Milk thistle (Silybum marianum) extract improves growth, immunity, serum biochemical indices, antioxidant state, hepatic histoarchitecture, and intestinal histomorphometry of striped catfish, Pangasianodon hypophthalmus

In aquaculture, phytobiotics can be used as feed supplements with attractive growth-promoting, immunomodulatory, antioxidant, and several health benefits for a variety of finfish species. Herein, we evaluated of the impacts of milk thistle extract (MTE; Silybum marianum) on the overall performances of Pangasianodon hypophthalmus juveniles. Fish (7.10 ± 0.00 g) were fed on diets containing graded MTE levels as 0.0 (control), 0.1%, 0.2%, and 0.3%. Fish were assigned into 4 triplicate groups and were hand-fed on the prepared corresponding diets thrice daily for 60 days with 3% of their wet body weight. Significant increases in the feed intake, final weight, weight gain, weight gain%, and specific growth rate were noticed in MTE-supplemented groups with regard to the control group. However, survival rate %, feed conversion ratio, body composition analysis, and amino acid content (% of protein) were statistically non-significant among all experimental groups. Liver function enzymes, intestinal histomorphometry (intestinal villus height, width, and crypt depth), and digestive enzymes (protease, lipase, and amylase) were increased in MTE groups compared to controls. Moreover, dose-dependent significant increases in serum lysozyme activities and total immunoglobulin content were remarked in all MTE groups in comparison with the controls. Liver CAT and SOD enzymes were significantly elevated, and malondialdehyde levels were significantly declined in liver homogenates of MTE groups compared with the controls. However, the levels of serum urea, creatinine, and uric acid were not significantly changed by dietary MTE. Of interest, the histological sections of the hepatopancreatic and intestinal tissues showed normal histoarchitecture of the hepatic cords and pancreatic acini as well as normal intestinal villi, crypts, and enterocytes with no lesions recorded among all the experimental groups. Collectively, the findings mentioned above suggest that MTE could improve the growth, enhance digestive enzymes and intestinal morphometry, and boost the immunity and hepatic antioxidant capacity of P. hypophthalmus. Thus, we suggest the possible application of MTE extract in aquafeed as a growth promotor, immunostimulant, and antioxidant. •Striped catfish juveniles were fed diets supplemented with graded levels of milk thistle extract (MTE) for 60 days.•MTE based diets enhanced growth, immunity, and antioxidant capacity.•Dietary MTE improved digestive enzyme activities and intest