Effects of Dietary Detoxified Jatropha curcas Protein Isolate on Some Physiological Parameters, Intestine, and Liver Morphology of Labeo rohita Fingerlings

The rising cost of aquafeed ingredients as global aquaculture expands has led researchers to look for other ingredient sources that are not in conflict with human food. In this regard, this study examined the possibility of incorporating detoxified jatropha protein isolate (JP) into the diet of Labeo rohita (rohu) and the effect on the haematology, innate immunity, and organ integrity. A total of 216 fish (3.25 ± 0.02 g/fish) were randomly distributed in 15 tanks and fed for 60 days. The control diet was formulated with soy protein isolate (SP) and gradually replaced with JP at 25%, 50%, 75%, and 100%. The results showed that the red blood cell (RBC) and haemoglobin (Hb) were not significantly influenced (p > 0.05). White blood cell (WBC) counts registered a significant overall effect and followed a quadratic trend (p = 0.001), while the haematocrit value showed overall significant effects (p < 0.05) but no linear or quadratic trends were observed (p > 0.05). Serum lysozyme activity increased with increasing JP level (p = 0.002), but the total immunoglobulin value was significantly higher in fish fed JP 100. The respiratory burst activity, malondialdehyde (MDA) content, superoxide dismutase, and catalase enzyme activities among the various groups did not differ significantly (p > 0.05). Compared to the control, the photomicrograph of the mid-intestine and liver of fish fed a JP-based diet showed no inflammatory or degenerative changes. In summary, the substitution of SP in the diet with JP improved the innate immunity of L. rohita without any negative impact on the blood profile or the histoarchitectural structure of the liver.