Beneficial Changes in Growth Performance, Antioxidant Capacity, Immune Response, Hepatic Health, and Flesh Quality of Trachinotus ovatus Fed With Oedocladium carolinianum

Abstract

The purpose of this study is to assess the feasibility of astaxanthin-rich Oedocladium carolinianum as an immunostimulant in the diet for Trachinotus ovatus. Three experimental diets containing 0% (OC0), 1% (OC1), and 5% (OC5) O. carolinianum powder were formulated for 6-week feeding trials. The results indicated that the OC5 diet boosted the growth performance through decreasing the feed conversion ratio and increasing digestive enzyme activities and intestinal villus length. Meanwhile, fish fed with the OC5 diet promoted antioxidant ability via stimulating the Nrf2-ARE signal pathway and enhancing antioxidant enzyme activities. Furthermore, the OC5 diet exerted hepatoprotective effects by suppressing the lipid deposition and inflammation response and enhancing the transport capacity of cholesterol. Besides, the OC5 diet improved the non-specific immunity by activating the lysozyme and complement system and increasing the nitric oxide content and total nitric oxide synthase activity. Dietary O. carolinianum supplementation promoted the deposition of astaxanthin in the whole body. Therefore, a diet supplemented with 5% O. carolinianum is recommended to boost the growth, antioxidant capacity, immune response, and flesh quality of T. ovatus.

Comparison of the Retention Rates of Synthetic and Natural Astaxanthin in Feeds and Their Effects on Pigmentation, Growth, and Health in Rainbow Trout (Oncorhynchus mykiss)

“…Thus, digestive function is closely correlated with intestinal development [ 34 ]. Earlier studies reported that an increase in villi length and villi thickness implies an enlargement of the surface area and, consequently, improved absorption of nutrients [ 14 , 35 ]. Muscular thickness is closely correlated with the peristaltic capacity of the intestine.…”

“…This study reveals that dietary astaxanthin down-regulates the activity of ALT and AST in plasma, which is consistent with previous observations in other fish species fed on diets supplemented with different sources and concentrations of astaxanthin [ 46 , 48 ]. It is noteworthy that fish in aquaculture are sensitive to environmental stressors and infections [ 14 ]. Accordingly, supplementing fish feed with astaxanthin is considered helpful in relieving environmental stress and protecting the liver, in turn improving fish health in cage culture [ 14 ].…”

“…It is noteworthy that fish in aquaculture are sensitive to environmental stressors and infections [ 14 ]. Accordingly, supplementing fish feed with astaxanthin is considered helpful in relieving environmental stress and protecting the liver, in turn improving fish health in cage culture [ 14 ].…”

“…Histological observation after hematoxylin and eosin staining was performed in accordance with the procedures presented in an earlier study [ 14 ]. Gut samples were fixed in 4% paraformaldehyde and then dehydrated in a graded ethanol series (75%, 4 h; 85%, 2 h; 90%, 2 h; 95%, 1 h; 100%, 1 h).…”

Effects of Dietary Carbohydrate Levels on Growth Performance, Body Composition, Antioxidant Capacity, Immunity, and Liver Morphology in Oncorhynchus mykiss under Cage Culture with Flowing Freshwater

“…of antioxidant parameters and gene expression [22]. Besides, from three fish randomly chosen from each cage, the liver was removed and fixed in 40 g/kg paraformaldehyde solution (Servicebio Technology Co., Ltd., Wuhan, China) for histological analysis.…”