Effects of dietary protein on growth and body composition of Nile tilapia, Oreochromis niloticus L.

The effects of dietary protein (25%, 30%, 35%, 40% and 45%) on growth, survival, feed conversion ratio (FCR), protein efficiency ratio (PER) and body composition were investigated for four sizes (0.51, 45, 96 and 264 g) of Nile tilapia, Oreochromis niloticus L. In all four experiments, there was a progressive increase in growth with increasing dietary protein. In fry (0.51 g), significantly higher growth, survival and feed conversion were recorded for fish fed 40–45% rather than 25–35% protein diets. Similar trends for growth and FCR were also noted in 45 g fish. For larger (96 and 264 g) tilapia, significant differences in growth and FCR were found only between fish fed 25% and 30–45% protein diets. FCR and PER decreased with increasing weight of fish, and both were found to be negatively correlated with dietary protein level. Whole-body composition of the smallest fish was significantly influenced by dietary protein content. Percentage body protein of the fish fed 40–45% protein was higher than that of fish fed 25–35% protein diets, whereas lipid content decreased with increasing dietary protein level. In 45 g fish, both protein and lipid contents were higher in fish fed 25% and 30% protein diets than in those fed 35–45% protein diets. In larger tilapia, no significant influence of dietary protein level on body protein content was found. Percentage lipid decreased with increasing dietary protein level, and no definite trends in ash content were found. The results of these studies indicate that O. niloticus fry (0.51 g) should be reared on a practical diet containing 40% protein, and larger tilapia (96–264 g) on a diet containing 30% protein.     

Optimum dietary protein level for maximum growth of juvenile olive flounder Paralichthys olivaceus (Temminck et Schlegel)

This experiment was conducted to determine the optimum dietary protein level for juvenile olive flounder Paralichthys olivaceus (Temminck et Schlegel) fed a white fish meal and casein‐based diets for 8 weeks. Olive flounder with an initial body weight of 4.1 ± 0.02 g (mean ± SD) were fed one of the six isocaloric diets containing 35%, 45%, 50%, 55% and 65% crude protein (CP) at a feeding rate of 4–5% of wet body weight on a dry‐matter basis to triplicate groups of 20 fish per aquarium. After 8 weeks of feeding, per cent weight gain (WG) and feed efficiency ratios of fish fed the 55% CP diet were not significantly higher than those from fish fed the 50% and 65% CP diets, but significantly higher than those from fish fed the 35% and 45% CP diets. Fish fed the 50%, 55% and 65% CP diets had significant higher specific growth rates than did fish fed the 35% and 45% CP diets; however, there was no significant difference among fish fed the 50%, 55% and 65% CP diets. The protein efficiency ratio was inversely related to the dietary protein level; that is, maximum efficiency occurred at the lowest dietary protein level. Broken‐line model analysis indicated that the optimum dietary protein level was 51.2 ± 1.8% for maximum weight gain in juvenile olive flounder. The second‐order polynomial regression analysis showed that the maximum WG occurred at 57.7% and it revealed that the minimum range of protein requirement was between 44.2% and 46.4%. These findings suggest that the optimum dietary protein level for maximum growth could be greater than 46.4%, but less than 51.2% CP in fish meal and casein‐based diets containing 17.0 kJ g^?1 energy for juvenile olive flounder.     

Optimum Dietary Protein Level and Protein-to-Energy Ratio for Growth of Juvenile Korean Rockfish Sebastes schlegeli

An 8-wk feeding trial was conducted to estimate the optimum dietary protein level and protein-to-energy (P/E) ratio in juvenile Korean rockfish Sebastes schlegeli. Twenty experimental diets were formulated with four energy levels and five protein levels at each energy level. Four gross energy levels of 14.2, 16.5, 18.6, and 20.9 kJ/g diet were included at various crude protein (CP) levels. Diets containing CP at 30, 40, 45, 50, and 55% had either 14.2 or 16.5 kJ/g energy; those with CP levels of 35, 40, 45, 50, and 60% had either 18.6 or 20.9 kJ/ g energy. After 2 wk of conditioning, fish initially averaging 7.3 ± 0.04 g (means ± SD) were randomly distributed into net cages as groups of 20 fish. Each diet was fed to fish in three randomly selected net cages for 8 wk. After 8 wk of the feeding trial, weight gain (WG) of fish fed 50% and 55% CP with 14.2 kJ/g diet was significantly higher than those of fish fed 30% and 40% CP diets (P 0.05). WG of fish fed 45, 50, and 55% CP with 16.5 kJ/g diet was significantly higher than those of fish fed 30% and 40% CP diets (P < 0.05). WG of fish fed 60% CP with 18.6 kJ/g diet was significantly higher than those of fish fed 35, 40, and 45% CP diets. WG of fish fed 45% CP with 20.9 kJ/g diet was significantly higher than those of fish fed 35, 40, and 60% CP diets. Generally, feed efficiency (FE) and specific growth rate (SGR) showed a similar trend as WG. However, protein efficiency ratio (PER) was negatively related to dietary protein levels. WG of fish did not always increase with increasing dietary protein and energy levels. Comprehensive comparison among diets containing 40, 45, and 50% CP with different energy levels indicated that the increase in protein from 40 to 45% significantly increased WG (P < 0.05), but such effect was not significant when protein increased from 45 to 50% at all energy levels. Increasing dietary energy significantly increased WG of fish fed 40% and 45% CP at each energy level; however, there was no difference in WG of fish fed 50% CP with energy levels of 18.6 and 2.9 kJ/g diet. There was no significant difference in WG of fish fed 50% CP with 18.6 kJ/g or 45 and 50% CP with 20.9 kJ/g diet. Broken-line analysis of weight gain indicated that the optimum dietary protein level was 50.9 ± 1.1% and PIE ratio was 35.4 ± 0.8 mg/kJ with 14.2 kJ/g diet; the optimum dietary protein level was 49.3 ± 5.0% and P/E ratio was 30.2 ± 1.0 mg/kJ with 16.5 kJ/g diet; the optimum dietary protein level was 46.2 ± 9.2% and P/E ratio was 24.7 ± 4.9 mg/kJ with 18.6 kJ/g diet; and the optimum dietary protein level was 45.1 ± 1.8% and P/E ratio was 21.5 ±0.7 with 20.9 kJ/g diet. Therefore, these data indicated that the concept of P/E ratio must be restricted to diets containing adequate protein and energy levels. Based on WG, the optimum P/E ratio was between 21.5 and 35.4 mg protein/kJ gross energy in juvenile Korean rockfish when gross energy ranged from 14.2 to 20.9 kJ/g diet.     

Growth and Body Composition of Nile Tilapia,Oreochromis niloticus,Fry Fed Organic Diets Containing Yeast Extract and Soybean Meal as Replacements for Fish Meal,with and without Supplemental Lysine and Methionine

Quantities of fish meal (FM) have remained level for the past several decades; however, demand has dramatically increased because of its inclusion in all animal production as a high‐quality protein source. Soybean meal (SBM) is the most widely used plant‐protein ingredient for replacing various proportions of FM in aquatic animal diets. However, use of SBM as the sole protein source has often resulted in reduced fish growth. There is a growing segment of consumers who desire organically grown seafood, and tilapia is one of the most‐cultured fish in the world. As tilapia have herbivorous/omnivorous feeding habits, tilapia fed organic diets may allow producers to enter this rapidly developing market. A feeding experiment was conducted to evaluate the combination of organic SBM and an organic yeast extract (YE) as complete replacements for FM in Nile tilapia, Oreochromis niloticus, fry diets. Nine diets were formulated to contain various percentages of organic YE (0, 15, 30, and 45%) in combination with organic SBM (84–34%) with and without amino acid (methionine and lysine) supplementation. At the conclusion of the study, fry fed a control diet containing 20% FM and fry fed a diet containing 45% YE/36%SBM with amino acid supplementation showed no significant differences (P > 0.05) in final weight, weight gain, and specific growth rate (SGR) compared to those fed all other diets. On the basis of these data, an organic diet which replaces FM with a combination of SBM and YE with added methionine and lysine is commercially feasible and further investigation into the increased use of these two ingredients as protein sources in aquaculture diets is warranted.     

美洲鲥幼鱼饲料中蛋白质的适宜含量

为研究饲料中不同蛋白质含量对美洲鲥幼鱼生长的影响,设置了蛋白质含量分别为35%、40%和45%的3组实验,经过41d的试验得出:蛋白质含量为40%的饲料组,幼鱼的增重率、特定生长率最高(P<0.05);蛋白质含量为40%组和45%组的蛋白质效率和饲料转化率无显著差异(P>0.05),但均高于35%组(P<0.05)。     

Evaluation of Gambusia, Gambusia affinis, Fish Meal in Practical Diets for Fry Nile Tilapia, Oreochromis niloticus

This study was conducted to evaluate the use of gambusia, Gambusia affinis, fish meal (GFM) in practical diets for fry Nile tilapia, Oreochromis niloticus (2.11 ± 0.11 g). Six isonitrogenous diets (35%) were formulated in which GFM replaced 0.0, 10, 25, 50, 75, or 100% of the protein supplied by herring fish meal (HFM). Fish were fed one of the test diets at a feeding rate of 4% of the fish body weight 6 d a week, 2 times a day for 13 wk. Results demonstrated that fish growth increased with increasing GFM up to 75%, which produced the highest growth of the treatments. The lowest fish growth was obtained at 100% GFM. Feed intake (FI), protein efficiency ratio (PER), and apparent protein utilization (APU) increased significantly, while feed conversion ratio (FCR) decreased significantly with increasing GFM up to 75%. FI, PER, and APU decreased significantly, while FCR increased significantly for diets containing 100% GFM. There were no significant differences in moisture, protein, lipid, or ash contents in final fish body following inclusion of GFM in fish diet. There was no significant difference in the digestibility coefficient of dry matter. The digestibility coefficients of protein and gross energy for diets containing 100% GFM replacement were the lowest as compared with other GFM levels. The present study recommended that GFM is a suitable protein source in practical diets for fry Nile tilapia and could replace HFM up to 75%.     

Optimum Dietary Protein Level and Protein‐to‐energy Ratio for Growth of Juvenile Parrot Fish,Oplegnathus fasciatus

An 8‐wk feeding trial was conducted to estimate the optimum dietary protein level and protein‐to‐energy (P/E) ratio in juvenile parrot fish, Oplegnathus fasciatus. Eight experimental diets were formulated with two energy levels and four protein levels for each energy level. Diets containing crude protein (CP) at 35, 40, 45, and 50% had either 12.5 or 14.6 kJ/g of energy. Fish averaging 7.1 ± 0.06 g (mean ± SD) were fed one of the experimental diets for 8 wk. At the end of the feeding trial, weight gain (WG) of fish fed 45 and 50% CP in the 12.5 kJ/g diet was significantly higher than fish fed the 35% CP diet (P < 0.05). WG of the fish fed 45 and 50% CP in the 14.6 kJ/g diet was significantly higher than fish fed the 35 and 40% CP diets (P < 0.05). Fish fed the 14.6 kJ/g diet had a higher WG compared with fish fed the 12.5 kJ/g diet at all CP levels. Feed efficiency (FE) and specific growth rate (SGR) showed a similar trend to the WG. WG, FE, and SGR improved with increasing dietary protein levels up to 45% and remained constant at 50% CP for both energy levels. However, protein efficiency ratio was negatively related to dietary protein levels. The results suggested that the optimum level of protein and the optimum P/E ratio for juvenile parrot fish should be 45% and 31.1 mg protein/kJ, respectively, in a diet containing 14.6 kJ/g energy.     

Influence of Dietary Phytic Acid on the Growth, Conversion Efficiency, and Carcass Composition of Mrigal Cirrhinus mrigala (Hamilton) Fry

Abstract.— The effects of phytic acid on growth, protein efficiency, feed conversion, and carcass composition of mrigal Cirrhinus mrigala fry (2.5–3.5 cm) reared indoors at 18–22 C in 70-L flow-through (1-1.5 L/min) circular tanks were examined. Fish were fed isonitrogenous (40% crude protein) and isocaloric (4.32 kcal/g) purified test diets in the form of moist cake containing different levels (0.5, 1.0, 1.5, 2.0 and 2.5%) of phytic acid (dodecasodiurn salt) at a rate of 4% body weight twice daily (0800 and 1600 h). The highest weight gain (94.87%). specific growth rate (133%). protein efficiency ratio (2.02), and best feed conversion ratio (1.21) were observed in fish fed the control diet containing no phytic acid. Live weight gain and specific growth rate were significantly reduced by dietary phytic acid inclusion above 1%. Dietary inclusion of phytic acid markedly influenced the carcass composition of the fish. Whole body crude protein and fat content declined significantly ( P < 0.05) in fish fed diets containing phytic acid, while percentage of moisture and ash in these fish was significantly ( P ≤ 0.05) higher than fish in control diets.     

Evaluation of optimum dietary protein-to-energy ratio in juvenile olive flounder Paralichthys olivaceus (Temminck et Schlegel)

An 8‐week feeding trial was conducted to estimate the optimum dietary protein to energy (P/E) ratio in juvenile olive flounder Paralichthys olivaceus. Eight experimental diets were formulated with two energy levels and four protein levels at each energy level. Two energy levels of 12.5 and 16.7 kJ g^?1 diets were included at crude protein (CP) levels of 25%, 30%, 35% and 45% with 12.5 kJ g^?1, and CP levels of 35%, 45%, 50% and 60% with 16.7 kJ g^?1. After 1 week of the conditioning period, fish initially averaging 8.1±0.08 g (mean±SD) were randomly distributed into the aquarium as groups of 15 fish. Each diet was fed on a dry‐matter basis to fish in three randomly selected aquariums at a rate of 3–5% of total wet body weight per day for 8 weeks. After 8 weeks of the feeding trial, weight gain (WG), feed efficiency ratio and specific growth rate of fish fed 45% CP with 16.7 kJ g^?1 energy diet were significantly higher than those from the other dietary treatments (P<0.05). WG of fish fed 12.5 kJ g^?1 energy diets increased with the increase of dietary protein levels. However, WG of fish fed 16.7 kJ g^?1 energy diets increased with the increase of dietary protein levels up to 45% CP and then decreased when fish fed 50% and 60% CP diets. Both dietary protein and energy affected protein retention efficiency and energy retention efficiency. Haemoglobin (Hb) of fish fed 35% and 45% CP diets with 12.5 kJ g^?1 energy were significantly high and not different from Hb of fish fed 45% and 50% CP diets with 16.7 kJ g^?1 energy. Haematocrit of fish fed 45% CP diet with 16.7 kJ g^?1 energy was significantly higher than those from fish fed 25% and 30% CP diets with 12.5 kJ g^?1 energy (P< 0.05). Based on the results of this experiment, we concluded that the optimum dietary P/E ratio was 27.5 mg protein kJ^?1 with diet containing 45% CP and 16.7 kJ g^?1 energy in juvenile olive flounder.     

Optimum Dietary Protein and Lipid Levels in Juvenile Filefish,Stephanolepis cirrhifer,Feed

A feeding trial was designed to assess the effects of dietary protein and lipid content on growth, feed utilization efficiency, body composition, and hematological indices of juvenile filefish, Stephanolepis cirrhifer. Eight experimental diets were formulated with a combination of four protein (35, 40, 45, and 50%) and two dietary lipid levels (7 and 14%). Each diet was fed to triplicate groups of fish (3.2 ± 0.06 g) to apparent satiation for 8 wk. Fish growth performance and feed utilization were significantly affected by increasing dietary protein and lipid levels, with no significant interactions between factors. The highest growth performance value, in terms of weight gain, was observed in groups fed the diets with 50% protein (399%). However, fish fed the diet containing 45% protein had comparable growth (357%) while achieving relatively higher protein efficiency ratio. Hepatosomatic index was significantly affected by interaction of dietary lipid and protein with the highest values observed in those fish fed the highest protein (45–50%) and lipid (14%) diets. There was a significant increase in body lipid content (5.1 to 6.6%) and a decrease in body protein (15.8 to 14.8%) and ash (2.47 to 2.16%) with increasing dietary lipid levels from 7 to 14%. Muscle lipid content was significantly affected by both dietary protein and lipid levels and tended to increase with increasing dietary protein and lipid levels, ranging from 0.13 to 1.20%. Liver lipid content (65.9 to 68.7%) was significantly increased with the increase in dietary lipid levels while liver moisture content (28.9 to 25.9%) showed a clear decreasing trend. Hematological values were also altered with the increase in either dietary protein or lipid levels. These findings may suggest that a diet containing 45% protein and 7% lipid, with a protein to energy ratio of 23.8 mg/kJ, could deliver sufficient nutrient and energy to support acceptable growth and feed utilization and avoid excessive fat deposition in juvenile filefish.     

Effect of Different Dietary Protein and Lipid Levels on Growth Performance and Body Composition of Juvenile Southern Flounder,Paralichthys lethostigma,Reared in a Recirculating Aquaculture System

The effects of six formulated diets containing different protein and lipid levels on growth performance and body composition of juvenile southern flounder were evaluated. Test diets were prepared with a combination of three crude protein (CP) levels (45, 50 and 55%) and two crude lipid (CL) levels (10 and 15%). Diets (CP/CL) were as follows: 45/10, 45/15, 50/10, 50/15, 55/10, 55/15 and a commercial diet (50/15). Southern flounder (1.10 g) were fed the respective diets for 42 d in triplicate recirculating tanks (20 fish/tank). Percent body weight gain (BWG) for fish fed diet 45/10 (413%) and the commercial diet (426%) were significantly (P < 0.05) lower than fish fed other diets (823–837%). Increasing protein level from 45 to 50% produced a significant increase in BWG for the 10% lipid diet (823%) but further increasing protein did not produce a significant effect on BWG irrespective of dietary lipid levels. Specific growth rate (SGR), feed intake, feed conversion efficiency (FCE), protein efficiency ratio (PER), and total lipid content in the whole body were significantly affected by different dietary protein and lipid levels. Results indicated that a combination of 50% protein and 10% lipid was optimal for the growth performance of southern flounder juveniles.     

不同蛋白质和脂肪水平对细鳞鲑幼鱼生长和肌肉氨基酸含量的影响

本研究旨在探讨不同蛋白质和脂肪水平对细鳞鲑(Brachymystax lenok)幼鱼生长、体成分以及肌肉氨基酸含量的影响。采用蛋白质水平为40%、45%、50%和55%,脂肪水平为8%和16%,共8组实验饲料。在水温为(16±0.2)℃的循环流水水族箱系统内进行为期10周的养殖试验。采用常规生化分析方法对该鱼肌肉营养学组成及含量进行测定分析。研究结果表明,不同蛋白和脂肪水平对细鳞鲑幼鱼增重率、特定生长率、肥满度和肝体比等均有显著影响(P0.05)。随着蛋白水平增加,增重率、特定生长率、肥满度和肝体比率先升高后降低,其肌肉粗蛋白含量也随之显著升高(P0.05),而对粗脂肪和粗灰分不存在显著影响;随着脂肪水平增加,其肌肉粗脂肪含量也随之显著提高(P0.05),而对水分、粗蛋白和灰分含量不存在显著影响。肌肉中共测定出17种氨基酸(除色氨酸),不同蛋白和脂肪水平对氨基酸总量(WTAA)和必需氨基酸的构成比例(WEAA/WTAA)不存在显著影响。综合生长性能与氨基酸模式的实验结果,本研究认为细鳞鲑幼鱼最适蛋白质和脂肪水平分别为50%和8%,适宜蛋能比为29.36 g/MJ。     

Growth and Body Composition of Juvenile Hybrid Bluegill Lepomis cyanellus × L. macrochirus Fed Practical Diets Containing Various Percentages of Protein

Growth, survival, and body composition were evaluated in two feeding trials using juvenile hybrid bluegill Lepomis cyanellus × L. macrochirus . In Experiment 1, hybrid bluegill (20 g) were stocked into 1.25-m³ cages at a rate of 300 fish/cage and fed diets containing 35, 40, 44, or 48% protein for 12 wk. Fish meal comprised 32% of the dietary protein in all diets. Fish were fed all they could consume in 40 min. No significant differences ( P > 0.05) in individual length, individual weight, specific growth rate (SGR), condition factor (K), and feed conversion ratio (FCR) were found among treatments and averaged 13.4 cm, 47.4 g, 1.02%/d, 1.96, and 4.06, respectively. Whole-body composition of hybrid bluegill indicated that fish fed a diet containing 35% protein had a significantly lower ( P < 0.05) percentage protein (56.3%) and a higher ( P < 0.05) percentage lipid (29.3%) compared to fish fed diets containing 40, 44, and 48% protein. In Experiment 2, 15 hybrid bluegill (15 g) were stocked into 110-L aquaria and fed one of four diets containing 28, 32, 36, or 38% protein for 10 wk. Fish were fed twice daily all they would consume in 20 min. Fish fed a diet containing 38% protein had higher ( P < 0.05) percentage weight gain (265%) than fish fed diets containing 28% (203%) and 32% (219%) protein, but were not significantly different ( P > 0.05) compared to fish fed a diet containing 36% protein (251%). Feed conversion ratio (FCR) of hybrid bluegill fed diets containing 36% and 38% protein (average 1.39) were significantly lower ( P < 0.05) than fish fed a diet with 28% protein (1.73). Results from these studies indicate that hybrid bluegill can be fed a practical diet containing 35–36% protein (with fish meal comprising 32% of the protein). Further refinement of the diet formulation may allow producers to reduce diet and production costs.     

饲料蛋白质、脂肪、碳水化合物水平对草鱼生长和组织营养成分组成的影响

采用蛋白质、脂肪、碳水化合物含量不同的７种颗粒饲料，饲养初始体重约１６ｇ的草鱼，经６０天后取样分析，发现草鱼相对生长率随饲料蛋白质添加量的升高而显著上升；高蛋白质饲料一定程度上升高全鱼和肌肉的粗蛋白含量，并显著增加肝胰脏脂质，主要是中性脂质的积累。全鱼、肌肉和肠－肠系膜脂肪含量随饲料脂肪添加量增加而显著升高。这表明，饲料蛋白质添加量是影响草鱼肝脏脂质积累的主要因素     

Effects of variable feed allowance with constant energy and ratio of energy to protein in a diet for constant protein input on the growth of common carp Cyprinus carpio L.

An 11‐week feeding trial was conducted to evaluate the effects of dietary protein and/or energy levels on growth, feed efficiency and proximate composition of juvenile (average weight: 21.5 g) common carp (Cyprinus carpio L.) fed various diets based on constant daily protein input. Five experimental diets were prepared. One group of diets (diets 1, 2 and 3) contained three crude protein (P) levels (35%, 40% and 45%) with a constant gross energy (GE) of 3.8 kcal g^?1 diet. The second group of diets (diets 4 and 5) were formulated to contain a GE of 4.3 or 4.9 kcal g^?1 diet and 40% or 45% protein levels, respectively, where GE/P was constant at 10.8 kcal g^?1 protein. Fish receiving diet 1 served as the control; they were hand‐fed to visual satiety. Feed allowance for diets 2 and 4 was 87.5% of the control. Feed allowance for fish receiving diets 3 and 5 was 77.8% of the control. Thus, all tanks received the same daily protein input. When gross energy in the diets was constant, 3.8 kcal g^?1 diet, weight gain of fish fed diet 2 at 87.5% satiation was significantly higher than that of fish fed diet 3 at 77.8% of satiation. When the GE/P in the diets was constant, 10.8 kcal g^?1 protein, weight gain of fish fed diet 1 was significantly higher than that of fish fed diet 5 at 77.8% satiation. The feed efficiency ratio (FER) for diets 2–5 was significantly higher than for diet 1 at constant GE and GE/P, and this improved linearly as dietary protein levels increased. The protein efficiency ratio (PER) for diet 2 was significantly higher than for diet 3 at constant GE. However, PER was not significantly different at constant GE/P. Protein retention of fish fed diet 2 was significantly higher than that of fish fed diet 3 at constant GE. Protein retention of fish linearly decreased at constant GE/P. The energy efficiency ratios (EER) for diets 2 and 3 were significantly higher than for diet 1 at constant GE. Moisture and protein contents of the whole body of fish were not significantly different at constant GE, but they decreased linearly at constant GE/P. The lipid content of fish fed diet 1 was significantly lower than that of fish fed diet 2 at constant GE, and body lipid content linearly increased at constant GE/P. These results indicate that growth and feed efficiency for common carp fed a 40% protein diet with 3.8 kcal g^?1 diet GE at 87.5% satiation rate was superior to those for the fish fed either a 35% protein diet with 3.8 kcal g^?1 diet GE at 100% satiation rate or a 45% protein diet with either a 3.8 or 4.9 kcal g^?1 diet GE at 77.8% satiation rate.     

Studies on the Nutrition of Spotted Sand Bass Paralabrax maculatofasciatus: Effect of the Dietary Protein Level on Growth and Protein Utilization in Juveniles Fed Semipurified Diets

Two feeding trials were conducted to determine the digestibility of a casein-based semi-purified diet and the effects of different protein levels on growth and protein use of spotted sand bass Paralabrax maculatofasciatus juveniles. For trial I, a semipurified diet with vitamin-free casein as the sole source of protein was fed three times a day to apparent satiation, for a period of 20 d. Feces were collected by siphoning each tank. The digestibility of the experimental diet was high: 97% for protein, 89% for lipids, and 84% for gross energy, whereas that of organic matter was 78%. For trial II, seven diets were formulated using vitamin-free casein at graded levels (25, 30, 35, 40, 45, 50, and 55% protein). Triplicate tanks for each dietary treatment were stocked with fish and fed by hand three times a day to apparent satiation for 6 wk. Perfomance of fish fed the different diets was evaluated for survival, percent weight gain, specific growth rate, feed conversion ratio, and protein efficiency ratio. Survival was 100% for all treatments. Growth of spotted sand bass juveniles increased as the dietary protein increased, but no evidence of reaching a plateau was found. The daily feed intake values showed an inverse relation to the protein content of the diets. The feed conversion ratio did not differ among diets containing 40% protein or greater. The results indicate that spotted sand bass juveniles with 2.5-g mean weight need at least 55% dietary protein for best growth when casein is the sole protein source. However, in terms of feed conversion ratio, the requirement apparently could be lower.     

Effect of varying levels of dietary protein on the growth performance and feed conversion efficiency of snakehead Channa striata fry

Six isocaloric test diets, based on fishmeal-groundnut oil cake and containing 350–600 g kg^?1 protein at 50 g kg^?1 incremental levels were fed to snakehead, Channa Striata (Bloch), fry at a rate of 10% of body weight per day under laboratory conditions to determine the effect of varying level of dietary protein on the growth response. On the basis of percentage weight gain, daily weight gain, specific growth rate and daily tissue protein deposition, the dietary protein requirement of fry was found to be 550 g kg^?1 when fish meal was used as the major source of protein. There was a significant increase in carcass protein and a significant decrease in ash content with progressive dietary protein substitution. Fry fed with high protein diets tended to have lower carcass lipid contents and higher moisture contents.     

Evaluation of the optimum dietary protein level for the maximum growth of juvenile beluga (Huso huso L.1758)

A 10‐week feeding trial was carried out to evaluate the optimum dietary protein level for the maximum growth of juvenile beluga, Huso huso. Fish averaging 1.34 ± 0.07 g (mean ± SD) was randomly distributed into 18 circular fibreglass tanks of 500 L capacity (20 fish per tank). Six iso‐caloric diets were formulated to contain 30 (CP₃₀), 35 (CP₃₅), 40 (CP₄₀), 45 (CP₄₅), 50 (CP₅₀) and 55% (CP₅₅) crude protein (CP). Fish were fed each of the six experimental diets in triplicate groups. At the end of feeding trial, weight gain (WG) and specific growth rate (SGR) in fish fed CP₄₀ and CP₄₅ diets were significantly higher than those of fish fed CP₃₀, CP₃₅, CP₅₀ and CP₅₅ diets (P < 0.05). Lipid retention increased significantly from 24.7% to 31.6%, but protein retention decreased from 54.6% to 35.6% with increasing protein levels from 30% to 50%. Muscle total essential and non‐essential amino acid (EAA & NEAA) concentrations increased with the dietary protein level up to CP₄₅ diets. Muscle total EAA concentrations (%) of fish fed CP₄₅ were significantly higher than those of fish fed CP₃₀, CP₃₅, CP₅₀ and CP₅₅, but there was no significantly different between those of fish fed CP₄₀ and CP₄₅. Muscle total NEAA concentration (%) of fish fed CP₄₅ were significantly higher than those of fish fed CP₃₀ and CP₃₅ diets. Broken‐line analysis of WG suggested that the optimum dietary protein level could be 38.9% for maximum growth performance in juvenile beluga (1.3–77 g).     

Effects of dietary protein levels on growth performance and body composition of juvenile parrot fish, <Emphasis Type="Italic">Oplegnathus fasciatus</Emphasis>

The present study was conducted to evaluate the effects of dietary protein levels on growth, biometrics, hematology and body composition in juvenile parrot fish Oplegnathus fasciatus. Fish averaging 7.1 ± 0.06 g (mean ± SD) was randomly distributed into 15 net cages (each size: 60 × 40 × 90 cm, W × L × H) as groups of 20 fish. Five isocaloric diets (16.7 kJ/g energy) were formulated to contain crude protein levels (CP) as 35 (CP₃₅), 40 (CP₄₀), 45 (CP₄₅), 50 (CP₅₀) and 60 % (CP₆₀) in the diets. Fish were fed one of the experimental diets at apparent satiation twice a day in triplicate groups. At the end of 8-week feeding trial, weight gain (WG) of fish fed with CP₅₀ and CP₆₀ diets were significantly higher than those of fish fed with CP₃₅, CP₄₀ and CP₄₅ diets. Fish fed with CP₄₅, CP₅₀ and CP₆₀ diets had higher feed efficiency (FE) and specific growth rate (SGR) than those of fish fed with CP₃₅ and CP₄₀ diets. Protein retention efficiency (PRE) decreased with increase of dietary protein levels among fish fed with the experimental diets. Whole-body crude protein and lipid contents increased with the dietary protein level up to CP₅₀ diet. In conclusion, analysis of variance (ANOVA) revealed that the optimum dietary protein level could be 50 % for maximum growth of juvenile parrot fish, while the broken-line analysis of WG suggested that the level could be 48.5 %, in a diet containing 16.7 kJ/g energy.     

Use of Defatted Soybean Meal and Blue Mussel Meat as Substitute for Fish Meal in the Diet of Tiger Puffer,Takifugu rubripes

A feeding experiment was conducted to examine the potential use of defatted soybean meal (SBM) and freeze‐dried meat of blue mussel (BM) as partial replacement of fish meal in the diet of tiger puffer. Eight experimental diets were formulated, in which 0, 20, 40 and 60% fish meal protein were replaced with SBM (S0B0, S20B0, S40B0, and S60B0), and 40 and 60% with a combination of SBM and BM (S30B10, S20B20, and S45B15, S30B30). Fish of 11 g initial body weight were fed the diets to satiation twice daily, 6 d/wk for 8 wk at 20 C. Specific growth rate, feed efficiency, and protein efficiency ratio (PER) of fish fed diets containing SBM as an alternative protein source for fish meal decreased with increasing level of SBM, and these parameters of fish fed S40B0 and S60B0 diets were significantly lower than those of the control. Growth of fish in dietary groups containing BM were statistically identical to those in the control, and tended to increase with increasing level of dietary BM both at 40 and 60% substitution levels. Growth and feed utilization of fish fed S20B20 were almost the same to those in the control.