy. In 2023, chicken liveweight production was recorded at 1.95 million metric tons (MMT): Reflecting a 4.3% increase from the previous year’s output of 1.87 MMT, highlighting steady growth in the sector (Philippine Statistics Authority, 2024). In the same year, the average Filipino consumed about 15.95 kilograms of poultry meat per year, totaling 1.934 MMT in national consumption (OECD-FAO, 2021). This is forecasted to increase by 9.6% to 2.12 MMT by 2025 and further to 2.287 million metric tons by 2030, with per capita consumption expected to reach 16.30 kilograms (OECD-FAO, 2021; IndexMundi, 2025). These trends underscore the growing demand for poultry meat and the need for sustainable and safe production practices.

Historically, antibiotics have been employed in animal production since the 1940s to enhance growth rates and feed efficiency (Castanon, 2007; Al-Khalaifah, 2018). The administration of antibiotics through animal feed, drinking water, or at sub-therapeutic levels has been widely adopted to enhance animal growth performance and productivity (Kumar et al., 2018). In poultry and livestock production, antibiotics are commonly utilized to improve growth rates, improve feed conversion efficiency, and prevent disease and treatment of E. coli infections, thereby enabling producers to achieve higher meat yields within shorter periods (Mehdi et al., 2018; Ghimpeteanu et al., 2022; Widodo et al., 2022; Ampode, 2024). However, the prolonged use of antibiotics has led to the emergence of antibiotic-resistant bacteria, posing significant public health challenges due to its contribution to the emergence and spread of antimicrobial resistance (AMR) (Tang et al., 2017; Kirchhelle, 2018; Nazeer et al., 2021; Xu et al., 2022).

The World Health Organization (WHO) estimates that bacterial antimicrobial resistance (AMR) was directly responsible for 1.27 million global deaths in 2019 and contributed to 4.95 million deaths. Projections suggest that, without effective interventions, AMR could lead to over 39 million deaths between 2025 and 2050 (WHO, 2025; Institute for Health Metrics and Evaluation, 2024). In response to these concerns, several countries have implemented bans on the use of antibiotic growth promoters (AGPs) in animal feed, including Sweden in 1986, the European Union in 2006, the USA in 2017, and China in 2020 (Grave et al., 2006; Thanner et al., 2016; Wen et al., 2022; EU, 2003). This has spurred research into sustainable alternatives, such as probiotics, enzymes, and phytobiotics, with dietary acidifiers showing potential as substitutes for antibiotics in poultry production (Hume, 2011; Rahman et al., 2022).

Phytobiotics, or plant-derived bioactive compounds, are increasingly studied for their potential to enhance poultry health and performance (Ampode and Mendoza, 2022). Among these, phytochemicals and phytogenics are particularly promising due to their immunomodulatory, antimicrobial, and antioxidant properties (El-Sayed et al., 2024). Their complex modes of action have prompted ongoing research into their effects on animal health and productivity (Kumar et al., 2022). Oregano (Origanum vulgare L.) is a notable example, rich in phenolic compounds and essential oils such as thymol and carvacrol, which exhibit strong antimicrobial, antioxidant, and anti-inflammatory activities (Zaazaa et al., 2022; Alagawany et al., 2018). Dietary inclusion of oregano in poultry has been associated with improved feed efficiency, digestion, and disease resistance, potentially reducing economic losses. However, its effects on broiler performance as an alternative to antibiotics remain underexplored. Hence, this study investigates the potential of oregano leaf powder as a phytobiotic alternative to synthetic antibiotics to enhance broiler growth, cell-mediated immunity, carcass yield, and economic traits, contributing to more sustainable poultry production systems.

MATERIALS AND METHODS

Experimental birds, design and treatments

The study was conducted in accordance with the standard rearing practices outlined in the Philippine National Standards for Good Animal Husbandry Practices, specifically addressing animal farming, health, and welfare (PNS/BAFPS, 2008). Seventy-five day-old broiler chicks, regardless of sex, were used in the study. The experiment employed a Completely Randomized Design (CRD) with five (5) dietary treatments, with three replicates per treatment and five birds per replicate. The treatments were as follows: T1: negative control (commercial ration); T2: Positive control (homemade ration [HMR] without oregano powder [OP] and without synthetic antibiotics [SA]); T3: HMR with 1% OP; T4: HMR with 3% OP; and T5: HMR supplemented with the recommended amount of synthetic antibiotic.

Preparation of brooder pen and cages

All facilities were cleaned and disinfected a week before the arrival of broiler chicks to prevent any potential disease outbreaks. The brooder pen was made of a plastic screen with a dimension of 1m x 2m which was used from day 1 to the 10th day. The commercial disinfectant was used to thoroughly clean and disinfect the pen before the experiment began or as needed. The broiler chicks were moved to experimental cages after the 10th day of the brooding period, with each bird receiving a standard floor space of one square foot per bird (PNS/BAFPS, 2008). The experimental cages were constructed in an elevated colony type made from bamboo and plastic screen with dimensions of 80cm x 100 cm.

Brooding and health management

Broiler chicks were housed in a brooding pen for 10 days with a 50-watt electric bulb as an artificial heat source to maintain body temperature. Chicks were also observed for behavioral indicators of health and stress, such as activity levels, vocalizations, and feeding behavior. Any abnormal behavior prompted immediate environmental adjustments. A commercial feed booster mash was provided ad libitum for 10 days, along with clean water. Feeding trays were cleaned regularly to support healthy growth and prevent disease. A commercial disinfectant solution was used to disinfect experimental pens. Proper sanitation and cleanliness were practiced during the study period. To ensure the experimental area was secure from disturbances, appropriate biosecurity precautions, such as erecting fences to keep out unauthorized persons or stray animals, were employed.

Preparation of oregano powder

Oregano leaves were collected from Brgy, Blingkong, Lutayan, Sultan Kudarat. The collected leaves were sun-dried for 5 days before grinding using a mechanical grinder. The powdered leaves were sent to Lipa Quality Control Center Inc., 001 J.P. Laurel, National Highway, Lipa City, Batangas, 4217 for the proximate analysis (AOAC, 2016).

Feed formulation

Proximate analysis was conducted on all feedstuffs, and the resulting data served as the basis for formulating the broiler diets. The nutritional requirements of the broiler chicks were considered in accordance with the Philippine Recommends for Livestock Feed Formulation to ensure a balanced and appropriate nutrient intake throughout the experimental period. The feed formulation process followed a trial-and-error method tailored to the two physiological stages of broiler chickens: The starter phase (20% crude protein [CP]) and the finisher phase (18% CP). The homemade rations were composed of ground yellow corn, rice bran D1, U.S. soybean meal, fish meal, copra meal, dicalcium phosphate, limestone, lysine HCl, DL-methionine, L-tryptophan, vitamin premix, salt, and vegetable oil. The calculated nutrient composition is presented in Table 1.

Feeding and water management

All experimental birds were fed ad libitum throughout the 38-day study period. Diets were administered according to the assigned treatments, which included homemade rations and oregano-supplemented feeds from the starter (11–24 days) to the finisher phase (25–38 days). Each treatment group was provided with a separate feed container to avoid cross-contamination. Feeders were monitored regularly, and once a significant reduction in feed volume was observed, additional feed was added promptly to maintain consistent availability. All feeds provided were weighed accurately to monitor and record feed intake per group, following standard practices in feed intake measurement (NRC, 1994; Leeson, 2007). Fresh, clean drinking water was provided ad libitum to all experimental groups. Feed and water containers were cleaned daily to maintain hygiene and minimize the risk of disease outbreaks, in line with proper poultry management protocols (FAO, 2003).

Table 1: Composition and calculated analysis of starter and finisher ration

	Starter 11−24 days	Finisher 25−38 days
Calculated analysis
Crude Protein, %	20.00	18.00
Metabolizable Energy, Kcal	2848.91	2883.31
Avail P, %	0.49	0.49
Calcium, %	0.87	0.99
Lysine, %	1.35	1.08
Methionine, %	0.45	0.45
Met+Cys, %	0.64	0.67
Tryptophan, %	0.35	0.37
Vit. Premix1, %	0.80	0.80

1Vitamin Premix (fine quality/texture; 500 g contains) dicalcium phosphate 97%, Vit. 150,000 units, Vit. D3 30,000 units, Vit. E 500 I.U., Potassium Iodine 100mg, Carrier q.s. ad 500mg, Manganese Sulfate 3,500mg, Ferrous Sulfate1,500mg, Copper Sulfate 1,500 mg, Cobaltous Sulfate 30mg, Zinc Sulfate 200mg.

Statistical analysis

All collected data were subjected to a one-way Analysis of Variance (ANOVA) using the Statistical Tool for Agricultural Research (STAR). Means with significant differences were further compared using the Tukeys Honest Significant (HSD) test. A p-value of <0.05 is considered significant.

RESULTS AND DISCUSSION

Body weight

The effect of oregano powder (OP) as a phytobiotic alternative to synthetic antibiotics on broiler growth performance is presented in Table 2. Body weight showed no significant differences among treatments throughout the experimental period (11–24 days, 25–38 days, and 11–38 days) (p > 0.05). At day 11, all treatment groups had statistically similar body weights, indicating initial uniformity and ensuring that any subsequent variation could be attributed to the dietary interventions. During the early growth phase (11–24 days): birds supplemented with 1% OP (T3) and 3% OP (T4) recorded the highest body weights, followed by those in the synthetic antibiotic group (T5). The negative control (T1) and the homemade ration without additives (T2) exhibited slightly lower weights. In the later phase (25–38 days): T4 maintained the highest body weight, followed by T3, suggesting that higher OP inclusion may support sustained growth. A similar trend was observed for final with T4 (1470.40 g) outperforming all other groups, followed by T3 (1434.93 g): T1 (1398.33 g): T5 (1394.67 g): and T2 (1358.13 g). Although these differences were not statistically significant, the numerical trends suggest that 3% OP supplementation may enhance growth performance comparably or even more effectively than synthetic antibiotics. These findings contrast with previous studies (Barreto et al., 2008; Avila-Ramos et al., 2012; Kirkpinar et al., 2014), which reported no growth-promoting effects of oregano or its essential oil constituents. Similarly, Ri et al. (2017) found no significant differences between birds fed antibiotics and those receiving OP; however, a notable improvement in growth was observed in OP-treated birds, particularly during the grower phase. The current results support the potential of OP as a viable alternative to antibiotics in promoting broiler growth.

Body weight gain and average daily gain

Statistical analysis revealed no significant differences in body weight gain (BWG) and average daily gain (ADG) among the treatment groups (P>0.05; Table 2). However, numerical trends suggest a potential benefit of oregano powder (OP) supplementation. Broilers fed 3% OP (T4) achieved the highest cumulative BWG (1181.47 g) and ADG (84.39 g/day): followed by the 1% OP group (T3) with 1146.33 g BWG and 81.88 g/day ADG. These gains surpassed those of the control group (T1: 1109.27 g BWG, 79.23 g/day ADG) and the 0% OP group (T2: 1068.47 g BWG, 76.32 g/day ADG): which showed the lowest performance. Interestingly, broilers fed synthetic antibiotics (T5) displayed growth metrics (1105.13 g BWG, 78.94 g/day ADG) comparable to the control but slightly lower than those in the OP-supplemented groups. This suggests that dietary supplementation of OP at 3% inclusion may offer superior physiological benefits compared to synthetic antibiotic growth promoters.

The parallel trends in BWG and ADG across treatments highlight their biological linkage, as ADG provides a daily measure of BWG. These improvements may stem from oregano’s bioactive compounds, such as thymol and carvacrol, which enhance digestive enzyme activity, nutrient absorption, and gut health (Zaazaa et al., 2022; Giannenas et al., 2018). The superior performance of the 3% OP group may also be attributed to oregano’s antimicrobial,

Table 2: Growth performance of broilers fed with graded levels of oregano powder as a phytobiotic alternative to synthetic antibiotic.

Parameters	Treatments					P-value	CV
Parameters	T1	T2	T3	T4	T5	P-value	CV
Body weight, g
Initial weight	289.07	289.67	288.60	288.93	289.53	0.626 ns	0.32
11-24, days	869.33	863.20	879.67	878.87	871.87	0.894 ns	1.60
25-38, days	1398.33	1358.13	1434.93	1470.40	1394.67	0.127ns	3.44
11-38, days	1398.33	1358.13	1434.93	1470.40	1394.67	0.127ns	3.44
Body weight gain, g
11-24, days	580.27	573.53	591.07	589.33	582.33	0.865ns	1.97
25-38, days	529.00	494.93	555.27	592.13	522.80	0.135ns	7.85
11-38, days	1109.27	1068.47	1146.33	1181.47	1105.13	0.121ns	4.31
Average daily gain, g
11-24, days	41.45	40.97	42.22	42.10	41.60	0.865ns	1.97
25-38, days	37.79	35.35	39.66	42.30	37.34	0.135ns	7.85
11-38, days	79.23	76.32	81.88	84.39	78.94	0.121ns	4.31
Feed intake, g
11-24, days	970.60ab	977.47ab	933.00b	934.60b	1010.07a	0.019*	1.26
25-38, days	1030.33	1018.27	1061.80	1066.33	1034.07	0.743ns	4.97
11-38, days	2000.93	1995.73	1994.80	2000.93	2044.13	0.817ns	2.91
Feed conversion ratio
11-24, days	1.68	1.71	1.58	1.59	1.74	0.069ns	3.95
25-38, days	1.96	2.09	1.91	1.80	1.98	0.523ns	9.87
11-38, days	1.80	1.88	1.74	1.69	1.85	0.184ns	5.30

CV: Coefficient of variation; ab superscripts within row indicates significant difference at p<0.05; nsnot significant (p>0.05); *means with different superscripts within row is significantly different (P<0.05); T1: Commercial Ration (Negative Control); T2: HMR (Homemade Ration) without OP (Oregano Powder) and SA (Synthetic Antibiotic); T3: HMR + 1% OP; T4; HMR + 3% OP; T5; HMR+ SA

antioxidant, and anti-inflammatory effects (Ampode and Mendoza, 2022; Al-Kassie, 2010): which likely reduce intestinal pathogen load and oxidative stress, improving energy utilization. As expected in broiler physiology, growth rates were generally higher during the starter phase (11–24 days) than the finisher period (25–38 days): aligning with findings by Ri et al. (2017): who noted that early rapid growth is associated with more efficient feed conversion, which diminishes with age.

Feed intake

As shown in Table 2, the feed intake of broiler chickens showed a significant difference during the early growth phase (11–24 days; p < 0.05): but no significant differences were observed during the finisher phase (25–38 days) or over the entire period (p > 0.05). During the early phase, birds fed the synthetic antibiotic (SA) treatment (T5) had the highest feed intake (1010.07 g): significantly greater than those receiving 1% OP (T3, 933.00 g) and 3% OP (T4, 934.60 g). The negative control group (T1) and the homemade ration without SA and OP group (T2) had intermediate values (970.60 g and 977.47 g, respectively). The elevated early feed intake in the SA group may be attributed to improved gut health and reduced pathogenic load, enhancing appetite. However, this increased intake did not translate to improved growth performance or feed efficiency, suggesting possible suboptimal nutrient utilization or digestibility in the antibiotic-fed birds compared to those receiving oregano supplementation.

In contrast, birds supplemented with 1% and 3% oregano powder consumed less feed during the early phase but achieved higher body weight gains and better feed conversion ratios. This indicates more efficient nutrient utilization, likely due to oregano’s bioactive compounds, such as carvacrol and thymol, which are known to enhance digestive enzyme activity, improve intestinal morphology, and modulate gut microbiota (Giannenas et al., 2018). The absence of significant differences in feed intake during the later phase and overall trial period suggests that early-phase dietary responses had a lasting impact on broiler growth performance. These findings highlight the importance of early gut development and feed efficiency in shaping long-term productivity (NRC, 1994; Azeem et al., 2023; Shani and Ilani, 2024). Overall, the results support the potential of oregano powder as an effective alternative to antibiotics in broiler diets, aligning with current efforts to reduce antibiotic use in poultry production.

Feed conversion ratio

The feed conversion ratio (FCR) was not significantly affected by dietary supplementation of oregano powder (Table 2). Although no significant differences were observed among treatments across all growth phases (p > 0.05): The numerical trends offer meaningful insights into feed efficiency associated with the different supplementation strategies. These trends may reflect subtle influences of OP inclusion levels on nutrient utilization and growth dynamics, even in the absence of statistically detectable effects. The lowest cumulative FCR (11–38 days) was recorded in broilers fed 3% oregano powder (T4 = 1.69): followed closely by those on 1% OP (T3 = 1.74). These values were better than the control group (T1 = 1.80) and notably better than the synthetic antibiotic group (T5 = 1.85) and the homemade ration with no OP (T2 = 1.88). This trend suggests that oregano powder improved feed efficiency, allowing birds to convert feed more efficiently into body mass. Improved FCR in oregano-supplemented groups is likely due to oregano’s bioactive compounds, which exhibit antimicrobial, antioxidant, and anti-inflammatory properties. These compounds can enhance gut health by reducing pathogenic bacteria, improving intestinal morphology, and stimulating digestive enzyme secretion (Giannenas et al., 2018). Enhanced digestive function increases the efficiency of nutrient absorption, which translates into better growth per unit of feed intake.

In contrast, birds fed the synthetic antibiotic-supplemented homemade ration (T5) had a poorer FCR despite consuming the most feed during the early phase. This indicates that higher feed intake did not produce proportional weight gain, suggesting suboptimal nutrient utilization. Antibiotics primarily function as growth promoters by altering gut microbiota; however, they may lack the multifunctional metabolic support provided by phytogenic additives like oregano (Zampiga and Calini, 2021) The numerically higher FCR in the control group further supports the performance-enhancing effects of dietary supplementation, especially with oregano. The slightly better FCR in 3% OP than 1% OP suggests a dose-dependent effect. However, performance did not improve further at higher OP concentrations in some parameters, indicating an optimal inclusion level of around 3%.

Dressed weight and dressing percentage

The dressed weight of broiler chickens was not significantly affected by dietary supplementation with oregano powder (Table 3; p > 0.05). However, numerically, birds fed 3% OP (T4) recorded the highest dressed weight (1031.00 g): followed by T2 (1002.33 g): T1 (961.00 g): T5 (937.33 g): and T3 (899.93 g). Although these differences were not statistically significant, the higher dressed weight observed in T4 suggests a potential positive effect of the 3% OP inclusion on carcass yield. Similarly, the dressing percentage did not differ significantly among treatments (p>0.05): but a numerical trend was observed. The highest dressing percentage was recorded in T4 (72.76%): followed by T5 (71.80%): T3 (71.45%): T1 (70.89%): and the lowest in T2 (69.72%).

Table 3: Dressed weight (g) and dressing percentage (%) of broilers fed with graded levels of oregano powder as a phytobiotic alternative to synthetic antibiotic

Parameters	Treatments					P-value	CV
Parameters	T1	T2	T3	T4	T5	P-value	CV
Dressed wt., g	961.00	899.00	1002.30	1031.67	937.33	6.52	0.07ns
Dressing percentage, %	70.89	69.72	71.45	72.76	71.80	5.01	0.87 ns

ns: not significant; CV: Coefficient of Variance; T1: Commercial Ration (Negative Control); T2: HMR (Homemade Ration) without OP (Oregano Powder) and SA (Synthetic Antibiotic); T3: HMR + 1% OP; T4; HMR + 3% OP; T5; HMR+ SA

Table 4: Cell-mediated immunity of broilers fed with graded levels of oregano powder as a phytobiotic alternative to synthetic antibiotic.

Parameters	Treatments					CV	P value
	1	2	3	4	5	CV	P value
Bursa of Fabricius, g	2.33	1.67	2.67	4.17	2.33	37.66	0.097 ns
Bursa Index, %	0.17	0.13	0.19	0.29	0.18	39.76	0.194 ns
Spleen Weight, g	1.67b	1.33b	3.00a	3.33a	2.50ab	28.34	0.020*
Spleen Index, %	0.12b	0.11b	0.21a	0.23a	0.19ab	29.64	0.044*

ab,* superscripts within row indicates significant difference at p<0.05: T1: Commercial Ration (Negative Control); T2: HMR (Homemade Ration) without OP (Oregano Powder) and SA (Synthetic Antibiotic); T3: HMR + 1% OP; T4; HMR + 3% OP; T5; HMR+ SA.

The findings align with those of Haliru et al. (2024): who reported no significant differences (p>0.05) in the mean weights of internal and external offal, except for the skull. This suggests that oregano supplementation may have a limited effect on carcass composition. Furthermore, similar conclusions were drawn in previous studies (Botsoglou et al., 2002; Lewis et al., 2003; Demir et al., 2003; Barreto et al., 2008; Marcinčák et al., 2008; Vlaicu et al., 2018): which found that oregano powder or oil had minimal impact on broiler growth performance and carcass yield.

Cell-mediated immunity

In this study, the inclusion of oregano powder (OP) in broiler diets did not result in a statistically significant difference (P>0.05) in the bursa index (Table 4). Numerically, birds in the T4 group (3% OP) showed the highest bursa weight (4.17 g) and bursa index (0.29%): while the lowest values were recorded in T2 (1.67 g and 0.13%, respectively). These results align with findings from Ampode and Mendoza (2022): who similarly reported no significant changes in immune organ indices with OP supplementation. In contrast, both spleen weight and spleen index were significantly influenced (P<0.05) by dietary treatments. The T4 group exhibited the highest spleen index (0.23%): while the T2 group had the lowest (0.11%). This suggests that higher levels of OP (3%) may enhance immune organ development, particularly of the spleen. The enhancement may be attributed to the bioactive compounds in oregano, especially thymol and carvacrol, which are known for their antimicrobial, antioxidant, and immunomodulatory properties (Giannenas et al., 2018; Al-Kassie, 2010).

The bursa of Fabricius is a primary lymphoid organ in birds responsible for the maturation of B-lymphocytes, critical for humoral immunity. Its size and weight are often used as indicators of immunocompetence. Meanwhile, the spleen plays a central role in both innate and adaptive immunity by filtering blood, removing senescent erythrocytes, and facilitating antigen presentation and lymphocyte proliferation (Wang et al., 2023). Therefore, increased spleen index may indicate elevated immune activation or responsiveness. Interestingly, the findings contrast with those of Ri et al. (2017): who reported no significant changes in immune organ indices following supplementation with antibiotics or oregano powder. These discrepancies may be due to differences in dosage levels, oregano variety, or experimental conditions.

Net income

The net income refers to the amount gained using the treatment of the study. It shows that the given treatment had a positive or negative impact on profit-gaining 9. Among the five dietary treatments, T4 with 3% OP had the highest return of Php 95.72, T3 followed this with Php 90.17; T5 with Php 80.04; T2 with Php 77.91, and T1 with Php 73.9 (Table 5). T4 (3% oregano powder) had the highest net income of Php 95.72 out of the five dietary treatments, closely followed by T3 (Php 90.17). This implies that adding oregano powder, especially at 3%, not only promotes the growth of healthy broilers but also improves financial returns. Improved feed conversion, better general health, and possibly a reduced reliance on synthetic antibiotics could all contribute to T4’s strong return on investment and, ultimately, cheaper production costs.

Table 5: Net income and return on investment of broilers fed with graded levels of oregano powder as a phytobiotic alternative to synthetic antibiotic.

Parameters	Treatments
Parameters	T1	T2	T3	T4	T5
Final live weight, kg	1398.33	1358.13	1434.40	1470.40	1394.60
Price/kg live weight, PhP	160.00	160.00	160.00	160.00	160.00
Gross return/head, PhP	223.73	217.30	229.50	235.26	223.14
Cost of DOC/head, PhP	38.00	38.00	38.00	38.00	38.00
Feed Consumption, kg/head
a. CBM, g	0.64	0.64	0.64	0.64	0.64
b. Starter, kg	970.60	977.47	933.00	934.60	1010.07
c. Finisher, kg	1030.33	1018.27	1061.80	1066.33	1034.07
Price/kg of Feed, PhP
a. CBM, g	49.00	49.00	49.00	49.00	49.00
b. Starter, kg	41.50	35.41	35.41	35.41	35.41
c. Finisher, kg	39.00	34.78	34.78	34.78	34.78
Total Feed Cost, PhP
a. CBM, g	31.36	31.36	31.36	31.36	31.36
b. Starter, kg	40.28	34.61	33.04	33.04	37.77
c. Finisher, kg	40.18	35.42	36.93	37.09	35.97
Total Cost, PhP	149.82	139.39	139.33	139.54	143.10
Net Income, PhP1	73.91	77.91	90.17	95.72	80.04
ROI, %2	49.33	59.89	64.72	68.60	55.93

1Net Income was computed by adding all the total costs (chick cost, feed cost); 2ROI: Return on Investment; T1: Commercial Ration (Negative Control); T2: HMR (Homemade Ration) without OP (Oregano Powder) and SA (Synthetic Antibiotic); T3: HMR + 1% OP; T4; HMR + 3% OP; T5; HMR+ SA; CBM: Chick Booster Mash

While T2 and T1 (control groups) produced returns of Php 77.91 and Php 73.90, respectively, T5 (with an additional inclusion level of synthetic antibiotic) also demonstrated a positive return of Php 80.04. Even though T4 produced the largest return, the fact that all treatments produced profitable outcomes shows that oregano powder, in different amounts, may be a good way to increase broiler profitability.

Conclusion

Despite the absence of statistical significance, 3% oregano powder (OP) supplementation consistently yielded the most favorable outcomes in growth performance, carcass yield, bursa index, and profitability. Notably, birds supplemented with 3% OP exhibited a stronger cell-mediated immunity, as evidenced by a higher spleen index compared to other treatments. These findings suggest that 3% OP inclusion is a promising phytobiotic alternative to synthetic antibiotics for enhancing broiler productivity, immunity, and economic efficiency. Therefore, incorporating 3% oregano powder in broiler diets is recommended to support antibiotic-free poultry production.

Acknowledgement

The authors gratefully acknowledge Dr. Ne Velasco and Professor Eva Rea Fame V. Inocente for their invaluable guidance and dedicated efforts in reviewing and correcting the manuscript.

Novelty Statement

This investigation offers novel insights into the physiological and economic benefits of oregano powder supplementation in broilers, positioning it as a potential alternative to synthetic antibiotics. While previous studies have examined oregano at varying inclusion levels, the current research focuses on its potential as a substitute for synthetic antibiotics a perspective not thoroughly explored in earlier studies. By directly evaluating its impact on growth performance, immunity, and carcass yield, the study bridges a crucial gap in context-specific nutritional strategies. It contributes to sustainable poultry production by aligning animal health and profitability in light of increasing concerns over antibiotic resistance.

Authors Contribution

The authors contributed equally to the conceptualization data gathering, statistical analysis, and manuscript writing and served as co-first authors of this manuscript.

Generative AI and AI-assisted technology statement

The authors declare that AI-assisted tools (Grammarly and ChatGPT) were used solely to improve English language quality and grammar. All outputs were reviewed by the authors. No AI tools were used for data analysis or interpretation.

Conflict of interest

The authors have declared no conflict of interest.

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