Non-fish Meal Diets Research Articles

Taurine prevented the decline of fillet quality and muscle antioxidant capacity in on-growing grass carp (Ctenopharyngodon idella) fed non-fishmeal diet

Taurine is abundantly present in fishmeal, while plant protein sources typically contain minimal to no taurine. This disparity in taurine content may explain variations in fish quality traits caused by the dietary substitution of fishmeal with plant protein sources. This research explored whether taurine supplementation to non-fishmeal (NFM) diet could improve fillet quality and muscle antioxidant capacity in grass carp. A total of 540 fish (255.74 ± 0.65 g) were distributed among six groups. One of them was provided with a fishmeal (FM) diet, while the remaining five groups received NFM diets, formulated with incremental concentrations of crystalline taurine (0, 0.5, 1.0, 1.5, 2.0 g/kg) for 60 days. Our data showed that, in comparison with the un-supplemented group, the optimal taurine supplementation to NFM diet yielded the following findings: (1) increased fillet nutritional values by improving crude protein content, free amino acid and fatty acid compositions; (2) improved fillet physicochemical properties by improving water holding capacity (WHC), tenderness, and preventing pH decline; (3) enhanced antioxidant enzymes activities and gene expressions through nuclear factor-erythroid 2-related factor 2 (Nrf2) signaling pathway. Additionally, this optimal NFM diet showed to be competitive with FM diet in terms of fillet quality. According to quadratic regression curves of ROS production and polyunsaturated fatty acids (PUFA) content, the optimal taurine supplementation levels in NFM diet for on-growing grass carp were 1.12 and 1.18 g/kg diet, respectively.

One-carbon metabolism nutrients impact the interplay between DNA methylation and gene expression in liver, enhancing protein synthesis in Atlantic salmon

ABSTRACT Supplementation of one-carbon (1C) metabolism micronutrients, which include B-vitamins and methionine, is essential for the healthy growth and development of Atlantic salmon (Salmo salar). However, the recent shift towards non-fish meal diets in salmon aquaculture has led to the need for reassessments of recommended micronutrient levels. Despite the importance of 1C metabolism in growth performance and various cellular regulations, the molecular mechanisms affected by these dietary alterations are less understood. To investigate the molecular effect of 1C nutrients, we analysed gene expression and DNA methylation using two types of omics data: RNA sequencing (RNA-seq) and reduced-representation bisulphite sequencing (RRBS). We collected liver samples at the end of a feeding trial that lasted 220 days through the smoltification stage, where fish were fed three different levels of four key 1C nutrients: methionine, vitamin B6, B9, and B12. Our results indicate that the dosage of 1C nutrients significantly impacts genetic and epigenetic regulations in the liver of Atlantic salmon, particularly in biological pathways related to protein synthesis. The interplay between DNA methylation and gene expression in these pathways may play an important role in the mechanisms underlying growth performance affected by 1C metabolism.

Effect of Additives Inclusion in Gilthead Seabream (Sparus aurata L.) Diets on Growth, Enzyme Activity, Digestibility and Gut Histology Fed with Vegetable Meals.

The fishmeal replacement by vegetable meals or other alternative sources, without affecting fish performance and productivity, is one of the principal challenges in aquaculture. The use of hydrolyzed porcine mucosa (HPM) and nucleotide (NT) concentrates, as feed additives in gilthead seabream (Sparus aurata L.) non-fishmeal diets was assessed in order to determine the possible effects on growth, feed efficiency, protein digestion, and gut histology when these were included in a plant-based diet (HPM 1% and 2%, P1 and P2; NT 250 and 500 ppm, N250 and N500), in comparison with two control diets, AA0 (100% plant-protein-based diet) and FM100 (100% fishmeal-protein-based diet). Diets were assayed in triplicate and the growth assay lasted 134 days. Results showed a significant improvement in all groups in terms of final weight and specific growth rate in comparison with the AA0 group. An improvement in the feed conversion ratio and the protein efficiency ratio was also observed when the additives were included in lower percentages (P1 and N250) compared to the FM100 group. Significant differences were found in hepatosomatic index, villi thickness, and goblet cells. Thus, the inclusion of NT and HPM was tested as beneficial for the improvement of efficiency of plant feed in seabream.

Utilization of microalgae Schizochytrium sp. in non‐fish meal, non‐fish oil diet for yellowtail ( Seriola quinqueradiata )

Two feeding experiments were conducted to develop non-fish meal and non-fish oil diet for yellowtail with plant protein sources and Schizochytrium meal. For the first experiment, three iso-nitrogenous and iso-lipidic diets were prepared. Control diet was composed with fishmeal and fish oil and the other diet was formulated with plant protein sources and fish oil [FO]. Fish oil in FO diet was totally substituted by rapeseed oil and Schizochytrium sp., which was rich in DHA [NFO1]. Duplicate groups of yellowtails (Seriola quinqueradiata, 190.6 g) were fed the diets for 99 days. NFO1 group showed the lowest palatability and growth. However, fatty acid profile of NFO1 group showed the similar trend to FO. Four non-fish meal diets were prepared for the second experiment with increased amount of feed attractant. 100FO diet was formulated similar to FO diet in the first experiment though higher amount of bonito peptide was contained. The other diets gradually employed Schizochytrium meal to substitute fish oil in 100FO diet for 35, 70 and 100%, respectively [65FO, 30FO, NFO2]. Duplicated groups of yellowtails (186.0 g) were fed the diets for 84 days. The growth result was improved by increasement of bonito peptide; however, it was inversely proportional to employment rate of algae meal. The results suggest possibility for developing non-fish meal diet for yellowtail with plant protein sources and Schizochytrium sp. by inducing enough amount of feed attractant. Moreover, it needs further study on essential fatty acid utilization for yellowtail while developing non-fish meal and non-fish oil diet with microalgae.

Enzymatic tuna hydrolysate supplementation modulates growth, nutrient utilisation and physiological response of pompano (Trachinotus blochii) fed high poultry-by product meal diets

Six experimental diets were prepared in a 3 × 2 experimental design involving three inclusion levels (0%, 50%, and 100%) of poultry by-product meal (PB) and two concentrations (0 and 60 mg/kg) of tuna hydrolysates (TH), labelled as PB0, PB0TH, PB50, PB50TH, PB100, and PB100TH, respectively. The diets were fed to juvenile pompano for 10 weeks to investigate the nutritional value of PB in conjunction with TH supplementation on growth, feed efficiency, biochemical composition, haematological and histological responses in the species. The results indicated that the final body weight, specific growth rate, and feed conversion ratio were negatively affected by the increasing replacement of fishmeal by dietary poultry by-product meal with or without TH supplementation compared to the control (P<0.05). A significant (P<0.05) reduction of whole-body protein was recorded in the PB100 diet while body lipid and ash levels neither increased nor decreased either by replacement levels or TH supplementation. Except for serum albumin and triglycerides, all other serum parameters were not influenced by PB diets supplemented with tuna hydrolysate (P ˃ 0.05). The histopathological alterations in the liver were appeared in fish fed PB50, PB100, and PB100TH diets. Fish fed fishmeal replacement diets showed reduced methionine, lysine, threonine, and valine contents compared to control (P < 0.05). Overall, this study demonstrates that fish fed non-fishmeal diets showed significantly lower growth and feed efficiency than those fed control diet, irrespective of tuna hydrolysate supplementation.

Impact of nucleotide enriched diets on the production of gilthead seabream, Sparus aurata fingerlings by modulation of liver mitochondrial enzyme activitity, antioxidant status, immune gene expression, and gut microbial ecology

The objective of this study was to evaluate the effect of fish meal replacement with a mixture of plant, and animal protein supplemented with a commercial nucleotide NucleoforceFish™, on growth, feed utilization, whole-body composition, biometric indices; liver mitochondrial enzyme activities, selected gene expression and influence on the gut microbiome of gilthead seabream, Sparus aurata. Six hundred and thirty gilthead seabream with an average initial body weight of 0.358 ± 0.002 g/fish, were used. Six experimental diets were formulated to be isonitrogenous, 45% crude protein (CP) and isocaloric 20 MJ/kg gross energy (GE). The control diet (D1) contained 25% of fish meal (FM25) and had no NucleoforceFish™ added (FM25/0), diets 2-3 contained FM at a level of 25% and supplemented with 250 (FM25/250) and 500 (FM25/500) mg/kg NucleoforceFish™, respectively. Diets 4-6 were a non-fishmeal formulation and had no NucleoforceFish™, (diet 4, FM0/0), 0%FM with 250mg/kg NucleoforceFish™ (diet 5, FM0/250), and 0%FM with 500mg/kg NucleoforceFish™ (diet 6, FM0/500). The results revealed that dietary nucleotides supplemented at 250mg/kg or 500mg/kg enhanced final body weight, weight gain, and specific growth rate of seabream either with dietary level of 25% FM diet (FM25) or non-fishmeal diet (FM0). All mitochondrial liver complex enzyme activities were recorded as having a significant positive response to the nucleotide dietary supplement. Gilthead seabream fingerlings fed FM0/250 diet for 150 days had significantly elevated liver mitochondrial enzyme (Complex III, Complex IV, Complex I and II) activities. In addition, gilthead seabream fed FM0/500 had significantly increased the gene expression of TCR-B and IL1-B, while fish fed FM25/250 increased significantly the gene expression of IGF1, while fish fed FM25/500 increased significantly the gene expression of Hepcidin (Hep) and the iron homeostasis hormone. There was a marked influence on specific bacteria comprising the gut microbiome namely Photobacterium; damselae; Vibrio anguillarum; Lactobacillus plantarum; Lactobacillus Enterococcus faecium subtilis. It can be concluded that FM25/250 and FM25/500 diets are expressing the best result, which explains that FM must be in the feed of gilthead seabream, and addition of NucleoforceFish™ at 250 mg/kg feed may further increase the performance.

Effect of graded levels of taurine supplementation to non-fishmeal diet on growth, nutrient digestibility, intestinal morphology and cytokines gene expression of juvenile red seabream, Pagrus major

Effect of graded levels of taurine supplementation to non-fishmeal diet on growth, nutrient digestibility, intestinal morphology and cytokines gene expression of juvenile red seabream, Pagrus major

(2-Carboxyethyl) dimethylsulfonium bromide supplementation in non-fish meal diets for on-growing grass carp (Ctenopharyngodon idella): Beneficial effects on immune function of the immune organs via modulation of NF-κB and TOR signalling pathway

The immune function of immune organs is extremely crucial for maintaining organism health status, which ultimately affects fish growth. Our previous study has found that dietary supplementation of (2-carboxyethyl)dimethylsulfonium Bromide (Br-DMPT) in non-fish meal (NFM) diet could promote the growth of grass carp (Ctenopharyngodon idella), whereas the underlying reason or mechanism for this results is largely unclear. Herein, we further explored whether dietary supplementation of Br-DMPT promoted fish growth is connected with the enhanced immune function in the immune organs (the head kidney, spleen and skin). In this study, 540 fish (216.49 ± 0.29 g) were irregularly distributed to six groups with three replicates (30 fish replicate−1) and fed corresponding diets group containing a fish meal (FM) diet group and five different NFM diets supplemented with gradational Br-DMPT (0–520.0 mg/kg level) group for 60 days. After the 60-days feeding trial, 8 fish from each replicate were selected and then conducted a challenge test with A. hydrophila for 14 days. Our results indicated that in the NFM diets, appropriate Br-DMPT: (1) significantly decreased the morbidity of skin haemorrhage and lesion after A. hydrophila infection (P < 0.05). (2) significantly improved the innate and adaptive immune components (lysozyme, complement 3, immunoglobulin M and antibacterial peptides et al.) (P < 0.05). (3) increased the gene expressions of main anti-inflammatory cytokines partially by referring to TOR signalling pathway, and decreased the gene expressions of main pro-inflammatory cytokines partially by referring to NF-kB signalling pathway (P < 0.05). Strikingly, no statistical difference could be found in the most of above immune parameters between 260.0 mg/kg Br-DMPT diet group and FM diet group (P > 0.05). Taken together, in non-fish meal diet, appropriate supplementation of Br-DMPT could improve the disease resistance capacity, non-specific immunity and ameliorate inflammation, and simultaneously could mitigate these adverse effects induced by the non-fish meal diet in fish immune organs. Moreover, this study may be helpful to decipher the underlying mechanisms of how Br-DMPT promote fish growth by immune organs and also provide scientific theoretical evidence for the future application of Br-DMPT as a new immunopotentiator in aquaculture industry.

(2-Carboxyethyl)dimethylsulfonium Bromide (Br-DMPT) improves muscle flesh quality and antioxidant status of on-growing grass carp (Ctenopharyngodon idella) fed non-fish meal diets

High-quality flesh plays crucial roles in affecting the acceptance and market value of the fish products. In previous study, (2-carboxyethyl)dimethylsulfonium Bromide (Br-DMPT) supplementation enhanced the growth and digestive capacity of fish fed non-fish meal diet, whereas its impacts on fish flesh quality remain unknown. Here, we examined whether dietary supplementation with Br-DMPT could improve muscle nutritive value, flesh flavor, healthy fatty, acids physical properties and antioxidant status in on-growing grass carp (Ctenopharyngodon idella), which fed a fish meal (FM) diet group and five non-fish meal (NFM) diets supplemented with graded Br-DMPT concentrations group (0, 130.0, 260.0, 390.0, 520.0 mg/kg Br-DMPT diet group), respectively. After 60 days feeding trial, we observed that NFM diets with supplementing appropriate Br-DMPT: (1) improved muscle nutritive value and flesh flavor by increasing protein and lipid contents, healthcare fatty acids (docosahexaenoic acid and eicosapentaenoic acid), umami and sweet related amino acids (Aspartic acid, Glutamic acid, Serine, Alanine and Glycine)；(2) accelerated muscle physical properties by increasing tenderness, water holding capacity and pH, and decreasing cathepsin (B and L) activities and lactate content; (3) increased muscle antioxidant status by increasing the activities and gene expression levels of antioxidant enzymes, which appears to be associated with nuclear factor-erythroid 2-related factor 2 (Nrf2) signalling pathway. Importantly, no noticeable difference was observed between 260.0 mg/kg Br-DMPT diet group and FM diet group with respect to the most of above these parameters. Overall, dietary Br-DMPT supplementation improved muscle nutritive values, flesh flavor, healthy fatty acids and enhanced physical properties, antioxidant status of fish. Furthermore, this study further demonstrated that it is feasible for achieving non-fish meal diet application in aquafeeds and also provided a practical data for the non-fish meal diet formulation for aquaculture industry.

Dimethyl-β-propiothetine (DMPT) supplementation under the all-plant protein diet enhances growth performance, digestive capacity and intestinal structural integrity for on-growing grass carp (Ctenopharyngodon idella)

This study aimed to investigate the effects of dimethyl-β-propiothetine (DMPT) supplementation under the all-plant protein diet on the growth, digestive capacity, oxidative damage and intestinal structural integrity of on-growing young grass carp (Ctenopharyngodon idella). A total of 540 healthy grass carp (216 ± 0.29 g) were randomly divided into six groups with three replicates and fed one fish meal (FM) diet and five all-plant protein diets with graded levels of DMPT (0 to 520 mg/kg diet) for 60 days. The results indicated that compared to the FM diet group, the all-plant protein diet without DMPT supplementation (all-plant protein diet group) significantly reduced feed intake (FI), specific growth rate (SGR), percentage weight gain (PWG), and digestive enzyme activities (trypsin, chymotrypsin, lipase and amylase activities) as well as damaged the intestinal histological structure of fish. However, these parameters could be restored to levels equal or superior to the FM diet group at DMPT supplementation levels under the all-plant protein diet up to 260.00 mg/kg diet. This is the first study to show that (1) DMPT supplementation under the all-plant protein diet increased FI and digestive enzyme activities in the intestine were partly related to improved neuropeptide Y content and cholecystokinin content, respectively. (2) DMPT supplementation under the all-plant protein diet enhanced the intestinal structural integrity of fish partially by alleviating oxidative damage and partially by up-regulating antioxidant enzyme activities as well as the mRNA levels of antioxidant enzyme (except CuZnSOD), which were partially related to [Keap1a (not Keap1b)/Nrf2] signalling. (3) Finally, based on the quadratic regression analysis for optimal growth performance indices (FI and PWG) and oxidative damage indices (protein carbonyl and malondialdehyde content), the appropriate levels of DMPT supplementation under the all-plant protein diet for on-growing grass carp were estimated as to be 278.30, 282.78, 326.52 and 299.25 mg/kg diet, respectively. In summary, DMPT supplementation under the all-plant protein diet improved the growth performance and digestive capacity and strengthened the intestinal structural integrity of on-growing grass carp. Simultaneously, it also provided a practical and effective approach to the highly efficient utilisation of plant protein and a reference for the non-fish meal diet formulation of fish.

First step of non‐fish meal, non‐fish oil diet development for red seabream, (Pagrus major), with plant protein sources and microalgaeSchizochytriumsp

A feeding experiment was conducted to develop non-fish meal and non-fish oil diet for red seabream by using plant protein source and Schizochytrium meal which is rich in 22:6n-3 (DHA). Three iso-nitrogenous and iso-lipidic experimental diets were prepared (CP 41.2% ± 0.4%, CL 16.4% ± 1%). Control diet contained both fish meal (40%) and fish oil (6%). In the second diet, fish meal was replaced by plant meals (soy protein concentrate, soybean meal, corn gluten meal) [FO]. In the third diet, fish meal and fish oil were replaced by algae meal (Schizochytrium sp. powder) and plant proteins [AO]. Duplicated groups of juvenile red seabream (8.8 g ± 1.5) were fed the experimental diets for 12 weeks to near satiation. There was no statistical difference among treatment in specific growth rate. Feed conversion ratio of AO diet group was higher than that of control. In wet basis, whole body protein level was significantly higher in AO diet than FO group while lipid content was lower than control group. In fatty acid profile, AO group had significantly lower 18:4n-3, 20:4n-3, 22:5n-3 and 20:5n-3 (EPA) level, but significantly higher 18:3n-3 and DHA level than the other two diet fed fish. The results might suggest that further developments in microalgae diet offer a promising lipid source of n-3 PUFA as essential fatty acid on marine fish. And it showed possibility to develop non-fish meal and non-fish oil feed for marine aquaculture fish by using microalgae.

Interactive effects of salinity and complete fishmeal replacement on growth, food consumption, and gene expression of hepatic IGF-I, IGF-II and growth hormone receptors in Nile tilapia,Oreochromis niloticus(L.)

A 12-week feeding trial was conducted using Nile tilapia, Oreochromis niloticus (L.) to evaluate the interactive effects of fishmeal replacement and salinity on growth, feed utilization efficiencies and relative expression of growth related genes. Two iso-nitrogenous and iso-energetic diets were prepared (32% protein). The control diet included 15% fishmeal (FM diet) and fishmeal component in non-fishmeal diet (NFM) was eliminated by a mixture of poultry by-product meal, high protein distillers dried grains and distillers dried grains with soluble. The NFM diet was supplemented with DL-methionine and L-lysine. Duplicated group of fish with initial mean weight of 6 g, reared in four salinity levels (0, 4, 8 and 12 g/L) were fed one of the two diets twice a day to near satiety. At the end of the experiment, growth, feed utilization efficiency and expression of growth related genes were compared. The specific growth rate (SGR), mean feed intake (MFI) and feed conversion ratio (FCR) were not affected by the diets while salinity effects were significant. The fish in the 4 g/L salinity showed the highest SGR and MFI while fish in the 0 g/L treatment showed the lowest FCR. Relative expression of hepatic IGF-I and IGF-II was regulated by salinity but not by the diet. Expression of growth hormone receptor gene was not affected by either diet or salinity. The present findings provide evidence for the possibility of total fishmeal replacement in saline waters (0–12 g/L) without compromising growth, feed utilization and body composition of Nile tilapia.

Effect of supplementation with enzyme complex to non-fish meal diet in adult red sea bream Pagrus major

Effect of supplementation with enzyme complex to non-fish meal diet in adult red sea bream Pagrus major

Effects of dietary soybean meal on the bile physiology in rainbow trout, Oncorhynchus mykiss

To clarify the effect of dietary soybean meal (SBM) on bile synthesis and enterohepatic circulation in rainbow trout, three isonitrogenous and isolipidic diets; a fishmeal based diet (diet FM), a SBM based non-fishmeal diet (diet SBM) and a 1% bile acid (taurocholate) supplemented SBM diet (diet C-tau) were prepared and acute/chronic effects of the diets on the bile physiology was examined. In the acute experiment (<24 h), fish fed the SBM based diets (diet SBM and C-tau) had higher expression levels of bile acid synthesis genes, cyp7a1-2, cyp8b1-1 and cyp8b1-2 in the liver compared to fish fed the FM diet. In the chronic experiment (10 weeks), fish fed the SBM and C-tau diets had significantly lower expression levels of cyp7a1 (-1 and -2), cyp8b1 (-1 and -2) genes compared with fish fed the FM diet. On the other hand, expression of bile acid synthesis inhibitor gene shp-2 was higher in fish fed the SBM diet compared with fish fed the FM and C-tau diets. Furthermore, fish fed the SBM based diet had reduced bile acid absorption rate. These data suggest that SBM up-regulates bile acid synthesis on a short-term basis, while long-term SBM administration down-regulates the bile acid synthesis and the recovery of bile through the enterohepatic circulation. The gallbladder weights of fish fed the C-tau diet were similar to those of fish fed the FM diet whereas the actual bile acid absorption ability was still suppressed in the C-tau group. This study contributes to the general knowledge of bile physiology in teleost fish under different nutritional conditions and to develop tailored and sustainable aquaculture feeds based on SBM.

Effects of stickwater hydrolysates on growth performance for yellow catfish (Pelteobagrus fulvidraco)

The intention of this study is to investigate the effects of stickwater hydrolysates on growth performance for yellow catfish (Pelteobagrus fulvidraco) fed with non-fish meal diets. Two experiments were designed. Experiment (A) was conducted to evaluate the effects of stickwater hydrolysates which were prepared by different methods. Ten diets were prepared: the control diet used fish meal as the main protein source and other nine non-fish meal diets were formulated with stickwater (SW), stickwater hydrolysate (HSW) or stickwater hydrolysate meal (HSM), supplying approximate 25%, 50% or 75% of fish meal protein in the control diet. Experiment (B) was conducted to determine how peptide and free amino acid content of HSW influence growth performance of fish. Ten diets were prepared: the control diet used fish meal as the main protein source and other nine non-fish meal diets were formulated with low degree of hydrolyzed stickwater hydrolysate (L-HSW), middle degree of hydrolyzed stickwater hydrolysate (M-HSW) or high degree of hydrolyzed stickwater hydrolysate (H-HSW), supplying approximate 15, 30 or 45% of fish meal protein in the control diet. All diets were fed to three replicate groups of yellow catfish (initial body weight of 15.67 ± 0.11 g for experiment A and 18.67 ± 0.11 g for experiment B) for 60 days. High weight gain was achieved in yellow catfish fed with HSW25 and M-HSW30, in which the fish in-fish out values (FIFO) were only about 27% to 32% of control diet. Growth performance of fish fed SW diets was significantly reduced compared to the control diet. No significant (P > 0.05) differences in SGR, FCR, PRR, and FRR were found in the fish fed with the HSW diets compared to the control diet. The weight gain had no significant (P > 0.05) differences among fish fed L-HSW30, M-HSW30, and basal diet, but it significantly reduced in fish fed H-HSW diets. Decreasing tendency of fish growth performance was obtained when we increase the content of SW, SHW, and SHM in diets, while the relative expression of PepT1 was significantly down-regulated. The present work gives evidence on the multi-dimensional effects of different SW hydrolysates on fish growth performance. These results suggest that in the commercial diet pattern containing same nitrogen, energy, phosphorus, and sum amino acid, we observed the equivalent biological valve between fish fed with HSW25 or M-HSW30 and basal diet. This indicates that stickwater hydrolysate is a promising fish meal replacement and the optimal level in diet is approximately 80 to 90 g kg−1 (dry matter), in which the FIFO value was only about 27% to 32% of the control diet. Poorer growth performance was observed in the fish fed with diets contain SW and hydrolysates (dry matter) >130 g kg−1. Besides, the H-HSW was not a good option for yellow catfish. It may be because of the considerable small nitrogen compounds of lower than 500 Da, which lead to high serum free amino acid and eventually result in the low digestion and absorption of protein by modulating the mRNA expression levels of PepT1.

Effects of dietary phospholipid level and fraction on the feed intake of non-fish meal diet in yellowtail, Seriola quinqueradiata Temminck &amp; Schlegel, 1845

Three feeding studies were conducted to investigate whether dietary soybean lecithin (SBL) enhanced feed intake of non-fish meal, SPC-based diet, in yellowtail, and also to clarify which fraction of phospholipid (PL) was effective to enhance feed intake. In experiments 1 and 2, fish were fed SBL level at 0%–5%, and it was revealed that the daily feeding rate (DFR) of fish was significantly higher for SBL 2% than for SBL 0%, while a further increase of SBL in the diet did not additionally increase the DFR. Moreover, the DFR of fish fed a diet without feeding stimulants (FS) was the lowest among the dietary treatments, indicating that the SBL does not have an effect of enhancing feed intake in yellowtail. In experiment 3, fish were fed a diet with several products containing PL at 2%. Phosphatidylcholine and phosphatidylinositol concentrations in these products positively correlated to the DFR of fish. This result revealed that these two fractions in the SBL are effective for enhancing feed intake of yellowtail when FS is present in the diet.

Effects of long-term feeding of corn co-product-based diets on growth, fillet color, and fatty acid and amino acid composition of Nile tilapia, Oreochromis niloticus

We conducted a 24-week feeding trial with Nile tilapia Oreochromis niloticus to evaluate the effects of long-term feeding of corn co-product-based diets on growth, fillet color, and fillet fatty acid and amino acid composition. Five iso-nitrogenous diets were prepared (34% protein). The control diet included 10% fishmeal. Fishmeal was eliminated from the other four diets, and 50% of the dietary protein was supplied by one of four corn co-products, namely high-protein distillers' dried grains (HPDDG), distillers' dried grains with solubles (DDGS), corn gluten meal (CGM), and corn protein concentrate (CPC). Fish with an initial mean weight of 21g were fed one of the five diets twice a day to near satiety. Fish fed the control, HPDDG, or DDGS diet had significantly higher (P<0.05) mean weight gain, specific growth rates, mean feed intake, protein efficiency ratio, and survival than those fed the other diets. Fish in these three treatments also had the lowest food conversion ratio. The dietary treatments did not affect the lightness, redness, yellowness, or crude protein and total amino acid content of fish fillets. Fillet lipid and ash content were highest in the CGM group. Fillet fatty acid composition was greatly affected by the dietary treatments. The CGM and CPC groups had significantly highest palmitic acid (16:0) and total saturated fatty acid levels, whereas linoleic acid (18:2n−6) and total polyunsaturated fatty acid levels were highest in the DDGS group. Similarly, the total n−6 level was highest in the DDGS group, followed by HPDDG. The total n−3 levels and n−3:n−6 ratios in the fillets of the control group were almost double those of the corn-based dietary groups. Our results suggest that dietary inclusion of HPDDG or DDGS in non-fishmeal diets at up to 50% of dietary protein does not negatively affect growth performance, feed utilization efficiency, or fillet color and amino acid composition, but further improvement of n−3 fatty acid composition is necessary to ensure human health benefits. Statement of relevanceFishmeal free diets ensure the sustainability of aquaculture.

Effect of Taurine Supplementation on Growth Response and Body Composition of Largemouth Bass

AbstractTaurine is “conditionally essential” for some fish species, particularly when fish meal levels in their diets are reduced. Taurine supplementation has not yet been evaluated in the Largemouth Bass Micropterus salmoides. A 12‐week feeding trial was conducted using a 2 × 2 factorial design with the main effects being fish meal inclusion (0% or 30%) or taurine supplementation (0% or 2%). The fish meal diets contained sardine fish meal while the nonfish meal diets used pork meal, which has a very low taurine content, as the animal source protein. The four experimental diets were formulated to contain 40% crude protein and 12% lipid. The feeding trial was conducted using juvenile Largemouth Bass (19.3 ± 3.9 g; mean ± SD) stocked at 25 fish/tank into twelve 230‐L aquaria within a recirculating system. Fish were fed to apparent satiation twice daily. Dissolved oxygen, pH, and temperature were monitored daily, while alkalinity, total ammonia nitrogen, and nitrite‐nitrogen were monitored three times weekly. Analysis of harvest data indicated a significant statistical interaction between fish meal inclusion and taurine supplementation only for feed conversion ratio (FCR). In diets containing no fish meal, the addition of taurine significantly increased the FCR (from 2.2 to 2.6). However, in fish fed diets containing fish meal, supplemental taurine significantly decreased the FCR (from 2.2 to 1.9). In terms of main effects, taurine supplementation did not significantly affect any of the measured growth or survival variables. Survival and growth in Largemouth Bass fed 0% fish meal were not significantly different from survival and growth in those fed 30% fish meal. Body composition variables were not significantly affected by either fish meal inclusion or taurine supplementation. These data support previous studies that found that by‐products from terrestrial animal sources can successfully replace fish meal in diets for Largemouth Bass. These data also indicate that Largemouth Bass do not have a significant dietary requirement for taurine.

Long-term Feeding of the Yellowtail Seriola quinqueradiata with Soy Protein Concentrate-based Non-fishmeal Diet Supplemented with Taurine

Long-term Feeding of the Yellowtail Seriola quinqueradiata with Soy Protein Concentrate-based Non-fishmeal Diet Supplemented with Taurine

Histological Observation on the Hepatopancreas of Fingerling Red Sea Bream Pagrus major Fed Defatted Soybean Meal Based Non-Fish Meal Diet Supplemented with Taurine

Histological Observation on the Hepatopancreas of Fingerling Red Sea Bream Pagrus major Fed Defatted Soybean Meal Based Non-Fish Meal Diet Supplemented with Taurine