Role of Phytase Enzyme to Immunity Responses, Hematology and Histopathology in Cyprinus carpio L. Against Saprolegnia spp. Challenge | ||||
| Egyptian Journal of Aquatic Biology and Fisheries | ||||
| Article 234, Volume 29, Issue 4, July and August 2025, Page 3287-3304 PDF (1.14 MB) | ||||
| DOI: 10.21608/ejabf.2025.450210 | ||||
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| Author | ||||
| ALsafah et al. | ||||
| Abstract | ||||
| This study aimed to investigate the effects of feeding common carp (Cyprinus carpio L.) challenged with Saprolegnia spp. on their hematological and immunological systems, using phytase enzyme supplementation, and to evaluate histological alterations. A total of 120 C. carpio (20.05–20.35 g initial body weight) were divided into six groups. The control group received a basal diet without phytase supplementation, while group T4 was fed a basal diet supplemented with β-glucan (8.5 g/kg diet). Groups T1, T2, and T3 received the basal diet plus phytase enzyme at 1000, 2000, and 4000 IU/kg diet, respectively. In addition, two control groups (positive and negative) were included for the infection test at the end of the 60-day trial. For the challenge, fish in the positive and negative control groups were exposed to a viable Saprolegnia spp. suspension (2 × 10⁴ live spores/ml). After 60 days of feeding, the inclusion of phytase enzyme significantly (P≤ 0.05) affected hemoglobin concentration (g/dl), WBC count, and other hematological parameters, particularly in group T3. Compared with the control group, T2 also showed a significant (P≤ 0.05) increase in these parameters. Furthermore, T3 exhibited significantly higher albumin and total protein levels compared with the control. The WBC count was significantly (P < 0.05) higher in T2 and T3 compared with T1, T4, and the control. In comparison with the positive and negative control groups, all phytase-supplemented diets showed a significant increase in respiratory burst activity (NBT reduction). Histopathological examination revealed that gills of fish infected with Saprolegnia spp. (positive control) displayed severe tissue alterations, including epithelial lifting, necrosis, mononuclear cell infiltration, and hyperplasia. In contrast, these changes were less pronounced in the gills and skin of fish fed phytase-supplemented diets. The skin of fish in the positive control group showed ulcerative epidermis, edema, mononuclear cell infiltration, and an increase in alarm cells. Liver tissue in both positive and negative control groups appeared normal, whereas fish fed phytase or β-glucan diets showed hepatocyte lipid vacuolation, fatty degeneration, and nuclear pyknosis. Overall, supplementation with phytase (T1, T2, and T3) demonstrated beneficial and protective effects against Saprolegnia infection in C. carpio, improving hematological and immunological responses while reducing the severity of histopathological damage. | ||||
| Keywords | ||||
| Cyprinus carpio; Immune; Hematology; Histopathology; Phytase enzyme; Saprolegnia spp | ||||
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