Aquaculture Nutrition最新文献

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.

Introduction: The use of glyphosate (Gly) has caused unnecessary economic losses to the aquaculture industry, but research on the effect of Gly on Eriocheir sinensis is very limited. The aim of this study is to reduce the negative effects of Gly, reduce yield loss, and improve economic benefits through nutritional feed control technology.

Methods: The experiment involved 80 crabs randomly divided into four groups: control group, Gly group (48.945 mg/L), microbe-derived antioxidant (MA) group, and Gly and MA treatment group. The study lasted for 7 days. In this study, the effects of Gly on the digestive function of E. sinensis were investigated using histology and spectrophotometer, and the gut microorganisms of E. sinensis were analyzed using high-throughput sequencing technology.

Results: The study found that exposure to Gly resulted in separation of the folds of the midgut mucosa of Eriocheir sinensis from the basement membrane, a decrease in the fold area of the hindgut mucosa, and an increase in the number of B cells in hepatic tubules. Additionally, the lipase activity of the intestine in the Gly group was significantly higher than that of the control group and the MA + Gly group, while the hepatopancreatic lipase decreased significantly. The amylase activity in the intestine and hepatopancreas of the Gly group was significantly lower than that of the control group. The trypsin activity in the hepatopancreas of the MA + Gly group was significantly higher than that of the Gly group. The Shannon diversity index in MA + Gly group was significantly lower than that in control group. At the phylum level, the abundance of the Campilobacterota in the MA + Gly group decreased. At the genus level, the proportion of the Citrobacter and Flavobacterium in the MA + Gly group decreased.

Conclusion: Gly has certain effects on the digestive tissue function, intestinal microbial diversity index and intestinal microbiota structure of E. sinensis, and MA can ameliorate the negative effects of Gly on E. sinensis.

In recent years, zinc oxide nanoparticles (ZnO NPs) have gained attention as feed additives due to their high bioavailability. However, research on their impact on fish growth and health is limited. To investigate the influences of dietary addition of ZnO NPs on growth performance and immune function of rare minnow, rare minnows were fed diets with different ZnO NPs content. Growth analysis showed that ZnO NPs had a negative effect on the weight of rare minnow, decreasing and then increasing condition factors (CFs) and specific growth rate. Additionally, the accumulated zinc (Zn) level was significantly higher (p  < 0.05), and the liver injury index was significantly higher (p  < 0.05) in the dietary ZnO NPs group compared to the control group. The number of erythrocytes and leukocytes in blood samples increased and then decreased after treatment with ZnO NPs. It was further found that ZnO NPs as a dietary supplement significantly increased the Zn content and markedly repressed the expression of growth-related genes after 60 days of accumulation in muscle tissues, and accumulation in liver tissues for 60 days significantly enhanced the expression of immune modulation–related genes expression (p < 0.05). The findings suggested that short-term supplementation of ZnO NPs could positively affect fish growth and immune function. However, prolonged supplementation of dietary ZnO NPs resulted in reduced body weight and compromised immune function owing to the buildup of Zn in different tissues.

The purpose of the study was to investigate the effects of astaxanthin on ovarian development of largemouth bass (Micropterus salmoides) female. Five isonitrogenous and isolipidic feeds with varying levels of astaxanthin (0.8, 19, 41, 97, and 200 mg/kg) were grouped as AS0, AS20, AS40, AS100, and AS200, respectively. The results indicated that the gonadosomatic index (GSI) was significantly greater in the AS40 and AS100 than in AS0 and AS200 (p < 0.05). The AS40 and AS100 exhibited a dramatically lower hepatosomatic index (HSI) compared to the other groups (p < 0.05). The content of vitellogenin (VTG) was significantly increased in AS100 compared to the AS0, AS20, and AS200 (p < 0.05). Testosterone (T) levels were significantly lower in the AS200 compared to the other groups (p < 0.05). The AS40, AS100, and AS200 groups exhibited significantly greater follicle-stimulating hormone (FSH) levels than the AS0 and AS20 group (p < 0.05). The luteinizing hormone (LH) level was significantly higher in AS100 compared to the other groups (p < 0.05). The estradiol (E₂) levels were significantly higher in AS40 compared to the AS0 and AS200 groups (p < 0.05). The total antioxidant capacity (T-AOC) was significantly higher in AS100 than the AS0 and AS20 groups (p < 0.05). The superoxide dismutase (SOD) activity was significantly higher in AS40 compared to the AS0 and AS200 groups (p < 0.05). The malondialdehyde (MDA) level was significantly decreased in AS40 than the other groups (p < 0.05). Transcriptomic analysis of ovarian tissue revealed that differentially expressed genes primarily involved in pathways such as “ovarian steroidogenesis,” “steroid hormone biosynthesis,” and “arachidonic acid metabolism.” The expression of genes involved in ovarian steroidogenesis and arachidonic acid metabolism, such as cytochrome P450 family 2 subfamily J member (cyp2j), insulin-like growth factor 1 (igf1), phospholipase A2 group (pla2g), FSH receptor (fshr), and acute regulatory protein (star), was significantly upregulated in the AS40 group (p < 0.05). In summary, appropriate amount of astaxanthin supplementation in the diet enhance gonadal development, antioxidant capacity, and sex hormone levels, promote the expression of genes related to gonadal development, and consequently, enhance reproductive performance of largemouth bass.

Atlantic salmon are one of the most important fish species in global aquaculture production. However, temperature increases attributed to climatic events impair the production of Atlantic salmon during summer. Additionally, the nutritional requirements for this species when reared under elevated temperatures require elucidation. To address this gap, a feeding trial was conducted to investigate the effect of glutamine supplementation—a functional amino acid (AA) important for energy production and gut health—on the growth, metabolism, gut morphology, antioxidant capacity and thermal tolerance of Atlantic salmon parr at elevated temperatures (22°C). Atlantic salmon were pair-fed three isoenergetic diets: a control diet (D1, no addition of glutamine), D2 (7% glutamine supplementation with other dietary AA levels reduced—isonitrogenous to D1) and D3 (6% glutamine and with the same AA profile as D1). Metabolic rate measurements and sampling commenced after 7.5 weeks on diets and 3 weeks of exposure to 22°C. Glutamine supplementation (D2 and D3) did not affect specific growth rate (SGR), condition factor, relative gut mass or carcass composition despite fish fed D3 having increased pyloric caeca fold height (hF). Resting, maximum and digestive metabolic rates were also unaffected by glutamine supplementation. Contrary to findings in other fish species at optimum temperatures, this study showed that glutamine supplementation did not improve the growth performance of Atlantic salmon parr at elevated temperatures despite enhancing pyloric caeca surface area.

This study evaluated the growth performance, immune response, hepatopancreatic health, and disease resistance in Litopenaeus vannamei fed diets supplemented with fermented pomegranate peel polyphenols (FPPP) for 45 days. Five diets were formulated to contain various levels of FPPP: FP0 (no FPPP), FPPP inclusion at 0.015% (FP1), 0.030% (FP2), 0.060% (FP3), and 0.120% (FP4). The results indicated there were no significant variations in weight gain rate (WGR), specific growth rate (SGR), and feed conversion rate (FCR) of shrimp in all treatment groups (p > 0.05), but the survival (SR) of shrimp was significantly higher in all groups with the addition of FPPP (p < 0.05). Compared with FP0 group, the contents of total protein (TP) and globulin (GLB) in serum biochemical indexes of FP3 and FP4 groups were significantly increased, and the content of blood urea nitrogen (BUN) was significantly decreased (p < 0.05). Compared with FP0 group, the activities of superoxide dismutase (SOD), catalase (CAT), alkaline phosphatase (AKP), acid phosphatase (ACP), and lysozyme (LZM) in the hepatopancreas and serum of FP3 and FP4 groups were significantly increased (p < 0.05). Similarly, the activities of glutathione peroxidase (GSH-Px), total antioxidant capacity (T-AOC), and phenoloxidase (PO) in the hepatopancreas and serum of FP2 group were significantly higher than those of FP0 group (p < 0.05). In addition, the content of malondialdehyde (MDA) in the hepatopancreas and serum of shrimp in FPPP-added groups was decreased (p < 0.05). Compared with FP0 group, the expression levels of SOD, CAT, glutathione S-transferase (GST), LZM, prophenoloxidase (ProPO), penaeidin-3 (Pen3), Crustin, immune deficiency (Imd), Toll, and Relish genes were significantly upregulated in the hepatopancreas of shrimp in FP3 and FP4 groups (p < 0.05). Additionally, increasing the addition level of FPPP resulted in a more compact hepatosomal arrangement of the shrimp’s hepatopancreas, a more visible star-shaped lumen structure, and a significantly higher number of B cells. Finally, the cumulative SR of shrimp in FPPP groups was significantly higher than that in FP0 group after 7 days of infection with Vibrio alginolyticus (p < 0.05). In summary, dietary supplementation of FPPP can improve SR, immunity, and hepatopancreatic health and resistance to Vibrio alginolyticus of L. vannamei.