Role of Phyllanthus emblica powder in enhancing antioxidant capacity of Salem Black goats under heat stress

Introduction

Small ruminants, particularly goats, are predominantly reared by resource poor and landless farmers in developing countries and play a vital role in livelihood security due to their adaptability and low input requirements (Singh et al., 2016) [17] . Goats are widely distributed across diverse agro-climatic regions and are known for their resilience; however, climate change induced heat stress poses a major challenge to their productivity and health. Elevated ambient temperature combined with high relative humidity disrupts thermoregulation, leading to physiological strain and compromised performance (Banerjee et al., 2014) [2] . Heat stress induces oxidative stress by increasing the generation of reactive oxygen species, which adversely affects metabolic functions in goats (Sejian et al., 2017) [15] . Supplementation of antioxidants has been shown to reduce oxidative damage and improve stress tolerance during periods of thermal stress. Natural antioxidants such as vitamin C are effective free radical scavengers and enhance antioxidant status under heat stress conditions (Kumar, 2009) [8] . Phyllanthus emblica (amla), a rich natural source of vitamin C and polyphenolic compounds, has gained attention as an economical antioxidant supplement. Due to its high antioxidant potential and stability in dried form, amla supplementation has been reported to lower oxidative stress and improve physiological adaptation in heat-stressed goats (Kumar, 2009) [8] .

Materials and Methods

The present study was carried out at the goat unit, Livestock Farm Complex, Veterinary College and Research Institute, Namakkal, Tamil Nadu, during the summer season from March to May 2025. The study area is located in the northwestern agro-climatic zone of Tamil Nadu and is characterized by a semi-arid to sub-humid climate with red loam soil. A total of 30 adult Salem Black female goats aged between 3 and 5 years were selected for the experiment. The animals were allotted into five experimental groups of six goats each based on body weight and body condition scoring. A two-week adaptation period was provided prior to the commencement of the study to acclimatize the animals to experimental conditions. Blood sampling was carried out at fortnightly intervals (0, 15, 30 and 45 days) to evaluate the influence of heat stress on haematological and oxidative stress parameters. Fresh amla (Phyllanthus emblica) was purchased, cut, dried, ground and provided to T 3 and T 5 groups at the rate of 15 g/day/goat. Plasma lipid peroxidation was estimated by measuring thiobarbituric acid reactive substances (TBARS) using the method of Esterbauer and Cheeseman (1990) [6] . Plasma samples were incubated at 37 ℃ for one hour, followed by the addition of trichloroacetic acid and thiobarbituric acid. The mixture was heated in a boiling water bath for 30 minutes, cooled and centrifuged at 3000 rpm for 15 minutes. The absorbance of the supernatant was read at 535 nm, and TBARS concentration was calculated using malondialdehyde as the standard. Catalase activity was assessed according to the method of Bonaventura et al. (1972) [3] . A small volume of plasma homogenate was added to hydrogen peroxide solution and the reaction was monitored spectrophotometrically at 240 nm at 25 ℃. The decline in absorbance was recorded at one-minute intervals for three minutes, reflecting the rate of hydrogen peroxide degradation. Catalase activity was expressed as units corresponding to the amount of enzyme required to decompose 1 µmol of hydrogen peroxide per minute. Body condition score (BCS) was evaluated following the guidelines described by Villaquiran et al. (2004) [19] and Ghosh et al. (2019) [7] . Under this scoring method, goats were assigned scores ranging from 1, indicating extremely poor body condition, to 5, representing excessive fatness.

Statistical analysis

The data obtained from this study were statistically analysed following the procedure described by Snedecor and Cochran (1996) [18] .

Results

The mean (± SE) lipid peroxidase activity in Salem Black goats subjected to different treatment regimens is depicted in Table 1. During the initial phase of the experiment (0ᵗʰ and 15ᵗʰ days), no statistically significant differences were observed among the treatment groups. However, marked differences emerged on the 30ᵗʰ (p<0.05) and 45ᵗʰ (p<0.01) days of the experimental period. On the 30ᵗʰ day, goats in T₄ (4.38±0.42) and T₂ (3.90±0.32) exhibited significantly higher (p<0.05) lipid peroxidase levels compared to T₁, T₃ and T₅, indicating increased oxidative stress associated with heat exposure. By 45ᵗʰ day, lipid peroxidase activity further increased in T₄ (4.83±0.30) and T₂ (4.35±0.25), with values being highly significant (p<0.01) when compared with the remaining treatment groups. The mean (± SE) catalase activity across the different experimental treatment groups is presented in Table 2. Statistically significant differences were not detected among the groups on 0ᵗʰ and 15ᵗʰ days of the study. However, on 30ᵗʰ day, goats in T₄ (135.35±8.95) and T₂ (129.55±6.94) showed significantly higher (p<0.05) catalase activity compared to T₁ (125.56±8.11), T₃ (121.08±8.20) and T₅ (124.21±8.10). A comparable pattern was evident on the 45ᵗʰ day, wherein catalase activity was markedly elevated in T₄ (139.58±7.15) and T₂ (133.61±4.50), with values being highly significant (p<0.01) relative to the remaining treatment groups. Body condition score did not differ significantly among the groups at day 0 and day 15. However, a significant decline (p<0.01) was observed in the sunlight-exposed unsupplemented group (T 4 ) from 30 day onwards, indicating adverse effects of heat stress. In contrast, the pen-housed control group (T₁) showed a significant improvement in BCS during the same period, recording the highest values at days 30 and 45. The amla-supplemented group (T₃) exhibited significantly higher BCS than T₂ but remained lower than T₁ (p<0.01), demonstrating that Phyllanthus emblica supplementation partially mitigated heat stress induced loss of body condition.

Discussion

The lipid peroxidase (LPO) activity in Salem Black goats varied from 3.05 to 4.83 nmol MDA/ml and differed significantly (p<0.01) among the treatment groups (Table 1). Substantially elevated LPO levels recorded in T₂ and T₄ suggested enhanced oxidative stress associated with grazing and direct exposure to solar radiation, whereas relatively reduced values observed in T₁ and T₃ indicated improved antioxidant status and minimized oxidative injury, which may be attributed to restricted sunlight exposure under pen conditions (T₁) and Phyllanthus emblica supplementation (T₃).

The present findings are in agreement with the observations of Randhawa et al. (2013), who reported a pronounced reduction in LPO levels (166.05 nmol MDA/g Hb) following amla supplementation in heat-stressed goats, thereby supporting the lower oxidative stress markers noted in the supplemented groups (T₃ and T₅) of the current study.

Similar trends were reported by Chaudhary et al. (2015) and Rathwa et al. (2017) [13] , who documented increased LPO concentrations (4.5 and 4.8 nmol MDA/ml) during hot seasons compared to cooler periods (3.1 and 3.5 nmol MDA/ml). Likewise, Megahed et al. (2008) [10] observed significantly higher lipid peroxidation during summer (4.97 µmol/l) than winter (4.03 µmol/l), further substantiating the role of heat stress in inducing oxidative imbalance. The mean plasma catalase activity in Salem Black goats ranged from 120.05 to 139.58 µmol/min/mg and exhibited significant differences (p<0.05) among the experimental treatment groups (Table 2). Elevated catalase activity recorded in T₂ and T₄ suggests a compensatory enhancement of antioxidant defense mechanisms in response to sustained heat stress, while the relatively lower enzyme activity observed in the remaining groups indicates a reduced oxidative burden in goats maintained under pen conditions (T₁) and those receiving Phyllanthus emblica supplementation (T₃ and T₅).

The present results are in agreement with the findings of Chandra (2009) [4] and Lallawmkimi et al. (2009) [9] , who documented higher catalase activity during the summer season (159.9 µmol/min/mg) compared to winter (153.8 µmol/min/mg) in cattle and buffaloes, thereby confirming the activation of antioxidant enzymes under thermal stress conditions. Likewise, Shi et al. (2020) [16] reported a significant elevation in catalase activity (2.16 to 2.55 U/ml) in heat-stressed lambs relative to control animals (1.79±0.30 U/ml), further supporting the observations of the present study. The body condition score of Salem Black goats differed significantly among treatments (p<0.01), with the control group maintaining the highest BCS, while the heat stressed group exhibited the lowest values, reflecting the adverse effect of prolonged solar exposure on body reserves. Goats supplemented with Phyllanthus emblica showed intermediate BCS, indicating partial protection against heatinduced loss of body condition. These findings concur with Sejian et al. (2014) [14] , who reported reduced BCS under heat stress and improvement with antioxidant supplementation. Similar seasonal declines in BCS were noted by Muthuramalingam et al. (2020) [11] , while Akinmoladun et al. (2020) [1] demonstrated improved body condition in vitamin C supplemented goats, supporting the beneficial role of P. emblica in mitigating heat-related metabolic stress.

Conclusion

The present study demonstrated that natural heat stress significantly increased oxidative stress in Salem Black goats, as evidenced by elevated lipid peroxidase and catalase activities, along with a decline in body condition score in heat-exposed groups. Supplementation with Phyllanthus emblica effectively reduced lipid peroxidation and modulated antioxidant enzyme activity, indicating improved antioxidant status under thermal stress. Goats receiving amla supplementation also maintained better body condition, reflecting enhanced energy balance and metabolic efficiency. These findings suggest that Phyllanthus emblica is a promising, economical antioxidant supplement for mitigating heat stress induced oxidative damage in goats. Overall, amla supplementation at the rate of 15 g/day/goat can be recommended as a practical nutritional strategy to improve stress resilience and productivity of Salem Black goats under tropical semi-arid conditions.

Acknowledgement

AcknowledgementsI sincerely acknowledge the Department of Livestock Production Management for their guidance, technical support and cooperation throughout the course of this research work. I extend my gratitude to Livestock Farm Complex, VCRI, Namakkal, for providing the necessary animals, facilities and assistance required for the successful conduct of the experiment. I am also thankful to the Veterinary College and Research Institute, Namakkal, for offering the institutional support and infrastructure that enabled the smooth completion of this research.

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