Fish Meal Substitution Effects with the Combined Animal Proteins in the Feeds of Olive Flounder (Paralichthys olivaceus) on Growth Performance, Feed Availability, and Disease Resistance against Streptococcus iniae.

This study aims to reveal the substitution impact of fish meal (FM) with the combined meat meal and chicken by-product meal (CMC) in the olive flounder (P. olivaceus) feeds on growth and feed availability. Seven experimental feeds were formulated. The control (CMC0) diet included 65% FM. In the CMC0 diet, the various (10%, 20%, 40%, 60%, 80%, and 100%) levels of FM were replaced with CMC, named as the CMC10, CMC20, CMC40, CMC60, CMC80, and CMC100 diets, respectively. The total number of 525 juvenile fish (9.2 ± 0.01 g; mean ± SD) was placed into 21 50-L flow-through tanks (25 juveniles/tank) with three replicates. Fish were hand-fed to apparent satiation for 8 weeks. After the 8-week feeding experiment, olive flounder fed the CMC10 (40.0 ± 0.60 g/fish, 2.99 ± 0.021%/day, and 39.57 ± 0.542 g/fish; mean ± SD), CMC20 (47.3 ± 2.58 g/fish, 3.24 ± 0.082%/day, and 45.16 ± 0.760 g/fish), and CMC40 (40.2 ± 1.17 g/fish, 3.00 ± 0.040%/day, and 39.43 ± 0.930 g/fish) diets attained superior (p < 0.0001 for all) weight gain, specific growth rate (SGR), and feed consumption compared to olive flounder fed the CMC0 (35.1 ± 0.96 g/fish, 2.81 ± 0.039%/day, and 33.75 ± 0.544 g/fish), CMC60 (31.7 ± 1.62 g/fish, 2.66 ± 0.068%/day, and 31.60 ± 1.080 g/fish), CMC80 (24.7 ± 0.63 g/fish, 2.33 ± 0.033%/day, and 25.27 ± 0.689 g/fish), and CMC100 (17.8 ± 0.32 g/fish, 1.92 ± 0.021%/day, and 18.99 ± 0.592 g/fish, respectively) diets. Weight gain, SGR, and feed consumption of olive flounder fed the CMC60 diet were comparable to olive flounder fed the CMC0 diet. Feed efficiency and protein efficiency ratio of olive flounder fed the CMC60 diet (1.02 ± 0.007 and 1.79 ± 0.034) were comparable to fish fed the CMC0 diet (1.04 ± 0.012 and 1.85 ± 0.021, respectively). None of the plasma and serum measurements, proximate composition, amino acid profiles, or survival of olive flounder after S. iniae infection were influenced by dietary treatments. In conclusion, CMC can substitute FM up to 60% (39% FM protein in the diet) without deteriorating growth performance, feed availability, or the survival of fish after S. iniae infection.

Impact on Growth and Feed Availability from Including Jack Mackerel (Trachurus japonicas) Meal in Rockfish (Sebastes schlegeli) Feeds Which Otherwise Replace Fish Meal with Chicken By-Product Meal.

This study was conducted to elucidate the impact on the growth and feed availability of rockfish (Sebastes schlegeli) from including jack mackerel meal (JMM) in feeds which otherwise substitute 20% fish meal (FM) with chicken by-product meal (CBM). Six formulated feeds were designed to be isonitrogenous and isolipidic. Specifically, 55% FM was included in the control (Con) diet. In the Con diet, 20% FM was substituted by CBM, and then the graded levels (0, 20, 40, 60, and 80%) of JMM were included instead of FM, named as the C20J0, C20J20, C20J40, C20J60, and C20J80 diets, respectively. Five hundred and forty juvenile rockfish (initial weight of 11.2 g) were assigned to 18 tanks. All experimental feeds were fed to triplicate groups of rockfish twice daily for 8 weeks. Superior weight gain, specific growth rate (SGR), and feed intake of rockfish fed the C20J60 and C20J80 diets compared to rockfish fed the Con and C20J0 diets were observed. However, the feed utilization, biological indices, proximate composition, amino acid profiles, and blood chemistry of the rockfish were not affected by the dietary treatments. The slightly but not significantly higher economic profit index and growth performance were obtained in the C20J60 diet compared to the C20J80 diet. In conclusion, the C20J60 diet was the most recommendable treatment based on the improvement in growth performance (weight gain and SGR) and feed intake of rockfish, and the highest economic return to farmers.

Dietary Replacement Effect of Fish Meal by Tuna By-Product Meal on Growth and Feed Availability of Red Sea Bream (Pagrus major).

The effect of substituting fish meal (FM) by tuna by-product meal (TBM) on growth and feed availability of red sea bream (Pagrus major) was investigated. Six experimental diets were crested to be isonitrogenous (51.5%) and isolipidic (14.5%). The control (Con) diet contained 55% FM. FM substitution in the Con diet was made in increments of 20 percentage points (20, 40, 60, 80, and 100%), named as the TBM20, TBM40, TBM60, TBM80, and TBM100 diets, respectively. Juvenile red sea bream were stocked into 18, 300 L flow-through tanks (50 fish/tank). Red sea bream were hand-fed with each diet until satiation for 8 weeks. No statistical differences in weight gain, specific growth rate (SGR), and feed consumption were found among red sea bream fed the Con, TBM20, and TBM40 diets. Furthermore, feed utilization of fish fed the TBM20, TBM40, TBM60, and TBM80 diets was comparable to red sea bream fed the Con diet. The biological indices, biochemical composition, and hematological parameters of fish were not statistically altered by dietary FM replacement with TBM. The greatest economic profit index was achieved in the TBM40 diet. In conclusion, the replacement of 40% FM with TBM in red sea bream diet appears to be the most recommendable approach without producing retarded growth and feed availability, but maximizing EPI to farmers.

Effects of Dietary Inclusion of a Crude Protein Source Exhibiting the Strongest Attractiveness to Red Sea Bream (Pagrus major) on Growth, Feed Availability, and Economic Efficiency.

Dietary incorporation of an attractive feed protein source is a practical method of enhancing feed intake and consequently improving the growth of fish. The attractiveness of 18 crude protein sources to juvenile red sea bream (Pagrus major) and the effects of the dietary inclusion of the crude protein source that exhibited the strongest attractiveness on growth, feed availability, and economic efficiency were determined. Jack mackerel meal (JMM) showed the strongest attractiveness to red sea bream among 18 crude protein ingredients. In an 8-week feeding trial, 810 juveniles were randomly distributed into 27 tanks (30 fish/tank). Nine experimental diets were prepared. The control (Con) diet included 60% fish meal (FM). Various levels (1, 3, 5, 10, 20, 40, 60, and 100%) of JMM were included at the expense of FM in the Con diet, and the resulting diets were named the JMM1, JMM3, JMM5, JMM10, JMM20, JMM40, JMM60, and JMM100 diets, respectively. Fish were hand-fed to apparent satiation twice daily for 8 weeks. The weight gain, specific growth rate, and feed consumption of red sea bream that were fed the JMM40, JMM60, and JMM100 diets were significantly (p < 0.0001 for all) higher than those of the fish fed all other diets. However, dietary JMM inclusion had no remarkable impacts on the feed utilization, biological indices, and chemical composition of the whole body of red sea bream. In terms of the economic view of the study, the economic profit index of red sea bream fed the JMM40, JMM60, and JMM100 diets was significantly (p < 0.0001) greater than that of the fish fed all other diets. In conclusion, the strongest attractiveness to red sea bream among 18 crude protein sources was observed in JMM. The inclusion of more than 40% JMM at the expense of FM in the diet of red sea bream is highly recommended for practical feed formulations to induce remarkable improvement in the growth performance of fish and the economic returns for farmers.

Substitution Impact of Tuna By-Product Meal for Fish Meal in the Diets of Rockfish (Sebastes schlegeli) on Growth and Feed Availability.

This experiment was performed to assess the substitution impact of fish meal (FM) with tuna by-product meal (TBM) in feeds on growth and feed availability of the early stage of juvenile rockfish (S. schlegeli). Six experimental feeds were prepared to be isonitrogenous and isolipidic. Fifty-five percent of FM was contained in the control (Con) diet. In the Con diet, 20, 40, 60, 80, and 100% FM were replaced by TBM, named the TBM20, TBM40, TBM60, TBM80, and TBM100 diets, respectively. A total of 540 early-stage juvenile rockfish averaging 2.4 g was divided into 18 tanks and hand-fed to satiation for 56 days. Weight gain and feed consumption of rockfish fed the TBM20 and TBM40 diets were comparable to rockfish fed the Con diet. The specific growth rate (SGR) of rockfish fed the Con diet was comparable to rockfish fed the TBM20, TBM40, and TBM60 diets. Feed efficiency, biometric indices, hematological parameters, proximate composition, and amino acid profiles of rockfish were not impacted by dietary treatments. The economic profit index (EPI) of the Con, TBM20, and TBM40 diets were higher than that of all other diets. FM up to 40% could be substitutable with TBM in the diets of rockfish without deteriorating weight gain and feed consumption, but producing the highest EPI.

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.

Efficacy of Chitosan-PLGA encapsulated trivalent oral vaccine against viral haemorrhagic septicemia virus, Streptococcus parauberis, and Miamiensis avidus in olive flounder (Paralichthys olivaceus).

The present study was conducted to assess the protective efficacy of a trivalent oral vaccine containing chitosan-PLGA encapsulated inactivated viral haemorrhagic septicemia virus (VHSV), Streptococcus parauberis serotype I and Miamiensis avidus antigens, followed by its oral (incorporated in feed) administration to olive flounder (Paralichthys olivaceus) fingerlings for a period of 15-consecutive days. After 35 days of initial vaccination, three separate challenge studies were conducted at the optimal temperature of the targeted pathogens using an intraperitoneal injection route. RPS analysis revealed moderate protection in the immunized group against all the three pathogens viz., VHSV (53.30% RPS), S. parauberis serotype-I (33.30% RPS), and M. avidus (66.75% RPS), as compared to the respective non-vaccinated challenge (NVC) control group. In addition, the immunized fish demonstrated significantly (p < 0.05) higher specific antibody titres in serum and significant (p < 0.05) upregulation in the transcript levels of immune genes of Igs (IgM, IgT, pIgR), TLRs (TLR 2, TLR 7), cytokines (IL-1ß, IL-8) and complement pathway (C3) in the mucosal and systemic tissues than those of NVC control fish, suggesting orchestration of pathogen-specific host immune responses thereby favouring its combativeness against the three pathogens. The expression dynamics of IFN-γ, Mx, caspase 3 genes post VHSV challenge; IFN-γ, TLR 2, caspase 1 genes post S. parauberis serotype I challenge and CD-8α, IL-10, TNF-α genes post M. avidus challenge further substantiates the efficacy of the vaccine in stimulating antiviral, antibacterial and antiparasitic immune responses in the host resulting in their better survival. The findings from the present study reflect that the formulated trivalent oral vaccine incorporating VHSV, S. parauberis serotype I and M. avidus antigens can be a promising prophylactic strategy to prevent the associated disease outbreaks in olive flounder.

Evaluation of the Optimal Protein Required in Granulated Microdiets for Rockfish (Sebastes schlegeli) Larvae.

Protein is an essential nutrient that supports fish growth, and the inadequacy in formulating their diets with an optimum protein level can deteriorate their growth performance. The protein requirement in granulated microdiets was estimated for rockfish (Sebastes schlegeli) larvae. Five granulated microdiets (CP42, CP46, CP50, CP54, and CP58) containing 42% to 58% crude protein levels with a 4% increment at a constant gross energy level (18.4 kJ/g diets) were prepared. The formulated microdiets were also compared with imported microdiets, Inve (IV) and love larva (LL) from Belgium and Japan, respectively, and a locally marketed feed (crumble). At the cessation of the study, the survival of larval fish was not different (P > 0.05), but the weight gain (%) of fish fed the CP54, IV, and LL diets was significantly (P < 0.0001) higher than that of larval fish fed the CP58, CP50, CP46, and CP42 diets. The crumble diet achieved the poorest weight gain of larval fish. Furthermore, the total length of rockfish larvae fed the IV and LL diets was significantly (P < 0.0001) longer than that of the fish fed all other diets. The chemical composition of the fish's whole body, except for ash content, was not influenced by the experimental diets. The experimental diets affected essential amino acid profiles, such as histidine, leucine, and threonine, and nonessential amino acid profiles, such as alanine, glutamic acid, and proline of the whole body of larval fish. Conclusively, based on the broken line analysis of weight gain of larval rockfish, protein requirement in granulated microdiets was estimated to be 54.0%.

Dietary inclusion effect of feed ingredients showing high feeding attractiveness to rockfish (Sebastes schlegeli Hilgendorf 1880) on the growth performance, feed utilization, condition factor and whole body composition of fish (II).

Dietary inclusion effect of feed ingredients showing high feeding attractiveness to rockfish on the growth, feed utilization, condition factor (CF) and whole body composition of fish was investigated. Three hundred sixty juvenile rockfish were randomly distributed into 18 50-L flow-through tanks (twenty fish per tank). Six experimental diets were prepared: the control (Con) diet containing 55% anchovy meal, and 5% anchovy meal in the Con diet was replaced with an equivalent amount of jack mackerel, sardine, Pollack, squid and shrimp meals, referred to as the JM, SM, PM, SQM and SHM diets, respectively. Each diet was assigned in triplicate and hand-fed to satiation twice daily for 8 weeks. Weight gain (20.7 ±â€¯0.03), amount of feed supply (20.1 ±â€¯0.05) and CF (1.50 ±â€¯0.002) of rockfish fed the JM diet were greater than those of fish fed all other diets, followed by the SM (20.3 ±â€¯0.04, 19.5 ±â€¯0.08 and 1.48 ±â€¯0.003), PM (19.9 ±â€¯0.09, 19.2 ±â€¯0.05 and 1.47 ±â€¯0.003), SQM (19.5 ±â€¯0.06, 18.8 ±â€¯0.07 and 1.45 ±â€¯0.002), SHM (19.0 ±â€¯0.12, 18.3 ±â€¯0.09 and 1.44 ±â€¯0.001) and Con diets (17.8 ±â€¯0.07, 17.2 ±â€¯0.05 and 1.43 ±â€¯0.005). However, feed efficiency, protein efficiency ratio and protein retention was not affected by the experimental diets. The proximate composition of the whole body of fish, except for ash content was not affected by the experimental diets. In conclusion, the greatest weight gain, amount of feed supply and CF of rockfish were obtained in the JM diet, followed by the SM, PM, SQM, SHM and Con diets, in order.

Expression of aquaporin-3 and -8 mRNAs in the parr and smolt stages of sockeye salmon, Oncorhynchus nerka: effects of cortisol treatment and seawater acclimation.

This study aimed to examine the role of 2 aquaporin (AQP) isoforms (AQP3, and -8) in sockeye salmon (Oncorhynchus nerka) in response to a hyperosmotic challenge from freshwater to seawater (SW) during the parr and smoltification (smolt) stages. AQP3 mRNA was primarily detected in the osmoregulatory organs, such as gills, while AQP8 mRNA was primarily found in the intestine. These results suggested that AQP isoforms play a role in osmoregulation in specific osmoregulatory organs. Similarly, AQP3 mRNA expression in the gills (mean values:1.06 ± 0.05 [parr] and 1.29 ± 0.07 [smolt]) was significantly higher than AQP8 mRNA levels (parr: 0.04 ± 0.003; smolt: 0.14 ± 0.004), and in the intestine, AQP8 mRNA expression (parr: 0.89 ± 0.007; smolt: 1.91 ± 0.03) was significantly higher than AQP3 mRNA levels (parr: 0.24 ± 0.006; smolt: 0.83 ± 0.005); these expression patterns were similar in vivo and in vitro. Additionally, AQP mRNA levels were lower in cortisol treated than in control groups. Therefore, these results suggest that AQPs play important roles in the water absorption mechanisms associated with multiple AQP isoforms, and that cortisol enhances the hypo-osmoregulatory capacity of fish in SW, and also controls the expression of AQPs in a hyperosmotic environment.

Morphometric and Histological Changes in Cyprinid Loach, Misgurnus anguillicaudatus, in the Early Growth Period.

In this study, we measured the morphometric and histological changes in the cyprinid loach, Misgurnus anguillicaudatus, during the early period of growth. Eyes, yolk length, yolk height, and yolk volume of the larva decreased for 16 days post hatching (DPH) (P<0.05). During 60 DPH (P>0.05), the most anterior extension of the head × the posterior end of the supraoccipital, the most anterior extension of the head × the origin of the dorsal fin, the most anterior extension of the head × the origin of the pectoral fin, the posterior end of the supraoccipital × the origin of the pelvic fin, and the origin of the dorsal fin × the ventral origin of the caudal fin gradually decreased, whereas the most anterior extension of the head × the dorsal origin of the caudal fin, the origin of the dorsal fin × the origin of the anal fin, the origin of the dorsal fin × the origin of the pectoral fin, and the insertion of the dorsal fin × the origin of the pelvic fin gradually increased (P<0.05). In the cyprinid loach, the retina is composed of six layers: the epithelial layer, ganglion cell layer, inner nuclear layer, inner plexiform layer, outer limiting membrane, and rod and cone layer (RCL). After hatching, part of the RCL gradually increased in density. The kidney and midgut epithelium were already formed in the cyprinid loach just after hatching and grew gradually in subsequent days.

Effect of dietary nutrient composition on the growth of olive flounder (Paralichthys olivaceus) with different feeding regimes.

We have examined the effect of dietary nutrient composition on the growth, body composition and blood chemistry of juvenile olive flounder (Paralichthys olivaceus) maintained on two different feeding regimes. Three experimental diets [HP (high protein), HE (high energy) and IPE (intermediate protein and energy)] were crossed in a two-factor design with the two feeding regimes, which consisted of 2WS + 2WF (2-week starvation and then 2-week feeding) and 4WS + 4WF (4-week starvation and then 4-week feeding)], for 8 weeks. The total days of feeding in all treatments were the same. The final weight of fish was affected by feeding regime, but not by dietary nutrient composition. Long-term starving and feeding (the 4WS + 4WF treatments) yielded higher growth than the alternating short-term starving and feeding regime (2WS + 2WF treatments). The feed consumption of fish was affected by dietary nutrient composition, but not by feeding regime, while the feed efficiency of fish was affected by feeding regime, but not by dietary nutrient composition. Moisture, crude protein and crude lipid contents of the liver of the fish were affected by dietary nutrient composition, but not by feeding regime.