Dietary Roselle ( Hibiscus sabdariffa ) Against Tebuconazole Exposure in Oreochromis niloticus : Growth, Digestive Enzymes, Intestinal Transporters, Inflammatory/Apoptotic Genes, and Histological Assays

Abstract

Fish health and the sustainability of aquaculture are seriously threatened by exposure to agricultural fungicides. Thus, the current study intended to assess how dietary roselle (Hibiscus sabdariffa) extract (ROS) protects Nile tilapia (Oreochromis niloticus) from tebuconazole (TEB)-induced toxicity. Fish (n = 160; 20.16 ± 0.23 g) were distributed into four groups (40 fish/group; 10 fish/replicate) for 60 days. The control and ROS groups were fed on basal diets containing 0% and 1% ROS, respectively. The TEB and ROS + TEB groups were subjected to TEB (0.52 mg/L) and given diets identical to those of the control and ROS groups. TEB exposure reduced the growth by reducing the final weight, weight gain, feed intake, average daily weight gain, and specific growth rate (p < 0.001), while increasing the feed conversion ratio and mortality (37.50%) (p < 0.001) of Nile tilapia. TEB exposure lowered the activities of digestive enzymes (trypsin, lipase, and amylase) and the serum level of growth hormone (p < 0.001), while increasing the leptin level (p < 0.001). TEB toxicity triggered oxidative stress through the elevation of malondialdehyde levels (p < 0.001), the reduction of total antioxidant capacity (p < 0.001), and the inhibition of glutathione peroxidase and superoxide dismutase activities (p < 0.001). The intestinal expression of nutrient transporters (solute carrier 15a1a and solute carrier 4a4) was down-regulated (p < 0.001), while the expression of pro-inflammatory (interleukin-6 and interleukin-8) and apoptotic (Bcl-2-associated X protein) genes was elevated as a result of TEB exposure (p < 0.001). TEB toxicity induced histological lesions in the intestine of the fish such as necrosis of the mucosal epithelium and oedema with infiltration of inflammatory cells (p < 0.001), along with reduced villus length (p < 0.001) and villus surface area (p < 0.001). ROS dietary intervention improved Nile tilapia growth (p < 0.05) and digestive enzyme activities (p < 0.001). ROS improved the antioxidant capacity (p < 0.05) and restored the intestinal histomorphology and gene expression (p < 0.001). Overall, ROS fortification at a level of 1% is recommended for Nile tilapia especially during TEB exposure.