Dual effects of dietary Lactobacillus helveticus and chlorogenic acid on growth performance, digestibility, immune-antioxidant capacity and resistance against heat stress of juvenile common carp.

It is essential to explore alternative and advantageous additives due to the essential requirement for ensuring the safety and well-being of aquatic animals. The present study investigated the role of Lactobacillus helveticus (Lh) and chlorogenic acid (CGA) on growth performance, hematology factors, digestive capacity, antioxidant activity, and stress in tissue prior and post-exposure to heat shock on common carp (Cyprinus carpio). For this purpose, 240 common carp with mean weight of 23.79 ± 0.49 g were allocated into four groups (20 fish each) and fed for 56 days on 0, 10 7 CFU g-1 Lh, 550 mg kg-1 CGA, and a combination of both elements (10 7 CFU g-1 + 550 mg kg-1 CGA) (T0, T1, T2, and T3). At the end of feeding period (56 days), growth performance, hematology indexes, digestive enzymes, antioxidant enzymes, stress, and immunity factors were evaluated. Thereafter, common carp was exposed to heat shock and levels of antioxidant enzymes and stress factors were estimated. There was an observable disparity in the growth parameters among various treatments, and the most prominent level was discovered in T3. There were no significant disparities in hematology indicators (p > 0.05). The levels of trypsin, chymotrypsin, pepsin, and protease were significantly higher in common carp fed with CGA and Lh. The total protein exhibited a significant increase in common carp fed with CGA and Lh (p < 0.05). The addition of CGA and Lh had no significant impact on urea and triglyceride content (p > 0.05). The lysozyme activity, ACH50, and total immunoglobulin exhibited a significant increase in common carp when subjected to CGA and Lh (p < 0.05). The effects of CGA and Lh on catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx) were significant both before and after heat stress. Moreover, these effects were more pronounced in fish that were fed with supplemented diets (p < 0.05). The malondialdehyde (MDA) levels demonstrated a significant decrease among the treatments before and after the heat challenge and the lowest level of MDA was recorded in T3 during both phases (p < 0.05). The aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), glucose, and cortisol levels also showed a significant decline in fish that were fed with supplemented diets both before and after heat stress (p < 0.05). Given the importance of L. helveticus and chlorogenic acid, the incorporation of both substances exhibits a powerful synergistic effect, thereby maximizing their advantageous properties in enhancing growth efficiency, digestion, hematological profile, biochemical markers, and immune-antioxidant capacity in common carp. [ABSTRACT FROM AUTHOR]