To investigate the effects of compound attractants on the growth performance, feed utilization, intestinal morphology, protein synthesis, and immune response of Litopenaeus vannamei, the following seven diets were formulated: a positive control (P), a negative control (N), and five diets with compound attractants which were labeled as A, B, C, D, and E, each with four of five tested attractants (yeast extract, squid visceral powder, fish soluble, and squid paste, shrimp paste), respectively. Shrimp (0.71 ± 0.00 g) were distributed to seven groups of four replicates and fed for 7 weeks. Results showed that the final body weight, feed intake, specific growth rate, and weight gain of shrimp in the B and D groups were the greatest. Hemolymph total antioxidant capacity of shrimp in the B, D, and E groups reached the highest level. In the hepatopancreas, the activity of total nitric oxide synthase, malondialdehyde content, the expression levels of sod, myd88, eif4e2, and raptor in shrimp fed the B diet were the highest, and the highest levels of dorsal and relish were observed in the C group. In the intestine, intestinal muscle thickness and expression levels of toll and eif2α in the C group were the highest, while the highest expression level of sod and relish occurred in the B group. In summary, the B and E diets promoted the feed intake, growth performance and the antioxidant enzyme activity of L. vannamei. The C diet enhanced the protein synthesis of shrimp. Regression analysis indicated that the WG and FI of shrimp were increased as the dietary inclusion levels of squid paste and shrimp paste increased, while they were decreased as the dietary inclusion levels of yeast extract and fish soluble increased.

This research aimed to examine the combined influence of Astragalus polysaccharide (APS) and Isatis indigotica extract (IIE) dietary supplements on oxidative-inflammatory status, cellular homeostasis, and intestinal integrity in large yellow croaker (Larimichthys crocea). Three replicates of experimental fish (n = 160) received one of five dietary regimens: a basal control (CON) diet, the CON diet containing 0.1% APS (AP), and the AP diet supplemented with 0.05%, 0.1%, and 0.15% IIE (AI1, AI2, and AI3) for 8 weeks. The combined supplements, particularly in the AI2 group, significantly improved intestinal morphology and enhanced the activities of key digestive enzymes. Gene expression analysis revealed that the APS-IIE combination consistently upregulated the intestinal mRNA abundance of major tight junction proteins (CLDN4, OCLN, ZO1, ZO2) compared to the CON or AP groups. Liver antioxidant capacity was strengthened (enhanced CAT capacity), as evidenced by a significant reduction in lipid peroxidation (MDA) levels. In the head kidney, the combination downregulated the expression of pro-inflammatory cytokines (IL8, TNF) and toll-like receptors (TLR1, TLR2, TLR5), and promoted the expression of anti-inflammatory cytokines (IL10, TGFB1). Furthermore, dietary supplementation modulated the crosstalk between autophagy and apoptosis, indicated by altered expression of key marker genes (e.g., increased MAP1LC3B and decreased CASP3/8/9). In conclusion, the simultaneous inclusion of APS and IIE in diets promotes intestinal health, strengthens antioxidant status, and alleviates inflammatory responses, with the 0.1% APS + 0.1% IIE (AI2) formulation demonstrating the most pronounced benefits.

Siganus fuscescens, an economically important species in southern China, is noted for its rapid growth and high nutritional value. Nonetheless, the prevalence of darkening syndrome, a condition marked by skin discoloration and significant mortality rates, presents a challenge to aquaculture practices, with its etiology remaining largely unexplored. This study aimed to examine the impacts of varying dietary lipid levels and multivitamin supplementation on the incidence of darkening syndrome in S. fuscescens. Five experimental diets were developed: a low-fat diet containing 10% lipids; a moderate-fat diet with 13% lipids; a moderate-fat diet with 13% lipids supplemented with multivitamins; a high-fat diet containing 16% lipids; and a high-fat diet with 16% lipids supplemented with multivitamins. A 55-day feeding trial was conducted on S. fuscescens specimens. The results indicate that, in this experiment, increasing dietary fat content led to a higher cumulative incidence of darkening syndrome in S. fuscescens. Serological and histological findings suggested that in the 16% lipid diet group, S. fuscescens exhibited liver injury and oxidative stress. Notably, supplementation with multivitamins alleviated these adverse effects. Overall, we recommend using an appropriate dietary fat level and further supplementing with antioxidant multivitamins, which may represent an effective strategy to mitigate darkening syndrome in S. fuscescens.