Aquaculture Nutrition

Infection with the pathogenic bacterium Vibrio parahaemolyticus typically causes severe hepatopancreatic damage in Penaeus vannamei, often resulting in acute shrimp mortality. Therefore, protecting the shrimp’s hepatopancreas is crucial for enhancing their disease resistance. Previous research has demonstrated that the probiotic strain Lactobacillus plantarum Ep-M17 inhibits the growth of V. parahaemolyticus E1 in vitro. However, it remains uncertain whether Ep-M17 can provide protective benefits to the shrimp’s hepatopancreas. To address this knowledge gap, our present study investigated the histological changes, enzyme activity, gene transcription, and metabolite levels in the hepatopancreas of shrimp after a 4-week diet supplemented with Ep-M17. The results revealed that incorporating Ep-M17 into the shrimp’s diet alleviated the damage by V. parahaemolyticus E1 infection in hepatopancreatic cells. In addition, the inclusion of Ep-M17 notably boosted the effectiveness of immunodigestive enzymes such as SOD, AKP, and CAT. Furthermore, Ep-M17 stimulated gene transcription in crucial immune response-related signalling pathways like the mitogen-activated protein kinase signaling pathway and the antigen processing and presentation pathway. Moreover, the incorporation of Ep-M17 into shrimp diets increased the levels of β-alanine, and histidine in the hepatopancreas, enhancing anti-inflammatory capacity and improving the shrimp’s immune response. Overall, the results indicate that incorporating Ep-M17 into the diet can enhance shrimp disease resistance by bolstering both immune response and metabolic activity within the hepatopancreas. These results underscore the importance of probiotics in controlling aquatic animal diseases and highlight Ep-M17 as a promising dietary supplement for enhancing shrimp health and immunity in aquaculture.

Cinnamaldehyde is an ideal feed additive with good immune enhancement and anti-inflammatory regulation effects. However, the anti-inflammatory regulation mechanism in fat greenling (Hexagrammos otakii, H. otakii) remains unclear. The nine targets of cinnamaldehyde were gathered in identified by the Traditional Chinese Medicine Systems Pharmacology database and Uniprot database, and 1,320 intestinal inflammation disease (IIF)-related proteins were screened from DrugBank, Online Mendelian Inheritance in Man (OMIM), Genecards, and Pharmacogenetics and Pharmacogenomics Knowledge Base (PHARMGKB) Databases. According to the Gene Ontology enrichment results and Kyoto Encyclopedia of Genes and Genomes pathway results, cinnamaldehyde may regulated the responses to bacteria, lipopolysaccharide, an inflammatory cytokine, and external stimuli via the nuclear factor kappa-B (NFκB) signaling pathway within on inflammatory network. In addition, the protein–protein interaction analysis assisted in obtaining the closely related inflammatory regulatory proteins, including the C5a anaphylatoxin chemotactic receptor 1 (C5aR1), transcription factor p65 (RELA), prostaglandin G/H synthase 2 (PTGS2), and toll-like receptor 4 (TLR4), which were confirmed as the bottleneck nodes of the network to be more deeply verified via the molecular docking. Moreover, a cinnamaldehyde feeding model was established for evaluating the anti-inflammatory effect of cinnamaldehyde in vivo. According to the current findings implied that cinnamaldehyde may play a protective role against IIF H. otakii by reducing inflammation through the C5 complement (C5)/C5aR1/interleukin-6 (IL-6) and TLR4/NFκB/PTGS2 pathway. The study focused on investigating the action mechanism of cinnamaldehyde on IIF through combining pharmacology and experimental verification in vivo, which provided a fresh perspective on the promoting effect of cinnamaldehyde on IIF in fish.

The effect of feeding greater amberjack with copepod nauplii (Acartia tonsa) on the ontogeny of the digestive system was observed until 40 days after hatching (DAH). Copepods are part of the diet of fish larvae in nature, and they are rich in highly unsaturated fatty acids and free amino acids that enhance the digestive capacity of the fish. In a marine hatchery, four cylindroconical tanks of 2,700 L were stocked with about 150 × 10³ greater amberjack larvae (Seriola dumerili) in each. The larvae were initially fed from 3 to 17 DAH in two tanks with copepod nauplii and rotifers (Brachionus sp.; Copepods group), while in the other two tanks, they were fed only with rotifers (Control group) during the same period. All the tanks were fed with rotifers (3–27 DAH), Artemia nauplii (12–22 DAH), enriched Artemia metanauplii (20–30 DAH), and formulated diet (25–40 DAH). Fish samples were taken regularly (every 2 or 4 days) for histological analysis and every day for the measurement of total length (TL). The TL was 3.7, 4.5 ± 0.1, 6.1, 11, 17.3 ± 0.1 and 20.3 ± 2.3 mm at 4, 10, 16, 22, 30, and 40 DAH, respectively. Copepod-fed fish showed higher TL in the last 2 days of the trial (), while mortality rates were lower in the beginning of the trial 10–17 DAH, (). In addition, copepods-fed fish had less skeletal deformities (). Pyloric caeca appeared earlier in the Copepods group compared with the Control, while the length and surface of the villi, the abundance of goblet cells/100 μm of intestine length, and the area covered with lipid vacuoles in the liver were significantly higher in the Copepods group (). We can conclude that the use of copepods in the diet of the greater amberjack larvae can improve the ontogeny of the digestive system.

This study aimed to assess the viability of replacing rice bran with spent coffee grounds (SCG) in the diets of Oreochromis niloticus (average body weight, 48.8 ± 0.42 g). The fish were randomly allocated into four sets of three groups each and placed in net cages (1 m × 2 m × 0.5 m) at a density of 30 fish per cage. They were fed diets with four different replacement levels: 0%, 5%, 10%, and 15% of SCG over a period of 90 days. Growth and serum biochemical indices were monitored three times at 30, 60, and 90 days. During the experiment, there were no significant differences () observed in growth indices, including weight gain (WG), daily WG, specific growth rate, feed conversion rate, protein efficiency ratio, and survival rate among the groups at 30, 60, and 90 days. Serum biochemical indices, such as aspartate aminotransferase and alanine aminotransferase, showed a similar trend with significant differences observed only on day 30, while the lowest and highest levels were found in the control and 15% SCG replacement groups, respectively. For total cholesterol, a significantly different result was found only on day 30. However, these differences were not sustained in subsequent assessments. Conversely, serum glucose, total protein, albumin, and globulin remained unaffected by SCG replacement throughout the experiment. The findings indicate that replacing rice bran with up to 15% SCG did not adversely impact the growth performance or key serum biochemical indices of Nile tilapia. To the researchers’ knowledge, these findings are the first in the field to substitute SCG for rice bran, opening a new avenue for further research.

Ocimum basilicum has antioxidant, anti-inflammatory, and antimicrobial effects. The present study was conducted to evaluate the effects of O. basilicum extract on growth yield, safety, and marinating physiologic functions of the rainbow trout. The fish were fed with food rations containing 0%, 1%, 2%, and 3% of basil extract. Basil extract, especially at 1% concentration food ration, significantly increased the growth parameters compared with the control group (). The biochemical parameters of hepatic function, renal function, glucose, triglyceride, and cholesterol level were significantly reduced in the treatment groups compared with the control group (). Feeding with basil extract led to a significant increase in Ig, lysozyme, and respiratory burst assay, with the most prominent elevation at 2% concentration food ration. The mucosal antibacterial activity was improved. The mortality rate after exposure to Yersinia ruckeri was lower in the treatment groups compared with the control group. The results of the present study suggest that adding 2% basil extract to the food rations of the fish may improve their physiologic function and growth yield and reinforce their immune system.

Yellow mealworm (Tenebrio molitor) meal was introduced to aquafeed as a suitable protein source to replace fish meal (FM) and soybean meal and, thereby, consistent aquaculture production. However, mealworms should be added at adequate levels due to the presence of antinutritional factors such as chitin. Consequently, sodium butyrate (SB) is suggested to improve feed quality and ensure aquatic animals’ productivity and welfare. In this study, parallel with the protein source (T. molitor meal or FM), dietary supplementation of SB (1 g/kg) is involved as a factor in the 2 × 2 factorial study. The first and the second diets were formulated using FM as a protein source with or without SB, while the third and fourth diets were prepared by replacing FM with T. molitor meal with or without SB supplementation. After 60 days, fish fed with FM or T. molitor and SB showed improved final body weight and weight gain, while those fed with T. molitor without SB had a reduced protein efficiency ratio. Histological analysis revealed that dietary SB improved intestinal histological features by increasing the height and branching of intestinal villi and immune cell infiltration near intestinal crypts in Nile tilapia-fed FM or T. molitor. Furthermore, fish-fed FM or T. molitor and SB had higher Hb, red blood cells, PCV, total protein, and globulin levels than fish-fed respective test diets without SB supplementation. Dietary SB addition to FM or T. molitor-based diets also significantly enhanced blood lysozyme and phagocytic activities, catalase, superoxide dismutase, glutathione peroxidase, and reduced MDA levels. Our results demonstrate that T. molitor meal can replace FM without compromising Nile tilapia’s growth performance and health status. Additionally, SB supplementation improved T. molitor meal utilization by Nile tilapia, thereby significantly enhancing the growth, digestion capacity, intestinal histological features, and antioxidative and immune responses. Consequently, dietary T. molitor meal reduces the reliance on FM and improves the sustainability and efficiency of Nile tilapia production.