Open Veterinary Journal, (2026), Vol. 16(4): 2360-2365

Short Communication

10.5455/OVJ.2026.v16.i4.36

Stress biomarkers and meat quality in broilers following certified halal slaughter

Pudji Astuti^1,2*, Claude Mona Airin^1,2, Rizki Fitrawan Yuneldi³, Sarmin Sarmin^1,2, Lily Arsanti Lestari^4,2, Yuny Erwanto^5,2 and Abdul Rohman^6,2

¹Department of Physiology, Faculty of Veterinary Medicine, Universitas Gadjah Mada, Yogyakarta, Indonesia

²Center of Excellence, Institute for Halal Industry and System, Universitas Gadjah Mada, Yogyakarta, Indonesia

³Research Center for Applied Zoology, Research Organization for Life Sciences and Environment, National Research and Innovation Agency (BRIN), Cibinong, Indonesia

⁴Department of Nutrition and Health, Faculty of Medicine, Public Health and Nursing, Universitas Gadjah Mada, Yogyakarta, Indonesia

⁵Departement of Animal Product Technology, Faculty of Animal Science, Universitas Gadjah Mada, Yogyakarta, Indonesia

⁶Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Universitas Gadjah Mada, Yogyakarta, Indonesia

*Corresponding Author: Pudji Astuti. Department of Physiology, Faculty of Veterinary Medicine, Universitas Gadjah Mada, Yogyakarta, Indonesia. Email: pastuti2 [at] ugm.ac.id

Submitted: 04/12/2025 Revised: 10/03/2026 Accepted: 22/03/2026 Published: 30/04/2026

---

ABSTRACT

Background: Animal slaughter in accordance with halal standards and animal welfare plays a crucial role in meat quality. One of the main factors influencing meat quality is the animal’s stress level during slaughter, which can be measured through corticosterone and superoxide dismutase (SOD) levels, which are biomarkers of stress.

Aim: This study aimed to evaluate the effects of knife sharpness by Juru Sembelih Halal (JULEHA)-certified and non-JULEHA (non-certified) knives, on stress levels and meat quality in broiler chickens.

Methods: This study employed a completely randomized design. A total of 120 broiler chickens aged 4 weeks were randomly assigned to four treatments (T): T1 (JULEHA + knife sharpened for 20 seconds); T2 (JULEHA + knife not sharpened); T3 (Non-JULEHA + knife sharpened for 20 seconds); and T4 (Non-JULEHA + knife not sharpened). Each treatment consisted of 30 chickens. All slaughtering procedures were conducted using knives (new with the same mark) that met halal slaughter and animal welfare requirements, ensuring that all knives were initially sharp. The measured parameters included corticosterone levels and SOD activity as stress biomarkers and meat quality (hardness, springiness, gumminess, and chewiness). Corticosterone and SOD data were analyzed using one-way analysis of variance followed by Duncan’s post hoc test, while meat texture data were analyzed using the Kruskal–Wallis test followed by pairwise comparisons with Bonferroni correction. All statistical analyses were performed using SPSS v.29.0 (IBM, NY, USA) with a 95% confidence level (α=0.05).

Results: Corticosterone levels in T1 were significantly different from those in T2 and T4, showing that T1 decreased stress levels. The results on springiness showed that T1 was significantly different from the other treatments, whereas the chewiness parameters of T1 and T2 were significantly different from those of T3 and T4, indicating that T1 had lower springiness and chewiness values, suggesting softer and more tender meat, improved textural quality, and potentially reduced physiological stress during slaughter.

Conclusion: T1 (JULEHA + knife sharpened for 20 seconds) proved to be the most effective halal slaughtering method, reducing broiler stress levels, such as decreasing corticosterone levels during slaughter, and producing better meat quality, especially reduced springiness and chewiness.

Keywords: Corticosterone, Halal, Knife sharpened, Meat quality, Superoxide dismutase.

---

Introduction

Animal slaughter is a crucial stage in the poultry industry and must be performed in accordance with applicable animal welfare standards (Njoga et al., 2023). Providing safe, high-quality halal meat requires not only adherence to religious requirements but also animal welfare and food safety (Ellahi et al., 2025). Juru Sembelih Halal (JULEHA) and the technical condition of the cutting equipment, particularly knife sharpness, are key determinants of slaughter efficiency and the physiological stress responses of poultry during slaughter (Karltun et al., 2016; Kumar et al., 2023).

Knife sharpness plays an important role in minimizing pain, stress, and tissue damage (Borzuta et al., 2019; Barrasso et al., 2020; Abd El-Rahim et al., 2023). A sharp knife ensures a quick and clean cut, thereby accelerating blood removal and reducing muscle activity and the risk of contamination (Borzuta et al., 2019; Abd El-Rahim et al., 2023). Conversely, a blunt knife can compromise animal welfare, increase blood loss, potentially lead to microbial contamination, reduce meat quality, and cause stress during slaughter (Terlouw et al., 2008; Aghwan et al., 2016; Waldman et al., 2020; Liu et al., 2022; Terlouw and Bourguet, 2022; Kumar et al., 2023; Ovuru et al., 2023). Increased stress can be indicated by elevated levels of corticosterone and changes in the activity of antioxidant enzymes such as superoxide dismutase (SOD), as well as changes in meat texture (Terlouw et al., 2008; Chainy and Sahoo, 2020; Chukwuebuka et al., 2021). Although transport, pre-slaughter, and post-slaughter stress have been assessed in numerous studies (Indriani et al., 2021; Njoga et al., 2023; Mohan et al., 2025), this study focused on the effect of slaughtering methods on animal stress and their impact on meat quality, which has not been previously investigated.

Therefore, this study aimed to evaluate the effects of knife sharpness by JULEHA-certified and non-JULEHA (non-certified) knives, on stress levels and meat quality in broiler chickens.

---

Materials and Methods

Study duration and location

The study was conducted from September to November 2025 at the Anas poultry slaughterhouse (RPU) in Sleman Regency, Yogyakarta. Meat texture analysis was conducted in broiler chickens at the Faculty of Animal Husbandry, and corticosterone and SOD levels were analyzed at the Laboratory of Physiology, Faculty of Veterinary Medicine, Universitas Gadjah Mada, Indonesia.

Experimental design, slaughtering, and collection of samples

This study employed a completely randomized design. A total of 120 broiler chickens aged 4 weeks were randomly allocated into four treatments (T), namely: T1 (JULEHA + knife sharpened for 20 seconds); T2 (JULEHA + knife not sharpened); T3 (Non-JULEHA + knife sharpened for 20 seconds); and T4 (Non-JULEHA + knife not sharpened). Each treatment consisted of 30 chickens. The knife was sharpened for 20 seconds after halal slaughter. A JULEHA-certified slaughterer has passed an official competency test and is nationally recognized by the Badan Nasional Sertifikasi Profesi (BNSP). A non-JULEHA is a slaughterer who has not taken an official competency test and is not nationally recognized by BNSP. The chickens were fasted for 1 day before slaughter. The restraint process, handling, and slaughter procedures were the same for all group chickens, which were placed lying on their left side, with their legs and wings gently held (Ismail et al., 2018).

All slaughtering procedures were conducted using a knife (new with the same mark) that met halal slaughter and animal welfare requirements, and all knives were initially sharp. Chickens were slaughtered using the halal method. Halal slaughter is conducted in accordance with halal standards and Shariah provisions. Each chicken is slaughtered individually by a trained slaughterer using a sharp knife, facing the Qibla, always reciting "Bismillah" and reciting the name of Allah. Furthermore, a single quick incision is made in the front of the neck to sever the jugular vein, carotid artery, trachea, and esophagus (Abd El-Rahim et al., 2023; Ilyas et al., 2023). This allows for complete bleeding and painless death (Awan and Sohaib, 2016). During the slaughtering process, approximately 2 ml of blood was collected from the jugular vein in all broiler chickens and centrifuged at 5,000 rpm. The resulting serum was stored in a −20°C until corticosterone levels and SOD activity were analyzed (Kelly and Alworth, 2013).

Analysis of the texture of broiler chicken meat

Meat texture analysis was performed according to the procedure described by Yuneldi et al. (2024) and As Sidiqi et al. (2023). Meat quality was evaluated using samples of the pectoralis major muscle, which were collected as raw meat immediately after slaughter, stored in a freezer at –20°C for 24 hours postmortem, and subsequently subjected to analysis. The following parameters were tested in the chicken meat: hardness (N), springiness, gumminess, and chewiness (N) using a Texture Analyzer TA1 (Ametek Lloyd Instruments Ltd., Fareham, UK). These meat texture analyses require a minimum size of 1 × 1 × 1 cm. The Texture Analyzer operation and data acquisition were performed using the Nexygenplus software (Ametek Lloyd Instrument Ltd.).

Corticosterone analysis

Corticosterone hormone level analysis was performed according to the procedure described by Janthakhin et al. (2022). Serum samples were examined for corticosterone hormone levels using an enzyme-linked immunosorbent assay (ELISA). The analysis was conducted according to the manufacturer's instructions in the corticosterone competitive ELISA kit (ABclonal Technology, Wuhan, China). The steps included reagent preparation, sample addition, and incubation. Absorbance was read using an ELISA or microplate reader (ZENIX-320) at an absorbance of 450 nm for 15 minutes.

SOD analysis

SOD levels were determined using an ELISA kit (Calbiotech^®, California, USA). All analytical procedures, including reagent preparation, sample addition, and incubation, were performed according to the manufacturer’s instructions. The absorbance was measured at 450 nm using a microplate reader (ZENIX-320).

Statistical analysis

The Shapiro–Wilk and Levene tests were used to assess data normality and homogeneity of variance. The data for chicken meat texture parameters did not meet the assumptions of parametric analysis; therefore, the Kruskal–Wallis test was used to compare the four treatments. Post hoc analyses were performed using pairwise comparisons with the Bonferroni correction. The levels of corticosterone and SOD were tested for normality and homogeneity using the Shapiro–Wilk and Levene tests. These variables met the assumptions for parametric testing and were analyzed using one-way analysis of variance followed by Duncan’s post hoc test. All statistical analyses were performed using the Statistical Package for the Social Sciences v.29.0 (IBM, NY, USA) with a 95% confidence level (α=0.05).

Ethical approval

The research procedures have met all ethical requirements for experimental animals, as evidenced by the ethical approval letter number 124/EC-FKH/Int./2025 issued by the Research Ethics Commission of the Faculty of Veterinary Medicine, Universitas Gadjah Mada, Indonesia.

---

Results and Discussion

The statistical analysis of corticosterone hormone levels as an indicator of stress levels in chickens revealed a significant difference (p < 0.05) in T1 (JULEHA + knife sharpened for 20 seconds), which was significantly different from T2 (JULEHA + knife non-sharpened) and T4 (Non-JULEHA + knife non-sharpened), as illustrated in Table 1. Statistical analysis showed no significant differences in SOD enzyme levels among treatments (p > 0.05) (Table 1). Furthermore, Figure 1 shows the standard curve of the hormone and enzyme. Halal slaughtering performed by JULEHA using a sharpened knife for 20 seconds (T1) resulted in lower stress levels, as indicated by significantly reduced corticosterone levels compared with the other treatments. These findings are consistent with the reports of Imlan et al. (2020) and Barrasso et al. (2020) which state that a sharp knife with appropriate blade dimensions is essential for achieving a fast and clean neck cut without stunning during halal slaughter. Using a sharp knife increases bleeding efficiency, reduces pain perception, and minimizes stress in animals. As reported by Kumar et al. (2023) more efficient blood removal also contributes to improved meat quality. Additionally, reduced glucocorticoid secretion (including corticosterone) can decrease the formation of reactive oxygen species (ROS) and help maintain a favorable antioxidant balance, as described by Sato et al. (2010). T3 (non-JULEHA + knife sharpened for 20 seconds) showed the highest SOD level (1.44), although it was not significantly different from the other treatments (p > 0.05) and intermediate corticosterone level. The use of a sharpened knife for 20 seconds may minimize stress in animals, although the corticosterone levels are not similar to those of T1. This finding may indicate a physiological response associated with moderate stress, as reflected by the intermediate corticosterone level in this treatment group. In poultry, stress can increase ROS production, leading to oxidative stress and disruption of cellular homeostasis. Antioxidant defense systems, including enzymes such as SOD, are activated to neutralize excess free radicals and maintain redox balance (Akbarian et al., 2016; Oke et al., 2024; Li et al., 2024; Tuong et al., 2023). Therefore, the elevated SOD activity observed in T3 may reflect an adaptive antioxidant response to short-term physiological stress.

Table 1. Corticosterone and SOD hormone levels in chickens slaughtered using sharp and non-sharp knives by JULEHA-certified and non-certified.

Fig. 1. Standard curve of the hormones and enzyme (a) Corticosterone, R²=0.9473, and (b) SOD, R²=0.9604. Corticosterone contents were examined using a competitive enzyme immunoassay method capable of converting the optical density (OD) value into content with a standard curve and the formulas y=−0.367ln(x) + 2.319 for the corticosterone standard and y=0.4111ln(x) + 0.1503 for the SOD standard.

The meat texture of the broiler chickens varied across the four treatments. Statistical analysis in Table 2 shows a significant difference (p < 0.05) in the springiness of T1 compared to the other treatments. Chewiness was also significantly different (p < 0.05) between T1 and T2 compared to T3 and T4. Hardness and gumminess were not significantly different (p > 0.05). Overall, the data trend indicates a positive effect of JULEHA halal slaughterers with a sharpened knife for 20 seconds on meat quality. Meat texture becomes softer and less elastic (decreased springiness value), and the meat texture feels softer and is not tiring when chewed (decreased chewiness value). Observations from this study correlate with reports by Hayat et al. (2024)that minimizing pre-slaughter stress contributes to the maintenance of muscle glycogen reserves and a more stable post-mortem pH, thereby reducing excessive muscle contraction and producing a softer final texture (decreased hardness, gumminess, chewiness, and springiness).

Table 2. Texture of broiler chicken meat slaughtered with sharp and non-sharp knives by JULEHA-certified and non-certified.

In contrast to T1, T4 showed increased corticosterone levels, indicating that the stress level of broiler chickens increased compared with T1. These results align with the findings of Kumar et al. (2023) who found that knife sharpness and proper slaughtering techniques enhance the bleed-out process and reduce pain and stress levels, thereby supporting the fulfillment of animal welfare principles. According to Son et al. (2022) stress conditions correlate with increased corticosterone levels. In broilers, increased corticosterone levels can increase oxidative parameters and decrease antioxidant capacity (Lin et al., 2004; Lin et al., 2009). According to Nawaz and Zhang (2021) and Xia et al. (2022) increased pre-slaughter stress levels can cause an increase in ROS and result in the disruption of antioxidant enzymes, resulting in the oxidation of muscle protein, which results in changes in meat quality.

The aforementioned results are consistent with the parameter “texture” of meat, which is significantly influenced by the stress level of the slaughtered animal. The results in T4 showed higher values of hardness, springiness, gumminess, and chewiness compared with the other treatments, indicating that the meat was tougher and more elastic. Pre- and post-slaughter stress can cause redox imbalance, mitochondrial dysfunction, and decreased meat quality (Liao et al., 2022). Oxidative stress in broilers increases ROS, causes mitochondrial damage, and weakens the antioxidant system, affecting meat quality (Chen et al., 2022). Increased ROS in chicken muscle decreases meat quality (drip loss, shear force) through oxidative mechanisms and cellular stress (Yan et al., 2022). Furthermore, excessive ROS production can damage muscle proteins and lipids, disrupt mitochondrial function, and generally reduce the quality of chicken meat (Nawaz and Zhang, 2021).

---

Conclusion

Conclusively, this study revealed that T1 (JULEHA + knife sharpened for 20 seconds) was the most effective slaughtering method, as it significantly reduced corticosterone levels, an indicator of stress levels, and improved meat quality, particularly in terms of springiness and chewiness in broiler chickens.

---

Acknowledgments

The authors express their gratitude to Direktorat Penelitian Universitas Gadjah Mada (UGM) for financial support through the research grant of Learning Center in Collaboration (LC-IC) UGM with contract number: 5242/UN1.P2/Dit-Lit/PT.01.03/2025 awarded to Prof. Dr. drh. Pudji Astuti, MP.

Conflict of interest

The authors declare no conflict of interest.

Funding

This research was supported by the Direktorat Penelitian Universitas Gadjah Mada (UGM) through the research grant of the Learning Center in Collaboration (LC-IC) UGM with contract number: 5242/UN1.P2/Dit-Lit/PT.01.03/2025 awarded to Prof. Dr. drh. Pudji Astuti, MP.

Author contributions

P.A., C.M.A., S.S., L.A.L., Y.E., and A.R.: planned and designed the study. P.A., C.M.A., R.F.Y., and S.S.: collected, analyzed, and drafted the manuscript. All authors have revised the manuscript, read, and approved the final version of the manuscript.

Data availability

All data supporting this study’s findings are available within the manuscript.

---

References

Abd El-Rahim, I.H.A., Mashat, B.H. and Fat’Hi, S.M. 2023. Effect of halal and stunning slaughter methods on meat quality: a review. Int. Food Res. J. 30, 149–158.

Aghwan, Z.A., Bello, A.U., Abubakar, A.A., Imlan, J.C. and Sazili, A.Q. 2016. Efficient halal bleeding, animal handling, and welfare: a holistic approach for meat quality. Meat Sci. 121, 420–428.

Akbarian, A., Michiels, J., Degroote, J., Majdeddin, M., Golian, A. and De Smet, S. 2016. Association between heat stress and oxidative stress in poultry; mitochondrial dysfunction and dietary interventions with phytochemicals. J. Anim. Sci. Biotechnol. 7, 1–14.

Awan, J.A. and Sohaib, M. 2016. Halal and humane slaughter: comparison between Islamic teachings and modern methods. Pak. J. Food. Sci. 26, 234–240.

Barrasso, R., Bonerba, E., Ceci, E., Roma, R., Alò, A., Mottola, A., Marchetti, P., Celano, G.V. and Bozzo, G. 2020. Evaluation of the animal welfare during religious slaughtering. Ital. J. Food Saf. 9, 39–43.

Borzuta, K., Lisiak, D., Janiszewski, P. and Grześkowiak, E. 2019. The physiological aspects, technique and monitoring of slaughter procedures and their effects on meat quality: a review. Ann. Anim. Sci. 19, 857–873.

Chainy, G.B.N. and Sahoo, D.K. 2020. Hormones and oxidative stress: an overview. Free Radic. Res. 54, 1–26.

Chen, Z., Xing, T., Li, J., Zhang, L., Jiang, Y. and Gao, F. 2022. Oxidative stress impairs meat quality of broilers by damaging mitochondrial function, affecting calcium metabolism and leading to ferroptosis. Anim. Biosci. 35, 1616–1627.

Chukwuebuka, N.B., Melish Elias, D.T., Ijego, A.E., Peggy, O.E., Ejime, A.C., Omeru, O., Yabrade, T.P.E., Nwanneamaka, E.C. and Ikemefune, E.E. 2021. Changes in antioxidant enzymes activities and lipid peroxidase level in tissues of stress-induced rats. Biomed. Pharmacol. J. 14, 583–596.

Ellahi, R.M., Wood, L.C., Khan, M. and Bekhit, A.E.D.A. 2025. Integrity challenges in halal meat supply chain: potential industry 4.0 technologies as catalysts for resolution. Foods 14, 1–32.

Hayat, M.N., Ismail-Fitry, M.R., Kaka, U., Rukayadi, Y., Kadir, M.Z.A.A., Radzi, M.A.M., Kumar, P., Nurulmahbub, N.A. and Sazili, A.Q. 2024. Assessing meat quality and textural properties of broiler chickens: the impact of voltage and frequency in reversible electrical water-bath stunning. Poult. Sci. 103, 1–14.

Ilyas, A., Zaifuddin, M. and Syarifuddin, S. 2023. Chicken slaughter mechanism in realizing halal product guarantee (study on the light lasinrang chicken slaughterhouse). Sci. J. Islam. Econ. 9, 448–454.

Imlan, J.C., Kaka, U., Goh, Y.M., Idrus, Z., Awad, E.A., Abubakar, A.A., Ahmad, T., Nizamuddin, H.N.Q. and Sazili, A.Q. 2020. Effects of slaughter knife sharpness on blood biochemical and electroencephalogram changes in cattle. Animals 10, 1–17.

Indriani, R., Astuti, P., Husni, A. and Airin, C.M. 2021. Day old chicken strain influence on the heterophil: lymphocyte ratio during transportation from Yogyakarta to Makassar. J. Ilmu. Peternak. Vet. Trop. 11, 107–111.

Ismail, S.N., Awad, E.A., Zulkifli, I., Goh, Y.M. and Sazili, A.Q. 2018. Effects of method and duration of restraint on stress hormones and meat quality in broiler chickens with different body weights. Asian-Aust. J. Anim. Sci. 32, 865–873.

Janthakhin, Y., Kingtong, S. and Juntapremjit, S. 2022. Inhibition of glucocorticoid synthesis alleviates cognitive impairment in high-fat diet-induced obese mice. Compr. Psychoneuroendocrinol. 10, 1–4.

Karltun, J., Vogel, K., Bergstrand, M. and Eklund, J. 2016. Maintaining knife sharpness in industrial meat cutting: a matter of knife or meat cutter ability. Appl. Ergon. 56, 92–100.

Kelly, L.M. and Alworth, L.C. 2013. Techniques for collecting blood from the domestic chicken. Lab. Anim. 42, 359–361.

Kumar, P., Abubakar, A.A., Imlan, J.C., Ahmed, M.A., Goh, Y.M., Kaka, U., Idrus, Z. and Sazili, A.Q. 2023. Importance of knife sharpness during slaughter: shariah and kosher perspective and scientific validation. Animals 13, 1–18.

Li, Y., Wang, K. and Li, C. 2024. Oxidative stress in poultry and the therapeutic role of herbal medicine in intestinal health. Antioxidant 13, 1–25.

Liao, H., Zhang, L., Li, J., Xing, T. and Gao, F. 2022. Acute stress deteriorates breast meat quality of broiler chickens by inducing redox imbalance and mitochondrial dysfunction. J. Anim. Sci. 100, 1–10.

Lin, H., Decuypere, E. and Buyse, J. 2004. Oxidative stress induced by corticosterone administration in broiler chickens: short-term effect. Comp. Biochem. Physiol. B. 139, 745–751.

Lin, H., Gao, J., Song, Z.G. and Jiao, H.C. 2009. Corticosterone administration induces oxidative injury in skeletal muscle of broiler chickens. Poult. Sci. 88, 1044–1051.

Liu, J., Ellies-Oury, M.P., Stoyanchev, T. and Hocquette, J.F. 2022. Consumer perception of beef quality and ways to control, improve and predict it. Foods 11, 1–27.

Mohan, S., Madheshwaran, M., Kumar, A., Mariappan, G., Biswas, A.K., Rokade, J.J., Nagesh, S., Tiwari, A.K. and Singh, Y. 2025. Evaluating the impact of pre-slaughter transport stress on broiler welfare and meat quality in India. Sci. Rep. 15, 1–11.

Nawaz, A.H. and Zhang, L. 2021. Oxidative stress in broiler chicken and its consequences on meat quality. Int. J. Life Sci. Res. Arch. 1, 45–54.

Njoga, E.O., Ilo, S.U., Nwobi, O.C., Onwumere-Idolor, O.S., Ajibo, F.E., Okoli, C.E., Jaja, I.F. and Oguttu, J.W. 2023. Pre-slaughter, slaughter and post-slaughter practices of slaughterhouse workers in Southeast Nigeria. PLoS One 18, 1–24.

Oke, O.E., Akosile, O.A., Oni, A.I., Opowoye, I.O., Ishola, C.A., Adebiyi, J.O., Odeyemi, A.J., Adjei-Mensah, B., Uyanga, V.A. and Abioja, M.O. 2024. Oxidative stress in poultry production. Poult. Sci. 103, 1–21.

Ovuru, K.F., Izah, S.C., Ogidi, O.I., Imarhiagbe, O. and Ogwu, M.C. 2023. Slaughterhouse facilities in developing nations: sanitation, hygiene, microbial contaminants and sustainable management system. Food. Sci. Biotechnol. 33, 519–537.

Sato, H., Takahashi, T., Sumitani, K., Takatsu, H. and Urano, S. 2010. Glucocorticoid generates ROS and induces oxidative injury in the hippocampus. J. Clin. Biochem. Nutr. 47, 224–232.

Son, J., Kim, H.J., Hong, E.C. and Kang, H.K. 2022. Effects of stocking density on growth performance, antioxidant status and meat quality of finisher broiler chickens under high temperature. Antioxidant 11, 1–12.

Sidiqi, A.A.A., Airin, C.M., Sarmin, S. and Astuti, P. 2023. A combination of Anadara nodifera shell and milkfish thorns powder effectively promote springiness index, serum testosterone, and breast muscle testosterone in Bangkok rooster. HAYATI. J. Biosci. 30, 701–710.

Terlouw, C. and Bourguet, C. 2022. Quantifying animal welfare preslaughter using behavioural and physiological indicators. In Preslaughter handling and slaughter of meat animals. Eds., Grandin, T. and De Vries, M. Wageningen, The Netherlands: Wageningen Academic Publishers, pp: 13–61.

Terlouw, E.M., Arnould, C., Auperin, B., Berri, C., Le Bihan-duval, E., Deiss, V., Lefèvre, F., Lensink, B.J. and Mounier, L. 2008. Pre-slaughter conditions, animal stress and welfare. Animal 2, 1501–1517.

Tuong, D.T.C., Moniruzzaman, M., Smirnova, E., Chin, S., Sureshbabu, A., Karthikeyan, A. and Min, T. 2023. Curcumin as a potential antioxidant in stress regulation of terrestrial, avian, and aquatic animals: a review. Antioxidants 12, 1–33.

Waldman, L., Hrynick, T.A., Benschop, J., Cleaveland, S., Crump, J.A., Davis, M.A., Mariki, B., Mmbaga, B.T., Mtui-Malamsha, N., Prinsen, G., Sharp, J., Swai, E.S., Thomas, K.M. and Zadoks, R.N. 2020. Meat safety in northern Tanzania. Front. Vet. Sci. 7, 1–16.

Xia, T., Xu, Y., Zhang, Y., Xu, L., Kong, Y., Song, S., Huang, M., Bai, Y., Luan, Y., Han, M., Zhou, G. and Xu, X. 2022. Effect of oxidation on thermal gelation of chicken breast myofibrillar protein. Food. Chem. 384, 1–9.

Yan, Y., Chen, X., Huang, J., Huan, C. and Li, C. 2022. H₂O₂-induced oxidative stress impairs meat quality via ROS/NF-κB signaling pathway in broiler thigh muscle. Poult. Sci. 101, 1–8.

Yuneldi, R.F., Airin, C.M., Saragih, H.T.S., Prawira, A.Y. and Astuti, P. 2024. Testosterone hormone levels and breast muscle performance of Pelung chickens after zinc sulfate and synthetic testosterone supplementation. Vet. World. 17, 2365–2369.