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1.
The optimum ration in relation to water temperature has been determined for juvenile sea bass (Dicentrarchus labrax). Fish were reared at 15 and 20°C. The spontaneous food intake was positively related to temperature. Four daily rations were tested at both temperatures. The optimum rations were 1.7% at 20°C and 1.2% at 15°C for fish weighing 20–30 g. The influence of temperature on growth rate, body composition and food conversion was studied. Increasing the temperature improved growth rate and gross conversion efficiency but not gross protein efficiency. The results are discussed in terms of energy utilization.  相似文献   

2.
The individual food intake of each fish in each of four groups of Atlantic halibut, Hippoglossus hippoglossus (L.) (mean weight: 422 g) was monitored by direct observation over a period of 21 days. Gross feed conversion efficiency (= growth·feed intake?1), net feed conversion efficiency and maintenance ration were estimated by regression analysis. Specific growth rates were found to be linearly related to weight-specific consumption at a temperature of 8–9°C: growth = 1.922· feed intake ? 0.242. Maintenance ration was 0.126% of body weight day?1. The gross feed conversion efficiency increased asymptotically with increasing feed intakes and growth rates, and was found to approach 1.9 at high growth rates (0.5 on a dry weight basis). One feeding per day seemed to be sufficient for maximum food intake and growth rate.  相似文献   

3.
The combined effects of stocking density (0.2, 0.5, 1, 2, 4 and 8 inds/ml) and dietary microalgal ration (20,000 and 40,000 cells/ml) and the sole effect of temperature (10, 12, 14, 16, 18 and 22°C) on the specific growth rate (SGR), per cent survival and per cent metamorphosis of auricularia larvae of the California sea cucumber, Parastichopus californicus, were evaluated in two separate experiments. The SGR was not significantly affected by stocking densities in the range of 0.2 to 4 inds/ml, but was significantly reduced at 8 inds/ml. The SGR of larvae fed 20,000 cells/ml was significantly reduced in comparison to those fed 40,000 cells/ml. Larvae had significantly higher per cent survival and per cent metamorphosis when reared at densities of 0.2 and 0.5 inds/ml compared with those reared at 2–8 inds/ml. Microalgal ration level did not significantly impact survival or metamorphosis. Larvae reared at 16 and 18°C had significantly higher SGRs and per cent metamorphosis than those held at all other temperatures, while per cent survival was highest at 16°C. Based on these results, we recommend rearing auricularia larvae of P. californicus at a stocking density at or below 0.5 inds/ml, a dietary ration of 40,000 cells/ml, and a temperature of 16°C.  相似文献   

4.
The effects of temperature and food ration on the growth of juvenile loggerhead turtle, Caretta caretta L. were examined in relation to body weight under controlled conditions in the laboratory. With increasing food ration there was increasing growth rate. The best daily growth rate at 20°C water temperature was 1.87%. Basal metabolism was reached at a daily feed rate of 1.01% body weight at 20.5°C derived from a formula for growth, namely g = Af ? B where g = 0.62f ? 0.63.  相似文献   

5.
A 74‐day trial was undertaken to evaluate the effects of temperature (16 and 22 °C) and dietary protein/lipid ratio on the performance of juvenile Senegalese sole (mean body weight: 6.4 g). Four experimental diets were formulated to contain two protein levels (550 g kg?1 and 450 g kg?1) combined with two lipid levels (80 g kg?1 and 160 g kg?1). Growth was higher at 22 °C and within each temperature in fish fed diets 55P8L and 45P16L. Feed efficiency, N retention (% NI) and energy retention (% EI) were higher at 22 and at both temperatures in fish fed diet 55P8L. Temperature affected whole‐body composition, with dry matter, protein, lipid and energy being higher and ash lower in fish kept at higher temperature. Independently of temperature, whole‐body lipid, energy and ash were higher and protein was lower in fish fed the high‐lipid diets. Visceral and hepatosomatic indices were not affected by diet composition but were higher in fish kept at 16 °C. Liver glycogen and lipid contents and activities of glutamate dehydrogenase, alanine and aspartate aminotransferases were not affected by diet or water temperature. Malic enzyme (ME) and glucose 6‐phosphate dehydrogenase activities were higher in fish fed the low‐lipid diets. ME activity was higher at lower temperature. In conclusion, increasing water temperature from 16 to 22 °C improves growth and feed efficiency of Senegalese sole juveniles; regardless of water temperature, the diet with 550 g kg?1 protein and 80 g kg?1 lipid promoted the best growth and feed efficiency.  相似文献   

6.
The effects of body size on the food intake, growth and conversion efficiency of the freshwater prawn Palaemon lamarrei have been studied. In captivity, fed on a restricted diet of the muscles of the fish Gambusia affinis, moulting in these prawns occurred once in 18 ± 5 days at a temperature of 26 ± 1°C. The importance of these cast moults, contributing a sizable amount of organic matter to the detritus deposit of freshwater habitats has been indicated. In a log-log system, both food intake and growth per day, represented as a percentage of body weight, showed an inverse relationship to the body size. Animals in the size range of 600–800 mg exhibited the highest conversion efficiency. The present study indicates that these prawns can be successfully reared and grown under laboratory conditions.  相似文献   

7.
Biological characteristics and culture methods were investigated for the spot prawn, Pandalus platyceros Brandt. Ovigerous adults were caught in the local fishery; six of these produced 2 628 to 4 669 larvae. The larval period ranged from 26 to 35 days (9.5–12.0°C). Maximum larval survival was about 70%, with mortalities being most frequent during ecdysis. The relation of wet weight (g) to carapace length (mm) for the first 26 months was calculated as log W = ?3.0843 + 2.9308 log L. Prawns showed good survival between 9.5 and 21.0°C. Mortality increased sharply when temperatures exceeded 21.0°C. Salinities below 22‰ resulted in a sharp increase in mortality.A diet of brine shrimp nauplii sufficed for newly hatched larvae. Growth was enhanced when larvae were fed a unicellular algal supplement (Phaeodactylum tricornutum), although mortality was somewhat higher. Larvae progressed rapidly to foraging on larger brine shrimp and diced foods. Six-month-old spot prawns raised on a squid diet averaged 3.4 g, and at 1 year the mean weight was 6.3 g. A feeding experiment, incorporating 12 diets, disclosed that highest growth rates and best food conversion ratios were achieved on a combined California seamussel and giant red sea urchin diet. However, the best growth rate achieved was considered marginal for mariculture.It was concluded that unless the growth rate could be accelerated by other food formulations or culture techniques, a monoculture system for mass cultivation would not be feasible. The spot prawn may have potential in a polyculture system.  相似文献   

8.
The effect of dietary protein reduction balanced by an increase in carbohydrate (starch) level on growth performance, feed utilization and intermediary metabolism of Senegalese sole juveniles was evaluated at two temperatures, 12 and 18°C. For that purpose two isolipidic (16% lipids) diets were formulated to contain 550gkg?1 protein and 90gkg?1 starch (diet HP:LC), and 450gkg?1 protein and 200gkg?1 starch (diet LP:HC). Each experimental diet was fed to triplicate groups of 20 fish (initial body weight: 15.9g) within each temperature. Diets had no effect on growth and feed utilization. Temperature affected growth but not feed efficiency, with fish growing more at 18°C. Fatty acid synthetase and glutamate dehydrogenase activities were higher at 12°C than at 18°C while activity of the other measured enzymes was not affected by water temperature. Glucokinase and malic enzyme activities were lower while fructose 1,6‐bisphosphatase activity was higher in fish fed the HP:LC diet. Our data suggest that protein can be reduced from 550 gkg?1 to 450 gkg?1 by increasing starch level in high lipid diets for Senegalese sole juveniles without affecting overall performance. A reduction in protein content through an increase in dietary starch decreases hepatic gluconeogenesis. Increasing temperature from 12°C to 18°C improves fish growth but does not affect feed efficiency.  相似文献   

9.
A series of experiments were conducted to evaluate the effect of temperature and the microalgae Isochrysis sp. concentration on the copepod Pseudodiaptomus euryhalinus cultured in laboratory conditions. First, the ingestion rate of P. euryhalinus was evaluated with different concentrations of Isochrysis sp. [2.74, 5.47, 8.21, 10.94 and 16.41 µg mL?1 organic dry weight (ODW)] during 24 h, at a temperature of 24.3 ± 0.3 °C. The ingestion rate increased in direct proportion to microalgae concentration, reaching an asymptotic point at 16.41 µg mL?1. P. euryhalinus was then cultured for 11 days at 24.4 ± 0.3 °C with different concentrations of Isochrysis sp. (5.47, 8.21, 10.94 and 16.41 µg mL?1 ODW) in order to quantify the optimal food density. It was observed that food concentration did not have a significant effect on the development, growth, maturity, fecundity and survival of P. euryhalinus. The effect of different temperatures (19.4 ± 0.5, 21.9 ± 1.0, 24.2 ± 0.3, 27.8 ± 0.5 and 30.1 ± 0.8 °C) on the development, growth, survival and sex ratio of P. euryhalinus fed with Isochrysis sp. at 5.47 µg mL?1 ODW was evaluated for 11 days of culture. The temperature had an inversely proportional effect on the time of development, and highest survival and growth were observed at 24.2 ± 0.3 °C. Finally, the effects of different temperatures (21.7 ± 0.5, 24.2 ± 0.3, 27.2 ± 0.3 and 30.7 ± 0.6 °C) in nauplii production of adult copepods were evaluated during 11 days. Nauplii production increased in direct proportion with the temperature. These results suggest that the optimum temperature and food concentration for P. euryhalinus culture are 24.2 ± 0.3 °C and 5.47 µg mL?1 ODW of Isochrysis sp., respectively.  相似文献   

10.
Abstract. Supplementary enzymes were added to a diet in order to increase its digestibility and improve the growth achieved by seawater Atlantic salmon, Salmo salar L. The supplementary enzymes were selected to hydrolyse proteins and carbohydrates. Three diets, with fishmeal as the only source of protein (C1), with fishmeal and soybean meal (C2) and diet C2 with supplementary enzymes (C3) were fed to seawater salmon (100g) for 12 weeks at nominal tank rations equivalent to 2·5% body weight per day. Consumption rates of individual fish were measured by radiography. The salmon fed C3 had higher rates of food consumption, significantly higher final weights and rates of growth and lower food conversion efficiencies and maintenance ration than those fed C2. Salmon fed C1 had similar food conversion efficiencies to the C3 fed fish. These results indicate that the addition of supplementary enzymes to diets containing soybean meal improves the growth and food conversion efficiency of salmon.  相似文献   

11.
To determine the optimal temperature for juvenile (0 year old) marbled flounder Pseudopleuronectes yokohamae, juveniles of 40–54 mm standard length were reared at six temperature conditions in the range of 8–26 °C, using group- and individual-based methods. Growth of juveniles increased from 8 to 20 °C but decreased from 20 to 26 °C, irrespective of the rearing method used. Food intake was greatest at 20 and 24 °C compared with other temperatures, while feed conversion efficiency was greater at 20 °C than 24 °C in individual rearing. Individual rearing provided more information such as individual variations in growth and food consumption, suggesting the importance of individual-based experiments for exploring the optimal temperature for fish.  相似文献   

12.
Aquarium-held bigmouth buffalo Ictiobus cyprinellus (Valenciennes) were fed the blue-green alga Spirulina platensis (Nordstedt) at a daily rate of 29 g dry weight/kg body weight for 28 days. Daily growth was 14 g/kg body weight, and food conversion was 2.0. Tilapia aurea (Steindachner) also was fed this blue-green alga; growth and food conversion were similar to those found for bigmouth buffalo. Fresh Spirogyra sp. fed to grass carp Ctenopharyngodon idella Valenciennes resulted in poor growth, and food conversion was about 10.  相似文献   

13.
When juvenile Penaeus merguiensis were fed four times daily they increased in weight more rapidly and utilized their food more efficiently than when fed once per day. The maximum ration for prawns given a commercial dry pellet was approximately 12.0% of the wet body weight per day and changed very little as the prawns grew from 0.5 to 1.3 g in indoor culture. Food conversion efficiency declined with increasing weight and ration size but the relative loss in efficiency was least when rations were maintained near to the maximum. Evidence is presented for the existence of a negative K-line relationship in P. merguiensis.  相似文献   

14.
Group-0 turbot Scophthalmus maximus L. were fed on artificial diets for 13 months, at 15° C. Partially defined diets containing about 40% protein were used and fish were fed once per day with moist pellets.The mean weight of the fish, at the beginning of the experiment, was 3.5 g. During the first 6 months, a fish gained 15 g weight on average, and 40 g in the following 6 months. The final mean weight was 62 g, and the final mean total length, 15.3 cm. The daily growth rate was 0.7% and the protein efficiency ratio (P.E.R.) ranged between 1.4 and 2.1.For fish fed on natural food at 15° C, the results were similar for the first 9 months. Subsequently, these fish grew faster than those fed artificial diets.  相似文献   

15.
The present paper describes the growth properties of juvenile Atlantic cod (Gadus morhua) reared at 7, 10, 13 and 16 °C, and a group reared under “temperature steps” i.e. with temperature reduced successively from 16 to 13 and 10 °C. Growth rate and feed conversion efficiency of juvenile Atlantic cod were significantly influenced by the interaction of temperature and fish size. Overall growth was highest in the 13 °C and the T-step groups but for different reasons, as the fish at 13 °C had 10% higher overall feeding intake compared to the T-step group, whereas the T-step had 8% higher feeding efficiency. After termination of the laboratory study the fish were reared in sea pens at ambient conditions for 17 months. The groups performed differently when reared at ambient conditions in the sea as the T-step group was 11.6, 11.5, 5.3 and 7.5% larger than 7, 10, 13 and 16 °C, respectively in June 2005. Optimal temperature for growth and feed conversion efficiency decreased with size, indicating an ontogenetic reduction in optimum temperature for growth with increasing size. The results suggest an optimum temperature for growth of juvenile Atlantic cod in the size range 5–50 g dropping from 14.7 °C for 5–10 g juvenile to 12.4 °C for 40–50 g juvenile. Moreover, a broader parabolic regression curve between growth, feed conversion efficiency and temperature as size increases, indicate increased temperature tolerance with size. The study confirms that juvenile cod exhibits ontogenetic variation in temperature optimum, which might partly explain different spatial distribution of juvenile and adult cod in ocean waters. Our study also indicates a physiological mechanism that might be linked to cod migrations as cod may maximize their feeding efficiency by active thermoregulation.  相似文献   

16.
The effects of feeding level on growth and energy partitioning were studied in rainbow trout growing from 150 to 600 g. Triplicate groups of fish (initial weight 158 g fish?1) were fed a practical diet at various feeding levels (25%, 50%, 75% and 100% of near satiation) for 24 weeks at 8.5°C. The final body weights of fish were 235, 381, 526 and 621 g. Restricted feeding levels significantly reduced live weight gain. Feeding levels had less pronounced effects on feed efficiency ratio, which were 0.98, 1.08, 1.02 and 0.83, respectively, for the 25%, 50%, 75% and 100% feeding levels. The growth of fish fed to near satiation was accurately described by the thermal‐unit growth coefficient. The growth data also showed that the widely used specific growth rate was not an appropriate model. Fish fed at the lowest feeding level (25%), which represented a maintenance ration (energy gain was less than 2 kJ fish?1 day?1), showed positive protein deposition but negative lipid deposition. This indicates that fish fed a maintenance ration mobilize body lipid reserve to support protein deposition. The efficiency of energy for growth (kg) was estimated to be 0.63. The factorial multiple regression approach estimated that the partial efficiencies of metabolizable energy utilization for protein deposition (kp) and lipid deposition (kf) were 0.63 and 0.72, and that maintenance energy requirement was about 19 kJ (kg BW0.824)?1, for rainbow trout held at 8.5°C.  相似文献   

17.
The experiment was designed to determine the combined effect of fish diet and water temperature on juvenile tench Tinca tinca (L.). Three diets were used: commercial dry diet for fish Aller Futura (diet F); frozen Chironomidae larvae (diet C); and Aller Futura substituted with Chironomidae at a ratio of 3:2 (dry weight; diet FC). Daily food rations and duration of the experiment were adjusted to temperatures of 20°C, 23°C and 26°C based on a correction factor q equal to 1.000, 0.779 and 0.609 respectively. The experiment lasted 92, 72 and 56 days for the respective temperatures. No mortality occurred. The highest relative growth rates were found at 26°C in diets F and FC. The lowest food conversion ratio of 1.12–1.22 (recalculated for dry weight of feed diet) was determined in fish fed diet F at 23°C and 26°C. A high value of condition index appeared to be the early warning of decreasing biological quality of fish and deformities. The lowest incidence of fish with deformities (IDef) was found in groups fed diet C (<1%), while the highest (90%) in fish fed diet F at 26°C. A lower share of dry diet in the fish food and a lower water temperature led to a lower IDef. Thus, amount of dry feed in fish diet was the major factor inducing body deformities, while water temperature only modified the effects of the dietary factor. Diet C at 23–26°C was the most cost‐effective of the tested combinations of diet and temperature.  相似文献   

18.
Two feeding trials were conducted to determine the effects of feeding rates in juvenile Korean rockfish, (Sebastes schlegeli) reared at 17 and 20 °C water temperature. Fish averaging 5.5 ± 0.2 g (mean ± SD) at 17 °C and 5.5 ± 0.3 g (mean ± SD) at 20 °C water temperature were randomly distributed into 18 indoor tanks. At each water temperature, triplicate tanks were randomly assigned to one of six different feeding rates: 2.8, 3.8, 4.1, 4.4, 4.7 % and satiation (4.99 % BW day?1) at 17 °C and 2.8, 3.8, 4.1, 4.4, 4.7 % and satiation (5.0 % BW day?1) at 20 °C. After 4 weeks of feeding trial, weight gain (WG) and specific growth rate of fish fed groups at satiation and 4.7 % (BW day?1) were significantly higher than those of fish fed groups at 2.8, 3.8 and 4.4 % (BW day?1) in both 17 and 20 °C temperature. Feed efficiency and protein efficiency ratio of fish fed group at 2.8 % (BW day?1) was significantly lower than those of fish fed groups at 3.8, 4.1, 4.4 and 4.7 % (BW day?1) in both experiments. Hematocrit was significantly higher in fish fed group at 4.4 % (BW day?1) at 17 °C, and there was no significant difference in hemoglobin content amongst all fish fed groups at 20 °C. Glutamic oxaloacetic transaminase and glutamic pyruvic transaminase of the fish fed group at 2.8 % (BW day?1) were significantly higher than those of all other fish fed groups in both experiments. Broken line regression analysis of WG indicated that the optimum feeding rate of juvenile Korean rockfish was 4.48 % (BW day?1) at 17 °C and 4.83 % (BW day?1) at 20 °C. Therefore, these results indicated that the optimum feeding rate could be >4.1 % but <4.48 % at 17 °C and >4.4 % but <4.83 % at 20 °C. As we expected, current results have indicated that 5 g of juvenile Korean rockfish perform better at 17 °C than at 20 °C water temperature.  相似文献   

19.
The optimum growth, food intake, food conversion efficiency, final body composition and mortality of juvenile Cichlasoma urophthalmus (Günther) was studied at different temperatures, ranging from 22.5 to 36.3°C. The results showed that food intake and specific growth rate increase rising to an apparent optimum at about 33.1°C. Multiple regression equations were derived which can be used to predict food intake and specific growth rate when temperature and initial body weight are known.  相似文献   

20.
Carp (Cyprinus carpio) larvae were fed on measured numbers of Artemia nauplii, and daily growth of the larvae monitored for a period of 10 days in order to determine the effect of varying feeding levels. A 34% reduction in specific growth rate was observed over the experimental period. At a temperature of 24 ± 0.5° C, carp larvae were found to require 200–250% of their body weight of Artemia nauplii per day for optimal growth and food conversion during the first five days of feeding, reducing to 100–120%/day over the following five days. The significance of these results is discussed in relation to potential economies of Artemia cyst use in hatcheries.  相似文献   

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