Introduction
In the recent year, most of fish produced by aquaculture are primarily composed of flounder Paralichthys olivaceus, rockfish Sebastes schle- geli, red seabream Pagrus major, sea bass Late- olabrax japonicus, mullet Mugil cephalus and so
on in Korea. And amount and value of total fish production from aquaculture was estimated to be 72,000 MT and 639 billion Won, respectively, in 2003 (KNSO, 2003) and flounder occupied over 48% (34,533 MT) and 58% (367 billion Won) in amount and value of total fish production, res- pectively. Therefore, flounder is regarded as one of the most commercially important fish for aquaculture in Korea.
Flounder required relatively low dietary ener-
Effect of Feeding on Different Days of the Week on Growth and Body Composition of Juvenile
Flounder, Paralichthys olivaceus
Sung Hwoan Cho* and In-Seok Park
Division of Ocean Science, College of Ocean Science & Technology, Korea Maritime University, Busan 606-791, Korea
The objective of this study was to determine the effect of feeding on different days of the week on growth and body composition of juvenile f lounder, Paralichthys olivaceus. Twenty-- five juvenile fish (mean body weight±SD : 37.9±0.26 g) were stocked into each of nine circular, flow-- through tanks. During the acclimation period and throughout the feeding trial, f lounder were fed commercial sinking flounder feed to satiation twice daily as designated. Three treatments of fish with three replicates each were prepared for this study. Fish in F6 were fed to satiation twice daily for six days consecutively and starved for one day during the week, as the control group. Fish in the F5 and F4 treatments were fed to satiation twice daily for five and four days and starved for two and three days during the week, respec- tively. Survival of flounder was not significantly affected by different days of feeding. Weight gain of flounder in F6 and F5 treatments was significantly higher (P⁄⁄0.05) than that of fish in F4. However, SGR for flounder was not significantly affected by different days of feeding. Feed consumption of f lounder in F6 and F5 was significantly higher (P⁄⁄0.05) than that of fish in F4. However, feed-- and protein-- efficiency ratios for f lounder were not significantly affected by different days of feeding. Moisture, protein, lipid and ash content of the whole flounder were not significantly affected by different days of feeding. In conclusion, growth of juvenile flounder in F5 was similar to that of fish in F6, but higher than that of fish in F4 during a week--basis. However, no significant difference in feed-- efficiency ratio, protein--efficiency ratio or chemical composition of the whole body of flounder was observed.
Key words : Flounder Paralichthys olivaceus, different days of feeding, weight gain, feed consumption, chemical composition
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*Corresponding author: [email protected]
gy level due to ecological characteristics like less movement because of bottom-dwelling fish (Lee et al., 2000a). Also, several studies on dietary nutrient requirements (Lee et al., 2000b; Kim et al., 2002a; Lee et al., 2002), optimum feeding frequency (Lee et al., 1999; Lee et al., 2002) and feeding strategy (Kim et al., 2002b; Cho and Lee, 2002) for growth of f lounder have been perfor- med. Especially, Kim et al. (2002b) showed that alternate day feeding regime was more recom- mendable than daily feeding regime due to effi- cient feed utilization when juvenile flounder was fed moist pellet three meals daily.
Flounder in fish farming or feeding trials in indoor or outdoor are likely to be fed for 6 days a week due to easy management or convenience.
However, no precise data on comparison of fewer days feeding than 6 days feeding a week on gro- wth and body composition of f lounder is availa- ble yet. Therefore, the objective of this study is to determine effect of different days of feeding in a week-basis on growth and body composition of juvenile flounder.
Materials and Methods
1. Experimental fish and conditions of the feeding trial
Juvenile flounder were purchased from private farm in Namhae (Gyeongsangnam-Do, Korea) and transferred into the laboratory in Korea Maritime University, Busan, Korea. Fish were acclimated to the experimental conditions before the initiation of the experiment. Twenty five juvenile fish (Mean body weight±SD : 37.9±0.26 g) were stocked into nine of 800-L circular flow- through tank (water volume: 250-L) each and water source was the filtered natural seawater.
During the acclimation period and throughout the feeding trial, flounder were fed the commer-
cial sinking flounder feed (Ewha Oil & Fat Indu- stry Co., Ltd, Busan, Korea) containing 55.6%
protein and 8.0% lipid to satiation twice daily (09 : 30, 17 : 00) based on Lee et al. (2000b)’s study.
Water flow rate in each tank was 10 L/min and photoperiod was 13h : 11h (light : dark cycle).
During the feeding trial, mean water tempera- ture ranged from 20.0~25.5� C (Mean±S.D.; 23.0
±1.43� C). Uneaten feeds were siphon-removed after every meal from all tanks and deducted from total feed consumption. At the end of the feeding trial, fish were collectively harvested and totally weighed.
2. Experimental design
Three treatments of fish with 3 replicates were prepared for this study. Fish in F6 was fed to satiation twice daily for 6 days consecutively and starved for a day during a week, as the control group. Fish in the F5 and F4 treatments was fed to satiation twice daily for 5 and 4 days and star- ved for 2 and 3 days during a week, respectively.
The experiment lasted for 6 weeks.
3. Chemical analysis
Ten fish randomly chosen at the beginning and termination of the feeding trial were sacrificed for proximate analysis based on standard me- thod (AOAC, 1990). Protein (Kjeldahl method), lipid (ether-extraction method), ash (muffle fur- nace, 600� C for 3 hours), and moisture contents (dry oven, 105� C for 24 hours) were determined for the sampled fish.
4. Statistical analysis
One-way ANOVA test was applied to test the significance of treatments. And if the signifi- cance was observed, Duncan’s multiple range test (Duncan, 1955) was applied to detect the difference among treatments by using SAS pro-
Table 1. Survival (%), weight gain (g/fish) and specific growth rate (SGR) of juvenile f lounder (Paralichthys olivaceus) with different days of feeding in a week-basis1
Treatments Initial weight (g/fish) Final weight (g/fish) Survival (%) Weight gain (g/fish) SGR2
F6 38.1±0.15 90.7±2.82a 77.3±5.81n.s. 52.8±2.78a 2.7±0.09a
F53 38.0±0.07 90.6±1.30a 96.0±0.00 52.7±1.34a 2.7±0.08a
F4 38.2±0.00 71.2±7.88b 82.0±6.00 32.1±8.48b 1.9±0.40b
1Values (Mean±SE) in the same column sharing a common superscript are not significantly different (P⁄0.05).
2SGR = (Ln final weight of fish-Ln initial weight of fish)/days of feeding trial.
3One tank from F5 treatment was excluded due to outbreak of disease.
n.s.: not significant (P¤0.05).
gram version 6.12 (SAS Institute, Inc., Cary, North Carolina, USA).
Results and Discussion
Survival (%), weight gain (g/fish) and specific growth rate (SGR) of juvenile flounder with dif- ferent days of feeding in a week-basis are given in Table 1. Survival of flounder was not signifi- cantly (P¤0.05) affected by different days of feeding. Survival was not different among fish fed daily for 8 weeks and fish fed daily after experienced starvation for a certain period of time (Wang et al., 2000; Xie et al., 2001).
Weight gain and SGR of flounder in F6 and F5 treatments, which was not significantly differ- ent, was significantly higher (P⁄0.05) than those of fish in F4 in this study. Kim et al., (2002b) demonstrated that weight gain of flounder with alternative day feeding was similar to that of fish with daily feeding throughout the 8-week feeding trial when fish were fed moist pellet three meals daily as designated.
Feed consumption (g/fish), feed efficiency ratio (FER), protein efficiency ratio (PER) of flounder with different days of feeding are presented in Table 2. Feed consumption of f lounder in F6 and F5, which was not significantly different, was significantly higher (P⁄0.05) than that of fish in F4. However, trend into an increase in feed con- sumption of flounder proportion to days of feed- ing was observed. Similar trend that feed con- sumption of fish was affected by duration of feeding was observed in several fish (Wang et al., 2000; Gaylord and Gatlin, 2001; Xie et al., 2001;
Kim et al., 2002b).
However, FER and PER for flounder was not significantly (P¤0.05) affected by different days of feeding in this study. This partially explained compensatory growth of flounder in F4 experi- enced starvation for a certain period of time. Kim et al. (2002b) showed that FER and PER for flounder with alternative day feeding was simi- lar to those for fish with daily feeding. Improv- ement for FER of fish experienced starvation for a certain period of time is commonly observed (Jobling et al., 1994; Qian et al., 2000; Gaylord and Gatlin, 2001; Cho and Lee, 2002). Unlike these studies, however, improved FER was not observed in fish achieving compensatory growth (Wang et al., 2000).
Chemical composition of the whole body of
flounder at the end of the feeding trial is shown in Table 3. Moisture, protein, lipid and ash con- tent of the whole fish were not significantly (P¤
0.05) affected by different days of feeding. Simi- lar result that moisture, protein and ash content of flounder, except for lipid content was not affe- cted by daily feeding strategy was reported (Kim et al., 2002b).
In conclusion, growth of juvenile flounder fed to satiation twice daily for 5 days after starved for 2 days was similar to that of fish fed to sati- ation twice daily for 6 days consecutively after starved for 1 day, but higher than that of fish fed to satiation twice daily for 4 days after starved for 3 days during a week-basis. However, no significant difference in feed efficiency ratio, pro- tein efficiency ratio or chemical composition of the whole body of f lounder was obtained among treatments.
Acknowledgement
This study was supported by Fund of Academic Improvement Program for a New Professor 2003 of Korea Maritime University.
Table 2. Feed consmption (g/fish), feed efficiency ratio (FER) and protein efficiency ratio (PER) of juve- nile flounder (Paralichthys olivaceus) with dif- ferent days of feeding1
Treatments Feed consumption
FER2 PER3
(g/fish)
F6 45.2±1.36a 1.17±0.026n.s. 2.10±0.047n.s.
F5 40.2±1.20a 1.32±0.028 2.36±0.032 F4 29.2±4.22b 1.08±0.134 1.94±0.242
1Values (Mean±SE) in the same column sharing a common superscript are not significantly different (P⁄0.05).
2Feed efficiency ratio (FER) = Weight gain of fish/feed fed.
3Protein efficiency ratio (PER) = Weight gain of fish/protein fed.
n.s.: not significant (P¤0.05).
Table 3. Chemical composition (%, DM basis) of juvenile f lounder (Paralichthys olivaceus) at the end of the feeding trial1
Treatments Moisture Crude protein Crude lipid Crude ash F6 73.6±0.05n.s. 17.2±0.25n.s. 3.1±0.76n.s. 3.6±0.36n.s.
F5 74.2±0.20 16.7±0.10 2.9±0.33 3.9±0.20 F4 73.2±0.48 17.1±0.05 3.3±0.37 4.3±0.32
1Values (Mean±SE) in the same row sharing a common super- script are not significantly different (P⁄0.05).
n.s.:not significant (P¤0.05).
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Received: June 24, 2004 Accepted: September 5, 2004
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