Influence of tulsi Ocimum sanctum extract on fish health: growth, hematology, serum immune parameters, and antioxidant status in Common Carp

Objective: In aquaculture, the trend is shifting towards using plant-derived alternatives that are abundant in phytochemicals as effective replacements for traditional antibiotics and synthetic feed additives. In the present study, the effects of tulsi Ocimum sanctum extract on growth performance, hemato-biochemical indices, serum immune parameters, and antioxidant parameters in Common Carp Cyprinus carpio were investigated. Methods: Common Carp (mean body weight ± SD = 10.6 ± 0.13 g) were fed experimental diets that contained tulsi leaf extract at 0.0 (control), 0.5, 1.0, and 1.5% for 60 d (25 fish/treatment). Results: The findings revealed a considerable enhancement in growth performance and a decreased feed conversion ratio, especially for the 1.0% tulsi-based diet. Additionally, weight gain and feed conversion ratio exhibited significance at both the linear and quadratic levels, as indicated by polynomial contrasts. The hematological and biochemical profiles exhibited improvements in groups receiving tulsi-enriched diets. The antioxidant status of fish serum exhibited a notable increase, as evidenced by elevated activities of total antioxidant capacity, superoxide dismutase, and catalase in fish that received the 1.0% and 1.5% tulsi-based diets. Tulsi-supplemented diets led to remarkable enhancements in serum lysozyme activity, alternative complement activity, and total immunoglobulin content. Moreover, tulsi supplementation at 1.0% and 1.5% showcased a significant reduction in serum glucose and cortisol levels compared to the other groups. Conclusions: In conclusion, tulsi extract emerged as a valuable asset, positively influencing growth, blood parameters, antioxidant balance, and serum immune response in Common Carp, particularly at supplementation levels ranging from 1.0% to 1.5% in the diet.