Reviews Environmental Contamination and Toxicology

The present study investigates if the total replacement of dietary fishmeal (FM) with poultry by-product meal (PBM), supplemented with methionine influences the muscle fatty acids composition, normal gut morphology, histological traits of the liver, muscle, and gill, liver enzymes, immune and antioxidant response, and stress-related gene in juvenile barramundi, Lates calcarifer in relation to growth and feed utilization. Barramundi (3.58±0.01g) were randomly distributed into six 300 L seawater recirculating tanks (25 fish/tank) and fed two formulated isonitrogenous and isolipidic diets for 6 weeks. The control diet had FM as the sole animal protein source, whereas other test diet had only PBM as an animal protein source. Dietary PBM affected the fish performance and feed utilization. Regarding muscle fatty acid profile, total saturated fatty acids and monounsaturated fatty acids elevated while total PUFA particularly n-3 LC-PUFA and EPA decreased in PBM fed fish than control diet fed fish. Liver, muscle, gill, and intestinal histology showed no obvious alteration in control diet fed fish, however, more lipid droplets and hepatic vacuolization in the liver, necrotic myotome in muscle, hyperplasia in secondary lamellae in gill and short and broken folds in the intestine were observed in PBM fed fish. Similar to light microscopy observation of intestinal morphology, the transmission electron microscopy (TEM) analysis revealed shorter and smaller microvilli in fish fed PBM. Histopathological alterations in the liver of PBM fed fish were further associated with the elevated levels of aspartate aminotransferase (AST) and glutamate dehydrogenase (GLDH) and the significant upregulation of stress-related genes, HSP70 and HSP90. Also, a negative influence on lysozyme activity, and antioxidant enzymatic activities were recorded in fish fed PBM. Overall, it can be concluded that a total substitution of FM protein by methionine supplemented PBM negatively influenced the growth performance, liver health, histological traits of different organs, immune and antioxidant response, and expression of stress-related genes in juvenile barramundi.

Total replacement of fishmeal with poultry by-product meal affected the growth, muscle quality, histological structure, antioxidant capacity and immune response of juvenile barramundi, Lates calcarifer.

A feeding trial was conducted to test the effects of partial replacement of fishmeal (FM) protein and fish oil (FO) with partially defatted black soldier fly, Hermetia illucens insect protein, and oil, respectively, on growth performance, immune response, gut and skin barrier status, and flesh quality in juvenile barramundi. Four isonitrogenous and isocaloric diets used in the study were a control diet based on FM, 30% FM replaced with H. illucens protein (HiP), 30% FO replaced with H. illucens oil (HiO), and both 30% FM and 30% FO replaced with H. illucens protein and oil (HiPO). Diets were fed twice a day to satiety in triplicated groups of barramundi with an initial body weight of 1.74 ± 0.15 g per fish. At the end of the trial, growth and feed utilization indices were found insignificant (p > 0.05) between the test diets and control. A significant increase in bactericidal activity was observed in fish fed the HiP diet while serum lysozyme activity was unchanged. Stress-related heat shock proteins (HSP70 and HSP90) did not differ significantly among the test diets while immune-relevant genes (IL-1β and IL-10) were significantly upregulated in HiP and HiOP groups. The number of mucin cells were increased in the gut and skin of HiP and HiOP fed fish when compared to the control diet. The total fatty acid compositions (∑SFA, ∑MUFA, ∑PUFA, ∑n-3, and ∑n-6) in the muscles of barramundi were not significantly influenced with H. illucens protein and oil diets when compared to the control.

https://www.mdpi.com/2079-7737/10/6/505/pdf

Black Soldier Fly, Hermetia illucens as an Alternative to Fishmeal Protein and Fish Oil: Impact on Growth, Immune Response, Mucosal Barrier Status, and Flesh Quality of Juvenile Barramundi, Lates calcarifer (Bloch, 1790).

Peanut (Arachis hypogaea) is mainly grown for oil extraction and the remaining oil-free seed referred as peanut meal (PM) leaves with high protein content which can be a possible substitute for fishmeal in aqua-diets. This study evaluates the suitability of three types of processed peanut seeds, namely untreated PM (UPM), fermented PM (FPM), and germinated PM (GPM) from peanut seeds to replace fishmeal in barramundi (Lates calcarifer) diets cultured under a commercial production environment. Nine formulated diets having 3 inclusion levels from the 3 different peanuts (15%, 30% and 60% fishmeal replacement) were evaluated against a control without PM. The performance of various types and levels of PMs was assessed by examining the growth, gut and liver condition and survival of fish after eight weeks of feeding the test diets. The immunological responses of juvenile barramundi were assessed by exposing the fish to the hypoxic conditions for 4 hours. The results showed that fermentation and germination significantly (P<0.05) reduced the tannins and alkaloid contents in the PMs. The fish fed 15% GPM diet grew faster and had higher survival than fish fed control diet, while fish fed diet including 60% GPM showed a significant reduction in growth and survival, and an increase in food conversion rate (FCR). FPM and UPM at any inclusion levels did not alter the growth, survival and FCR. Histology analysis revealed that fish fed 60% GPM and UPM showed higher amount of lipid droplets in liver, myodigeneration in fish muscle and a decrease number of acidic mucins in distal gut compare to all other test diets. Stress caused by reduced dissolved oxygen did not change the sodium, potassium, chlorides and alanine aminotransferase concentrations of plasma of fish fed any diet. However, the stress did increase plasma cortisol significantly (P<0.05) in fish fed 60% GPM, 30% and 60% UPM diets. These results suggest that the PMs can partly replace the fishmeal in juvenile barramundi diet and the processing further improves the PMs quality by reducing its antinutritional factors which in turn can increase either its inclusion level in the barramundi diets or improved growth and health status of the species.

/pdf/growth-and-health-of-juvenile-barramundi-lates-calcarifer-2yc2hmcykj.pdf

Growth and health of juvenile barramundi (Lates calcarifer) challenged with DO hypoxia after feeding various inclusions of germinated, fermented and untreated peanut meals.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/jwas.12810

A review on cobia, Rachycentron canadum, aquaculture

Substituting fishmeal with lupin Lupinus angustifolius kernel meal in the diets of cobia Rachycentron canadum: Effects on growth performance, nutrient utilization, haemato-physiological response, and intestinal health

The study examined the effects of supplemental organic selenium (Se) extracted from selenoyeast on the growth performance, glutathione peroxidase (GPx) activity, biochemical status and liver histochemistry of juvenile cobia Rachycentron canadum. Six experimental diets were prepared supplemented with Se with total concentration of 1.52 (Se-1.52), 1.93 (Se-1.93), 2.29 (Se-2.29), 2.71 (Se-2.71) and 3.14 (Se-3.14) mg/kg of total Se in the diets and a fishmeal-based control diet without Se supplementation containing 1.15 (Se-1.15) mg/kg of Se was used as control. Experimental diets were fed to the fish of six treatment groups in triplicate twice daily for 8 weeks. Juvenile cobia fed dietary Se of 1.93, 2.29 and 2.71 mg/kg showed increased final body weight (FBW), specific growth rate (SGR) and feed intake (FI) than the fish fed the control diet. Se accumulations in the muscle and liver tissue displayed a positive linear relationship with dietary Se levels. Se deficiency was apparent in fish fed the control diet and displayed reduced growth and feed efficiency. Red blood cell (RBC) counts were significantly (P < 0.05) higher in cobia fed dietary Se between 1.52 to 2.71 mg/kg than the fish fed 3.14-mg/kg Se diet. Glutathione peroxidase activity significantly (P < 0.05) declined in the group fed with control diet compared to fish fed Se-supplemental diet. Juvenile cobia fed the highest Se level (Se-3.14 mg/kg) showed toxic effects in the liver, including histopathological lesions in the liver. Based on the results obtained for FBW, SGR, tissue Se retention and haematological parameters, we conclude that optimal dietary Se requirement for juvenile cobia fed commercial diets is 2.32 mg/kg.

Total Bioavailable Organic Selenium in Fishmeal-Based Diet Influences Growth and Physiology of Juvenile Cobia Rachycentron canadum (Linnaeus, 1766)

The dietary selenium (Se) requirement has been determined for cobia Rachycentron canadum using purified diet; however, its role in the utilisation of plant-derived ingredients has not been evaluated in the species. Therefore, a 3 x 2 factorial experimental design involving three inclusion levels (0, 210 and 315 g/kg) of lupin Lupinus angustifolius kernel meal (LKM) and two concentrations (0 and 0.8 mg/kg) of Se was used to evaluate the effects of Se supplementation in conjunction with LKM on the growth, feed utilisation and physiological responses in the cobia. Six isonitrogenous (46.5 % crude protein) and isoenergetic (21 MJ/kg gross energy) diets were formulated and fed to cobia for 7 weeks in a flow-through seawater system. The results showed significant effects of Se supplementation and its interaction with dietary lupin on the growth and feed efficiency of cobia. Se supplementation significantly improved the growth and feed utilisation efficiency in cobia fed lupin-based diets. The nutrient digestibility of fish fed supplemental Se lupin-based diets was significantly higher than that of fish fed diets without Se supplementation at each inclusion level of LKM. There were no significant effects of dietary Se supplementation on the survival, muscle composition or muscle amino acids, whereas regression analysis indicated a positive linear relationship between tissue Se accumulation and dietary Se levels. An enhancement of haematological responses was also observed in cobia fed Se-supplemented diets. In summary, cobia fed lupin-based diets required higher dietary Se supplementation for higher feed utilisation efficiency than previously quantified for the casein-based diet.

/pdf/feed-utilisation-efficiency-of-lupin-inclusion-in-cobia-role-y8thbu2vqj.pdf

Chau Minh Nguyen

Papers

Substituting fishmeal with lupin Lupinus angustifolius kernel meal in the diets of cobia Rachycentron canadum: Effects on growth performance, nutrient utilization, haemato-physiological response, and intestinal health

Total Bioavailable Organic Selenium in Fishmeal-Based Diet Influences Growth and Physiology of Juvenile Cobia Rachycentron canadum (Linnaeus, 1766)

Feed Utilisation Efficiency of Lupin Inclusion in Cobia: Role of Dietary Organic Selenium Supplementation