A preliminary study on the protein requirements of Chanos chanos (Forskal) fry in a controlled environment

Milkfish (Chanos chanos) fry with an average weight of 40 mg per fish were stocked in 60-l wooden-glass aquaria filled with 30 l of filtered sea water with a salinity of 32–34 p.p.t. and a temperature of 25–28°C. They were fed diets containing 20, 30, 40, 50 and 60% protein and 2740 kcal of digestible energy per kg at a daily rate of 10% of the biomass for a period of 30 days. Fish which were fed the diet containing 40% protein had the highest weight gain which was significantly higher (P < 0.05) than those of fish receiving the lower dietary levels of protein. Slightly lower weight gains were obtained when fish were fed diets containing 50 and 60% protein. Although feed conversion values were not statistically different (P < 0.05) among all treatments, the value for the 40% protein diet (1.96) was the best. The mean survival rates were low for all treatments but was highest for the 40% protein diet. No significant difference (P < 0.05) was found in the survival rates of fish receiving different treatments. Results show that a dietary level of 40% protein was required by milkfish fry for maximum growth, efficient feed conversion and high survival rate.     

Effects of Dietary Protein and Lipid Levels with Different Protein‐to‐Energy Ratios on Growth,Feed Utilization,and Plasma Biochemical Parameters of Dianchi Golden‐line Barbell,Sinocyclocheilus grahami

An 8‐wk feeding trial was conducted to evaluate the effects of varying dietary protein and lipid levels with different protein‐to‐energy (P/E) ratios on growth, feed utilization, and plasma biochemical parameters of Sinocyclocheilus graham. Nine experimental diets were formulated to contain three protein levels (35, 40, and 45%), and each with three lipid levels (4, 8, and 12%), to produce a range of P/E ratios from 71.31 to 98.64 mg protein/kcal. Each diet was randomly assigned to triplicate groups of 25 fish. Fish grew best when fed the diet containing 45% protein and 12% lipid. However, fish fed the diet with 40% protein and 8% lipid had similar weight gain and specific growth rate as those fed the above diet but showed relatively better feed conversion ratio, protein efficiency ratio, and protein and energy retentions. Additionally, plasma total amino acids and blood urea nitrogen contents and γ‐glutamyltransferase, aspartate aminotransferase, and alanine aminotransferase activities in fish fed the diet containing 40% protein and 8% lipid were relatively low among the dietary treatments. These results may indicate that a diet containing 40% protein and 8% lipid with P/E ratio of 84.05 mg protein/kcal would be suitable for the optimal growth, feed utilization, and health of S. graham.     

Influence of initial weight during the change from live to compound feed on the survival and growth of four cyprinids

In a series of trials, larvae of common carp (Cyprinus carpio L.), silver carp (Hypophthalmichthys molitrix Rich.), grass carp (Ctenopharyngodon idella Val.) and bighead carp (Aristichthys nobilis Rich.) were transferred directly from a diet of zooplankton to a dry, compound feed. The dry diet was based on a previously described diet of yeast and freeze-dried animal tissues. Common carp larvae showed the best growth on live zooplankton (46.3 mg individual weight after 14 days) compared to fish fed solely on dry feed (13.8 mg). Transfer of common carp larvae to dry diet when they reached 4.27 mg significantly improved growth, but no dependence was observed on two diets tested. Grass carp larvae grew equally well on live food and on the best compound diet (8.7 mg after 15 days), but fish transferred to dry diet at 4.3 mg showed significantly improved growth. The growth rate, however, depended on the diet (12.9–23.5 mg). Silver carp grew better when fed solely on dry diet (23.5 mg), compared to live zooplankton (15.8 mg after 15 days), but this was due to an insufficient supply of suitable live food. Transfer of fish at 6.8 mg to dry diet improved the growth only slightly, and dependence on the kind of dry diet was observed. Bighead carp larvae showed better growth on live zooplankton (42.2 mg after 15 days) than on the best compound diet (18.6 mg). Fish transferred at 5.6 mg to dry diets showed good growth, but high mortality was observed. It was concluded that common carp larvae are the most “difficult” to raise solely on dry diet, whereas silver carp larvae are the “easiest”. The present study has shown that the transfer of four cyprinids to dry diet improved their growth rate and that the transfer is possible at the individual wet weight of 5–6 mg.     

梭子蟹粉代替鱼粉和大豆蛋白对仿刺参幼参生长的影响

在水温25.6～27.0℃、盐度31、光照2000lx条件下饲育仿刺参苗种,研究了鱼粉、大豆蛋白与梭子蟹粉3种蛋白源对仿刺参幼参生长的影响。在饲料中分别按海藻质量的1‰、2‰、3‰分别添加鱼粉、大豆蛋白与梭子蟹粉。在27个容积为56L的玻璃钢水槽中分别放入一片30cm×40cm的波纹板和200头(0.1g/头)幼参,适量充气进行培育。试验结果表明,鱼粉试验组中以1‰的添加量效果最好,20d内质量增加175.0%,平均每头幼参质量日增加(3.75±0.9)mg;大豆蛋白试验组中以1‰的添加量效果最好,20d内质量增加165.0%,平均每头幼参质量日增加(3.25±0.3)mg;梭子蟹粉试验组中以3‰的添加量效果最好,20d内质量增加203.5%,平均每头幼参日质量增加(5.17±0.7)mg。3种蛋白源的1‰添加量中,效果依次为:鱼粉>蟹粉>大豆蛋白>空白组,空白组与添加蛋白源组之间差异极显著(P<0.01);2‰添加量中,效果依次为:蟹粉>鱼粉>大豆蛋白>空白组,蟹粉与鱼粉和大豆蛋白之间差异显著(P<0.05),空白组与添加蛋白源组之间差异极显著(P<0.01);3‰添加量中,效果依次为:蟹粉>鱼粉>大豆蛋白>空白组,蟹粉与鱼粉和大豆蛋白之间差异极显著(P<0.01),空白组与添加蟹粉试验组之间差异极显著(P<0.01)。试验结果证明,用梭子蟹粉作蛋白源效果显著好于鱼粉和大豆蛋白。     

Juvenile cobia (Rachycentron canadum) can utilize a wide range of protein and lipid levels without impacts on production characteristics

Two, 6 week feeding trials were conducted to evaluate the impacts of protein and lipid on weight gain, feed efficiency ratio values and biological indices of juvenile cobia (Rachycentron canadum). Utilizing a 2 × 3 factorial design, experimental diets containing two levels of crude protein (CP; 40 and 50%) and three levels of lipid (6, 12 and 18%), providing 14.4, 15.1 and 16.6 kJ available energy/g dry diet (calculated), respectively, were formulated for use in both feeding trials. In the first trial, cobia (initial weight 49.3 g per fish) was randomly assigned to one of the six experimental diets and fed to apparent satiation twice daily. At the end of the first trial, weight gain in cobia was not significantly impacted by protein levels with values ranging from 333% (50% CP) to 353% (40% CP). However, lipid significantly (P < 0.05) affected weight gain with fish fed the diet containing 18% total lipid returning the lowest growth of 293%. Feed efficiency ratio values were not significantly impacted by dietary protein or lipid levels and ranged from 0.46 (50% CP/18% lipid) to 0.51 (50% CP/6 and 12% lipid). Survival was significantly impacted by protein and lipid with fish fed the diets containing 50% CP and 18% lipid having lower (P < 0.05) survival rates of 90%.In the second trial, smaller fish were utilized (7.4 g average initial weight) under identical experimental conditions and dietary formulations. Weight gain was not significantly affected by protein or lipid levels and ranged from 1099% in fish fed the diet containing 40% CP/18% lipid to 1305% in fish fed the diet containing 50% CP/12% lipid. Feed efficiency ratio values, visceral somatic and hepatosomatic indices were significantly affected by protein and/or lipid. Muscle and liver lipid were impacted by dietary lipid (P = 0.0203 and 0.0012, respectively). Muscle protein was significantly impacted by dietary protein levels, while liver protein was affected by both main effects. Dietary protein and lipid had no impact on muscle ash.These data suggest that juvenile cobia can thrive on a wide range of protein and lipid levels, as well as a range of protein to energy ratios. Positive impacts of optimizing the protein component in terms of economic and environmental concerns, coupled with the ability to maintain the rapid growth rates this species are renowned for at lower dietary lipid levels, point towards beneficial consequences of further refinement of commercial cobia production feeds.     

Effect of using okara meal,a by‐product from soymilk production as a dietary protein source for Nile tilapia (Oreochromis niloticus L.) mono‐sex males

The main objectives of this study was to evaluate the effect of partial and total replacement of fishmeal protein by okara meal (OM) protein in practical diets on growth performance, feed utilization and body composition of Nile tilapia (Oreochromis niloticus L.) mono‐sex males. Fish of an average initial weight of 2.67 ± 0.01 g were stocked in 15 glass aquariums (80 L each) at a rate of 15 fish per aquarium. Fishmeal protein (18% of the diet) was used as the sole source of animal protein in the control diet. Percent replacement of fish meal (FM) by OM on the basis of crude protein was as follows: 0% (control diet A), 25% (diet B), 50% (diet C), 75% (diet D) and 100% (diet E). Diets were fed to fish at a rate of 5%, and then gradually reduced to 4% of the total fish biomass daily, for a period of 12 weeks. The results revealed that the fish fed diets A (100% FM control), B (25% OM), C (50% OM) and D (75% OM) had significantly the best average body weight, weight gain g, specific growth rate (SGR % day^?1), weight gain % and feed intake g fish^?1 compared with diet E (100% OM) which had the lowest values. There were no significant differences (P > 0.05) among all experimental diets and control in terms of feed conversion ratio (FCR), protein efficiency ratio (PER) and survival rate %. Whole body protein contents for fish fed diets B, C and D were superior to the control diet. Incorporation of OM in the diets increased significantly whole body fat content. Incorporation of OM in the diets significantly increased apparent digestibility coefficient of crude protein crude fat and energy. Therefore, these findings suggest that up to 75% of FM protein can be replaced by OM protein in Nile tilapia, mono‐sex male diets.     

Comparison of Practical Diets with and without Animal Protein at Various Concentrations of Dietary Protein on Performance of Channel Catfish Ictalurus punctatus Raised in Earthen Ponds1

Abstract— A 2 × 5 factorial experiment was conducted using practical-type extruded feeds containing 20, 24, 28, 32, or 36% crude protein with or without animal protein. The animal protein supplement consisted of 4% menhaden fish meal and 4% meat, bone and blood meal. Channel catfish fingerlings (average size: 26.3 g/fish) were stocked into 50 0.04-ha ponds at a rate of 24,700 fishha. Five ponds were used for each dietary treatment. Fish were fed once daily to satiation for 202 d. There were no differences in feed conversion ratio (FCR), percentage fillet moisture, and survival among treatments. In fish fed diets containing no animal protein, feed consumption, weight gain, and percentage dressout were lower for fish fed the 20% protein diet than those fed diets containing 28% and 32% protein. Fish fed 28, 32, or 36% protein diets without animal protein did not differ in respect to percentage dressout and percentage visceral fat; fish fed the 36% protein diet had higher percentage fillet protein and a lower percentage fillet fat than fish fed other diets with the exception of fish fed the 28% protein diet. In fish fed diets containing animal protein, feed consumption, weight gain, percentage fillet protein and ash, and percentage dressout were lower and visceral fat was higher for fish fed the 20% protein diet than those fed other diets. Fish fed diets containing 24% protein and above with animal protein were not different in respect to weight gain and feed consumption, but fish fed the 24% protein diet had a higher percentage fillet fat than fish fed a 32% or 36% protein diet. Fish fed the 32% protein diet had a lower visceral fat. Considering animal protein vs non-animal protein with the data pooled across all diets without regard to dietary protein level, weight gain and FCR of fish fed diets containing animal protein were higher than those fed diets containing no animal protein. However, weight gain of fish fed diets containing 20, 28, or 32% protein with or without animal protein did not differ. Dressout percentage and fillet protein were higher and fillet fat was lower for fish fed diets containing no animal protein than those fed diets containing animal protein. Data from this study indicated that animal protein may not be a necessary dietary ingredient for fish fed 28% or 32% protein diets typically used for grow out of pond-raised channel catfish under satiation feeding conditions. Whether animal protein should be included in catfish diets containing less than 28% protein is unclear, since fish fed the 24% protein diet benefited from animal protein but those fed the 20% protein diet did not benefit from animal protein. Additional studies to provide more information on low-protein, all-plant diets are currently being conducted.     

Low-Quality Diets for Growout of Channel Catfish,Ictalurus punctatus

Abstract

A feeding trial was conducted to evaluate low-quality diets for growout of pond-raised channel catfish. Five practical diets containing various levels of protein (10-28%) of varying quality (with or without animal protein and/or soybean meal), and with or without certain nutrient supplements (vitamin, minerals, lysine, or fat) were fed to channel catfish, Ictalurus punctatusstocked in 0.04-ha earthen ponds at a rate of 17,290 fish/ha. The diets were as follows: (1) 28% protein, nutritionally complete control; (2) 28% protein without supplemental vitamins, minerals, or fat; (3) 18% protein + supplemental lysine, vitamins, and minerals, but without animal protein; (4) 10% protein without animal protein, soybean meal, or supplemental vitamins and minerals; and (5) 10% protein + supplemental lysine, vitamins, and minerals, but without animal protein or soybean meal. Each diet was fed once daily to apparent satiation to fish in five replicate ponds for a single growing season. Fish fed diets containing 18% or 28% protein without supplements had similar diet consumption rates and weight gain as those fed the 28% control diet, but the fish fed the control diet converted diet more efficiently. Fish fed the 10% protein diet without supplements consumed less diet, converted diet less efficiently, and gained less weight than fish fed diets containing higher levels of protein. The addition of supplements to the 10% protein diet increased weight gain and processing yield as compared to fish fed the 10% protein diet without supplements. Body fattiness increased, fillet protein decreased, and carcass, fillet and nugget yields decreased as dietary protein decreased. The data show that pond-raised channel catfish can be grown effectively on a diet containing 18% protein that is of relatively low quality, but fattiness is increased and processing yield is decreased. However, because of the negative aspects of this diet, we would not recommend it for general use in commercial catfish culture. It could be used where fattiness and processing yield are not of consequence, such as recreational ponds. For that matter, the 10% diet without supplements could be used as well in these situations if maximum growth is not desired.     

Effect of mixed feeding schedules with varying dietary protein levels on the growth of sutchi catfish, Pangasius hypophthalmus (Sauvage) with silver carp, Hypophthalmichthys molitrix (Valenciennes) in ponds

A 6‐month feeding trial was conducted in field condition using 10 farm ponds (400–600 m²) to investigate the effect of mixed feeding schedules on the growth of sutchi catfish, Pangasius hypophthalmus with silver carp, Hypophthalmichthys molitrix. Fish were stocked at a ratio of 80:20 (sutchi catfish, 4.9±0.5 g: silver carp, 12.0±0.8 g) at the total rate of 25 000 ha^?1. Two diets of high protein (30%, HP) and low protein (16%, LP) were prepared using locally available feed ingredients. Five different feeding schedules of high‐protein diet continuously (HP), low‐protein diet continuously (LP), 1‐day low–protein/1‐day high‐protein diet (1LP/1HP), 7 days low–protein/7 days high‐protein diet (7LP/7HP) and 14 days low–protein/14 days high‐protein diet (14LP/14HP) were tested. The fish were fed twice daily at the rate of 15%, 10%, 8% and 5% of their body weight for first, second, third month and rest of experimental period respectively. Feeding rate was calculated only on the basis of sutchi catfish weight only and was adjusted every 2 weeks according to weight gain. Fish fed LP and HP on alternate day (1LP/1HP) resulted in significantly (P<0.05) higher growth rate, feed utilization and production among the treatments. However, there were no significant differences (P>0.05) between the growth rates and production of fish fed HP regularly and fish fed 7 days LP followed by 7 days HP (7LP/7HP). Fish maintained on LP grew the least. The feed conversion ratio (FCR) values for sutchi catfish ranged between 2.04 and 2.79 with feeding schedule 1LP/1HP showing the best FCR. The total production of fish (including silver carp) ranged between 8310 and 12 422 kg ha^?1 6 months^?1 with 1LP/1HP feeding schedule resulting in the highest production and net profit. The study demonstrated that feeding fish continuously with HP is less economical. Thus, for profitable sutchi catfish culture with silver carp, farmers can use the mixed feeding schedule of alternate day feeding of LP and HP as a means of reducing feed costs.     

Effect of dietary protein content on growth performance, feed utilization and carcass composition in the Australian freshwater crayfish, Cherax albidus Clark and Cherax destructor Clark (Decapoda, Parastacidae)

Cherax albidus (A) and Cherax destructor (D) male juveniles (mean weight 0.95 ± 0.03 g) were reared for 20 weeks on isoenergetic diets containing 150 g kg^?1 protein (A 15, D15) or 300 g kg^?1 protein (A30, D30). Mean weight, percentage weight gain, and specific growth rate (%) were substantially higher for both species on the 300 g kg^?1 protein diet. Mean percentage weight gain ranged from 2.39% day^?1 (D15) to 17.59% day^?1 (A30). A maximum weight of 33.81 g was attained by C. albidus on the higher protein diet. The most effective utilization of food was observed in C. albidus when fed the higher protein diet (food conversion ratio, 0.79; protein efficiency ratio, 4.21; apparent net protein utilization, 44.64%). Carcass composition was influenced by feed type. The higher protein diet resulted in an increase in carcass protein and ash and a decrease in carcass lipid and energy relative to the low-protein diet (150 g kg^?1 protein diet –C. albidus: 37.15% protein, 15.00% lipid, 25.20% ash, 15.55kJ g^?1 energy; C. destructor: 38.10% protein, 15.43% lipid, 25.70% ash, 15.65kJ g^?1 energy; 300 g kg^?1 protein diet –C. albidus: 46.10% protein, 8.71% lipid, 27.36% ash, 14.94kJ g^?1 energy; C. destructor: 42.99% protein, 8.56% lipid, 26.44% ash, 14.71kJ g^?1 energy). Carcass moisture and calcium were not affected by feed type. The time spent in the intermoult phase of growth was highly dependent on the premoult weight and varied according to diet and to species. A comparison of animals of similar weight (< 8 g) revealed that elevated dietary protein caused a reduction in the intermoult period by 11 days in C. albidus and 7 days in C. destructor. The moult increment, however, was independent of animal weight, and the highest percentage weight increment occurred for C. albidus fed the 300 g kg^?1 protein diet (per cent weight increase; A15, 33.1%; A30, 61.3%; D15, 31.2%; D30, 56.5%). Dietary induced morphological changes were also recorded. Animals of a standard carapace length had significantly larger abdomens (both species) and larger claws (C. albidus) when fed the higher protein diet.     

Replacement of Herring Fish Meal by Soybean Flour in Practical Diets for Red Tilapia,Oreochromis niloticus × O. mossambicus,Grown in Concrete Tanks

ABSTRACT

A feeding experiment was conducted for 100 days to evaluate the suitability of soybean flour (SBF) as a partial or complete substitute for the protein supplied by herring fish meal (HFM) in diets for growth of red tilapia, Oreochromis niloticus ×O. mossambicus, fingerlings (mean weight of 0.65 g/fish) grown outdoors in concrete tanks. Five isonitrogenous and isocaloric diets containing 35% crude protein and 3.36 kcal of digestible energy (DE)/g of diet were formulated in which SBF replaced 0%, 25%, 50%, 75% and 100% of the protein supplied by HFM. Results demonstrated that SBF has good potential as a substitute protein source for up to 75% of the protein supplied by HFM (diet 4) in red tilapia diets with no significant (P>0.05) adverse effects on growth, feed efficiency, body composition, and apparent digestibility of protein compared to the HFM-based control diet. The highest growth performance and best economic efficiency of fish weight gain were obtained with fish fed diet contained 50% of the protein from HFM and the other 50% from SBF. Fish fed this diet had the highest weight gain (11.95 g/fish), percent increase in weight (1838%) and growth rate (0.120 g/day) among fish fed all the other test diets. The lowest feed efficiency and growth performances were shown in the fish fed diet containing SBF as a complete substitute for protein supplied by HFM. Fish fed this diet had the lowest weight gain (4.70 g/fish), percent increase in weight (723%) and growth rate (0.047 g/day) among fish fed all the other test diets. Survival of fish was not statistically different (P>0.05) among all treatments. The apparent protein digestibility values showed wide variation between diets, ranging from 70.13% to 82.12% and the values were remarkably high in fish fed SBF-based diets. At the conclusion of the study, substituting HFM-protein with SBF-protein in diets for red tilapia did not affect the final fish protein, ash and moisture contents, but lipid content was significantly higher (P <0.05) in fish fed diets in which SBF substituted for 50% or more of the protein supplied by HFM. Hematological characteristics of red tilapia were examined at the end of the study and the results showed that all the blood parameter values were within normal values for fish. Economic analysis of diets suggested the possibility of using SBF as an alternative source of protein in red tilapia diets.     

Dietary supplementation of lysine and/or methionine on performance, nitrogen retention and excretion in pacu Piaractus mesopotamicus reared in cages

A study was conducted to evaluate the effect of dietary supplementation of lysine and/or methionine on growth performance, nitrogen retention and excretion in pacu juveniles reared in cages. Five diets were prepared; four diets based on plant ingredients containing 23% digestible protein (DP), basal: Lys- and Met-deficient, 23L: basal supplemented with lysine only, 23M: basal supplemented with methionine only, and 23LM: basal supplemented with both amino acids and a protein-bound AAs diet based on fish and soybean meal, containing 30% DP. Survival, specific growth rate, protein efficiency rate and feeding cost were not influenced by the dietary treatments (P > 0.05). Fish fed basal diet showed the lowest mean of N retention. Fish fed 30DP diet showed the best results of weight gain (WG) and apparent food conversion rate (FCR) among the dietary treatments. On the other hand, WG in the 23LM group and FCR in the 23LM and 23M groups were not significantly different from the group fed 30DP diet, and showed the highest mean of N retention. There was higher N excretion (P < 0.05) when the fish were fed 30DP and 23L diets than the other dietary treatments. Fish fed plant protein-based diets containing 23% DP supplemented with both amino acids or methionine alone showed satisfactory growth and N retention results when compared with fish fed 30DP diet, with the advantage of lower N emissions into water. The results also evidence the pacu's great potential to be reared in cages.     

Enhancement of Monosex Hybrid Red Tilapia,Oreochromis mossambicus × O. niloticusProduction in Portable Canvas Tanks Through Mixed-Feeding Strategies

Abstract

The viability of mixed-feeding schedules utilizing low-and high-protein diets for the production of monosex hybrid red tilapia, Oreochromis mossambicus × O. niloticuswas evaluated. Male red tilapia juveniles (mean initial weight 16.8±0.08 g) stocked at a rate of 159 fish/m³ in canvas tanks (3.05m × 0.92m × 1.22m) were grown under five different feeding schedules for 24 weeks. Two schedules, using low (25%, A) and high (35%, B) dietary protein were designated as control. Three mixed-feeding schedules tested were: the feeding of 1 day of low protein diet followed by 3 days of high-protein diet (1A/3B); 2 days of low-protein diet followed by 3 days of high-protein diet (2A/3B); and 3 days of low-protein diet followed by 3 days of high-protein diet (3A/ 3B). Results showed that growth performance parameters, such as specific growth rate (% SGR), percent gain, and weight gain were significantly higher (P < 0.05) for fish maintained on the feeding schedule of 3A/3B. Similarly, the feed conversion ratio, protein efficiency ratio, and protein retention values were also significantly better for fish grown under this schedule. In terms of production, the 3A/3B feeding schedule also resulted in the highest total yield (kg/m³) and yield above 250 g. The 3A/3B feeding schedule resulted in a 10.1% protein saving relative to Diet B. These results suggest that a 3A/3B feeding schedule be adopted for the best biological and economical performance of red tilapia.     

Effects of Dietary Protein and Lipid Levels on Growth and Body Composition of Juvenile Japanese Flounder,Paralichthys olivaceus,Fed Diets Containing Intact Proteins or Crystalline Amino Acids

Abstract

The influence of eight semi-purified diets having different protein and lipid levels on growth performance and body composition of Japanese flounder, Paralichthys olivaceus, was evaluated. The sources of protein were either intact protein (IP) or a mixture of IP and crystalline amino acids (CAA). In trial 1 (IP group), four test diets were prepared from IP sources (casein-gelatin) with combination of two protein levels (35% and 50%) and two lipid levels (10% and 20%). In trial 2 (PA-group), another four test diets were formulated using IP and CAA with combination of the same two protein and two lipid levels as used for trial 1. The juveniles (about 2.00 g initial weight) were fed the respective test diets for 42 days in duplicate tanks. In both trials, weight gain was the highest for juveniles fed the diet containing 50% protein with 10% lipid and the lowest in those fed the 35% protein with 10% lipid diet. Weight gain of juveniles was significantly increased when the lipid levels were increased in low protein (35%) diets for both trials. In high protein (50%) diet, however, increase lipid levels from 10 to 20% with 50% protein resulted in decrease in weight gain, irrespective of protein sources. Specific growth rate, feed intake, feed conversion efficiency were significantly affected by different dietary protein and lipid level. Content of neutral lipids in the whole-body particularly, triglycerides was statistically higher for fish fed the high-lipid diets than those fed the low-lipid diets irrespective of protein sources. But, polar lipid did not show any differences either for different protein or lipid levels. Level of individual amino acids in the whole-body showed little difference among the dietary treatments. Results suggest that Japanese flounder grew better on low lipid level with 50% protein-based diets and supplementation of CAA did not show any adverse effect on the growth performance with different levels of protein and lipid in the diets.     

Replacement of Fish Meal by Plant Proteins in the Diet of Nile Tilapia: Digestibility and Growth Performance

Apparent digestibility coefficient (ADC) values for a number of ingredients of plant or animal origin were obtained in order to formulate diets based on such values and to evaluate growth performance of Nile tilapia Oreochromis niloticus fed four experimental diets in which fish meal was gradually replaced by a mixture of other ingredients.The digestibility of various diet components was measured by using an inert marker in the feed and by using the Guelph faeces collecting system. ADC values of the ingredients tested were generally high, especially for fish meal. It was found that extruded pea seed meal (92.6%), defatted soybean meal (94.4%), full-fat toasted soybean (90.0%) and micronized wheat (88.6%) were the best vegetable proteins tested. Lupin seed meal and faba bean meal had similar ADC values for protein and energy.Groups of tilapia, initial mean body weight (SD) 6.7 (0.1) g, were fed experimental diets with the same digestible protein (DP) and digestible energy (DE) containing graded levels of a mixture of vegetable ingredients as partial or total replacement of fish meal protein. A growth trial was conducted over 12 weeks as partial or total replacement of fish meal protein. A growth trial was conducted over 12 weeks at a water temperature of 25 °C. Significant differences were observed for weight gain among tilapia fed diets D0, D33, D66 and D100 (containing only animal protein, 33, 66, and 100% of plant protein, respectively). No significant differences were observed for voluntary intake among tilapia fed diets D0, D33 and D66. These values were significantly lower than those observed for tilapia fed plant protein based diet (D100) and suggest the possibility of partial replacement of fish meal by vegetable proteins without negative effects.     

Evaluation of Cow Pea Seed Meal,Vigna sinensis,as a Dietary Protein Replacer for Nile tilapia,Oreochromis niloticus (L.), Fingerlings

The main objectives of this study were to evaluate the effect of partial and total replacement of fish meal (FM) protein by cow pea seed meal (CPSM) protein in practical diets on growth performance, feed utilization, and body composition of Nile tilapia, Oreochromis niloticus (L.). Fish of an average initial weight of 4.6 ± 0.2 g were stocked in 15 glass aquariums (80 L each) at a rate of 15 fish per aquarium. FM protein (30% of the diet) was used as the sole source of animal protein in the control diet. Percent replacement of FM by CPSM on the basis of crude protein were as follows: 0% (control diet A), 25% (diet B), 50% (diet C), 75% (diet D), and 100% (diet E). Diets were fed to fish at a rate of 4% of the total fish biomass daily, for a period of 16 wk. The results of this study revealed that the fish fed control diet A (100% FM) had the best average final body weight, specific growth rate (SGR %/d), weight gain (g/fish), weight gain %, while the poorest results for all parameters were obtained with fish fed diet E (100% CPSM). The same parameters of fish fed diets B (25% CPSM) and C (50% CPSM) were not significantly different (P > 0.05) from those of fish fed the control diet A. Feed utilization parameters of fish fed diets A, B, C, and D were better than for diet E. Proximate composition of whole‐body moisture and ash contents were not significantly different (P > 0.05) among all experimental diets and control diet. Whole‐body protein contents for fish fed diets B and C were superior to the control diet A. Incorporation of CPSM in the diets significantly increased whole‐body fat content. Incorporation of CPSM in the diets significantly decreased apparent digestibility coefficient of crude protein crude fat and energy. Diets B and C were not significantly different from control diet A. Therefore, these findings suggest that up to 50% of FM protein can be replaced by CPSM protein in Nile tilapia diets without any adverse effects on growth performance, feed utilization, body composition, and digestibility.     

Effects of several factors on growth of milkfish (Chanos chanos Forskal) fingerlings reared with artificial diets in aquaria

This paper presents the effects of feeding level, feeding frequency, salinity of water, kind and particle size of diets, and stocking density on the growth of milkfish (Chanos chanos Forskal) fingerlings which were reared with artificial diets in laboratory tanks. Experimental groups were designed using orthogonal array L₈, and the results were evaluated statistically. Growth of the milkfish fingerlings varied markedly with the kind of diets used and feeding level. The feeding frequency and particle size of the diets also affected growth of the fingerlings significantly, but the salinity of the water did not. The weight gain of the fingerlings did not vary with the stocking densities significantly, whereas the increase (%) in body length was greater at a lower stocking density. The milkfish fingerlings showed the best growth in terms of both weight gain and increase in body length when reared on a purified diet containing 35% casein and 15% gelatin as protein sources under the following conditions: feeding level, 30–35% of body weight; feeding frequency, twice a day; particle size of diets, 125–250 μm diameter; and stocking density, $\text{5 fish}\text{5-liter}$ tank. The means and confidence limits of the weight gain (%) and increase (%) in body length of milkfish fingerlings under the best conditions adopted were estimated to be 360 ± 63.7 and 62.1 ± 10.6, respectively.     

Partial substitution of soybean meal with animal protein sources in diets for channel catfish

Nine-week laboratory feeding experiments were conducted to evaluate partial substitution of animal protein sources into a 32% protein soybean-meal-corn basal diet for channel catfish (Ictalurus punctatus) fingerlings. In the first experiment, substitution of 5, 10, 20, and 40% menhaden fish meal into the basal diet resulted in increases in weight, protein, and fat gains as fish mean was increased to 20% (P < 0.05), and an increase in fat gain as fish meal was increased to 40% (P < 0.05). In the second experiment, the basal diet was supplemented with 5 and 10% fish meal or isonitrogenous amounts of protein from meat and bone meal (5.6 and 11.3%), blood meal (3.4 and 6.8%), and a 60:40 combination of meat and bone and blood meals (5 and 10%). Weight, protein, and fat gains were improved (P < 0.10) when the lower level of each animal protein, except blood meal, was substituted into the basal diet. Increasing the dietary level of each animal protein, except blood meal, improved gains over those from diets containing the lower level of the animal protein (P < 0.10). Fish meal improved gains more than isonitrogenous levels of the other animal proteins at both dietary levels (P < 0.10). Estimated amino-acid contents of the diets indicate that the increase in growth produced by including fish meal may be explained on the basis of increasing dietary levels of the most limiting amino acids; however, the increase in growth effected by including the other animal protein sources in the diet cannot be explained on that basis. Food consumption during the first 3 days of experiment indicated that inclusion of fish meal, meat and bone meal, or the meat and bone-meal-blood-meal combination improved diet palatability.     

Growth and body composition of juvenile Colossoma macropomum Cuvier 1818 (Characoidei) feeding on artificial diets

Juvenile Colossoma macropomum were fed for 56 days with six pelleted feeds which contained fish meal and blood meal as sources of animal protein in varying proportions. Blood meal can be incorporated in a diet together with fish meal but it was inadequate as the only source of animal protein for young C. macropomum. Growth rates from 1.1 to 2.5% dry weight/day were proportional to dietary crude protein levels (25–37%) while dry matter content of whole fish bodies (35-26%) was inversely proportional to growth rate. Body composition on a dry matter basis shows highest protein (53%) and lowest fat level (26%) for the fastest growing fish.     

Crude protein levels in diets for two growth stages of Nile tilapia (Oreochromis niloticus) in a biofloc system

Biofloc technology (BFT) provides an additional feed source for aquatic organisms through the conversion of waste in microbial flocs. Because of this, the suitable protein level in a diet for animals in this system could be different from those in conventional systems. Our objective was to determine the suitable protein level in the diet of Nile tilapia juveniles reared with BFT. Two experiments were carried out with tilapia weighing ~10 g (first experiment) and about 50 g (second experiment) during 61 and 98 days respectively. Five crude protein (CP) levels (within 17% and 33%) were tested. The increment of CP resulted in a reduction in dissolved oxygen, pH, alkalinity and an increase in dissolved phosphorus, total suspended solids and total ammonium nitrogen. The crude protein level had a significant effect (p < 0.05) on animal performance. The linear response plateau model was the best fit for the final weight and weight gain data in the two growth phases. In conclusion, tilapia juveniles of 10–60 g and 60–230 g in biofloc can be fed on diets with 28% of CP (26% of digestible protein) and 22% CP (20% of digestible protein) respectively.