Aquaculture Nutrition最新文献

L-Carnitine is widely recognized for its involvement in lipid metabolism, but its effects on muscle quality and gut health in carp have not been well studied. The research aimed to investigate how L-carnitine influences muscle quality and intestinal health in high-fat-fed carp. The study was separated into four groups that received either the standard diet, a high-fat diet (HFD), or a HFD supplemented with 500 mg/kg L-carnitine (LLC), or a HFD supplemented with 1000 mg/kg L-carnitine (HLC) for 56 days. L-Carnitine was found to significantly reduce blood lipid levels. In addition, L-carnitine increased the crude protein content and decreased the crude fat content of high-fat-fed carp muscle while improving muscle fiber morphology and muscle quality. L-Carnitine increased the expression of genes related to intestinal tight junction proteins (claudin-2, occludin, and zo-1), improved the expression of genes related to intestinal inflammation, and enhanced the physical barrier function and organization of the intestine. Analysis of intestinal flora and intestinal metabolites showed that L-carnitine increased the diversity of the intestinal flora, increased the abundance of Cetobacterium, and influenced intestinal levels of bile acids, arachidonic acid, and tryptophan-related metabolites. In conclusion, supplementation with 1000 mg/kg L-carnitine improved muscle quality and intestinal health significantly in high-fat-fed carp by regulating muscle nutrient metabolism and intestinal flora.

Biofloc technology is an aquaculture production system that has gained popularity with tilapia production. Probiotics provide benefits for the host and/or aquatic environments by both regulating and modulating microbial communities and their metabolites. When a probiotic feed is combined with a biofloc system, the production amount may be improved through better fish growth, disease resistance, and/or improved water quality by reducing organic matter and stabilizing metrics such as pH and components of the nitrogen cycle. Two research trials measured Nile tilapia (Oreochromis niloticus) growth performance and composition of the microbial communities in the water and within the fish fecal material, following feeding with top-coated probiotic treatments. Trial A incorporated tilapia (71.4 ± 4.4 g), and a commercial diet (Control) that was top coated with either Bacillus velenzensis AP193 (AP193; 1 × 10⁷ CFU g¹) and BiOWiSH Feedbuilder Syn3 (BW; 3.6 × 10⁴ CFU g⁻¹). In Trial B, juvenile tilapia (5.34 ± 0.42 g) were fed treatment diets top coated with two different concentrations of BiOWiSH Feedbuilder Syn3 at final concentrations of 3.6 × 10⁴ CFU g⁻¹ (BWx1) and 7.2 × 10⁴ CFU g⁻¹ (BWx2). Tilapia were offered commercial feed (38% protein floating tilapia feed) as a control diet for both trials. Results from both growth trials indicated no differences in growth performance due to the probiotic additions, except for feed conversion ratio (FCR) in Trial B. Both BWx1 and BWx2 showed improved survival, water quality, solids management, and bacterial composition of water and fecal matter. Even though growth performance results presented no significant differences, results could differ based on the probiotic concentration, the route of probiotic administration, or their impact on the microbial community of the biofloc system culture water. Trial results indicated that testing on a larger scale with varied probiotic doses may be necessary to achieve an effective dosage for improving tilapia growth performance.

One of the main challenges in aquaculture is the constant search for sustainable alternative feed ingredients that can successfully replace fishmeal (FM) without any negative effects on fish growth and health. The goal of the present study was to develop a toolbox for rapidly anticipating the dynamics of fish growth following the introduction of a new feed; nonlethal, biochemical, and molecular markers that provide insights into physiological changes in the fish. A nutritional challenge by feeding a conventional feed rich in FM protein (FM diet) versus an experimental feed rich in plant protein (PP) and low FM inclusion (PP diet), in 20 different families of gilthead sea bream (Sparus aurata) was performed. Fifteen and 30 days after the initiation of the nutritional challenge, the transcriptional response of gilthead seabream erythrocytes along with classical hematological biochemical markers were compared. Zootechnical, biochemical, and transcriptome data from each family under different dietary treatments were combined into a classification model to identify variables that can predict the growth rate at the end of the 14-month farming period (July 2018–September 2019). A highly accurate model was produced (A > 80%) based on the combination of seven markers (five molecular and two biochemical markers) and with high potential in separating faster and slower growing fish as early as 30 days after the initiation of feeding.

High levels of nitrogen compounds can lead to acute toxicity in aquatic organisms. Ammonia, a by-product of protein breakdown, is the most prevalent contaminant in freshwater environments. Increasing salinity in water sources can cause fluctuations in salinity levels within breeding ponds. The interaction of these elements can occur in breeding ponds, significantly impacting the physiology and quality of the aquatic products. The purpose of this study was to examine the relationship between salinity and ammonia-N stress and their effects on the quality and fatty acid profile of tilapia fish (Oreochromis niloticus). The fish were divided into 12 distinct treatment groups, each characterized by varying salinity levels (0, 4, 8, and 12 ppt) and different concentrations of ammonia-N (0, 50% of 50% lethal concentration [LC₅₀]-96 h, and 30% of LC₅₀-96 h) arranged in a factorial design. The calculated LC₅₀-96 h for ammonia-N was 0.86 mg/L. Significant increases were observed in cortisol and glucose levels associated with various salinity treatments and ammonia levels. The levels of carcass protein in the salinity treatments (4, 8, and 12 ppt) did not show any significant differences when compared to the control treatment. However, the protein percentage at 50% of LC₅₀-96 h of ammonia-N was lower than that of the control treatment. In salinity treatments and ammonia levels (50% and 30% of LC₅₀-96 h of ammonia-N), a significant increase in the percentage of lipid, highly unsaturated fatty acids (HUFA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) was observed. To draw the conclusion, our assessment indicates that a salinity concentration of 8 ppt over a 96-h period without feeding has produced positive effects on the quality of tilapia carcasses.

The antioxidant and anti-inflammatory functions of genistein (GEN) and the regulatory mechanisms have been intensively investigated in mammals; however, there was a paucity of studies in aquatic animals. The purpose of this study was to evaluate the effects of GEN on lipopolysaccharide (LPS)-induced hepatic oxidative stress and inflammatory responses in turbot (Scophthalmus maximus L.) juveniles. Turbots (20 g body weight) were intraperitoneally injected with PBS (the Control group), LPS (50 μg/g), and LPS (50 μg/g) + GEN (0.05, 0.5 and 5 μg/g), respectively. Results showed that the content of the total bilirubin, the activities of the alanine aminotransferase, aspartate aminotransferase, γ-glutamyl transpeptidase, and alkaline phosphatase were significantly decreased with increasing levels of GEN injection (p < 0.05). Results exhibited that hepatic proinflammatory factors, oxidative stress-related factors, and apoptotic factors mRNA expression were significantly upregulated after intraperitoneal injection of LPS in turbot, compared with the Control group (p < 0.05). Meanwhile, the mRNA expressions of these apoptosis- and inflammation-related factors showed significant linear or quadratic terms of downregulation with increasing levels of GEN injection (p < 0.05) and almost reached the lowest values at 0.5 μg/g or 5 μg/g of GEN injection levels. The symptoms of LPS-induced disorganization of hepatocyte arrangement, vacuolization of hepatocytes, and inner mitochondrial cristae damage in turbot were significantly improved after GEN injection. Furthermore, the main signaling pathways associated with inflammation included Herpes simplex virus 1 infection, RIG-I-like receptor, NOD-like receptor, C-type lectin receptor, and p53 signaling pathways. Moreover, results of weighted correlation network analysis indicated that vascular endothelial growth factor A–A (vegfaa) and signal transducer and activator of transcription 3 (stat3) were likely to be hub genes. Meanwhile, mRNA expressions of vegfaa, vegfab, stat1, stat2, stat3, stat4, stat5a, and stat5b exhibited significantly linear or quadratic downregulation with increasing levels of GEN injection (p < 0.05). The above results confirmed that intraperitoneal injection of GEN significantly alleviated LPS-induced hepatic oxidative stress and inflammatory injury in turbot, and vegfaa and stat3 possibly play a key role in this process.

Two short-term feeding trials were conducted on Salmo salar, with the interaction between dietary zinc (Zn) and fat level in trial 1 and with the interaction between dietary Zn and n-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA) in trial 2, focusing on postprandial plasma parameters, intestinal Zn and fat uptake and transport. After 4-week feeding interventions, samples were collected at different postprandial time points, ranging from 0 to 36/38 h after feeding. Results showed that increased Zn level in feed significantly increased the postprandial plasma Zn level in trial 1 (8–9°C). On the contrary, the postprandial plasma Zn level was not affected by the dietary Zn under higher temperature conditions (trial 2, 10−12°C). Further, analyzed markers related to intestinal Zn uptake and transport were not affected by dietary fat level and n-3 LC-PUFA. In addition, analyzed markers related to intestinal fat uptake and transport were not affected by dietary Zn. Intestinal Zn transport plays a key role in regulating body Zn storage, while intestinal fat transport influences lipid accumulation within the intestine. Understanding how these processes respond to dietary components is critical for maintaining fish health and welfare.

Malabar snapper (Lutjanus malabaricus) is an economically important marine fish throughout the Indo-Pacific, with an emerging aquaculture industry. Although generic marine feeds are available for production, these are not optimised for this species. Understanding energy utilisation and balance can provide insight into suitable macronutrient profiles for new species to provide a baseline for future development. This study, therefore, evaluated the effect of dietary macronutrient composition (i.e., protein, fat, and carbohydrate) on the utilisation efficiencies of digestible energy (DE) in juvenile Malabar snapper using two isonitrogenous diets (high fat: HF and low fat: LF) with contrasting fat and carbohydrate content. Each diet was fed at four feeding levels (100%, 75%, 50%, and 25% apparent satiation) for 56 days, creating a 2 by 4 factorial design. The maintenance energy requirement of Malabar snapper was estimated to be 76.7 kJ kg^−0.8 day⁻¹, while the utilisation efficiencies of digestible protein (DP) and fat were 73.6% and 68.3%, respectively. Fish fed with LF, which has lower dietary fat and higher dietary carbohydrate levels, had significantly reduced energy utilisation efficiency for growth and significantly higher partial energy utilisation efficiency of digestible fat (DF) (p  < 0.05). Since body moisture is usually proportional to body fat content in fish, this implies that the energy from carbohydrates preferentially enters lipogenesis rather than being available for somatic growth, and adiposity does not directly result in weight gain. Malabar snapper utilises DF in preference to protein for metabolism, demonstrating a protein-sparing effect from lipids at DE intake levels below the maintenance requirement. Conversely, given the higher efficiency of fat retention than protein retention, protein is likely used before fat when energy intake is above maintenance. These findings suggest that Malabar snapper requires high levels of DP in its diet to support growth and that energy from dietary carbohydrates is diverted towards adiposity, consequently reducing growth.

A 56-day culture experiment was conducted to assess the effects of lysophospholipid added to a low-fishmeal diet on growth performance, hepatopancreas health, and intestinal microbiome of Litopenaeus vannamei. Three experimental diets were set up in this study: normal fishmeal positive control diet (20% fishmeal, P), low fishmeal negative control diet (12% fishmeal, N), and low fishmeal + lysophospholipid diet (12% fishmeal with 0.1% lysophospholipid, L). The obtained results proved that L. vannamei fed the group N diet could inhibit growth performance (final body weight, weight gain, and specific growth rate), decrease whole-body crude protein, and inhibit hepatosomatic antioxidant capacity and digestive capacity. These adverse effects were significantly alleviated in group L. Compared with group P, the expression of hepatopancreas lipid metabolism genes and the triglyceride content were both increased in group N. The triglyceride level of group L was significantly higher than that of group P but lower than group N. Histological analysis showed that the addition of lysophospholipid could maintain the normal morphology of hepatopancreas and reduce pathological changes such as cell melanosis caused by a low fishmeal diet. In addition, the proportion of dominant colonizers of intestinal flora was unbalanced in group N. In group L, the imbalance was alleviated. In conclusion, the supplementation of lysophospholipid in the low-fishmeal diet of L. vannamei improved the weight gain, antioxidant capacity, digestive capacity of hepatopancreas, regulate hepatopancreas lipid metabolism and maintain healthy tissue morphology, and also regulate the intestinal flora structure.

Feed quality is among the most determinative criteria for aquaculture success. Along with feed ingredient quality and its production process, feed storage conditions would also affect feed quality, especially in terms of adventitious toxins. Mycotoxins are frequent food and feed contaminants and are considered important health threats to both human and animal health. In this context, the effects of mycotoxins on aquatic animals were reviewed with an emphasis on aflatoxin B₁ (AFB₁), which is obviously reported in aquafeed. Severe tissue damage, increased susceptibility to infectious diseases, compromised immune system function, and increasing unknown death risks are among the most frequent symptoms of aflatoxicosis in aquatic animals. The lowest observable effect level for AFB₁ has also been documented for different fish species. Considering the importance of such fungal toxins on the economic viability of aquaculture enterprises, it is recommended that further knowledge be obtained concerning the safe levels of AFB₁ in terms of fish health and final product safety to human consumers.

Biofloc technology (BFT) is a relatively new microbial-based cultivation system that can be adopted to accomplish more sustainable aquaculture and circularity goals. This review explores aspects of BFT integrating the utilization of probiotics and phytobiotics as dietary and water supplements. This scientific-based snapshot unpacks some physiological pathways and brings a literature review on how these supplements can boost water quality, as well as aquatic species’ growth, health, and survival. Probiotics, live microorganisms that confer health benefits on the host when administered in adequate dosage, are noted for their ability to bolster animal defenses and sustain water quality in farming conditions. Recent studies showcased that selected bacteria, yeast, and fungi, once added into biofloc-based systems can enhance animal performance, act as a tool for water quality management and protect fish and crustaceans against diseases. On the other hand, phytobiotics are additives sourced from plants that normally are added into compounded feeds and are known for their health and growth benefits in aquatic animals. These additives contain plant-based substances/extracts that play a key role to suppress inflammation, pathogens, and can also act as antioxidants. These selected ingredients can promote healthy gut microbiota, improve feed efficiency, and turn on genes responsible for immunity improving disease resistance of fish/shrimp. According to this review, the adoption of probiotics and phytobiotics in BFT can greatly increase farm outputs by producing healthier animals, as well as promoting growth and consistent yields. Lastly, this review showcases the importance of proper section of probiotics and phytobiotics in order to achieve a functioning BFT. Despite its numerous advantages, BFT faces several challenges, especially related to microbial management. Probiotics and phytobiotics are practical tools that can play a crucial role to obtain a more stable environment with a desirable microbial population in water and gut. Future directions in the field should focus on optimizing the utilization of these supplements for a more resilient and sustainable BFT aquaculture.