Fish Meal Replacement Level Research Articles

Replacement Effect of Fish Meal by Plant Protein Sources in Olive Flounder (Paralichthys olivaceus) Feeds with an Addition of Jack Mackerel Meal on Growth, Feed Availability, and Biochemical Composition.

Application of feed stimulants is very helpful to increase the feed intake of fish, especially in the development of low fish meal (FM) diets. FM replacement effect by various plant protein sources (corn gluten meal (CGM), soy protein concentrate (SPC), and corn protein concentrate (CPC)) in diets with an addition of jack mackerel meal (JMM) as feed stimulants on growth, feed availability, and biochemical composition of olive flounder was elucidated. An experimental design of two-way (two replacement levels (25% and 50%) × 3 replacement sources (CGM, SPC, and CPC)) analysis of variance was adopted. Seven diets were formulated. Amount of 60% FM was contained in the control (Con) diet. In the Con diet, 25% and 50% FM were replaced by CGM, SPC, and CPC with an addition of 12% JMM as feed stimulants, referred to as the CGM25, CGM50, SPC25, SPC50, CPC25, and CPC50 diets, respectively. Four hundred and twenty juvenile fish were distributed into 21 flow-through tanks. All diets were assigned to triplicate groups of fish. Fish were hand-fed to satiation twice a day for 56 days. Both dietary replacement levels and sources had statistical effect on weight gain (P < 0.0001 and P < 0.045, respectively), specific growth rate (SGR) (P < 0.0001 and P < 0.033), and feed consumption (P < 0.0001 and P < 0.03) of fish. Dietary increased FM replacement levels lowered weight gain, SGR, and feed consumption of fish. Weight gain, SGR, and feed consumption of fish fed the Con and CGM25 diets were statistically (P < 0.05) greater than those of fish fed the CGM50, SPC50, and CPC50 diets. Both replacement level and source had no statistical effect on feed utilization, biochemical composition except for statistical effect of replacement source on glycine content of fish, and lysozyme and superoxide dismutase (SOD) activities of fish. FM up to 25% could be substituted with CGM, SPC, and CPC in the olive flounder feeds supplemented with 12% JMM as feed stimulants without compromising growth, feed utilization, and lysozyme and SOD activities.

Single cell protein from methanotrophic bacteria as an alternative healthy and functional protein source in aquafeeds, a holistic approach in rainbow trout (Oncorhynchus mykiss) juveniles

Bacterial single cell protein (BSCP) obtained from methanotrophic bacteria was tested as an alternative protein source to fishmeal (FM) in compound diets for rainbow trout (Oncorhynchus mykiss) juveniles (initial body weight, BW = 11.3 ± 0.2 g, mean ± standard deviation). Different levels of FM replacement (0, 25, 50, 75 and 100%) by a BSCP (0, 3.75, 7.5, 11.25 and 15% of Uniprotein® Aqua) were tested in isoproteic (crude protein: 42%) and isolipidic (crude fat: 21%) extruded diets. The trial was divided in two different parts, a nutritional trial that lasted 83 days during which the impact of experimental diets was evaluated in terms of key performance indicators (KPIs) associated to fish growth performance and feed utilization, which was followed by a challenge with a pathogenic bacterium (Aeromonas salmonicida subsp. salmonicida) to evaluate the immunological competence of fish fed the experimental diets (15 days). At the end of the nutritional trial, somatic growth in terms of body weight (BW) responded quadratically (P < 0.05) to the dietary inclusion of BCSP with the lowest BW values (183.4 ± 4.5 g) recorded in fish fed 100% FM replacement with BSCP, whereas the rest of dietary groups showed similar BW values (191.3–201.2 g). Feed intake was not affected by the level of FM replacement by BSCP, whereas feed conversion ratio (FCR) slightly increased with increasing levels of BSCP (P < 0.05), even though the lowest FCR values were found in fish fed 50% FM replacement by BSCP (0.79 ± 0.01) in comparison to the control group (0.81 ± 0.01). When using quadratic linear regression, the optimal dietary FM replacement by BSCP in terms of BW values was estimated as 41.7%. The nutritional quality of the fillet was not altered with experimental diets; all dietary groups showed similar amino acid levels as well as their content in HUFA n-3 and n-6 that remained unaltered (P > 0.05) and lipid nutritional indexes (P > 0.05). No negative effects were observed in the histological organization of the liver nor the proximate intestine, neither in the lipid peroxidation levels nor activity of antioxidative stress enzymes in the liver from fish fed increased inclusion levels of BSCP (P < 0.05). The replacement of FM by the tested BSCP obtained from methanotrophic bacteria did not cause an imbalance or dysbiosis in the intestinal microbiota in rainbow trout regardless of the level of FM replaced. The replacement of FM by BSCP at 50% improved disease resistance in rainbow trout exposed to furunculosis when compared to the control diet (cumulative mortality = 83.3 ± 7.2% vs. 49.2 ± 15.6%; P < 0.05), which suggested that this ingredient may also have some immunomodulatory properties that would protect fish from infections, although their mode of action deserves further attention. Current results indicated that the tested BSCP from methanotrophic bacteria is a safe, functional, and sustainable alternative protein source for aquafeeds.

Affecting mechanism of Chlorella sorokiniana meal replacing fish meal on growth and immunity of Litopenaeus vannamei based on transcriptome analysis

The purpose of this study was to analyze the affecting mechanism of Chlorella sorokiniana meal replacing fish meal on the growth performance and immune function of Pacific white shrimp, Litopenaeus vannamei by transcriptomics analysis. In a control diet containing 560 g % /kg fish meal, chlorella was used to replace 0 %, 20 %, 40 %, 60 %, 80 % and 100 % of dietary fish meal to form six iso-nitrogenous and iso-lipidic diets (C0, C20, C40, C60, C80, C100). The six diets were fed to white shrimp (1.37 ± 0.02 g) for 8 weeks. Compared to the control group, the final body weight (FBW), specific growth rate (SGR) and feed efficiency (FE) of the C20 group were significantly improved (P < 0.05). There was no significant difference in growth performance between the C40 group and the C0 group (P > 0.05). When the replacement level of fish meal by chlorella was ≥ 60 %, the FBW, SGR and FE of shrimp were significantly decreased (P < 0.05). In the analysis of the hepatopancreatic transcriptome, the amount of differentially expressed genes (DEGs) in C20, C40, C60, C80 and C100 groups were 322 (176 up and 146 down), 482 (246 up and 236 down), 804 (487 up and 317 down), 1080 (684 up and 396 down) and 1262 (827 up and 435 down), respectively, when compared to the C0 group. GO Term and KEGG pathway enrichment analysis of DEGs showed that DEGs between the C20 and C0 groups were significantly enriched in chitin binding and inositol metabolism processes. Several immune-related signaling pathways were also enriched, including the C-type lectin receptor pathway, complement and coagulation cascades, the B-cell receptor pathway, and most of these genes were up-regulated in the C20 group. Compared to the C0 group, DEGs in C40, C60, C80 and C100 groups were significantly enriched in lysosomal, protein digestion, and absorption pathways. In addition, in the C80 and C100 groups, the DEGs were also significantly enriched in lipid catabolism process. The high replacement of fish meal with chlorella meal affected the absorption and utilization of nutrients by regulating the signaling pathways related to protein digestion and absorption, and aggravated lipid catabolism of the body, thereby affecting the growth of shrimp. The high replacement of fish meal might also affect the homeostasis of shrimp cells and reduce immunity through the lysosomal signaling pathway. In summary, the low replacement of fish meal (20 %) with chlorella meal significantly improved the growth performance of Litopenaeus vannamei, which might be realized through activating the C-type lectin receptor signaling pathway to regulate immune function of the body, but the high substitution of fish meal (≥ 60 %) reduced the growth performance and immunity by affecting the lysosomal signaling pathway.

Kidney bean protein hydrolysate as a fish meal replacer: Effects on growth, digestive enzymes, metabolic functions, immune-antioxidant parameters and their related gene expression, intestinal and muscular gene expression

A feeding trial for 70 days was designated on Nile tilapia, Oreochromis niloticus (O. niloticus). A total of 200 fish (34.38 ± 0.05 g) were assigned into five groups, four replicates for each (10 fish/replicate; 40 fish/group) and received five isonitrogenous and isocaloric diets with five replacement levels of fishmeal (FM) with kidney bean (Phaseolus vulgaris L) protein hydrolysate (KBH) (0, 25, 50, 75, 100%). The findings demonstrated a significant increase in the performance metrics (final body weight, total weight gain, average daily weight gain, protein efficiency ratio, and specific growth rate) with a considerable improvement in the feed conversion ratio across all replacement levels, with the greatest value obtained in the KBH75 and KBH100 groups. Regarding the broken line regression analysis, the optimum FM replacement level with KBH was 76%. By replacing FM with KBH, the growth hormone and digestive enzymes (amylase and protease) levels were significantly increased, whilst the glucose and leptin hormone levels significantly declined. The amino acid transporters (solute carrier family 15 member 2 and solute carrier family 26 member 6), insulin growth factor-1, the immune-associated genes (interleukin-8, toll-like receptors-7, and cc-chemokine), and the antioxidant-associated genes (glutathione peroxidase, superoxide dismutase, and Glutathione synthetase) expression was substantially boosted in all replacement levels, where the KBH50 group recorded the highest expression. As well as the mRNA expression of myostatin was down-turned in all replacement levels relative to the KBH0 group. Improving the immune functions (lysozyme, complement 3, nitric oxide, phagocytic %, and phagocytic index) was noticed by FM replacement with KBH. The cumulative mortality as a result of challenging with Aeromonas sobria at the end of the feeding trial was decreased by increasing the replacement level (80, 40, 37, 30, and 25% for KBH0, KBH25, KBH50, KBH75, and KBH100, respectively). From the economic point of view, the feed costs and feed cost/ kg gain declined in the KBH75 and KBH100 diets. From the aforementioned outcomes, KBH could replace the FM up to 100% with improving the growth and their related genes expression, digestive enzymes activity, and immune/antioxidant parameters and their encoding gene expression, and the optimal replacement level was 76%. The replacement of FM with KBH was economically efficient.

Effects of defatted yellow mealworm (Tenebrio molitor) on growth performance, intestine, and liver health of turbot (Scophthalmus maximus)

Yellow mealworm Tenebrio molitor is an emerging feed ingredient with several key advantages. However, research on the T. molitor as a fishmeal substitute reported discrepancies in feasibility in different fish species, with a particular need for T. molitor products to be widely evaluated. In this research, an eight-week feeding trial was conducted to evaluate the effect of T. molitor on turbot Scophthalmus maximus mainly from the perspective of growth performance and health status of the intestine and liver. Turbot with an initial weight of approximately 150 g were randomly assigned six isonitrogenous and isolipidic diets, including fishmeal-based control diet or diets with gradually increasing level of defatted T. molitor meal (TM) to replace 15 % (TM15), 30 %, 45 %, 60 % and 75 % of fishmeal compared to the control diet. Weight gain of turbot increased significantly at the 30 % replacement level (P < 0.05). However, TM in 45 %, 60 % and 75 % of fishmeal replacement level impaired overall growth performance. There was no obvious impairment in the assayed levels of TM towards the intestine from the view of structure, activities of brush border enzymes, antioxidant conditions, or immunity of proximal, middle and distal segments. However, the amount of goblet cells was significantly decreased by TM (P < 0.05). Similarly, TM in the assayed levels did not induce any negative effects on the antioxidant and immune status of the liver. But TM45, TM60 and TM75 diets induced weight loss in the liver and smaller hepatocytes, accompanied by a decrease of liver lipid content as well as decreases in levels of triglyceride and cholesterol in plasma. In conclusion, the optimal dietary level of TM for turbot was 24.5 %, corresponding to a 30 % substitution of fishmeal from the control group. Dietary TM can improve the antioxidant and immune function of the intestine and liver, but excess TM will disturb lipid metabolisms.

1H-NMR-Based Metabolic Profiling in Muscle and Liver Tissue of Juvenile Turbot (Scophthalmus maximus) Fed with Plant and Animal Protein Sources

Circular economy driven feed ingredients and emerging protein sources, such as insects and microbial meals, has the potential to partially replace fishmeal in diets of high-trophic fish. Even though growth and feed performance are often unaffected at low inclusion levels, the metabolic effects are unknown. This study examined the metabolic response of juvenile turbot (Scophthalmus maximus) to diets with graded fishmeal replacement with plant, animal, and emerging protein sources (PLANT, PAP, and MIX) in comparison to a commercial-like diet (CTRL). A 1H-nuclear magnetic resonance (NMR) spectroscopy was used to assess the metabolic profiles of muscle and liver tissue after feeding the fish the experimental diets for 16 weeks. The comparative approach revealed a decrease in metabolites that are associated with energy deficiency in both tissues of fish fed with fishmeal-reduced diets compared to the commercial-like diet (CTRL). Since growth and feeding performance were unaffected, the observed metabolic response suggests that the balanced feed formulations, especially at lower fishmeal replacement levels, have the potential for industry application.

Effects of Yellow Mealworm (Tenebrio molitor) on Growth Performance, Hepatic Health and Digestibility in Juvenile Largemouth Bass (Micropterus salmoides).

This study investigated the effects of yellow mealworm meal (TM) on growth performance, hepatic health and digestibility in juvenile largemouth bass (Micropterus salmoides). The fish were fed with the basic feed and the test feed (70% basic feed and 30% raw materials) containing Cr2O3, and feces were collected for digestibility determination. The fish were fed with five isonitrogenous (47% crude protein) and isolipidic (13% crude lipid) diets, in which fishmeal (FM) was replaced with 0% (TM0), 12% (TM12), 24% (TM24), 36% (TM36) and 48% (TM48) TM. The fish were reared in cylindrical plastic tanks in a recirculating aquaculture system for 11 weeks. The apparent digestibility coefficients (ADC), of dry matter, crude protein and crude lipid, in largemouth bass of TM were 74.66%, 91.03% and 90.91%, respectively. The ADC of total amino acid (TAA) of TM in largemouth bass was 92.89%, and the ADC of essential amino acid (EAA) in TM in largemouth bass was 93.86%. The final body weight (FBW), weight gain rate (WGR) and specific growth rate (SGR) in the TM24 group were significantly higher than those in other groups. Similarly, the highest mRNA expression levels of hepatic protein metabolism genes (pi3k, mtor, 4ebp2 and got) and antioxidant enzyme (glutathione peroxidase, Gpx; catalase, Cat) activities were observed in the TM24 group. Moreover, the expression levels of anti-inflammatory factors (il-10 and tgf) in liver were up-regulated and the expression levels of pro-inflammatory factors (il-8 and il-1β) in liver were down-regulated. Quadratic regression model analysis, based on weight gain rate (WGR) against dietary TM level, indicated that the optimum level of dietary TM replacing FM in largemouth bass diet was 19.52%. Appropriate replacement levels (less than 36%) of FM by TM in the diets can enhance the antioxidant capacity and immunity of largemouth bass. However, high levels of FM substitution with TM (more than 48%) in the feeds can damage the liver health and inhibit the growth of largemouth bass. Notably, largemouth bass has high ADC and high utilization of TM, which indicates that it is feasible to use TM as feed protein source for largemouth bass.

Fish Meal Replacement and Early Mild Stress Improve Stress Responsiveness and Survival of Fish after Acute Stress.

Stress responsiveness and fish meal (FM) replacement are two of the most important concerns toward achieving sustainable aquaculture. The purpose of this study was to see how early mild stress (netting) and FM replacement with meat and bone meal (MBM) affected oscar (Astronotus ocellatus; 5.2 ± 0.9 g) growth, hematology, blood biochemistry, immune responses, antioxidant system, liver enzymes, and stress responses. Oscars were subjected to a 3 × 3 experimental design (three fish meal replacement levels: 250, 180 and 110 g/kg of FM in diets; three stress periods: 0-, 2- and 3-times early mild stress). After ten weeks of the experiment, FM levels in diets did not affect growth data, but the survival rate after the acute confinement (AC) stress was lower in 11FM treatments (47.7% compared to 67.7%) than others. Fish exposed to the 3Stress schedule had a lower growth (31.03 ± 6.50 g) and survival rate (55.5%) after the AC stress than the 2Stress group (38.92 ± 6.82 g and 70.0%). Lower survival and growth rate in the 3Stress and 11FM groups coincided with the lowest blood performance, total protein, lysozyme, complement C4, complement C3, immunoglobulin, superoxide dismutase, catalase, glutathione peroxidase, and the highest glucose, cortisol, low-density lipoprotein and aspartate aminotransferase serum levels. Altogether, this study revealed that it is possible to replace FM with MBM up to 28% (180 g/kg of FM) without negative effects on the growth and health of juvenile oscar as dietary 110 g/kg of FM impaired fish health. While fish welfare should be considered, we can conclude that mild stress (2Stress) during the farming period, but without adding excessive alternative protein sources, can improve the stress responsiveness of oscar.

Effects of poultry by-product meal replacing fish meal on growth performance, feed utilization, intestinal morphology and microbiota communities in juvenile large yellow croaker (Larimichthys crocea)

An 8 weeks feeding trail was conducted to evaluate the potential of poultry by-product meal (PBM) replacing fish meal (FM) in the diet of juvenile large yellow croaker (Larimichthys crocea). Five iso-nitrogenous (45% crude protein), iso-lipidic (10% crude lipid) and iso-energetic (about kcal 400 g diet −1) diets were formulated with 0, 25%, 50% 75% and 100% FM being replaced by PBM (marked as FM, PBM25, PBM50, PBM75 and PBM100). Crystal methionine and lysine were added into PBM-containing diets to match its concentration in FM diet. Each diet was randomly assigned to triplicate groups of 30 fish (initial weight 18.43 ± 1.28 g) in floating sea cages. The weight gain, specific growth rate and feed efficiency of L. crocea decreased significantly when the replacement level of FM was higher than 25%. The feed intake of fish fed PBM100 was significantly lower than those fed FM, PBM25 and PBM50. Juveniles fed PBM-containing diets showed significantly lower value of muscular thickness in intestine when compared to those fed FM. Villi length decreased significantly when the replacement of FM in diets was more than 50%. Fish fed FM diet had the relative higher abundances of Exiguobacterium (from order to genus), Bacillus (from order to genus), Pseudomonadales (from order to genus) and Acinetobacter genus, those fed PBM25, PBM50 and/or PBM75 showed higher abundance of Peptostreptococcaceae and Vibrio. Overall, PBM replacing dietary FM may inhibit growth performance of L. crocea through reducing digestibility via declining the abundance of intestinal bacteria that producing digestive enzyme, and improving the abundance of pathogen. Peptostreptococcaceae and Vibrio could be the indicator in the intestinal of L. crocea fed high PBM diets. The optimum dietary FM replacement level by PBM was 25% for L. crocea.

Replacement of Dietary Fishmeal by Black Soldier Fly Larvae (Hermetia illucens) Meal in Practical Diets for Juvenile Tench (Tinca tinca)

The development of specific diets for the juvenile stage is a main target for culture intensification of tench (Tinca tinca). Aquafeeds still rely heavily on the use of fishmeal (FM) but concerns about economic and ecological sustainability make the use of alternative protein sources necessary. Insect meals are considered a promising substitute to replace FM. In a 90-day experiment, 6 diets with different replacement levels of FM by partially defatted black soldier fly larvae meal (BSFLM): 0%, 15%, 30%, 45%, 60% and 75%, were tested on juvenile tench. Survival rates were high (95.8–100%) without differences between treatments. Diet with 45% FM replacement allowed for best growth performance in terms of total length (TL = 66.4 mm) and weight (W = 4.19 g), without differences with 60% and 75% of replacement. A cubic relationship was evidenced between the level of FM replacement and growth. From the regression equations, the estimated optimal level of FM replacement was 47% (356 g BSFLM kg−1 diet). Externally visible deformities were always under 0.05%. The whole-body lipid content of the fish had a significantly negative linear regression with BSFLM (r2 = 0.80). The content of the essential amino acids (EAA) arginine, leucine, lysine, phenylalanine, methionine, and threonine in diets decreased with dietary BSFLM inclusion. However, it did not have a negative effect on growth performance, suggesting that EAA requirements were covered. The amount of essential amino acids in whole-body juveniles was similar independently of the diet provided. The results allow considering BSFLM as a sustainable protein source for juvenile tench feeding.

Effects of Replacing Fishmeal with Defatted Black Soldier Fly (Hermetia illucens Linnaeus) Larvae Meal in Japanese Eel (Anguilla japonica) Diet on Growth Performance, Fillet Texture, Serum Biochemical Parameters, and Intestinal Histomorphology.

An 8-week feeding trial was conducted to investigate the effects of replacing fishmeal with defatted black soldier fly larvae meal (DBSFLM) in the diets of Japanese eel on their growth performance, fillet texture, serum biochemical parameters, and intestinal histomorphology. Six isoproteic (520 g kg-1), isolipidic (80 g kg-1), and isoenergetic (15 MJ kg-1) diets were formulated with fishmeal replacement levels of 0% (R0), 15% (R15), 30% (R30), 45% (R45), 60% (R60), and 75% (R75). The growth performance, feed utilization efficiency, survival rate, serum liver function enzymes, antioxidant ability, and lysozyme activity of fish were not affected (P > 0.05) by DBSFLM. However, the crude protein and cohesiveness of the fillet in groups R60 and R75 significantly decreased, and the fillet hardness significantly increased (P < 0.05). Additionally, the intestinal villus length significantly decreased in the R75 group, and the goblet cell densities were significantly lower in the R45, R60, and R75 groups (P < 0.05). Overall, high levels of DBSFLM did not affect growth performance and serum biochemical parameters but significantly altered fillet proximate composition and texture and intestinal histomorphology (P < 0.05). The optimal fishmeal replacement level is 30% with 184 g kg-1 DBSFLM.

Fish Meal Replacement by Mixed Plant Protein in the Diets for Juvenile Yellow Catfish Pelteobagrus fulvidraco: Effects on Growth Performance and Health Status.

Increasing dietary replacement levels of fish meal by alternative plant proteins are of value for aquaculture. Here, a 10-week feeding experiment was undertaken to explore the effects of fish meal replacement by mixed plant protein (at a 2 : 3 ratio of cottonseed meal to rapeseed meal) on growth performance, oxidative and inflammatory responses, and mTOR pathway of yellow catfish Pelteobagrus fulvidraco. Yellow catfish (2.38 ± 0.1 g, mean ± SEM) were randomly divided into 15 indoors fiberglass tanks, 30 fish each tank, and fed five isonitrogenous (44% crude protein) and isolipidic (9% crude fat) diets with fish meal replaced by mixed plant protein at 0% (the control), 10% (RM10), 20% (RM20), 30% (RM30), and 40% (RM40), respectively. Among five groups, fish fed the control, and RM10 diets tended to have higher growth performance, higher protein content, and lower lipid content in livers. Dietary mixed plant protein substitute increased hepatic free gossypol content and damaged liver histology and reduced the serum total essential amino acids, total nonessential amino acids, and total amino acid contents. Yellow catfish fed the control, and RM10 diets tended to have higher antioxidant capacity. Dietary mixed plant protein replacement tended to promote proinflammatory responses and inhibited mTOR pathway. Based on the second regression analysis of SGR against mixed plant protein substitutes, the optimal replacement level of fish meal by mixed plant protein was 8.7%.

Effects of dietary plant and animal protein sources and replacement levels on growth and feed performance and nutritional status of market-sized turbot (Scophthalmus maximus) in RAS

One part of aquaculture sustainability is reducing the environmental footprint of aquaculture feeds. For European aquaculture, this means finding feed ingredients that are produced within the economic community, and that are not in conflict with human consumption. This is especially challenging when formulating diets for carnivorous fish such as turbot with low tolerance to fishmeal replacement that are both nutritious and economically and environmentally sustainable. Therefore, we investigated the effects of two novel and innovative feed formulation concepts on growth and feed performance and the nutritional status of market-sized turbot in a recirculating aquaculture system. In a 16-week feeding trial, 440 turbot (300 ± 9 g) were fed twice a day with a control diet (CTRL), based on a commercial formulation, and four experimental diets. The experimental diets were designed to investigate the effects of two formulations concepts based on sustainable terrestrial plant proteins (NoPAP) or processed animal proteins (PAP) and of 30% and 60% fishmeal replacement with emerging feed ingredients (fisheries by-products, insect meal and fermentation biomass). Turbot from the CTRL group had a similar growth and feed performance than fish fed the NoPAP30 formulation, with a significant decline of performance in the fish fed both PAP formulations and the NoPAP60. Comparing the two formulation concepts with each other the voluntary feed intake and protein efficiency ratio on tank basis as well as the individual weight gain and relative growth rate was significantly higher in the fish from the NoPAP groups than PAP groups. Furthermore, the apparent digestibility of nutrients and minerals was significantly reduced in the fish fed with the diets with 30% and 60% fishmeal replacement level compared to the fish from the CTRL group. In conclusion, the performance of the fish fed the NoPAP30 formulation concept highlights the potential of the used combination of sustainable ingredients, such as fisheries by-products, insect meal, microbial biomass and plant protein for turbot. Furthermore, this study shows that turbot has a higher tolerance to the incorporation of plant and insect protein than of processed animal protein.

High replacement of fishmeal by Chlorella meal affects intestinal microbiota and the potential metabolic function in largemouth bass (Micropterus salmoides).

Microalgae have beneficial effects on the performance of fish as additives and they are becoming a promising alternative to fishmeal as macronutrient ingredients. However, the impact on the fish intestinal microbiome and the function, caused by microalgae as protein sources in diets, remains unclear. This study aimed to determine the composition and potential function of the intestinal microbial community of largemouth bass (Micropterus salmoides) fed diets at five replacement levels (0, 25, 50, 75 and 100%) of fishmeal by Chlorella meal in a basal diet (400 g kg−1) after 8 weeks. The results showed significant decreases in unique amplicon sequence variants in the intestine at the higher levels of fishmeal replacement. At 50% of fishmeal replacement, dietary inclusions of Chlorella meal had no impact on species richness and Shannon diversity and the community structure of the intestinal microbiota. However, high levels of fishmeal replacement (75 and 100%) significantly induced intestinal community disturbance and diversity loss in largemouth bass. Responding to the high fishmeal replacement level, the dominant genus Cetobacterium and Pleslomonas sharply increased and several taxa from Lactobacillus decreased significantly. Functional data predicted by PICRUSt revealed that nutrition-related metabolism was dominant in the intestinal microbiota of fish fed all the five diets, although some potential functions, particularly amino acid and lipid metabolisms, and energy metabolism, were upregulated firstly, and then downregulated in fish fed diets with the increase of dietary Chlorella meal. Meanwhile, certain pathways were not enriched in intestinal microbiome until up to 75% of fishmeal replacement, such as carbohydrate metabolism, and cofactors and vitamins metabolism. To conclude, this study reveals that fishmeal replacement (50%) by Chlorella meal at the level of 237 g kg−1 in diets is feasible for largemouth bass without impairing the microbiome structure and the metabolism function, providing an alternative strategy for evaluating the possibility of fishmeal replacement by microalgae in aquafeeds.

Effects of replacing dietary fish meal with enzyme-treated soybean meal on growth performance, intestinal microbiota, immunity and mTOR pathway in abalone Haliotis discus hannai

In addition to eliminating most of the anti-nutritional factors in soybean meal, enzyme-treated soybean meal (ESBM) can also increase the proportion of small peptides. It was found that ESBM can replace fish meal (FM) either partially or completely in diets for some fish and shrimp species. In the present study, the effects of replacing dietary FM with ESBM on growth performance, intestinal microbiota, immunity and mTOR pathway in abalone Haliotis discus hannai (initial weight: 16.75 ± 0.09 g) were investigated after a 100-day feeding trial. Five experimental diets were designed to replace 0%, 25%, 50%, 75% and 100% of dietary FM by ESBM, which were named as ESBM0 (control), ESBM25, ESBM50, ESBM75 and ESBM100, respectively. Results showed that ESBM could replace up to 75% of FM in the diet without significant effect on the weight gain rate (WGR, 118.05%–124.16%) of abalone. The increasing dietary ESBM levels significantly decreased the trypsin activity from 418.52 to 286.52 U/mg protein in the digestive gland. No significant differences in the contents of total cholesterol (T-CHO), ammonia (BLA) and malondialdehyde (MDA) in cell-free hemolymph were observed among the groups with replacement levels of dietary FM by ESBM from 0% to 75%. Excessive replacement level of FM with ESBM (ESBM100) significantly increased the MDA content (2.33 nmol/mg prot.) and pro-inflammatory-related gene expression in digestive gland. Compared with the control group, the mTOR pathway in muscle was significantly upregulated in the ESBM75 group. The digestive gland in the ESBM100 group contained more golden refractile spherules than those in the other groups. The abundance of intestinal microbes such as Halomonas, Zobellella and Bacillus was decreased in the ESBM100 group. In conclusion, up to 75% of replacement of dietary FM by ESBM had no negative effects on the growth performance, intestinal microbiota, immunity and mTOR pathway of abalone.

Replacement of dietary fishmeal by cottonseed protein concentrate on growth performance, feed utilization and protein metabolism of large yellow croaker Larimichthys crocea

A 90-day feeding trial was conducted to evaluate the effects of cottonseed protein concentrate (CPC) replacing dietary fishmeal on growth performance, feed utilization and protein metabolism of large yellow croaker (initial body weight: 191.60 ± 1.36 g). Seven iso-nitrogenous and iso-lipidic experimental diets were formulated by replacing 0%, 15%, 30%, 45%, 60%, 75% and 100% of dietary fishmeal with CPC. The experimental diets were named as CPC0, CPC15, CPC30, CPC45, CPC60, CPC75 and CPC100, respectively. Results showed that when CPC replacement level was less than 60%, there were no significant differences in survival, weight gain rate, feed intake, feed conversion ratio, protein efficiency ratio, hepatosomatic index, visceral somatic index and condition factor of large yellow croaker compared with those in the CPC0 group (P > 0.05). The dorsal muscle proximate compositions and amino acid profiles were not significantly affected by dietary CPC replacement levels (P > 0.05). Compared with those in the control group, digestive and absorptive enzymes activities in the intestine and liver in the CPC75 and CPC100 groups decreased significantly (P < 0.05). The perimeter ratio, muscularis thickness and villus height in the intestine decreased linearly with increasing replacement levels of dietary fishmeal by CPC (P < 0.05). Compared with those in the CPC0 group, the mRNA levels of mammalian target of rapamycin, ribosomal protein S6, eukaryotic translation initiation factor 4E in the muscle were down-regulated with increasing dietary CPC levels, and while the expressions of eukaryotic translation initiation factor 4E-binding protein, general amino acid control nonderepressible 2 and eukaryotic translation initiation factor 2 α were up-regulated. Take the growth performance, feed utilization and protein metabolism into account, 60% of dietary fishmeal could be replaced by CPC in large yellow croaker.

Replacement of dietary fish meal with Clostridium autoethanogenum meal on growth performance, intestinal amino acids transporters, protein metabolism and hepatic lipid metabolism of juvenile turbot (Scophthalmus maximus L.)

Clostridium autoethanogenum meal (CAM) is a novel single-cell protein, which is produced from bacteria using carbon monoxide (CO) as sole carbon source. To evaluate the efficiency of CAM as an alternative for dietary fish meal, a 56-days growth experiment was performed on juvenile turbot (Scophthalmus maximus L.) with initial average weight of 9.13 ± 0.02 g. Six iso-nitrogenous (crude protein, 51.0%) and iso-lipidic (crude lipid, 11.5%) diets were formulated with 0%, 15%, 30%, 45%, 60% and 80% dietary fish meal protein substituted by CAM protein, which were designated as CAM0 (the control group), CAM15, CAM30, CAM45, CAM60 and CAM80, respectively. Results showed that no significant differences were observed in survival rate (over 97.50%) among different dietary treatments (p > 0.05). The specific growth rate (SGR) was not significantly affected when replacement levels of dietary fish meal with CAM were less than 45% (p > 0.05). The feed intake (FI) was significantly linear reduced with increasing dietary CAM (p < 0.05), whereas no significant differences were observed in feed efficiency ratio (FER), protein efficiency ratio (PER) and protein retention (PR) among different dietary treatments (p > 0.05). With increasing dietary CAM, lipid retention (LR) and carcass lipid tended to be increased in both significantly linear and quadratic patterns (p < 0.05). The apparent digestibility coefficient (ADC) of crude protein and some essential amino acids, including threonine, valine, lysine, histidine and arginine, showed significantly linear increase with increasing dietary CAM (p < 0.05). Furthermore, with the increase of dietary CAM, the gene expression of intestinal peptide and amino acids transporters was first up-regulated and then down-regulated with significantly quadratic pattern (p < 0.05), peaking in fish fed with diets CAM30 or CAM45, which was similar to the expression of genes related protein degradation in muscle. For genes related to protein metabolism in liver and muscle, the expression of mammalian target of rapamycin (mtor) was not significantly affected by dietary CAM, while the general control nonderepressible 2 (gcn2) tended to be first up-regulated and then down-regulated with significantly quadratic pattern (p < 0.05). Apart from that, the lipid metabolism of turbot was also affected by high dietary CAM, evidenced by increased expression of hepatic genes related to lipogenesis as well as reduced expression of genes related to lipid oxidation and lipid transport. In conclusion, CAM can replace up to 45% fish meal protein in diet for juvenile turbot without significantly adverse effects on growth performance. But excessive dietary CAM would result in significant growth reduction, and excessive lipid deposition may also occur in fish fed diets with high levels of CAM.

EFFICACY OF REPLACING FISH MEAL WITH EARTHWORM (Eudrilus euguniea) MEAL ON GROWTH AND SURVIVAL OF AFRICAN CATFISH FINGERLINGS (Clarias gariepinus, BURCHEL 1822)

The efficacy of earthworm (Eudrilus euguniea) meal on growth and survival of African catfish fingerlings (Clarias gariepinus) was carried out in Maiduguri with the aim of producing substantial amount of the earthworm to replace fish meal in the diet of Clarias gariepinus for growth and survival. Earthworms were produced using mixture of animal dung (cow, sheep and rabbit) by introducing 100 unsexed adults on 5kg of the animal dung. Fingerlings were purchased from Garbati fish farm located in Damboa road and conveyed to teaching and research fish farm university of Maiduguri where the research was conducted. Forty (40% CP) diet was formulated by replacing fish meal with earthworm at the substitution level of 0, 25, 50, 75 and 100% and fed to one hundred and fifty (150) forty days old Clarias gariepinus grouped into five treatments according to the replacement level of the fish meal with the earthworm. The feeding trial lasted for 90 days. Data generated from the research were subjected to analysis of variance (ANOVA). The result presented better growth Performance in fingerlings fed 0 and 50% replacement level of fish meal with earthworm. Therefore, fish meal can be replaced with earthworm in the diet of Clarias gariepinus at 50% for better growth.

Effects of Clostridium autoethanogenum protein as substitute for dietary fishmeal on the growth, feed utilization, intestinal health and muscle quality of large yellow croaker Larimichthys crocea

A 90-day feeding trial was conducted to evaluate the effects of Clostridium autoethanogenum protein (CAP) replacing dietary fishmeal on growth, feed utilization, intestinal health and muscle quality of large yellow croaker (Initial body weight: 189.9 ± 1.11 g). The control diet (CAP0) contains 62% fishmeal, which was replaced with CAP at 15% (CAP15), 30% (CAP30), 45% (CAP45), 60% (CAP60), 75% (CAP75) and 100% (CAP100), respectively. Results showed that the weight gain rate, protein efficiency ratio, feed intake, condition factor and intestinal villus height of fish significantly decreased when the replacement level of dietary fishmeal by CAP exceeded 30%, while feed conversion ratio increased significantly in the CAP60, CAP75 and CAP100 treatments (P < 0.05). Increasing replacement levels of dietary fishmeal by CAP linearly decreased the activities of intestinal digestive and absorptive enzymes (P < 0.05). In addition, the mRNA expression level of intestinal peptide transporter 1 and nuclear factor κB genes was up-regulated with increasing dietary CAP level, while the intestinal peptide transporter 2, occludin-like and interleukin 10 genes was down-regulated (P < 0.05). The muscle amino acid compositions and skin color were not significantly affected by dietary CAP supplementation. Compared with those in the CAP0 group, fish in the CAP75 and CAP100 group showed a significantly lower muscle firmness, water holding capacity and myofiber diameter, and a higher myofiber density (P < 0.05). The mRNA expression of myogenic differentiation, myogenin, myogenic factor 5 and paired box 7 genes was significantly up-regulated, while the expression of myostatin gene was significantly down-regulated in the muscle of fish in the CAP75 and CAP100 group (P < 0.05). In conclusion, CAP can replace up to 30% of dietary fishmeal protein for large yellow croaker without negative effects on the growth, feed utilization, intestinal health and muscle quality.

Influences of replacing dietary fish meal by Antarctic krill meal on growth performance, immunity and muscle quality of white shrimp Litopenaeus vannamei

The present study was conducted to investigate the effects of Antarctic krill Euphausia superba meal replacing dietary fish meal on the growth performance, immunity and muscle quality of white shrimp Litopenaeus vannamei (initial body weight: 4.080 ± 0.143 g, mean±SD). The replacement levels were designed as 0%, 5%, 15%, 30%, 45%, 60%, 75% and 100%, respectively. After a 52-day feeding trial, results showed that the specific growth rate (P = 0.129) and feed intake (P = 0.217) of shrimp were not significantly affected. Feed conversion ratio (FCR, P = 0.000), protein efficiency ratio (PER, P = 0.000) and protein retention (PR, P = 0.000) were significantly affected with a quadratic positive trend for FCR, a linear and quadratic negative trend for PER and a quadratic negative trend for PR. The total haemocyte count (P = 0.307), respiratory burst (P = 0.168), activities of superoxide dismutase (P = 0.221) and glutathione reductase (P = 0.170) in serum were not significantly affected. While, malondialdehyde content (P = 0.000), acid phosphatase (P = 0.000) and alkaline phosphatase activity (P = 0.000) in serum were significantly decreased both in linear and quadratic trend. The carotenoid content in exoskeleton (P = 0.019) and pH in muscle (P = 0.000) were linearly increased. With the increasing replacement levels, n-3 PUFA content (P = 0.001) in muscle significantly decreased and n-6 PUFA (P = 0.000) increased. The ratio of essential amino acid to total amino acid (P = 0.000) and the inosinic acid content in muscle (P = 0.002) were significantly increased with the dietary replacement levels in a linear trend. In conclusion, Antarctic krill meal can totally replace dietary fish meal without negative impact on the growth of L. vannamei. From the perspective of feed utilization, after the quadratic regression analysis of FCR, PER and PR, the appropriate replacement level of dietary fish meal by krill meal for L. vannamei was 52.78%, 68.50% and 47.41%, respectively (i.e., dietary krill meal level was 13.27%, 17.22%, and 11.92%, respectively).