Effects of dietary squid oil on breeding performance and embryonic and larval development of butter catfish Ompok pabda

The present study was conducted to determine the effects of squid oil on the endangered butter catfish, Ompok pabda to confer enhanced breeding with embryonic and larval development for promoting its aquaculture. A total of 360 fish were obtained from the Brahmaputra River, Mymensingh, Bangladesh, of which, 60 fish stocked in each tank having an initial weight and length of 16.35 ± 0.57 g and 15.25 ± 0.38 cm, respectively, in the cisterns of 1.22 × 2.44 × 1.25 m (total 6 cisterns) maintained at 90 cm water depth. During the experimental period, a constant physico-chemical conditions of water such as temperature, pH, and dissolved oxygen (DO) were 26.5 ± 2 °C, 7.4 ± 0.2, and 6.7 ± 0.5 ppm, respectively, were maintained in each cistern. As the source of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), dietary 1 % squid oil (SQO) was supplemented in the diet of the treated group (SQO diet) to compare while the control group offered with basal diet without SQO supplementation (CON diet). The fecundity, spawning, fertilization, hatching rate, and survival rate of fry in SQO group were significantly (P < 0.01) higher than in the CON group. Moreover, better early embryonic and larval development of fish was observed in the SQO group i.e. size of fertilized egg diameter, growth and early developmental stages of larvae but not significantly different from the control group. Collectively, the results of the present study showed that dietary SQO supplementation improved the breeding and reproductive performances of butter catfish. The findings of this study could assist to develop a nutrient-rich diet for the better broodstock development of butter catfish at the farm level which may ultimately reduce the mortality and poor survival of offspring of this commercially important catfish species.

The effects of two dietary synbiotics on growth performance, hematological parameters, and nonspecific immune responses in Japanese Eel

OBJECTIVE

Feed additives have attracted increased attention in aquaculture due to their ability to modulate fish gut microbiota, resulting in improved fish growth and immunity. This study assessed the effects of two synbiotics in Japanese Eel Anguilla japonica: Bacillus subtilis with mannooligosaccharides (MOS) and Enterococcus faecium with fructooligosaccharides (FOS).

METHODS

Six diets, including a control (CON) diet, oxytetracycline (OTC) diet, and four synbiotic diets (B. subtilis at 1 × 106 or 1 × 107 colony-forming units [CFU]/g with MOS at 5 g/kg [BS6MO and BS7MO; collectively, BSMOS diets] and E. faecium at 1 × 106 or 1 × 107 CFU/g with FOS at 5 g/kg [EF6FO and EF7FO; collectively, EFFOS diets]), were fed to triplicate groups of 20 fish (average weight ± SD = 6.00 ± 0.07 g) for 8 weeks.

RESULT

Fish fed the BSMOS diets showed significantly higher weight gain, specific growth rate (SGR), and feed efficiency compared to fish fed the CON and OTC diets, but the values were not significantly different from those of fish fed the EFFOS diets. Weight gain and SGR of fish that were given EFFOS diets were not significantly different from those of fish fed all other diets. Fish fed the OTC diet showed a higher mean aspartate aminotransferase level, although the difference was not statistically significant. The myeloperoxidase activity of fish fed the BS7MO diet was significantly higher than those of fish receiving all other diets, and the superoxide dismutase activity of fish fed the BS7MO diet was also significantly higher than that of fish fed the EF7FO diet. Overall, the BSMOS synbiotic diets were significantly more effective than the CON diet in enhancing fish survival against a Vibrio anguillarum challenge.

CONCLUSION

Our findings suggest that synbiotics can be a preferable alternative to antibiotics in aquaculture.

Effect of Four Functional Feed Additives on Growth, Serum Biochemistry, Antioxidant Capacity, Gene Expressions, Histomorphology, Digestive Enzyme Activities and Disease Resistance in Juvenile Olive Flounder, Paralichthys olivaceus

An 8-week feeding trial was executed to evaluate the efficacy of four functional feed additives in replacing antibiotics in juvenile olive flounder, Paralichthys olivaceus, fed with a low-fish-meal diet. A basal diet without feed additives was used as a control (CON); other diets were formulated by supplementing 0.50% taurine (TW), 0.30% peptide (PT), 0.23% mineral water (MW), 0.35% yeast-extracted nucleotides (GRO), 0.35% GRO + 0.50% taurine (GROTW), 0.35% GRO + 0.30% peptide (GROPT) and 0.35% GRO + 0.23% mineral water (GROMW) into the basal diet; in addition, one diet was supplemented with oxytetracycline (OTC) at 0.5% as a positive control. Triplicate groups of 25 fish with an average weight of 5.15 ± 0.06 g (mean ± SD) were fed one of the nine experimental diets. At the end of the feeding trial, the weight gain, specific growth rate and protein efficiency ratio of fish fed the GRO, GROMW, GROPT and GROTW diets were significantly higher than those of fish fed the CON diet (p < 0.05). The feed efficiency of fish fed the GRO, GROMW, GROPT and GROTW diets was significantly higher than that of fish fed the TW and OTC diets. However, the survival, hepatosomatic index, viscerosomatic index and condition factor of fish, as well as their whole-body proximate composition, were not significantly affected by the experimental diets (p > 0.05). The serum glutamic pyruvic transaminase of fish fed the GROPT diet was significantly lower than that of fish fed the CON diet. However, glutamic oxaloacetic transaminase, glucose and total protein were not significantly affected by the experimental diets (p > 0.05). The serum superoxide dismutase activity of fish fed the PT, TW, GRO, GROMW, GROPT and GROTW diets was significantly higher than that of fish fed the CON diet. The lysozyme activity of fish fed the PT, GRO, GROMW, GROPT and GROTW diets was significantly higher than that of fish fed the CON and OTC diets. The myeloperoxidase activity of fish fed the TW, GRO, GROMW, GROPT and GROTW diets was significantly higher than that of fish fed the CON, PT and MW diets (p < 0.05). The flounder growth hormone gene expression of fish fed the TW, GRO, GROMW, GROPT, GROTW and OTC diets was significantly higher than that of fish fed the CON, PT and MW diets (p < 0.05). The interleukin 1β and interleukin 10 gene expressions of fish fed the GRO, GROMW, GROPT and GROTW diets were significantly higher than those of fish fed the CON, PT, TW and MW diets (p < 0.05). Intestinal histology showed a significantly higher villi length for fish fed the GRO, GROMW, GROPT and GROTW diets compared to that of fish fed the CON diet (p < 0.05). Digestive enzyme activities such as trypsin activity were significantly higher in fish fed the GROMW, GROPT and GROTW diets than those in the rest of the diet groups (p < 0.05). Amylase activity in fish fed the MW, GRO, GROMW, GROPT, GROTW and OTC diets was significantly higher than that of fish fed the PT, TW and CON diets (p < 0.05). On the other hand, the lipase activity of fish fed the TW, GRO, GROMW, GROPT and GROTW diets was significantly higher than that of fish fed the CON, PT, MW and OTC diets (p < 0.05). The cumulative survival rate of fish fed the PT, GROTW, GROPT and GROMW diets was significantly higher than that of fish fed the CON, TW and MW diets after thirteen days of the challenge testing. Overall, the results demonstrate that the GRO, GROMW, GROPT and GROTW diets could be beneficial feed additives to replace antibiotics in juvenile olive flounder fed low-fish-meal diets.

Evaluation of Yeast Hydrolysate in a Low-Fishmeal Diet for Whiteleg Shrimp (Litopenaeus vannamei)

An eight-week feeding trial was performed to evaluate the effects of yeast hydrolysate (YH) supplementation in a low-fishmeal diet on the growth, immune responses, intestinal histology and disease resistance of whiteleg shrimp (Litopenaeus vannamei). Five experimental diets were produced by supplementing YH at 0 (CON), 0.5 (YH0.5), 1 (YH1), 2 (YH2) and 4 (YH4) % to a basal diet containing 10% fishmeal and compared with a positive control with 25% fishmeal (FM25). Shrimp with an initial average weight of 0.43 ± 0.005 g (mean ± SD) were stocked in 18 tanks and fed the experimental diets (38% protein and 8% lipid) four times a day. Results showed that shrimp fed the FM25 diet exhibited significantly higher final body weight, weight gain, specific growth rate and protein efficiency ratio than those fed CON, YH0.5, YH1 and YH2 diets (p < 0.05). However, there were no significant differences between shrimp fed the YH4 and FM25 diets (p > 0.05). In addition, there were no significant differences in whole-body proximate composition, hemolymph biochemical parameters and non-specific immune responses among treatments. Intestinal villi length and muscular layer thickness of shrimp fed the YH4 and FM25 diets were significantly higher than the other groups. At the end of the bacterial (Vibrio parahaemolyticus) challenge test, shrimp fed YH4 and FM25 diets showed a significantly higher survival rate than those of shrimp fed CON, YH0.5 and YH1 (p < 0.05). These results suggest that supplementing 4% YH in diet containing 10% fishmeal could beneficially influence growth, intestinal morphology and disease resistance of whiteleg shrimp.

Interactive Effect of Dietary Gamma-Aminobutyric Acid (GABA) and Water Temperature on Growth Performance, Blood Plasma Indices, Heat Shock Proteins and GABAergic Gene Expression in Juvenile Olive Flounder Paralichthys olivaceus

Gamma-aminobutyric acid (GABA) is an important inhibitory neurotransmitter in the central nervous system of living organisms and has the ability to reduce the magnitude of stress in humans and animals. In this study, we evaluated the supplemental effects of GABA on normal and high water temperature based on growth, blood plasma composition as well as heat shock proteins and GABA-related gene expression in juvenile olive flounder. For this, a 2 × 2 factorial design of experiment was employed to investigate the dietary effects of GABA at 0 mg/kg of diet (GABA0 diet) and 200 mg/kg of diet (GABA200 diet) in water temperatures of 20 ± 1 °C (normal temperature) and 27 ± 1 °C (high temperature) for 28 days. A total of 180 fish with an average initial weight of 40.1 ± 0.4 g (mean ± SD) were distributed into 12 tanks, of which, each tank contained 15 fish based on the 4 dietary treatment groups in triplicate. At the end of the feeding trial, the results demonstrated that both temperature and GABA had significant effects on the growth performance of the fish. However, fish fed the GABA200 diet had a significantly higher final body weight, weight gain and specific growth rate as well as a significantly lower feed conversion ratio than the fish fed the GABA0 diet at the high water temperature. A significant interactive effect of water temperature and GABA was observed on the growth performance of olive flounder based on the two-way analysis of variance. The plasma GABA levels in fish were increased in a dose-dependent manner at normal or high water temperatures, whereas cortisol and glucose levels were decreased in fish fed GABA-supplemented diets under temperature stress. The GABA-related mRNA expression in the brains of the fish such as GABA type A receptor-associated protein (Gabarap), GABA type B receptor 1 (Gabbr1) and glutamate decarboxylase 1 (Gad1) were not significantly affected by GABA-supplemented diets under normal or temperature stressed conditions. On the other hand, the mRNA expression of heat shock proteins (hsp) in the livers of the fish, such as hsp70 and hsp90, were unchanged in fish fed the GABA diets compared to the control diet at the high water temperature. Collectively, the present study showed that dietary supplementation with GABA could enhance growth performance, and improve the feed utilization, plasma biochemical parameters and heat shock proteins and GABA-related gene expression under the stress of high water temperatures in juvenile olive flounder.

Evaluation of dietary fermented tuna by-product meal as partial replacement for unprocessed tuna by-product meal in fishmeal-based diets for juvenile olive flounder Paralichthys olivaceus

This study examined the effects of feeding fermented tuna by-product (FTBP) on the growth, non-specific immune response, liver and intestinal morphology, and disease resistance of olive flounder Paralichthys olivaceus. Olive flounders (n = 20; 2 g) were randomly assigned into four dietary groups in triplicates. Fish were fed four test diets (50% crude protein; 10% crude lipid) for 10 weeks in which unprocessed tuna by-product (TBP) meal was replaced (on a protein basis) with 0% (FTBP0 as the control diet), 15% (FTBP15), 30% (FTBP30), and 60% (FTBP60) of FTBP protein. Results showed that growth performance, blood parameters, and proximate composition were not influenced by FTBP inclusion. Non-specific immune parameters such as superoxide dismutase activity in the FTBP30 and FTBP60 groups were significantly higher than in the FTBP15 and the control groups, whereas lysozyme and myeloperoxidase activities were not different. Liver histopathology revealed normal architecture in groups fed FTBP0 and FTBP15 diets although mild alterations were noted in the FTBP30- and FTBP60-fed groups. Intestinal villi height and muscular thickness were not significantly altered with FTBP inclusion. Moreover, higher cumulative survival rate was observed in the FTBP60-fed group than fish fed with the other diets following the 13-day challenge with E. tarda. Together, these results demonstrate that fermented tuna by-product meal could be included at 60% in olive flounder diets.

Dietary Supplementation with γ-Aminobutyric Acid Improves Growth, Digestive Enzyme Activity, Non-Specific Immunity and Disease Resistance against Streptococcus iniae in Juvenile Olive Flounder, Paralichthysolivaceus

Simple Summary

γ-aminobutyric acid (GABA) is a very important biomolecule that is found in all lifeforms and serves innumerable essential biological functions in pathways ranging from neural transmission to metabolism and immunity. In recent years, GABA was identified as an important metabolite involved in the modulation of the gut microbiome, and even appetite, in fish. The current trial aims to assess the effects of GABA as a supplement for nutritionally important biomarkers of fish health. Our results show that approximately 229–282 mg/kg of the total dietary GABA has important benefits for juvenile olive flounder, most significantly with improved disease resistance against Streptococcus iniae.

Abstract

Recent research is increasingly shedding light on the important role that microbial metabolites such as γ-aminobutyric acid (GABA) play in the context of nutrition, cognition, immune function, and the modulation of the gut microbiome. Yet, very few trials were conducted to assess the effects of its supplementation on biomarkers of fish health. Therefore, an eight-week feeding trial was devised to evaluate GABA supplementation in juvenile olive flounder, (Paralichthys olivaceus). A total of 630 fish with an average weight of 4.90 ± 0.10 g (±SD) were randomly assigned to one of seven triplicate groups and fed a non-GABA supplemented diet (CON, with 92 mg/kg GABA content), a positive control with 4 g/kg oxytetracycline (OTC), and five other diets supplemented with 50, 100, 150, 200 and 250 mg/kg GABA (corresponding to a total GABA content of 154, 229, 282, 327 and 352 mg/kg, respectively). Growth, blood chemistry, nonspecific immunity, digestive enzyme activity and disease resistance were assessed. The results showed that 100 and 150 mg/kg GABA supplementation consistently yielded significant improvements (p < 0.05) in growth, intestinal amylase, serum lysozyme, and survival against infection with Streptococcus iniae. Based on polynomial analysis, the optimal supplementation level was determined to be 237 mg/kg. These results support GABA as an important functional feed additive in juvenile olive flounder.

Evaluation of Dietary Probiotic Bacteria and Processed Yeast (GroPro-Aqua) as the Alternative of Antibiotics in Juvenile Olive Flounder Paralichthys olivaceus

We investigated the three probiotic bacteria and a processed yeast (GroPro-Aqua) as the replacers of antibiotics in juvenile olive flounder. A total of seven diets were used, that is, one basal or control (CON) diet; and six other diets, of which, three diets were prepared by supplementing probiotic bacteria such as Bacillus subtilis WB60 (BSWB60) at 1 × 10⁸ CFU/g diet, Bacillus subtilis SJ10 (BSSJ10) at 1 × 10⁸ CFU/g diet, and Enterococcus faecium SH30 (EFSH30) at 1 × 10⁷ CFU/g diet; one diet with processed yeast (GRO) at 0.35% diet; and two other diets were supplemented with oxytetracycline (OTC) and amoxicillin (AMO) at 4 g/kg of each. Triplicate groups of fish (average 12.1 g) were fed one of the diets for eight weeks. At the end of the feeding trial, the fish that were fed the probiotic bacteria-supplemented diets had a significantly higher final weight, weight gain, and specific growth rate compared to the CON, OTC, and AMO diets. Fish that were fed the GRO diet had significantly higher feed efficiency and protein efficiency ratios than those of the fish that were fed the CON diet. Serum glutamic pyruvic transaminase, glutamic oxaloacetic transaminase, glucose, and total protein were not affected by the diets. Lysozyme activity in fish that were fed the BSSJ10, BSWB60, and EFSH30 diets were significantly higher compared to the CON and OTC diets, whereas myeloperoxidase activity of fish fed the BSWB60 and EFSH30 diets were significantly higher than those of fish fed the CON and AMO diets. Flounder growth hormone gene expressions of fish that were fed BSWB60 and GRO diets were significantly higher compared to the CON, OTC, and AMO diets. The interleukin-1β gene expression of fish that were fed the BSSJ10, BSWB60, EFSH30, OTC, and GRO diets was significantly higher than those of fish fed the CON diet. The interleukin-10 gene expression of fish that were fed the BSSJ10, EFSH30, and GRO diets was significantly higher than those of fish fed the CON and AMO diets. Posterior intestinal histology of fish showed significantly higher villi length in fish that were fed the BSSJ10, BSWB60, EFSH30, and GRO diets compared to the CON diet. After 15 days of challenge test with pathogenic bacteria Edwardsiella tarda, the cumulative survival rate of fish that were fed the BSSJ10, BSWB60, EFSH30, and GRO diets were significantly higher than those of fish that were fed the CON diet. Overall, the results indicate that dietary supplementation of B. subtilis (10⁸ CFU/g diet), E. faecium (10⁷ CFU/g diet), and processed yeast (GroPro-Aqua at 0.35% diet) could replace the antibiotics in terms of improving growth, immunity, gut health, and disease resistance in juvenile olive flounder.

Nutritional evaluation of some economically important marine and freshwater mollusc species of Bangladesh

Molluscs are the most important resources among all the seafood items in South-East Asian countries. However, very little information available on nutritional value of molluscs in these regions. In this study, we evaluated the 7 economically important species of molluscs in terms of proximate composition, amino acids profile, fatty acids profile, cholesterol and heavy metal contents in the bivalves (mussels, oysters, clams and cockles) and univalve (snail) collected from freshwater and marine environments of Bangladesh. The results of the proximate analyses revealed that significantly higher amount of crude protein contents were present in marine water oysters, clams and cockles (59.3 ± 0.3 to 75.4 ± 0.2%) than the freshwater mussels and snail (36.9 ± 0.4 to 49.6 ± 0.6%) on dry matter basis. However, carbohydrate contents were significantly higher in freshwater mussels and snail (30.2 ± 0.9 to 57.3 ± 0.2%) compared to the marine water bivalves (8.1 ± 0.4 to 20.2 ± 0.6%). Crude lipid contents were ranged from 2.5 ± 0.2 to 11.2 ± 0.1% and ash from 11.4 ± 0.1 to 16.8 ± 0.6% among the bivalves and snail species. The amino acid contents were comparatively higher in marine water bivalves than their freshwater counterparts. Saturated fatty acid contents were found to be higher in marine water bivalves than the freshwater mollusc species. The results also show that the omega-3 (eicosapentaenoic acid, EPA and docosahexaenoic acid, DHA) fatty acids were comparatively higher in oysters, clams and cockles in marine water than those in freshwater mussels and snail. However, omega-6 fatty acids like linoleic acid (LA), α- linolenic acid (ALA) and arachidonic acid (ARA) were higher in freshwater mussels and snail than in the marine bivalves. The n-3/n-6 ratio were significantly higher in oysters and cockle species than the other groups of bivalves and snail. The index of atherogenicity and index of thrombogenicity of the mollusc species ranged from 0.74 ± 0.1 to 1.74 ± 0.2 and 0.5 ± 0.1 to 2.6 ± 0.2, respectively. The results show that marine water bivalves contained higher amount of potassium, sodium, iron, chlorine especially oyster species contained significantly higher iodine than the freshwater bivalves and snail. However, freshwater mussels and snail showed significantly higher amount of zinc contents than the marine bivalves. The heavy metal contents such as arsenic, chromium and mercury were absent or present in very tiny amounts among the mollusc species. Significantly higher amount of cholesterol was present in marine bivalves and freshwater snail species than the freshwater mussels. Overall, the results indicate that marine bivalves can be good sources of high quality protein and lipid especially EPA and DHA. On the other hand, freshwater mussels and snails also could be good sources of protein, LA and ARA but scarcity of EPA and DHA.

Evaluation of dietary selenium, vitamin C and E as the multi-antioxidants on the methylmercury intoxicated mice based on mercury bioaccumulation, antioxidant enzyme activity, lipid peroxidation and mitochondrial oxidative stress

Mercury (Hg) in high exposures can be a potent life threatening heavy metal that bioaccumulate in aquatic food-chain mainly as organic methylmercury (MeHg). In this regard, fish and seafood consumptions could be the primary sources of MeHg exposure for human and fish-eating animals. The objective of the present study was to elucidate the effects of dietary supplementation of some antioxidants on induced mercury toxicity in mice model. In this study, a 30-day long investigation has been conducted to evaluate the dietary effect of selenium (Se) in combination with vitamin C and vitamin E on methylmercury induced toxicity in mice. Total 54 mice fed the diets with three levels of Hg (0, 50 or 500 μg kg^-1) and two levels of Se in combination with vitamin C and E (Se: 0, 2 mg kg^-1; vitamin C: 0, 400 mg kg^-1; vitamin E: 0, 200 mg kg^-1) in triplicates. The results show that Hg accumulated in blood and different tissues such as muscle, liver and kidney tissues of mice on dose dependent manner. The bioaccumulation pattern of dietary Hg, in decreasing order, kidney > liver > muscle > blood. Superoxide dismutase levels in blood serum showed no significant differences in mice fed the diets. However, dietary antioxidants significantly reduced the levels of thiobarbituric acid reactive substances in mice fed the mercury containing diets. Cytochrome c oxidase enzyme activities showed no significant differences as the mercury level increases in liver and kidney tissues of mice. Kaplan-Meier curve showed a dose- and time-dependent survivability of mice. Cumulative survival rate of Hg intoxicated mice fed the antioxidant supplemented diets were increased during the experimental period. Overall, the results showed that dietary Se, vitamin C and vitamin E had no effect on reducing the mercury bioaccumulation in tissues but reduced the serum lipid peroxidation as well as prolonged the cumulative survival rate in terms of high Hg exposures in mice.

Evaluation of Dietary Soluble Extract Hydrolysates with or without Supplementation of Inosine Monophosphate Based on Growth, Hematology, Non-Specific Immune Responses and Disease Resistance in Juvenile Nile Tilapia Oreochromis niloticus

Simple Summary

This study was conducted to elucidate the effects of dietary soluble extract hydrolysates obtained from fishery by-products, such as shrimp soluble extract (SSE), tilapia soluble extract (TSE) and squid soluble extract (SQSE). Furthermore, we used a nucleotide, inosine monophosphate (IMP), as an additive in different concentrations along with shrimp soluble extract to understand their effects on growth, immunity and disease resistance in juvenile Nile tilapia. Our results demonstrated that dietary SSE could improve growth performance, non-specific immune responses and disease resistance against pathogenic bacteria Aeromonas hydrophila in juvenile Nile tilapia. Moreover, IMP did not add further benefits to the SSE diet. Further research is needed to better understand the effects of fishery by-products and IMP on fish diets.

Abstract

We performed an 8-week feeding trial to evaluate dietary soluble extract hydrolysates from fishery by-products, such as shrimp soluble extract (SSE) with or without inosine monophosphate (IMP), tilapia soluble extract (TSE) and squid soluble extract (SQSE), in juvenile Nile tilapia. A diet without feed additives was used as the control diet (CON); and five other experimental diets were formulated with 2% soluble extracts consisting of 100% SSE, 98% SSE + 2% IMP (SSEP₂), 96% SSE + 4% IMP (SSEP₄), 100% SQSE and 100% TSE. The diets were fed to 4.9 ± 0.07 g (mean ± SD) juvenile Nile tilapia in triplicate groups. The weight gain and specific growth rates of fish fed the SSE, SSEP₂ and SSEP₄ diets were significantly higher than those of fish fed the CON and SQSE diets. The superoxide dismutase activity levels of fish fed the SSE and SSEP₄ diets were significantly higher than those of fish fed the CON, SSEP₂, SQSE and TSE diets. Myeloperoxidase activity levels of fish fed the SSE and SSEP₄ diets were significantly higher than those of fish fed the CON, SSEP₂ and SQSE diets. Lysozyme activity levels of fish fed the SSEP₄ and SQSE diets were significantly higher than those of fish fed the SSE and SSEP₂ diets. Feed efficiency, protein efficiency ratio, survival rate, whole body proximate composition and hematological parameters were not significantly different among the groups. After ten days of challenge = against Aeromonas hydrophila, the cumulative survival rate of fish fed the SSE diet was significantly higher than those of fish fed the CON, SQSE and TSE diets. In conclusion, dietary shrimp soluble extract could improve the growth performance, non-specific immune responses and disease resistance in juvenile Nile tilapia, and inosine monophosphate did not add further benefits to this ingredient.

Dietary Supplementation of Bacillus sp. SJ-10 and Lactobacillus plantarum KCCM 11322 Combinations Enhance Growth and Cellular and Humoral Immunity in Olive Flounder (Paralichthys olivaceus)

Experiments were conducted to identify different ratios of Bacillus sp. SJ-10 and Lactobacillus plantarum KCCM 11322 mixtures at a concentration of 1 × 10⁸ CFU/g diet; the effects on growth and cellular and humoral immune responses and the characteristics of disease protection in olive flounder (Paralichthys olivaceus). Flounder were divided into six groups and fed control diet D-1 (without Bacillus sp. SJ-10 and L. plantarum KCCM 11322), positive control diets D-2 (Bacillus sp. SJ-10 at 1 × 10⁸ CFU/g feed) and D-3 (L. plantarum KCCM 11322 at 1 × 10⁸ CFU/g feed); or treatment diets D-4 (3:1 Bacillus sp. SJ-10 and L. plantarum KCCM 11322 at 0.75 + 0.25 × 10⁸ CFU/g feed), D-5 (1:1 Bacillus sp. SJ-10 and L. plantarum KCCM 11322 at 0.50 + 0.50 × 10⁸ CFU/g feed), or D-6 (1:3 Bacillus sp. SJ-10 and L. plantarum KCCM 11322 at 0.25 + 0.75 × 10⁸ CFU/g feed) for 8 weeks. Group D-4 demonstrated better growth and feed utilization (P < 0.05) compared with the controls and positive controls. Similar modulation was also observed in respiratory burst for all treatments and in the expression levels of TNF-α, IL-1β, IL-6, and IL-10 in different organs in D-4. D-4 and D-5 increased respiratory burst, superoxide dismutase, lysozyme, and myeloperoxidase activities compared with the controls, and only D-4 increased microvilli length. When challenged with 1 × 10⁸ CFU/mL Streptococcus iniae, the fish in the D-4 and D-5 groups survived up to 14 days, whereas the fish in the other groups reached 100% mortality at 11.50 days. Collectively, a ratio-specific Bacillus sp. SJ-10 and L. plantarum KCCM 11322 mixture (3:1) was associated with elevated growth, innate immunity, and streptococcosis resistance (3:1 and 1:1) compared with the control and single probiotic diets.

Probiotic effects of mixture of Groenewaldozyma salmanticensis and Gluconacetobacter liquefaciens on growth and immune responses in Paralichthys olivaceus

This study was performed to evaluate the effects of dietary probiotics on growth, non-specific immune responses and disease resistance in olive flounder, Paralichthys olivaceus. During 8 weeks, the fish were fed the five experimental diets such as a basal commercial diet (CON), oxytetracycline (OTC) and three basal diets containing Bacillus subtilis (BS), a commercial microbial product (CES) and a mixture of yeast and bacterium (PI), respectively. Fish fed all the probiotics diets and OTC showed a significantly higher growth than fish-fed CON (P < 0·05). Fish-fed PI had a significantly higher nitroblue tetrazolium activity, whereas fish-fed CES showed a higher lysozyme level (P < 0·05). A 7-day challenge test also showed that fish-fed PI had a cumulative survival rate equivalent to that of fish-fed OTC (P < 0·05). Moreover, the diet (PI) appeared to increase the diversity of microbial community in the fish. All these results suggest that the probiotics diet could function as a potential antibiotic replacer in the olive flounder. SIGNIFICANCE AND IMPACT OF THE STUDY: This study is unique in revealing that a diet mixture of yeast, Groenewaldozyma salmanticensis and bacterium Gluconacetobacter liquefaciens can enhance growth, innate immunity and diversity of microbial community including dominant species in the olive flounder. All these indicate that the diet mixture could function as a potential antibiotic replacer in one of the most commercially important fisheries in South Korea.

[Efficacy tubular paraspinal approach and conventional semi-laminar approach in treating lumbar stenosis]

Objective: To analysis of the efficacy of tubular paraspinal approach and conventional semi-laminar approach in treating lumbar stenosis. Methods: Retrospective research of clinical data of 56 lumbar stenosis cases who were operated in neurosurgery department of first center of PLA general hospital from May 2015 to June 2018. Collecting the information of sex, age, operating time, intraoperative blood loss, postoperative duration in bed, as well as length of hospital stay of those patients. The 2 groups of cases, tubular paraspinal approach group (n=35)and semi-laminal approachgroup (n=21), compared by Japanese orthopedic association (JOA) score and visual analogue scale to assess the functional situation of the patients before operation, 1 week after operation, 1 month after operation, 6 months after operation, and the last follow up. Results: The operating time(83.1±7.3 vs 86.1±9.6 min), intraoperative blood loss(18.2±3.9 vs 40.5±13.3 ml), postoperative duration in bed(37.4±7.8 vs 63.7±15.8 h), as well as length of hospital stay (3.8±1.1 vs 6.5±2.0 d)were all obviously better in tubular paraspinal approach group than in traditional semi-laminar approach group(P<0.05). The postoperative 1 week, 1month, and 6 months JOA score (21.8±3.4, 23.6±2.4, 24.2±2.4 vs 19.9±3.7, 21.6±2.8, 22.4±2.1)and VAS (2.2±1.0, 2.0±1.1, 0.4±0.1 vs 3.1±1.2, 2.6±1.3, 0.5±0.1) were better in tubular paraspinal approach group than semi-laminar approach group (P<0.05). While at the last follow up, the JOA score and VAS were similar in the 2 groups (P>0.05) . Conclusions: In non-fusion techniques for treating lumbar stenosis, tubular paraspinal approach demonstrated less blood loss, shorter stay in bed as well as in hospital, and better symptom relief in early postoperative period than traditional semi-laminal approach. While at long term follow up, both approaches achieved satisfactory outcome.

Effects of partial replacement of dietary fish meal by bioprocessed plant protein concentrates on growth performance, hematology, nutrient digestibility and digestive enzyme activities in juvenile Pacific white shrimp, Litopenaeus vannamei

BACKGROUND

Bioprocessing of plant feedstuff can be a novel approach for reducing the overwhelming dependence on fish meal in aquaculture. The objective of this study was to evaluate the performance of Pacific white shrimp Litopenaeus vannamei fed solid-state fermented protein concentrates in order to replace fish meal in the diet.

RESULTS

In the first trial, a group of 15 shrimp (average 3.88 g) were randomly distributed into aquaria in triplicate according to the experimental diets. Ten isonitrogenous (400 g kg-1 CP) and isolipidic (90 g kg-1 CL) diets were formulated to contain high-protein fish meal (HFM) and low-protein fish meal (LFM), and four types of bioprocessed protein concentrates (BPCs) as a replacement of fish meal (BPC-A, -B, -C and -D) each at 30% and 50% FM replacement levels. BPC-A was a solid-state fermented mixture of soybean and corn gluten meals; BPC-B was pre-treated acid-hydrolyzed BPC-A; BPC-C and BPC-D were BPC-A + 2% shrimp soluble extract (SSE) and BPC-B + 2% SSE, respectively. After 8 weeks, shrimp fed the HFM, BPC-B, BPC-C and BPC-D diets showed significantly higher growth performance at 30% FM replacement than those of shrimp fed the BPC diets at 50% FM replacement. Interestingly, shrimp fed the BPC-D diet could replace up to 50% FM replacement. In the second trial, the results show that apparent digestibility coefficients of feeds and apparent digestibility coefficients of ingredients for crude protein were significantly higher in fish fed the BPC-B, BPC-C and BPC-D diets.

CONCLUSIONS

The results demonstrated successful partial replacement of high-protein fish meal using high-quality fermented protein concentrates from plant sources. © 2019 Society of Chemical Industry.

Effects of Bacillus subtilis WB60 and Lactococcus lactis on Growth, Immune Responses, Histology and Gene Expression in Nile tilapia, Oreochromis niloticus

An eight-week feeding trial was conducted to evaluate the effects of a basal control diet (CON), Bacillus subtilis at 107 (BS7) and at 108 CFU/g diet (BS8), Lactococcus lactis at 107 CFU/g (LL7) and at 108 CFU/g diet (LL8), and oxytetracycline (OTC) at 4 g/kg diet on Nile tilapia. Fish with initial body weight of 2.83 ± 0.05 g (mean ± SD) were fed two times a day. Weight gain, specific growth rate, feed efficiency, protein efficiency ratio and lysozyme activity of fish fed BS8, LL8 and LL7 diets were significantly higher than those of fish fed CON diet (p < 0.05). Superoxide dismutase and myeloperoxidase activity of fish fed BS8, LL8, BS7, LL7 and OTC diets were significantly higher than those of fish fed CON diet. Intestinal villi length and muscular layer thickness of fish fed BS8, LL8 and LL7 diets were significantly higher than those of fish fed CON and OTC diets. Also, heat shock protein 70 (HSP70), interleukin (IL-1β), interferon-gamma (IFN-γ) and tumour necrosis factor (TNF-α) gene expression of fish fed BS8 and LL8 diets were significantly higher than those of fish fed CON diet. After 13 days of challenge test, cumulative survival rate of fish fed BS8 and LL8 diets were significantly higher than those of fish fed CON, BS7 and OTC diets. Based on these results, B. subtilis and L. lactis at 108 (CFU/g) could replace antibiotics, and have beneficial effects on growth, immunity, histology, gene expression, and disease resistance in Nile tilapia.

Tuna byproducts as a fish-meal in tilapia aquaculture

Potentiality of the use of tuna byproducts as a fish-meal replacement on Nile tilapia (Oreochromis niloticus) was examined for 84 weeks by tracking the concentrations of cadmium and mercury in the internal organs, muscles and fish whole body through generation including their immature eggs and their larvae. The results confirmed that the tuna byproducts can be used as a fish-meal substitute in tilapia aquaculture, because their acceptable ranges for cadmium and mercury consequently did not exceed the food safety values (both < 0.5 mg kg^-1), despite their proportional increases in the fish body. The use of tuna byproducts as a protein source is expected to reduce the cost of feed with other fishmeal substitutes in tilapia aquaculture. However, fish (flounder) indiscriminately consuming tuna byproduct feed were prohibited and recalls of sales were issued by the government (July 2018, Republic of Korea), as the threshold for mercury in the fish bodies had been exceeded (0.6-0.8 mg kg^-1). Further study of the use of tuna byproducts as fishmeal replacements for other species in aquaculture is needed, as concentration ratios can vary depending on the species.

Heat-killed Bacillus sp. SJ-10 probiotic acts as a growth and humoral innate immunity response enhancer in olive flounder (Paralichthys olivaceus)

Investigations were carried out to evaluate and quantify the effects of dietary supplementation with heat-killed (HK) Bacillus sp. SJ-10 (BSJ-10) probiotic (1 × 10⁸ CFU g^-1) on the growth and immunity of olive flounder (Paralichthys olivaceus). Flounder (averagely 9.64 g) were divided into two groups, and fed control and HK BSJ-10 (HKBSJ-10)-inoculated diets for 8 weeks. Investigations were carried out on growth and feed utilizations, innate immunity, serum biochemical parameters, microvilli length, and pro- and anti-inflammatory cytokine gene (tumor necrosis factor [TNF]-α, interleukin [IL]-1β, IL-6, and IL-10) transcriptions. Compared to control, HKBSJ-10 diet significantly (P < 0.05) enhanced weight gain and protein efficiency ratio, 1.17 and 1.11 folds respectively. Humoral innate immune parameters, lysozyme and superoxide dismutase in treatment group were also elevated by 1.34 and 1.16 folds. Similarly, an increased (P < 0.05) relative expressions of TNF-α, IL-1β, IL-6 were recorded in liver (2.71, 3.38, and 4.12 folds respectively), and gill (2.08, 1.98, and 1.81 folds respectively) than that of controls. Moreover, after challenge with Streptococcus iniae (1 × 10⁸ CFU mL^-1), the HKBSJ-10-fed group exhibited significantly higher protection (P < 0.05) against streptococcosis compared to controls, validating the observed changes in immune parameters and induction on the cytokine-encoding genes. Therefore, HKBSJ-10 increases growth, modulates innate immune parameters, and protects olive flounders against streptococcosis.

Synergistic effects of dietary supplementation of Bacillus subtilis WB60 and mannanoligosaccharide (MOS) on growth performance, immunity and disease resistance in Japanese eel, Anguilla japonica

This study evaluated the synergistic effects of dietary Bacillus subtilis WB60 and mannanoligosaccharide (MOS) in juvenile Japanese eel, Anguilla japonica. Seven treatment diets were formulated to contain three different levels of B. subtilis (0.0, 0.5, and 1.0 × 10⁷ CFU/g diet denoted as BS₀, BS_0.5, and BS₁, respectively) with two MOS levels (0 and 5 g/kg diet denoted as M₀ and M₅, respectively), and one diet with oxytetracycline (OTC) at 5 g/kg diet. Each diet (BS₀M₀ (CON), BS₀M₅, BS_0.5M_0, BS_0.5M_5, BS₁M_0, BS₁M₅, and OTC) was fed to triplicate groups of 20 fish averaging 9.00 ± 0.11 g (mean ± SD) for eight weeks. Average weight gain, feed efficiency, specific growth rate and protein efficiency ratio of fish fed the BS_0.5M₅ and BS₁M₅ diets were significantly higher than those of fish fed CON, BS_0.5M₀ and OTC diets (P < 0.05). Significant increases in the nonspecific enzymatic activities (e.g., lysozyme and myeloperoxidase) were detected from fish fed the BS_0.5M₅, BS₁M₅, and OTC diets compared to the CON, BS_0.5M₀, and BS₀M₅ diets (P < 0.05). Whereas, immunoglobulin M expressions were recorded significantly higher for fish fed the BS_0.5M₅ and BS₁M₅ diets compared to those of fish fed the other diets (P < 0.05). Also, heat shock protein 70 mRNA levels of fish fed BS_0.5M₅ and BS₁M₅ diets were significantly higher than those of fish fed the CON diet (P < 0.05). Histological observations of the intestinal morphology showed healthier gut for fish fed BS_0.5M₅ and BS₁M₅ diets than those fed CON, BS₀M₅, and OTC diets. Additionally, resistance to bacterial challenge with Vibrio anguillarum was recorded significantly lower for fish fed the CON diet than those fed other diets (P > 0.05). Therefore, the results for growth performance, non-specific immune responses, intestinal morphology, and disease resistance demonstrated that supplementation of B. subtilis at 0.5 × 10⁷ CFU/g diet and mannanoligosaccharide at 5 g/kg diet could have beneficial synergistic effects in Japanese eel. The isolated probiotic from eel and the selected prebiotic could lead to the development of a specific and potential synbiotic in Japanese eel aquaculture.

Synergistic effects of dietary Bacillus sp. SJ-10 plus β-glucooligosaccharides as a synbiotic on growth performance, innate immunity and streptococcosis resistance in olive flounder (Paralichthys olivaceus)

Bacillus sp. SJ-10 (BSJ-10) was identified from traditional Korean fermented fish, the previously recognized prebiotic β-glucooligosaccharides (BGO), and their combination as a synbiotic were prepared to evaluate their individual and synergistic effects in olive flounder (Paralichthys olivaceus). Four diets (one control and three treatments) were formulated containing neither BSJ-10 nor BGO (control), 1 × 10⁸ CFU g ^-1 BSJ-10 (BSJ-10), 0.1% BGO (BGO), and 1 × 10⁸ CFU g^-1 BSJ-10 + 0.1% BGO (BSJ-10 + BGO). Triplicates of 15 fish (weight 10 ± 0.25 g) were randomly allocated to the four diet groups and fed one of the diets for 8 weeks. At the end of the experiment, fish weight gain (WG), specific growth rate (SGR), feed conversion ratio, and protein efficiency ratio in BSJ-10, BGO and BSJ-10 + BGO diets were positively modulated (P < 0.05) compared with control. Specially, WG and SGR were significantly (P < 0.05) higher in BSJ-10 + BGO than that of BSJ-10 and BGO (individual component). The innate immune parameters such as respiratory burst, superoxide dismutase, and lysozyme activity (LSZ) of fish fed BSJ-10 and BSJ-10 + BGO (both groups) were significantly (P < 0.05) higher than the control. Moreover, myeloperoxidase activity (MPO) and LSZ of fish fed BSJ-10 + BGO were significantly higher compared with individual component. Compared with control, intestinal BSJ-10 content, expression of interleukin (IL)-1β in liver and kidney, and tumor necrosis factor (TNF)-α in liver were higher in both groups, but microvillus length was increased (P < 0.05) only in BSJ-10 + BGO. During in vivo challenge experiment with Streptococcus iniae (1 × 10⁸ CFU ml^-1), survival rate of fish was significantly higher in all treatment groups versus control. Moreover, in BSJ-10 + BGO, protection against S. iniae infection and transcription of TNF-α and IL-6 in gill were significantly (P < 0.05) higher than the individual component. Collectively, an improved WG, SGR, MPO, LSZ, transcription of IL-6 and TNF-α, and cumulative survival rate against streptococcosis clearly demonstrates a synergistic outcome of diet BSJ-10 + BGO as synbiotic in olive flounder.

Dynamic filtration with a perforated disk for dewatering of Tetraselmis suecica

Dynamic filtration equipped with a perforated disk was adopted for the first time to dewater and concentrate Tetraselmis suecica, from a typical solution of 2-100 g/L of dense biomass suited for the downstream process. An ultrafiltration membrane, polyethersulfone 150 kDa, was found to best perform in terms of high biomass retention and filtration rate. At 1600 rpm, the highest rotation speed of the disk we tested, plateau permeate flux increased up to 20.2 times higher than those with no rotation; this improvement was attributed to fouling reduction (up to 98%) via distinctively high-shear stress on the membrane surface. Even at a high biomass concentration (100 g/L) where fouling formation was very serious, the heightened shear stress caused high flux to be maintained and fouling resistance to be reduced in an effective way. When trans-membrane pressure was increased in a stepwise manner, flux continuously rose at high rotation speed; at low speed, on the other hand, the limiting flux was observed. The dynamic filtration with the perforated disk, which was an effective high-shear stress generator, was proven to be a promising dewatering means of T. suecica, and especially so for the production of highly concentrated biomass.

Interactive effect of dietary vitamin E and inorganic mercury on growth performance and bioaccumulation of mercury in juvenile olive flounder, Paralichthys olivaceus treated with mercuric chloride

A 6-week feeding trial was carried out to evaluate the effects of dietary vitamin E (dl-α-tocopheryl acetate, TA) on growth and mercury (Hg) accumulation in juvenile olive flounder (Paralichthys olivaceus) treated with mercuric chloride (HgCl₂). Vitamin E and HgCl₂ were added to the semi-purified basal diet. Six semi-purified diets in a 2 × 3 factorial design were formulated to contain 2 levels of Hg (0 or 20 mg HgCl₂/kg diet) and 3 levels of vitamin E (0, 100, or 200 mg TA/kg diet). Experimental fish (n = 360, 9.99 ± 0.15 g) were randomly allocated into 30-L tanks at a density of 20 fish per tank with 3 replicates in each treatment and were fed twice a day. At the end of the feeding trial, dietary Hg depressed the growth performances in terms of weight gain (WG), specific growth rate (SGR), feed efficiency (FE) and protein efficiency ratio (PER) in fish, while fish fed the diets supplemented with vitamin E showed significant growth improvement in both presence and absence of HgCl₂ in the diets (P < 0.05). Survival rate was not affected in fish fed the experimental diets. Whole body compositions of fish such as lipid and moisture contents were influenced by dietary vitamin E supplementation. Total Hg contents of muscle, liver and kidney tissues were significantly reduced in fish fed diets supplemented with vitamin E (P < 0.05), while the two-way ANOVA showed that increasing Hg concentration has resulted in a reduction in vitamin E. Whole body fatty acids of fish like eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) contents were decreased by dietary Hg. However, supplementation of dietary vitamin E improved the α-linolenic acid (ALA) and EPA contents in fish. Our results suggest that dietary supplementation of vitamin E has potential effects on growth improvement and ameliorating inorganic Hg bioaccumulation in juvenile olive flounder.

Comparative evaluation of dietary probiotics Bacillus subtilis WB60 and Lactobacillus plantarum KCTC3928 on the growth performance, immunological parameters, gut morphology and disease resistance in Japanese eel, Anguilla japonica

The current experiment was conducted to evaluate and compare the efficacy of two different probiotics Bacillus subtilis WB60 and Lactobacillus plantarum KCTC3928 in diet of Japanese eel, Anguilla japonica. Seven experimental diets were formulated to contain no probiotics (CON), three graded levels of B. subtilis at 10⁶ (BS₁), 10⁷ (BS₂), 10⁸ (BS₃) and L. plantarum at 10⁶ (LP₁), 10⁷ (LP₂), 10⁸ (LP₃) CFU/g diet. Twenty fish averaging 8.29 ± 0.06 g were distributed in to 21 aquaria and were randomly assigned to one of the experimental diets in triplicate groups. Average weight gain (WG), feed efficiency (FE), and protein efficiency ratio (PER) of fish fed B. subtilis at 10⁷ (BS₂) and 10⁸ (BS₃) CFU/g diet were significantly higher than those of fish fed other experimental diets (P < 0.05). Nonspecific enzymatic activities including lysozyme, superoxide dismutase (SOD), myeloperoxidase (MPO) from fish fed B. subtilis at 10⁷ (BS₂) and 10⁸ (BS₃) CFU/g diet were detected to be significantly higher than that from fish fed CON diet (P < 0.05). Whereas, level of intestine glyceraldehyde-3-phosphate dehydrogenase (GAPDH), heat shock protein 70, 90 (HSP70, 90) and immunoglobulin (IgM) from fish fed B. subtilis at 10⁷ and 10⁸ CFU/g diet were recorded to be significantly higher than those of fish fed other experimental diets (P < 0.05). Parameters for intestinal morphology and histology suggested a healthier gut for the fish fed10⁸ (BS₃) CFU/g diet as compared to other treatment groups. Whereas, results from the disease challenge test with bacteria Vibrio angulillarum showed significantly lower survival rate for fish fed CON diet than those of fish fed other experimental diets. Therefore, these results indicated that oral supplement of B. subtilis at 10⁸ (BS₃) CFU/g diet could be a more effective source of probiotic compared to L. plantarum in Japanese eel.

Comparison of the effects of dietary single and multi-probiotics on growth, non-specific immune responses and disease resistance in starry flounder, Platichthys stellatus

An 8-week feeding trial was conducted to evaluate the effects of dietary probiotics on growth performance and non-specific immune responses in starry flounder, Platichthys stellatus. Fish averaging 46.5 ± 0.65 g (mean ± SD) were fed one of the six experimental diets; one control (Cont), and five other diets were prepared by supplementing single-probiotics 1 (Bacillus subtilis; SP₁, 2 × 10⁹ CFU kg^-1 diet), single-probiotics 2 (Bacillus licheniformis; SP₂, 2 × 10⁹ CFU kg^-1 diet), multi-probiotics 1 (Bacillus subtilis + Bacillus licheniformis; MP₁, 2 × 10⁹ CFU kg^-1 diet), multi-probiotics 2 (commercial probiotics; Bacillus subtills + Bacillus licheniformis + Paenibacillus polymyxa + Aspergillus oryzae + Saccharomyces cerevisiae; MP₂, 2 × 10⁹ CFU kg^-1 diet) and oxytetracycline (OTC) at 5 g OTC kg^-1 diet. At the end of 8 weeks feeding trial, weight gain (WG) and specific growth rate (SGR) of fish fed SP₁, MP₁ and MP₂ diets were significantly higher than those of fish fed control diet (P < 0.05). Superoxide dismutase (SOD) activity of fish fed MP₂ diet was significantly higher than those of fish fed OTC diet (P < 0.05). Nitro blue tetrazolium (NBT) activity and lysozyme activity of fish fed SP₁, MP₁ and MP₂ diets were significantly higher than those of fish fed OTC diet (P < 0.05). However, there was no significant difference among fish fed SP₁, SP₂, MP₁ and MP₂ diets. During the Edwardsiella tarda challenge test, the first mortality occurred on day 2. After the 14 days challenge test, cumulative survival rate of fish fed MP₁ and MP₂ diets were significantly higher than those of fish fed control diet (P < 0.05). However, there was no significant difference among fish fed SP₁, SP₂, MP₁, MP₂ and OTC diets in survival rate at the termination of the challenge test. Although there was little advantage in immunological parameters with fish fed MP diets, single and multi-probiotics were equally effective statistically. These results demonstrated that single or multi-probiotics had equal beneficial effect as an antibiotic replacer in terms of growth performance, non-specific immune responses and disease resistance in starry flounder.

Dietary vitamin C reduced mercury contents in the tissues of juvenile olive flounder (Paralichthys olivaceus) exposed with and without mercury

A 2×3 factorial design was employed to evaluate the effects of dietary vitamin C (l-ascorblyl-2-monophosphate, C2MP) levels on growth and tissue mercury (Hg) accumulations in juvenile olive flounder, Paralichthys olivaceus. Six experimental diets with two levels of mercuric chloride (0 or 20mg HgCl2/kg diet) and three levels of vitamin C (0, 100, or 200mg C2MP/kg diet) were added to the basal diet. At the end of 6 weeks feeding trial, in presence or absence of dietary Hg, fish body weight gain, specific growth rate, feed efficiency, protein efficiency ratio and whole body lipid content were increased in a dose-dependent manner as dietary vitamin C level increased in the diets. Interestingly, fish fed 100 or 200mg C2MP/kg diets showed significant interactive effects on reducing Hg content in kidney tissue. These results revealed that dietary vitamin C as 100 or 200mg C2MP/kg diet had protective effect against Hg accumulation in juvenile olive flounder.

Evaluation of Optimum Dietary Threonine Requirement by Plasma Free Threonine and Ammonia Concentrations in Surgically Modified Rainbow Trout, Oncorhynchus mykiss

This study was carried out to evaluate the dietary threonine requirement by measuring the plasma free threonine and ammonia concentrations in rainbow trout, Oncorhynchus mykiss after dorsal aorta cannulation. A total of 70 fish (average initial weight 506±8.2 g) were randomly distributed into each of the 14 net cages (5 fish/cage). After 48 hours (h) of feed deprivation, each group was intubated at 1% body weight with one of the seven L-amino acid based diets containing graded levels of threonine (0.42%, 0.72%, 0.92%, 1.12%, 1.32%, 1.52%, or 1.82% of diet, dry matter basis). Blood samples were taken at 0, 5, and 24 h after intubation. Post-prandial plasma free threonine concentrations (PPthr) of fish 5 h after intubation with diets containing 1.32% or more threonine were significantly higher than those of fish intubated with diets containing 1.12% or less threonine (p<0.05). Post-absorptive free threonine concentrations (PAthr) after 24 h of intubation of the fish with diets containing 0.92% or more threonine were significantly higher than those of fish intubated with diets containing 0.72% or less threonine. Post-prandial plasma ammonia concentrations (PPA, 5 h after intubation) were not significantly different among fish intubated with diets containing 1.12% or less threonine, except the PPA of fish intubated with diet containing 0.42% threonine. Broken-line model analyses of PPthr, PAthr, and PPA indicated that the dietary threonine requirement of rainbow trout should be between 0.95% (2.71) and 1.07% (3.06) of diet (% of dietary protein on a dry matter basis).

Evaluation of the Efficacy of Fermented By-product of Mushroom, Pleurotus ostreatus, as a Fish Meal Replacer in Juvenile Amur Catfish, Silurus asotus: Effects on Growth, Serological Characteristics and Immune Responses

The present experiment was conducted to evaluate the efficacy of dietary fermented by-product of mushroom, Pleurotus ostreatus, (FBPM) as a fish meal (FM) replacer in juvenile Amur catfish, Silurus asotus. A total number of 225 fish averaging 5.7±0.1 g (mean±standard deviation) were fed one of the five experimental diets formulated to replace FM with FBPM at 0%, 5%, 10%, 20%, and 30% (FBPM₀, FBPM₅, FBPM₁₀, FBPM₂₀, and FBPM₃₀, respectively). At the end of eight weeks of the experiment, average weight gain (WG) of fish fed FBPM₀ or FBPM₅ were significantly higher than those of fish fed FBPM₂₀ or FBPM₃₀ diets (p<0.05). However, there was no significant differences in WG among the fish fed FBPM₀, FBPM₅ or FBPM₁₀, and between fish fed FBPM₁₀ or FBPM₂₀, and also between those fed FBPM₂₀ or FBPM₃₀ diets. Lysozyme activity of fish fed FBPM₀ or FBPM₅ were significantly higher than those of fish fed FBPM₁₀, FBPM₂₀ or FBPM₃₀ diets (p<0.05). The chemiluminescent response of fish fed FBPM₅ was significantly higher than those of fish fed FBPM₀, FBPM₂₀ or FBPM₃₀ diets (p<0.05). Broken line regression analysis of WG suggested that the maximal dietary inclusion level for FBPM as a FM replacer could be 6.3% without any adverse effects on whole body composition and on serological characteristics. Therefore, these results may indicate that the maximal dietary inclusion level of FBPM as a FM replacer could be 6.3% in juvenile Amur catfish.

The Optimum Feeding Frequency in Growing Korean Rockfish (Sebastes schlegeli) Rearing at the Temperature of 15°C and 19°C

Two feeding trials were conducted to determine the optimum feeding frequency in growing Korean rockfish, (Sebastes schlegeli) reared at the temperatures of 15°C and 19°C. Fish averaging 92.2±0.7 g (mean±standard deviation [SD]) at 15.0±0.5°C and 100.2±0.4 g (mean±SD) at 19.0±0.5°C water temperature were randomly distributed into each of 15 indoor tanks containing 250-L sea water from a semi-recirculation system. A total of five feeding frequency groups were set up in three replicates as follows: one meal in a day at 08:00 hour, two meals a day at 08:00 and 17:00 hours, three meals a day at 08:00, 14:00, and 20:00 hours, four meals a day at 08:00, 12:00, 16:00, and 20:00 hours, and one meal every 2 days at 08:00 hour. Fish were fed at the rate of 1.2% body weight (BW)/d at 15°C and 1.5% BW/d at 19°C. At the end of 8 wks of feeding trial weight gain and specific growth rate were significantly higher at the fish fed groups of one meal a day and two meals a day at 15°C and fish fed groups of 1 meal every 2 days at 19°C were significantly lower than those of all other fish fed groups. Glutamic oxaloacetic transaminase and glutamic pyruvic transaminase of fish fed group at 1 meal every 2 days was significantly higher than those of all other fish fed groups in both experiments. Weight gain, specific growth rate and condition factor were gradually decreased as the feeding frequency increased. The results indicate that growing Korean rockfish 92 and 100 g perform better at 15°C than 19°C water temperature. As we expected, current results have indicated that a feeding frequency of 1 meal a day is optimal for the improvement of weight gain in growing Korean rockfish grown from 92 g to 133 g at 15°C and 100 g to 132 g at 19°C water temperature.

Re-evaluation of the Optimum Dietary Vitamin C Requirement in Juvenile Eel, Anguilla japonica by Using L-ascorbyl-2-monophosphate

This study was conducted to re-evaluate the dietary vitamin C requirement in juvenile eel, Anguilla japonica by using L-ascorbyl-2-monophosphate (AMP) as the vitamin C source. Five semi-purified experimental diets were formulated to contain 0 (AMP₀), 30 (AMP₂₄), 60 (AMP₅₂), 120 (AMP₁₀₈) and 1,200 (AMP₁₁₃₇) mg AMP kg-1 diet on a dry matter basis. Casein and defatted fish meal were used as the main protein sources in the semi-purified experimental diets. After a 4-week conditioning period, fish initially averaging 15±0.3 g (mean±SD) were randomly distributed to each aquarium as triplicate groups of 20 fish each. One of five experimental diets was fed on a DM basis to fish in three randomly selected aquaria, at a rate of 3% of total body weight, twice a day. At the end of the feeding trial, weight gain (WG) and specific growth rate (SGR) for fish fed AMP₅₂ and AMP₁₀₈ were significantly higher than those recorded for fish fed the control diet (p<0.05). Similarly, feed efficiency (FE) and protein efficiency ratio (PER) for fish fed AMP₅₂ were significantly higher than those for fish fed the control diet (p<0.05). Broken-line regression analysis on the basis of WG, SGR, FE and PER showed dietary vitamin C requirements of juvenile eel to be 41.1, 41.2, 43.9 and 43.1 (mg kg⁻¹ diet), respectively. These results indicated that the dietary vitamin C requirement could range from 41.1 to 43.9 mg kg⁻¹ diet in juvenile eel when L-ascorbyl-2-monophosphate was used as the dietary source of vitamin C.

Effects of Feeding Rate and Water Temperature on Growth and Body Composition of Juvenile Korean Rockfish, Sebastes schlegeli (Hilgendorf 1880)

Three feeding trials were conducted to evaluate the effects of feeding rate and water temperature on growth and body composition of juvenile Korean rockfish, Sebastes schlegeli rearing at 3 different water temperatures. A total of 270 fish (each experiment) individual body weight (BW) averaging 16±0.3 g (mean±SD) were fed a commercial diet for 4 wk at 16°C, 20°C, and 24°C. At each temperature, triplicate tanks were assigned to one of 6 feeding rates: 1.5%, 2.5%, 2.8%, 3.1%, 3.4%, and satiation (3.7% BW/d) at 16°C, 1.9%, 2.9%, 3.2%, 3.5%, 3.8% and satiation (4.1% BW/d) at 20°C and 1.7%, 2.7%, 3.0%, 3.3%, 3.6%, and satiation (3.9% BW/d) at 24°C water temperature. Weight gains of fish in satiation and 3.4% groups at 16°C, in satiation and 3.8% groups at 20°C and in satiation and 3.6% groups at 24°C were significantly higher than those of fish in the other treatments (p<0.05). A broken line regression analysis of weight gain indicated that optimum feeding rates of juvenile Korean rockfish were 3.41% at 16°C, 3.75% at 20°C and 3.34% at 24°C water temperature. Results of the present study indicate that the optimum feeding rate could be >3.1% but <3.41% at 16°C, >3.5% but <3.75% at 20°C and >3.0% but <3.34% at 24°C. As we expected results suggest that fish performed better at 20°C than 16°C or 24°C water temperature and the optimum feeding rate could be 3.1% BW/d to 3.7% BW/d in 16 g of juvenile Korean rockfish.

Effects of Different Dietary Cadmium Levels on Growth and Tissue Cadmium Content in Juvenile Parrotfish, Oplegnathus fasciatus

This feeding trial was carried out to evaluate the effects of different dietary cadmium levels on growth and tissue cadmium content in juvenile parrotfish, Oplegnathus fasciatus, using cadmium chloride (CdCl₂) as the cadmium source. Fifteen fish averaging 5.5±0.06 g (mean±SD) were randomly distributed into each of twenty one rectangular fiber tanks of 30 L capacity. Each tank was then randomly assigned to one of three replicates of seven diets containing 0.30 (C₀), 21.0 (C₂₁), 40.7 (C₄₁), 83.5 (C₈₃), 162 (C₁₆₂), 1,387 (C_1,387) and 2,743 (C_2,743) mg cadmium/kg diet. At the end of sixteen weeks of feeding trial, weight gain (WG), specific growth rate (SGR) and feed efficiency (FE) of fish fed C₂₁ were significantly higher than those of fish fed C₈₃, C₁₆₂, C_1,387 and C_2,743 (p<0.05). Weight gain, SGR and FE of fish fed C₀, C₂₁ and C₄₁ were significantly higher than those of fish fed C₁₆₂, C_1,387 and C_2,743. Protein efficiency ratio of fish fed C₀, C₂₁ and C₄₁ were significantly higher than those of fish fed C_1,387 and C_2,743. Average survival of fish fed C₀, C₂₁, C₄₁ and C₁₆₂ were significantly higher than that of fish fed C_2,743. Tissue cadmium concentrations increased with cadmium content of diets. Cadmium accumulated the most in liver, followed by gill and then muscle. Muscle, gill and liver cadmium concentrations of fish fed C₀, C₂₁, C₄₁ and C₈₃ were significantly lower than those of fish fed C₁₆₂, C_1,387 and C_2,743. Based on the ANOVA results of growth performance and tissue cadmium concentrations the safe dietary cadmium level could be lower than 40.7 mg Cd/kg diet while the toxic level could be higher than 162 mg Cd/kg diet.

Effects of dietary methylmercury on growth performance and tissue burden in juvenile green (Acipenser medirostris) and white sturgeon (A. transmontanus)

Triplicate groups of juvenile green and white sturgeon (30 ± 2 g) were exposed to one of the four nominal concentrations of dietary methylmercury (MeHg, 0 (control), 25, 50, and 100mg MeHg/kg diet) for 8 weeks to determine and compare the effects on growth performance and mercury (Hg) tissue burden in the two sturgeon species. Mortality, growth performance as measured by percent body weight increase per day, hepatosomatic index, proximate composition of whole body, and Hg burden in the whole body, gill, heart, liver, kidney, and white muscle were determined to assess the adverse growth effects and bioaccumulation of dietary MeHg in sturgeon. Significantly higher mortality and lower growth rate (p<0.05) were noted in green and white sturgeon fed the MeHg diets compared to the controls. Green sturgeon fed the MeHg diets exhibited earlier and more severe adverse effects compared to white sturgeon. Mercury accumulated in all tissues in a dose-dependent manner regardless of species, and the highest Hg concentrations were found in the kidneys of both species. Dietary MeHg had no significant effect (p>0.05) on the whole body proximate compositions of either sturgeon species. In conclusion, green sturgeon was more susceptible to dietary MeHg toxicity than white sturgeon in our 8-week growth experiment based on the higher mortality and lower growth rate and body energy contents.

Competition between selenomethionine and methionine absorption in the intestinal tract of green sturgeon (Acipenser medirostris)

l-Selenomethionine (SeMet) is a dominant form of selenium (Se) found in organisms at all levels of aquatic food chains and a key source of Se bioaccumulation and ecotoxicity. In mammals, intestinal absorption of SeMet is at least partly via the Na(+)-dependent neutral amino acid transporter. The mechanism of SeMet absorption and competitive effects of other dietary components on SeMet absorption in fish are unknown. Thus the in vitro uptake rates of l-methionine (Met) and the competitive effect of SeMet on Met absorption, an indicator that SeMet uses the same nutrient transporter(s) for absorption, in the various regions of the green sturgeon (Acipenser medirostris) intestine were investigated using intact tissues (a modified everted sleeve method). Intestinal tissue was incubated in Ringer's solution containing 0-10mmolL(-1) Met or SeMet (n=5 for each substrate's concentration and intestinal region), respectively, as well as constant tracer levels of isotope-labeled Met. The data indicate that SeMet uptake was mediated by the same transporter(s) as Met and that the absorption kinetics were similar for both substrates. When there were differences in absorption they appeared to be mostly due to higher permeability (passive uptake) of the tissue for Met than for SeMet, particularly in the pyloric caeca (PC) and distal intestine (DI). Maximum rates of absorption, on the other hand, tended to be higher for SeMet than Met in the mid intestine and DI, whereas differences in affinity for the transporters varied between these tissues but were very similar in the PC. These differences may be due to differences in regional intestinal characteristics such as amount of mucus secreted and degree of tissue contraction, and/or substrate differences regarding solubility in and movement through the mucus, influence on tissue contraction, permeability through membranes or between cells, intracellular metabolism, as well as basolateral transport. Interestingly, an increasing proximal-to-distal gradient for rates of methionine and putative SeMet absorption was observed in green sturgeon which differs from the declining gradient usually observed for substrate absorption in other fish species and mammals.

Species-specific PCR detection of the fish pathogen, Vibrio anguillarum, using the amiB gene, which encodes N-acetylmuramoyl-L-alanine amidase

Vibrio anguillarum is the causative agent of the fish disease vibriosis and is the most intensely studied species of Vibrio. In the present study, specific primers and a PCR assay were designed to detect V. anguillarum. The primers were designed to amplify a 429-bp internal region of the V. anguillarum amiB gene, which encodes the peptidoglycan hydrolase N-acetylmuramoyl-L-alanine amidase. PCR specificity was demonstrated by successful amplification of DNA from V. anguillarum and by the absence of a PCR product from 25 other Vibrio strains and various enteric bacteria. The PCR produced a 429-bp amplified fragment from as little as 1 pg of V. anguillarum DNA. The limit of detection for this PCR technique was c. 20 bacterial colonies in 25 mg of infected flounder tissue. These results suggest that this PCR system is a sensitive and species-specific detection method, and is possible to use as a diagnostic tool to detect V. anguillarum.

A mixture of cottonseed meal, soybean meal and animal byproduct mixture as a fish meal substitute: growth and tissue gossypol enantiomer in juvenile rainbow trout (Oncorhynchus mykiss)

Diets incorporating three different sources of extracted cottonseed meal (CM), soybean meal and an animal protein mixture were evaluated for juvenile rainbow trout. Fish averaging 0.96 g were divided into groups of 30; 3 groups per treatment, and each group was fed one of four diets for a 16-week period. Fish meal (FM) was replaced on a 25% protein basis by each of three different sources of CM from California (CA), Tennessee (TN), and Arkansas (AR), U.S.A. In the three CM-containing diets another 25% soybean meal protein and 50% animal protein mixture were also incorporated to completely replace FM protein. The results of growth rate and feed utilization showed that FM could be entirely replaced by a mixture of plant proteins (CM and soybean meal) and animal by-product proteins. Hematocrit levels were significantly lower in the group fed CM-containing diets than in the control. The findings suggest that CM can be used as a good protein source by the incorporation of at least 15% in diets (25% of fish meal protein replacement), and that the nutritive values of CM in juvenile trout can be different due to their different origin. Significantly higher concentrations of total gossypol were found in faeces of CM-TN (5.8 +/- 0.4 micromol/g) and CM-AR (5.6 +/- 0.6) groups than in that of CM-CA (3.7 +/- 0.4) group. It was documented that gossypol enantiomers, present in an equal proportion in diets, selectively accumulated in liver and bile, whereas equal proportions of (+)- and (-)-enantiomers were found in whole-body and faeces. Depending on CM source, fish can absorb approximately 35-50% of dietary gossypol, and the majority of the absorbed gossypol seemed to be excreted.

Molecular basis of albinism in the rhesus monkey

Sequence analysis of the tyrosinase (TYR) coding region from one albino rhesus monkey (Macaca mulatta) family revealed that the two monkeys with phenotype similar to human TYR-negative oculocutaneous albinism (OCA) were homozygous for a missense mutation (S184TER) in exon 1 at codon 184. The offspring of one of the albino monkey ("Kangkang") are all heterozygous for the S184TER mutation, but the S184TER mutation was not observed in 93 control individuals. We conclude that the point mutation is responsible and sufficient to generate the albino rhesus monkey phenotype. The rough age of the S184TER nonsense mutation may be about 0.8 million years using a rate of 0.16% per million years.

Vitamin B-6 deficiency and level of dietary protein affect hepatic tyrosine aminotransferase activity in cats

Total activity [pyridoxal 5'-phosphate (PLP) added in the assay] of hepatic tyrosine aminotransferase (TAT) measured in cats at 0300, 0900, 1500 and 2100h was 10.3 +/-1.1, 14.0 +/- 0.7, 9.8 +/- 1.3 and 11.0 +/- 0.7 nkat/g liver, indicating little diurnal variation. Activity after 18 h of food deprivation was 10.0 +/- 0.3 nkat/g liver, also not different from cats that were eating ad libitum. These findings support the idea that cats have only limited changes in the activity of hepatic TAT compared with rats. Total TAT activity was measured in cats fed high protein (550 g/kg) and low protein (180 g/kg) diets for 4 wk. Cats fed a high protein diet had activities significantly higher (about twice) than cats fed the low protein diet. Hepatic TAT activity of vitamin B-6-deficient cats (diet without pyridoxine for 9 wk) was compared with cats given the same diet with 8 mg pyridoxine/kg. Total hepatic TAT activity in deficient cats was significantly (P < 0.05) lower per gram soluble or total protein (but not per gram liver) than control cats; holoenzyme activity and percentage of active enzyme in deficient cats were also significantly lower by 75 and 64%, respectively. The apparent Km of TAT from cats for tyrosine (2.1 mmol/L) was similar to that for rats (1.9 mmol/L), but higher for PLP in cats (0.16 micromol/L) than rats (0.034 micromol/L). Part of the reason for the higher plasma tyrosine in vitamin B-6-deficient cats than rats is the higher Km of TAT for PLP in cats than rats.

Brainstem auditory evoked potential interwave intervals are prolonged in vitamin B-6-deficient cats

Vitamin B-6 deficiency has been reported to produce behavioral, neurophysiological and neuropathological abnormalities in a variety of species. In this investigation we used brainstem auditory evoked potentials (BAEP) to determine if vitamin B-6 deficiency in cats affected peripheral and brainstem auditory pathways. Brainstem auditory evoked potentials were recorded from growing cats as they developed vitamin B-6 deficiency, which was confirmed using clinical, hematological and urinary criteria. The BAEP interwave intervals measured from early (wave 1 or 1N) to late waves (5N) or from middle (wave 3) to late waves increased significantly, whereas interwave intervals from early to middle waves did not differ significantly. These results indicate that vitamin B-6 deficiency affects one or more structures of the brainstem that generate the later parts of the BAEP. The finding of prolonged interwave intervals in vitamin B-6-deficient animals is consistent with slowed axonal conduction velocity secondary to defective myelination. Recording BAEP provided a noninvasive means of detecting effects of vitamin B-6 deficiency on specific parts of the central nervous system.