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1.
Abstract. Two experiments were conducted in which glass eels, Anguilla anguilla L., were fed with six different diets. Two natural diets, cod roe and minced bovine spleen, and four artificial diets, an unflavoured trout fry crumble and three trout fry crumble diets with added feeding stimulants, were used. The feeding stimulants tested were cod roe extract, spleen extract and a mixture of synthetic L-amino acids. In the first experiment the glass eels were fed at a restricted feeding level and in the second experiment at an ad libitum feeding level. The intake of metabolizable energy (ME) was determined as the sum of retained energy and heat production. Metabolizability of the diets decreased with increasing feeding level and was 75-95% for cod roe, 35-50% for spleen and 40-60% for the artificial diets. Since utilization of ME for maintenance and growth was not affected by feeding level and diet, differences in growth rates could be explained by differences in ME intake. Group ME intake in turn was determined by the fraction of the fish which were actually eating. The uniform feeding response of the glass eels fed the natural diets resulted in the highest ad libitum ME intake (80-90 kJ/kg0.8/day) and growth rate (4-4-4-9g/kg0.8/day). Addition of feeding stimulants significantly increased the ad libitum ME intake of the artificial diets from 45 kJ/kg0.8/day to 50-60 kJ/kg0.8/day, which resulted in an increase in growth rate from 1·3 g/kg0.8/day to 24 g/kg0.8/day.  相似文献   

2.
Factorial determinations of energy and protein requirements in growing Sparus aurata were carried out at 23–24°C. The energy content in the whole fish was dependent on fish weight and ranged from 5 to 11 MJ kg−1 body mass for 1–250 g fish, whereas the protein content remained constant at 179 g kg−1.
During starvation the fish lost 42.5 kJ body weight (BW) (kg)−0.83 day−1 and 0.42 g protein BW (kg)−0.70 day−1. The maintenance requirement for energy was calculated to be 55.8 kJ BW (kg)−0.83 day−1 and for protein 0.86 g BW (kg)−0.70 day−1. Utilization of digestible energy and digestible crude protein below and at maintenance was determined as 0.72 and 0.51, respectively. Utilization of digestible energy and digestible crude protein for growth above maintenance was determined as 0.46 and 0.28, respectively.
These values allow estimation of requirements for growing Sparus aurata .  相似文献   

3.
Abstract. The effect on the growth of freshwater angelfish, Pterophyllum scalare (Lichtenstein) (Pisces; Cichlidae), of different densities of population and diet compositions was studied. The results show that increasing the population density from 50 fish/m2 to 200/m2 significantly decreased the rate of growth of fingerlings, and that this effect is correlated to the size of fish. No significant differences were observed in growth between diets containing 37%, 41% or 47% protein. However, the addition of live food (artemia) to the diet significantly raised the growth rate, especially in the higher protein diets.
Body composition shows no changes during the growth periods, with a mean of 64·68% body protein, 35·47% dry weight fat and no significant differences in the percentage of residual ash through the growth period.
The food conversion rate was very low, ranging from 1·15 to 1·31. Total production increased with density, from 4·0g/m2/day (50 fish) to 13·7g/m2/day (200 fish) over a period of 60 days.  相似文献   

4.
Abstract. Artificially reproduced pacu, Colossoma mitrei Berg, fingerlings (initial weight 41 g) were stocked (100/m3) in plastic cages (1·0m3) within a freshwater reservoir. Three diets containing 30, 35 and 40% protein were tested in quadruplicate over a 76-day experimental feeding period. Fish were fed 7 days a week, twice daily at a feeding regime of 4% body weight/day from stock to 100g and thereafter at 3% until harvest. Mean water temperature over the trial was 26·7°C. Significant differences were observed in total and daily gain and in protein efficiency ratio, while no differences were obtained in the feed conversion ratio between treatments. Based on this study a 35% protein ration is recommended for pacu within floating cages.  相似文献   

5.
The present work aimed to study metabolic utilization of energy and protein by juvenile European seabass reared at 25 °C and to estimate maintenance requirements, based on indirect calorimetry and nitrogen excretion measurements. Duplicate groups of fish (IBW = 22 g) were fed a practical diet, for 28 days, at ration levels of 0, 0.25, 0.5, 1 and 1.5% of body weight. At the end of this period, oxygen consumption and ammonia nitrogen excretion were measured in fed and unfed fish. Weight gain linearly increased with ration level. Feed efficiency significantly increased with nitrogen intake up to 0.68 g N/kg/day. Nitrogen retention (% N intake) was positive at all feeding levels, being maximum at 0.5% BW and then decreased with increasing ration levels. There was negative energy balance at the lowest ration level and significantly increased at higher ration levels. Daily oxygen consumption (g/kg body mass) and ammonia excretion (mg N–NH4/kg body mass) significantly increased with ration level. Heat production and heat increment of feeding (kJ/kg/day) remained low at low ration levels and significantly increased as ration level increased from 0.5 to 1.5% BW. Below maintenance, protein energy represented 34% of total energy expenditure and significantly increased to 49–56% above maintenance. Based on indirect calorimetry and ammonia excretion data, maintenance energy and protein requirements were estimated to be 56.8 kJ DE/kg/day and 1.15 g DP/kg/day, respectively. The efficiencies of energy and protein utilization were estimated to be 0.83 and 0.66, respectively.  相似文献   

6.
Abstract. The autccology of chub, Leudscus cephalus (L.), in the Renlina Stream, Greece, was carried out in an effort to obtain information on the age, growth, mortality and reproduction of this species. Fork length increment during the first year of life was 8·9cm, after which it decreased. Life span was short (maximum age 8 years) and the instantaneous mortality rates were higher for the older age-groups. Chub reached sexual maturity at the second year of life for both sexes and spawning occurred from the second fortnight of April into May, at a mean water temperature of 18°C. The relationship between fecundity ( F ) and fork length (1) was F = 0·0797 L3·63 The average density and biomass were 1·06 fish.m−2 and 11·38g.m−2 respectively. The relationship between L and the pharyngeal bone size [gape ( G ), tip ( T ) and shank ( S )] in mm and caudal fin length ( C ) (cm) can be described by the equations: L = 0·8605 + 1·550 G , L = -0·0703 + 1·332 S, L = 1·092 + 1·615 T and L = 1·032 + 2·934 C .  相似文献   

7.
Abstract. Oxidation treatment of sugarmill waste using duckweed ( Lemna sp.) as part of the system, to reduce effluent nutrient concentrations and biological oxygen demand (BOD), was evaluated during a 6 month milling season in Negros Oriental, Philippines. Mean ammonia concentration in effluent water was reduced from 0·87 to 0·31 mg/l NH3-N and orthophosphate from 0·93 to 0·51 mg/l P2O5, while mean BOD was reduced from 611 to 143mg/t BOD5, after treatment. Seasonal mass fish kills in the adjoining bay no longer occurred during the 3 years following introduction of this treatment. The mean duckweed production (dry weight) was 8–8g/m2/day. Duckweed was harvested from a 1·9ha area of the system and transferred to an adjacent milkfish, Chanos chanos Forskal, farm. Its fertilization effect, in terms of lablab production ( lablab is the biological complex of bluegreen algae, diatoms, bacteria and various animals which forms a mat at the bottom or floats in patches), was evaluated in the milkfish ponds. This was compared with ponds fertilized with either inorganic fertilizers or cow manure, in the traditional way. Lablab growth was significantly increased using duckweed, with ash-free dry weight production averaging 32g/m2/day following fertilization with duckweed compared with 4g/m2/day using inorganic fertilizers. Milkfish net production averaged 320 kg/ha/90-day crop in inorganically fertilized ponds. 545kg/ha/90-day crop for cow manure and 820kg/ha/90-day crop in duckweed-fertilized ponds. The system is described and the benefits of this integrated waste treatment-fish production facility are discussed.  相似文献   

8.
Abstract – Age and growth of juvenile tilapia, Oreochromis niloticus , from Lakes Zwai, Langeno and Chamo (Ethiopia) were studied from microincrements in otoliths. Growth in length was best described by the Gompertz model. Average growth rate of the fish was most rapid in Lake Chamo (0.39 mm  ·  day−1, 1.14%  ·  day−1), intermediate in Lake Zwai (0.20 mm  ·  day−1, 0.72%  ·  day−1) and slowest in Lake Langeno (0.16 mm  ·  day−1, 0.62%  ·  day−1). Similarly, back-calculation from otolith increment widths gave growth rates of 0.28 to 0.43 mm  ·  day−1, 0.15 to 0.32 mm  ·  day−1 and 0.11 to 0.28 mm  ·  day−1 for Chamo, Zwai and Langeno fish, respectively. In addition, Fulton's condition factor was largest for Chamo tilapia and smallest for Langeno tilapia; the difference between fish from Langeno and Zwai was small. Rapid growth of juvenile O. niloticus in Lake Chamo was attributed to warm temperature and better food quality. Note  相似文献   

9.
Abstract – Seasonal changes in protein and fat were investigated in brown trout ( Salmo trutta L.) of a stunted population from a small, temperate zone lake. The lake was ice-covered during winter (about 200 days), and hypolimnic water temperature during winter was about 4°C. During winter there was an increase in specific fat, in particular among the larger sized fish, while there was a general decrease in specific protein content among both small (<5 winters) and large (age 5 or older) trout. During winter (end of October to mid-May) an average trout gained 32 kJ of fat, but protein energy content decreased by 14 kJ, yielding a net energy increase of 18 kJ or a daily energy gain of 0.09 kJ  ·  day−1. During the ice-free season (mid-May to the end of October) the trout increased mainly in protein content with daily energy gains of about 1.4 kJ  ·  day−1, a value about 14 times higher than the corresponding winter value. Trout living in lakes may store considerable amounts of fat during wintertime in contrast to the depletion of fat reserves found among stream-living trout in the same area, which face lower water temperatures in the winter period. Note  相似文献   

10.
Abstract. Growth and survival response of Penaeus stylirostris (Stimpson) to fertilization, pelleted feeding and stocking density were analysed for the conditions prevailing on the Baja California peninsula (Mexico). Three 0·25-ha earthen ponds were longitudinally divided in half with mesh structures. One half received inorganic fertilization (trial F) and the other supplementary feeding using a pelletized ration (trial PF). The initial stocking rates were approximately 5, 10 and 15 PL5/m2 in both trials. After 210 days, final mean weights ranged from 15·0 to 5·3g and survival from 48·6 to 17·8%. Growth and survival were analysed by means of a reparameterization of the von Bertalanffy's growth model and the exponential mortality equation. Results indicated that: (1) final mean weight was dependent on density in both trials ( P < 0·01) although growth rate was only affected in trial PF ( P < 0·01); (2) pelleted feeding produced both greater final mean weight and increased growth rate at densities higher than 5 PL/m2 ( P < 0·005); (3) the ratio tail weight/total weight was influenced by density in trial F ( P < 0·015); (4) the mortality equation served to explain differences in survival to a limited extent. An increase in growth rate after 170 days occurring at the intermediate density in trial PF was attributed to an increase in mortality, which allowed the remaining individuals to attain larger sizes. Further research to increase biomass yields should focus on the optimization of pond depth, the supply of vigorous post-larvae and on the possible influences of seasonal variations of planktonic communities of the lagoons on the productivity of ponds.  相似文献   

11.
Abstract. Tiger shrimp, Penaeus monodon Fabricius, post-larvae (32·0±3mg, 1·43±0·03 cm) were exposed to control, 0·12, 0·60, 1·20 and 2·40mg/l ammonia-N (un-ionized plus ionized ammonia as nitrogen) which is equivalent to control, 6,32,63 and 126μg/1 NH3-N (un-ionized ammonia as nitrogen) for 8 weeks in 25 ppt, as pH of 7·85–8·18 and 26–28°C by static renewal method. Growth in weight and length of the shrimps exposed to 1·20 and 2·40 mg/l ammonia-N were significantly lower (P < 0·05) than those exposed to control. The EC50 (concentration that reduced growth by 50% of that of the controls) was 1·33 mg/l ammonia-N, 70 μg/l NH3-N for weight gain, and 2·35 mg/1 ammonia-N, 123μg/l NH3-N for length gain of P. monodon post-larvae. The'maximum acceptable toxicant concentration'(MATC) of ammonia-N and NH3-N for P. monodon post-larvae was 0·60mg/l and 32μg/l, respectively after 6 weeks of exposure.  相似文献   

12.
Abstract. Six groups of tropical freshwater catfish, Mystus nemurus (Cuvier & Valenciennes)(mean weight. 20·45 ± l·5g), were reared in 0·34m3 fibreglass tanks at different stocking densities (105, 195, 285, 375, 465 and 555 specimens/m3 water) for 84 days. The objective of the study was to determine the effect of various stocking densities on the growth, nutrition, biochemical composition and survival of M. nemurus. The lowest growth rate appeared in fish at the highest density and the highest was observed in fish stocked in moderate density of 285 and 375 fish/m3 water. Fish production was also lower at relatively low stocking densities of 105 and 195 fish/m3. Food conversion ratio (FCR), protein efficiency ratio (PER) and biochemical composition of M. nemurus indicate that there exists an optimum stocking density which lies between 285 and 375 fish/m3.  相似文献   

13.
Abstract. A 156-day cage feeding trial was conducted with fingerling seabass, Lates calcarifer (Bloch), and grouper, Epinephelus tauvina (Forskal), so as to test six different dietary feeding regimes, namely no exogenous feeding (NF), frozen fish (FF), commercial shrimp finisher pellet (SP), in-house prepared dry pellet RDI (RDI) and RD2 (RD2), and an in-house prepared moist pellet (frozen fish: diet Rd1, 40:60 mixture w/w — code MP). Seabass fed FF and MP displayed the best growth response, with fish (30/m3) growing from an initial weight of 8·9g and 8·5g to a final weight of 285·5g and 257·5 g in 156 days, with a food conversion ratio of 3·77–5·10 (dry matter basis 1·15 – 1·95), and with a survival of 93·3 and 93·3% respectively. Similarly, grouper fed FF and MP also displayed the best growth response, with fish (30/m3) growing from an initial weight of 23·8 g and 25·8g to a final weight of 471·7g and 388·7g in 156 days, with a food conversion ratio of 3·53–4·16 (dry matter basis 0·89–1·06) and 1·73–2·96 (dry matter basis 1·06–1·80), and with a survival of 90 and 98·3% respectively. The results are analysed from an economical viewpoint and discussed on the basis of other published studies.  相似文献   

14.
Abstract Two groups of European catfish, Silurus glanis L., fingerlings were infected with channel catfish virus (CCV) by either intraperitoneal injection with 105 TCID50 of CCV, or bathing in water containing 105 TCID50 of CCV per 1·0 ml. The virus was isolated from spleen, intestine and brain of CCV-injected fish at day 1 and the titres ranged from 102·1 to 103·3 TCID50/g. However, the tissue distribution of CCV was irregular and no virus was isolated after day 3 post-exposure. In CCV-bathed fish, the virus was isolated only from the liver of one specimen at day 3 post-exposure. No clinical signs of CCV disease developed in any of the fish. Specimens in each regime from all sampling periods showed some minor histopathological changes, but there were no differences between treatments. Lesions included oedema and focal haemorrhage in the liver and the spleen was congested. Electron micrographs of tissue samples showed the presence of a few virus particles around the nuclei of kidney, spleen and intestinal cells, and in or around a myelinated nerve within the optic lobes of infected fish during the first 4 days of infection.  相似文献   

15.
Two feeding experiments were conducted to assess the quantitative cholesterol requirement of the juvenile prawn, Penaeus japonicus . The prawns were fed casein-based (experiment 1) and casein- or crab protein-based (experiment 2) diets with or without supplemental cholesterol. The daily increases in quantities of body cholesterol (mg kg−1 prawn day−1) at maximum growth and dietary cholesterol intake over a 40-day feeding period were determined. Prawns fed 5 g kg−1 supplemental cholesterol, regardless of protein sources, gave the highest weight gain. Body retention efficiencies of dietary cholesterol (cholesterol retained × 100/cholesterol intake) vary among prawns fed 5 g kg−1 supplemental cholesterol (diets 3, 5 and 7) but dietary cholesterol requirements expressed as mg kg−1 body weight (BW) day−1 were not significantly different (180 to 200 mg kg−1 BW day−1). Based on dietary cholesterol requirement, the optimum dietary cholesterol levels for the juvenile prawns were estimated in relation to feeding levels. When feeding levels were 3%, 5% and 7% of body weight, optimum dietary cholesterol levels were 5.0 to 6.0, 3.6 to 4.0, and 2.6 to 2.9 g kg−1 of dry diet, respectively. The present study showed the advantages of determining daily cholesterol requirement (mg kg−1 BW day−1) at maximum growth through a factorial method in determining optimum dietary cholesterol levels in P. japonicus .  相似文献   

16.
A two-factor experiment was carried out to investigate the change in skin colour and plasma cortisol response of cultured Australian snapper Pagrus auratus to a change in background colour. Snapper (mean weight=437 g) were held in black or white tanks and fed diets containing 39 mg unesterified astaxanthin kg−1 for 49 days before being transferred from white tanks to black cages (WB) or black tanks to white cages (BW). Skin colour values [ L * (lightness), a * (redness) and b * (yellowness)] of all snapper were measured at stocking ( t =0 days) and from cages of fish randomly assigned to each sampling time at 0.25, 0.5, 1, 2, 3, 5 and 7 days. Plasma cortisol was measured in anaesthetized snapper following colour measurements at 0, 1 and 7 days. Fish from additional black-to-black (BB) and white-to-white (WW) control treatments were also sampled for colour and cortisol at those times. Rapid changes occurred in skin lightness ( L * values) after altering background colour with maximum change in L * values for BW and WB treatments occurring within 1 day. Skin redness ( a *) of BW snapper continued to steadily decrease over the 7 days ( a *=7.93 × e−0.051 × time). Plasma cortisol concentrations were highest at stocking when fish were held at greater densities and were not affected by cage colour. The results of this study suggest that transferring dark coloured snapper to white cages for 1 day is sufficient to affect the greatest benefit in terms of producing light coloured fish while minimizing the reduction in favourable red skin colouration.  相似文献   

17.
Mature winged bean Psophocarpus tetragonolobus seeds were quick-cooked and the full-fat meal derived was used to completely replace menhaden fish meal as a dietary protein source for the African catfish Clarias gariepinus . Five dry practical diets (400 g crude protein kg−1 and 17.5 kJ gross energy g−1 dry diet) containing menhaden fish meal (diet 1) or winged bean meal with or without graded levels of supplemental L -methionine (diets 2, 3, 4 and 5; 0, 5, 10 and 15 g kg−1, respectively) were fed to catfish fingerlings (5.8  +  1.2 g) for 70 days. Weight gain, growth rate, feed conversion and protein utilization by catfish fed a winged bean meal diet without L -methionine supplementation (diet 2) was inferior ( P  > 0.05) to that in catfish fed the other diets, where performance differed nonsignificantly. Carcass protein of catfish was lower ( P  < 0.05) while liver protein was higher ( P  < 0.05) in catfish fed the winged bean meal diet without methionine supplementation. Results suggest that winged bean meal cannot replace fish meal as a protein source in catfish diets except with a minimum supplementation with 5 g L -methionine kg−1 diet.  相似文献   

18.
Five iso-nitrogenous (300 g protein kg−1 diet) and iso-lipidic (80 g kg−1 diet) semi-purified experimental diets with variable energy levels of 10.5 (D-1), 12.5 (D-2), 14.6 (D-3), 16.7 (D-4) and 18.8 (D-5) MJ kg−1 diets were fed to Puntius gonionotus fingerlings (average weight 1.79 ± 0.02 g) in triplicate groups (15 healthy fishes per replicate) for a period of 90 days to assess the optimum dietary energy level and protein-to-energy ratio (P/E). Fifteen flow-through cement tanks of 100 L capacity with a flow rate of 0.5 L min−1 were used for rearing the fish. Maximum specific growth rate, protein efficiency ratio, protein productive value, RNA : DNA ratio, whole body protein content, digestive enzyme activity and minimum feed conversion ratio was found in fish-fed diet D-3 with 14.6 MJ kg−1 energy level. There were no improvements in all these parameters with the further rise in dietary energy level. Hence, it may be concluded that the optimum dietary gross energy level for maximum growth and nutrient utilization of silver barb is 14.6 MJ kg−1 diet with a resultant P/E ratio of 20.2 g protein MJ−1 diet, when the dietary protein and lipid are maintained at optimum requirement levels of 300 and 80 g kg−1 diet, respectively, for this species.  相似文献   

19.
投饲率对草鱼生长、体组成和能量收支的影响   总被引：2，自引：0，他引：2  
为了建立草鱼(Ctenopharyngodon idella)的精准投喂模型管理系统,研究了不同投喂水平下草鱼的能量收支。实验在水温(27.5±2.0)℃条件下,选用初始体重(71.03±1.13)g的草鱼,共设5个不同投饲水平(饥饿、1%鱼体重(1%BW)、2%BW、4%BW和饱食),研究摄食水平对草鱼生长、鱼体组分和能量收支的影响。结果显示:随投喂水平的增加,草鱼鱼体水分减少,粗蛋白含量、粗脂肪含量和能量增加,灰分含量先减少后增加。特定生长率和热积温生长系数均随投喂水平的增加先增加再降低,在5%鱼体重时达到最大,且高于饱食投喂组。饵料转化率(FE)在投喂水平为体重2%组最高,且显著高于其他各组。干物质和能量表观消化率随投喂水平的增加而显著增加,蛋白质表观消化率在投喂水平为体重2%组显著高于其他组。生长能比例随投喂水平的增加而显著增加,而在体重2%组到饱食组间均无显著性差异;代谢能与生长能相反。在最大投喂水平下的能量收支方程为:100 C=21.72 F+4.25 U+45.85R+28.18 G或100 A=61.94R+38.06G。结果表明,5%鱼体重的投喂量为草鱼此阶段的最佳投喂水平。  相似文献   

20.
Abstract. Biomass productivity, photosynthetic efficiency and fatty acid profiles of the marine microalga Tetraselmis sp. in a turbidostat culture system using an outdoor photobioreactor are described. The maximum productivity depended on the units in which it was expressed; it reached 5·41 × 10−3 g/l/h in volumetric units, and 7·26g/m2/day in surface units, the former at the smallest culture depth (0·12m) and the latter at the greatest culture depth (0·25 m). Data from the experiments were adjusted to an equation for light limitation. The comparison of fatty acid composition at both depths showed that biosynthesis of polyunsaturated fatty acids (PUFAs), including eicosapentaenoic acid (EPA), was favoured when available light was low (0·17 m). Moreover, fatty acid 16:0 seemed to be an indicator of the type of limitation in the culture, i.e. nutrient or light limitation.  相似文献   

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