Dietary effect of powdered herbal seeds on zootechnical performance, hemato-biochemical indices, immunological status, and intestinal microbiota of European sea bass (Dicentrarchus labrax)

Abstract

Phyto additives and their bioactive ingredients prove to be effective in enhancing the nutritional content of fish feed. This study aimed to elucidate the impact of incorporating powdered herbal seeds (fennel, fenugreek, and anise) as feed supplements at 5 g / kg of feed on zootechnical performance, entire body chemical composition, hemogram, hepato-renal biomarkers, immune response, and the diversity of the intestinal microbiota of European sea bass (Dicentrarchus labrax). During a 90-day feeding trial, a cohort of 240 fish with an average body weight of 9.52 ± 0.17 g were mono-cultured in concrete tanks within the hapa net enclosures (1 m3) at a stocking density of 20 fish/hapa. The results revealed significant enhancements in weight gain (P ≤ 0.001), feed conversion ratio (P < 0.05), visceral somatic index (P ≤ 0.001), relative gut length (P ≤ 0.001), Fulton's factor (P ≤ 0.01), along with a reduction in mortality rate (P ≤ 0.01) across dietary groups compared to the control one. Nonetheless, proximate body composition and hepato-renal function measures were not significantly affected (P > 0.05). Whereas lymphocytes, neutrophils, globulin, lipid profile, phagocytic activities, and lysozyme activities exhibited significant improvements (P < 0.05 to ≤ 0.001) due to the herbal supplementation. The herbal supplements displayed prebiotic-like effects by significant (P < 0.05 to ≤ 0.0001) reducing the count of Vibrio spp. and total fecal coliform together with significant enhancing (P ≤ 0.01–0.001) colonization of lactic acid bacteria in Sea bass's gut. These findings emphasize that seed powder can enhance growth performance, biometry indices, innate immunity, lipid metabolism, and modulate gut microbiota without adverse effects on the haemato-biochemical profile of fish.