Kyoung-Duck Kim

Effect of dietary essential fatty acids on growth, body composition and blood chemistry of juvenile starry flounder (Platichthys stellatus)

Abstract A 10-week feeding experiment was conducted to investigate the effects of dietary lipid source and n-3 highly unsaturated fatty acids (n-3 HUFA) level on growth, body composition and blood chemistry of juvenile starry flounder. Three replicate groups of fish (average weight 1.9 g) were fed diets containing different n-3 HUFA levels ranging from 0.0% to 2.7% adjusted by either lauric acid as sole lipid source or different proportions of corn oil, linseed oil and squid liver oil at 10% of total lipid. Survival was not affected by dietary lipid source or n-3 HUFA level. Weight gain, feed efficiency and protein efficiency ratio of fish fed the diets containing squid liver oil were significantly higher than those fed the diets containing lauric acid, corn oil or linseed oil as the sole lipid source. However, there were no significant differences in weight gain, feed efficiency and protein efficiency ratio among fish fed the diets containing different n-3 HUFA levels ranging from 0.6% to 2.7%. Dietary n-3 HUFA requirement when using a broken line model was estimated at 0.9% for weight gain of fish. Crude lipid content of fish fed the diet containing lauric acid was significantly lower than that of other groups. Fatty acid compositions of neutral and polar lipid of fish were directly reflected by dietary fatty acid composition. The highest 14:0, 18:2n-6, 18:3n-3 and n-3 HUFA contents were observed in fish fed the diets containing lauric acid, corn oil, linseed oil and squid liver oil, respectively. The contents of n-3 HUFA in fish linearly increased with increasing dietary squid liver oil. Plasma cholesterol concentration and aspartate aminotransferase activity were affected by dietary lipid sources. These results indicate that dietary n-3 HUFA are essential and a value of at least 0.9% of n-3 HUFA in the diet could be recommended for optimum growth and efficient feed utilization of juvenile starry flounder.

Utilization of glucose, maltose, dextrin and cellulose by juvenile flounder (Paralichthys olivaceus)

A study was conducted to determine the ability of juvenile flounder to utilize different sources of carbohydrate in their diets. Triplicate groups of fish (average weight, 4 g) were hand-fed visual satiety one of seven diets containing 15% cellulose, 15% glucose, 15% maltose, and 5–25% dextrin for 45 days in flush-out aquarium system. Weight gain, feed efficiency ratio, protein efficiency ratio (PER), energy retention efficiency, hepatosomatic index (HSI), and liver glycogen were measured. Fish fed the diet containing 15% cellulose had the lowest weight gain (P<0.05) among all groups. Weight gain of fish fed the diets containing 15% maltose and 15–25% dextrin was higher than that of fish fed the diets containing 15% cellulose and 5% dextrin. The feed efficiency ratio and PER of fish fed the diets containing 15–25% dextrin were significantly higher (P<0.05) than those of the other groups. Growth and feed utilization increased with an increase in the dextrin level of the diet. Lipid content of the whole body and liver decreased with an increase in dietary dextrin level. Liver glycogen and HSI of fish fed the 15% glucose and 15% maltose diets were higher (P<0.05) than those of fish fed the other carbohydrates, however these values were not affected by an increase in dextrin intake. Flounder (average weight, 15 g) were fasted for 48 h for a glucose tolerance test and blood was collected after feeding at 0, 1, 3, 5, 8, 11, 16, 24 and 48 h. Plasma glucose concentrations of fish fed the diets containing 15% glucose and 15% maltose peaked at 5–8 h (200 mg/100 ml) and 5 h (148 mg/100 ml), respectively, then decreased at 24 and 16 h. Fish fed the diets containing 5–25% dextrin showed a lower glucose level (87–97 mg/100 ml) than fish fed the other diets and it peaked between 3 and 5 h. Flounder utilized dextrin more efficiently than glucose, and dextrin was a better source of energy than lipid. The best growth and feed utilization were achieved with the diet containing 25% dextrin and 6% lipid.

Requirement of dietary n-3 highly unsaturated fatty acids for juvenile flounder (Paralichthys olivaceus)

Abstract The effect of dietary n-3 highly unsaturated fatty acids (n-3 HUFA) level on growth and body composition was investigated to determine the n-3 HUFA requirement for juvenile flounder. Eight diets of different n-3 HUFA levels ranging from 0.0% to 2.4% were fed to juvenile flounder for 8 weeks. For varying n-3 HUFA level, mixtures of mainly EPA (0.0–1.1%) and DHA (0.0–0.9%) were used except one diet containing only 1.2% EPA. Weight gain, feed efficiency and protein efficiency ratio increased significantly with increasing dietary n-3 HUFA level up to 0.8%; however, those values gradually decreased after n-3 HUFA level became higher than 1.6%. The result of second-order polynomial regression showed that the maximum weight gain could be attained at 1.0% n-3 HUFA level. The weight gain was significantly lower for the diet containing 1.2% EPA than for the 1.2% n-3 HUFA diet containing both EPA and DHA. The contents of DHA and n-3 HUFA in whole body polar lipid increased with dietary n-3 HUFA level. Monoenoic fatty acids content and 18:1n/n-3 HUFA ratio decreased with increasing dietary n-3 HUFA level. The results suggest that the requirement of dietary n-3 HUFA for juvenile flounder is about 0.8–1.0%; however, excessive n-3 HUFA supplement may impair the growth of juvenile flounder.

Influences of feeding frequency of extruded pellet and moist pellet on growth and body composition of juvenile Japanese flounder Paralichthys olivaceus in suboptimal water temperatures

This study was carried out to investigate the influences of feeding frequency of extruded pellet and moist pellet on growth and body composition of juvenile flounder (initial mean weight 6.3 g) in sub optimal water temperatures. A 2 (diets: extruded pellet and moist pellet)×2 (feeding frequencies: two and three times daily)×2 (water temperatures: 12 and 17°C) factorial design with three replications was used. After 60 days of feeding, the feeding frequency did not significantly affect growth performance of fish. Weight gain, daily feed intake, feed efficiency and protein efficiency ratio were significantly (P<0.05) higher for fish reared at the higher water temperature. At the same water temperature, weight gain, feed efficiency, and protein efficiency ratio were significantly (P<0.05) higher for fish fed the extruded pellet than moist pellet. The results of this study indicate that feeding frequency of two times daily is sufficient for optimal growth of juvenile flounder when reared in suboptimal water temperatures, and an increase in water temperature from 12 to 17°C improved growth and feed efficiency.

Effects of dietary supplementation of citrus by-products fermented with a probiotic microbe on growth performance, innate immunity and disease resistance against Edwardsiella tarda in juvenile olive flounder, Paralichthys olivaceus (Temminck & Schlegel).

Two consecutive studies were conducted to evaluate the dietary supplementation of citrus by-products (CB) fermented with probiotic bacteria on growth performance, feed utilization, innate immune responses and disease resistance of juvenile olive flounder. In Experiment I, five diets were formulated to contain 0% (control) or 3% four different CB fermented with Bacillus subtilis (BS), Enterococcus faecium (EF), Lactobacillus rhamnosus (LR) and L. plantarum (LP) (designated as CON, CBF-BS, CBF-EF, CBF-LR and CBF-LP, respectively). During 10 weeks of a feeding trial, growth performance and feed efficiency were not significantly different among all the fish groups. However, fish fed CBF containing diets had significantly higher survivals than the CON group. Disease resistance of fish against Edwardsiella tarda was increased by the fermentation of CB. In Experiment II, we chose the BS as a promising probiotic and formulated five diets to contain 0%, 2%, 4%, 6% and 8% CBF-BS. Growth performance was not significantly affected by the CBF-BS supplementation during 6 weeks of a feeding trial. Innate immunity of fish was significantly enhanced by CBF-BS supplementation. Myeloperoxidase and lysozyme activities were increased in a dose-dependent manner by dietary CBF-BS inclusions. In a consecutive challenge test against E. tarda, an increased disease resistance was found by CBF-BS supplementation. These studies indicate that the fermentation process of CB with probiotic has beneficial effects on innate immunity and thereby increases disease resistance of olive flounder against E. tarda. Bacillus subtilis can be used as a promising probiotic microbe for by-product fermentation in fish feeds.

Effects of Dietary Protein and Lipid Levels on Growth and Body Composition of Juvenile Far Eastern Catfish Silurus asotus.

A 3×2 factorial experiment was conducted to determine the effects of dietary protein and lipid levels on the growth and body composition of juvenile far eastern catfish. Six diets were formulated to contain three levels of protein (20%, 30% and 40%) and two levels of lipid (9% and 17%). Triplicate groups of fish (initial body weight of 7.6 g) were hand-fed to apparent satiation for 66 days. Final mean weight was improved with increasing dietary protein and lipid levels, and the highest final mean weight was observed in fish fed the 40/17 (% protein/% lipid) diet. No significant difference was observed in final mean weight for fish fed between 30/17 diet and 40/9 diet. Feed efficiency of fish fed the diets containing over 30% protein levels with 9% and 17% lipid levels were significantly higher than those of fish fed the 20% protein levels. Feed efficiency of fish fed the 30/17 diet was not significantly different from that of fish fed the 40/9 diet or 40/17 diet. Feed efficiency and protein efficiency ratio of fish fed the 20% protein diets with 17% lipid level were significantly higher than those of fish fed 9% lipid diet. Daily feed intake of fish tended to decrease with increasing dietary protein and lipid levels. Moisture content of whole body in fish fed the 9% lipid diets was significantly higher than that of fish fed the 17% lipid diets at the same protein level, but the opposite trends were found for crude lipid content. Significant effects of dietary lipid were observed for most fatty acids, according to their relative values in the diets. The results of this study suggest that the protein requirement for maximum growth of juvenile far eastern catfish may be higher than 40%, and an increase of dietary lipid level from 9% to 17% can improve growth and feed utilization.

Comparison on proximate composition and nutritional profile of red and black sea cucumbers (Apostichopus japonicus) from Ulleungdo(Island) and Dokdo(Island), Korea

The proximate composition, fatty acid, and amino acid profile of the body wall and viscera of each red and black sea cucumber (Apostichopus japonicus) from Ulleungdo(Island) and Dokdo(Island) in Korea were compared. Moisture, ash, crude protein, and crude lipid contents ranged between 80.26–91.49, 2.57–6.85, 1.13–3.99, and 0.14–2.12%, respectively. The fatty acid values varied depending on the species and the regions of collection. The anteiso C17:0, C16:1Δ9, C17:1Δ7, C18:1Δ11, and C16:2Δ7 were only observed in the body wall. Among the tested fatty acids, the C18:1Δ11 was specific in red sea cucumber, and C20:4Δ6 (17.7%) and C20:5Δ3 (17.6%) were the predominant polyunsaturated fatty acids (PUFA) in all samples. The contents of the C18:0 dimethyl acetal (C18:0 DMA), C16:1Δ7, C16:1Δ5, and C18:1Δ5 were compared in details. Total amino acids (TAA) of body wall were 1.3–1.9 times higher than those of viscera. Glutamic acid and aspartic acid constituted the major TAA of sea cucumbers. The ratio of essential amino acids (EAA): nonessential amino acids (NEAA) on TAA ranged from 1.15 to 0.67 of sea cucumbers. Viscera of red sea cucumber from Dokdo(Island) were rich in free amino acids (FAA) and showed a high content in leucine.

Effects of Dietary Lipid Source and Level on Growth Performance, Blood Parameters and Flesh Quality of Sub-adult Olive Flounder (Paralichthys olivaceus)

This study was conducted to investigate the effects of dietary lipid source and level on growth performance, blood parameters, fatty acid composition and flesh quality of sub-adult olive flounder Paralichthys olivaceus. Eight experimental diets were formulated to contain 5% squid liver oil (SLO), 5% linseed oil (LO), 5% soybean oil (SO), a mixture of 1% squid liver oil, 2% linseed oil and 2% soybean oil (MIX), no lipid supplementation with high protein level (LL-HP), 10% squid liver oil (HL-SLO), a mixture of 1% squid liver oil, 4.5% linseed oil and 4.5% soybean oil (HL-VO), and 1% squid liver oil with high starch level (LL-HC), respectively. Two replicate groups of fish (average initial weight of 296 g) were fed the diets for 17 wks. After 5 wks, 11 wks and the end of the feeding trial, five fish from each tank were randomly sampled for analysis of body composition. At the end of the feeding trial, final mean weight of fish fed the LL-HP diet was significantly (p<0.05) higher than that of fish fed the HL-VO diet, but did not differ significantly from those of fish fed the SLO, LO, SO, MIX, HL-SLO and LL-HC diets. Fish fed the LL-HP diet showed significantly higher feed efficiency than fish fed the LO, HL-SLO and HL-VO diets. Feed efficiency of fish fed the LO, SO and MIX diets were similar to those of fish fed the SLO and HL-SLO diets. Fish fed the HL-SLO diet showed significantly higher total cholesterol content in plasma compared with other diets. Fatty acid composition of tissues was reflected by dietary fatty acid composition. The highest linoleic (LA) and linolenic acid (LNA) contents in the dorsal muscle were observed in fish fed the SO and LO diets, respectively, regardless of feeding period. The highest eicosapentaenoic acid (EPA) content in the dorsal muscle was observed in fish fed the LL-HP and LL-HC diets after 11 and 17 weeks of feeding, respectively. Fish fed the SLO and HL-SLO diets showed higher docosahexaenoic acid (DHA) content than that of other treatments after 11 and 17 weeks of feeding, respectively. Dietary inclusion of vegetable oils reduced n-3 HUFA contents in the dorsal muscle and liver of fish. The n-3 HUFA contents in tissues of fish fed the SLO and HL-SLO diets were higher than those of fish fed other diets, except for the LL-HP and LL-HC diets. Hardness, gel strength, chewiness and cohesiveness values of dorsal muscle in fish were significantly affected by dietary lipid source. The results of this study indicate that fish oil in fish meal based diets for sub-adult olive flounder could be replaced by soybean oil and linseed oil without negative effects on growth and feed utilization

Optimum Feeding Rates in Juvenile Olive Flounder Paralichthys olivaceus Fed Practical Expanded Pellet at Low and High Water Temperatures

Two feeding trials were conducted to investigate the optimum feeding rates in juvenile olive founder Paralichthys olivaceus fed practical expanded pellet(EP) containing 58.1% crude protein, 10.7% crude lipid, and 10.8% ash at low and high water temperatures. In the first experiment, triplicate groups of 15 fish with average weight of 7.7 g were fed at one of seven feeding rates(0, 1, 1.5, 2, 2.25, or 2.5% of body weight/day or to satiation) for 4 weeks at low water temperature. In the second experiment, quadruplicate groups of 20 fish with average weight of 5.5 g were fed at one of eight feeding rates(0, 3, 3.5, 4, 4.25, 4.5, or 4.75% of body weight/day or to satiation) for 4 weeks at high water temperature. Based on growth performance, we estimated that the optimum feeding rates for juvenile olive flounder were 1.97-2.51% and 4.82-6.36% of body weight/day at low and high water temperatures, respectively. Key words; Olive flounder, Optimum feeding rates, Low temperature, High temperature, Extruded pellet

Comparison of Extruded and Moist Pellets for Growth Performance, Water Quality and Histology of Olive Flounder Paralichthys olivaceus in Jeju Fish Farm

Abstract Two types of diets, extruded pellet (EP) and raw-fish-based moist pellet (MP) were fed to compare growth, water quality and histology of olive flounder, Paralichthys olivaceus in Jeju fish farm. Two groups of 7000 fish per each tank (initial mean weight 51 g) were fed one of two diets for 7 months. At the end of the feeding trial, significant differences were found in weight gain and feed utilization. Dissolved oxygen (DO) level of the MP tank was decreased from 7.98 to 6.89 after feeding. There were no significant differences in hematocrit, hemoglobin, alanine aminotransferase and aspartate aminotransferase of fish fed the two diets. Whole body protein content of fish fed the EP was significantly higher than that of fish fed the MP. While the feeding rate by month indicated numerically decreased, fish fed the MP had higher feed intake than that of fish fed the EP. Histological examination of hepatopancreas, kidney, and anterior intestine of fish fed the EP did not show any negative effects compared to those of fish fed the MP. This study revealed that EP could substitute for MP in terms of growth performance, blood parameters, water quality and histology of olive flounder.Key words : Olive flounder, Extruded pellet, Moist pellet, Dissolved oxygen, HistologyCorresponding author : 064-754-3423, kjlee@jejunu.ac.kr* 2014 .