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1.
Yusuke Ito Hiroki Yasuma Reiji Masuda Kenji Minami Ryuichi Matsukura Saho Morioka Kazushi Miyashita 《Fisheries Science》2011,77(2):161-167
The swimming angle of larval Japanese anchovy (Engraulis japonicus) was measured in a tank, and target strength (TS) was calculated using a theoretical scattering model. The mean swimming
angle was 12.8° (SD ±22.1). Increased speeds of flow led to increased mean swimming angles. The mean swimming angle at flow
of 5 cm s−1 was higher than at other speeds. TS values were estimated using a distorted-wave Born approximation model for two cases.
Average values were 1–3 cm s−1 (11.5° ± 22.1) and 5 cm s−1 (16.6° ± 21.7) for cases 1 and 2, respectively. For case 1, TS ranged from −92.0 to −74.7 dB with a mean of −79.4 dB at 120 kHz.
For case 2, TS ranged from −92.2 to −75.2 dB with a mean of −79.9 dB. The mean TS in case 2 was lower than that in case 1,
with the maximum difference being 1.0 dB at 120 kHz (standard length 22.0 mm). However, there were no significant differences
between the regression lines of cases 1 and 2. Thus, changes in flow speed altered the swimming angle of larval Japanese anchovy,
but had little influence on TS. 相似文献
2.
Rainbow trout acclimated to soft water were submitted to an incremental velocity trial, and exhibited a 14% decrease in critical
swimming speed (U
crit ∼ 1.37 ± 0.055 vs. 1.54 ± 0.044 m s−1) compared to fish kept in hard water. After a standardized swimming protocol, soft-water-acclimated fish had higher blood
lactate concentrations (6.5 ± 0.66 and 6.0 ± 0.64 mmol L−1 (soft water) vs. 5.0 ± 0.46 and 3.9 ± 0.32 mmol L−1 (hard water)), revealing a greater use of anaerobic metabolism for the same exercise. Cardiovascular parameters were investigated
while fish were swimming at increasing water velocities, revealing that soft-water-acclimated fish had lower increases in
heart rate (105% vs. 118% of pre-exercise values), due to higher heart rates observed during acclimation and during the first
10 min of the swimming trial. This was also reflected by the plateau in heart rate and stroke volume observed during the swimming
protocol, which can be attributed to increased cardiovascular function in response to soft-water acclimation. These results
are in accord with previously reported increases in blood-to-water diffusion distance, due to proliferation of chloride cells
at the gills in response to soft-water conditions, and underscore the costs and limitations of soft-water acclimation.
R. C. Playle—Deceased. 相似文献
3.
The GreenshellTM mussel, Perna canaliculus, is a commercially important species forming New Zealand’s largest aquaculture export product. Losses of P. canaliculus spat from culture ropes between larval settlement and the time mussels reach initial reseeding size (c. 10 mm) are common. To test whether water velocity affects growth and retention of post-settlement P. canaliculus spat, and whether there is a threshold effect of increasing velocities on spat migration, a laboratory-based experiment was
conducted. Spat were grown for 8 weeks in experimental tanks on culture ropes at four velocities typical of velocities within
mussel farms (40, 10, 4, and 1 cm s−1). Spat migration was observed at all the velocities tested, but the number of spat migrating decreased as water velocity
increased. Spat retention was highest at the 40 cm s−1 velocity. Mean spat size increased significantly with increasing water velocity. At the highest velocity tested (40 cm s−1), migration increased as the spat grew suggesting that migration was density-driven. The results of this experiment indicate
the potential for mussel farmers to reduce seeded spat loss and to increase the growth rate of spat by modification of the
water flow within their farms, or placement of seeded ropes in locations of certain existing water velocities, and indicate
that velocities in the range 15–40 cm s−1 promote higher spat growth and spat retention for P. canaliculus. 相似文献
4.
The European eel migrates 5,000–6,000 km to the Sargasso Sea to reproduce. Because they venture into the ocean in a pre-pubertal
state and reproduce after swimming for months, a strong interaction between swimming and sexual maturation is expected. Many
swimming trials have been performed in 22 swim tunnels to elucidate their performance and the impact on maturation. European
eels are able to swim long distances at a cost of 10–12 mg fat/km which is 4–6 times more efficient than salmonids. The total
energy costs of reproduction correspond to 67% of the fat stores. During long distance swimming, the body composition stays
the same showing that energy consumption calculations cannot be based on fat alone but need to be compensated for protein
oxidation. The optimal swimming speed is 0.61–0.67 m s−1, which is ~60% higher than the generally assumed cruise speed of 0.4 m s−1 and implies that female eels may reach the Sargasso Sea within 3.5 months instead of the assumed 6 months. Swimming trials
showed lipid deposition and oocyte growth, which are the first steps of sexual maturation. To investigate effects of oceanic
migration on maturation, we simulated group-wise migration in a large swim-gutter with seawater. These trials showed suppressed
gonadotropin expression and vitellogenesis in females, while in contrast continued sexual maturation was observed in silver
males. The induction of lipid deposition in the oocytes and the inhibition of vitellogenesis by swimming in females suggest
a natural sequence of events quite different from artificial maturation protocols. 相似文献
5.
The experiment aimed at determining the efficient use of phytase (Phy) in Atlantic salmon diets that had low (4.5%) fishmeal
and contained 60% soy protein concentrate (SPC). Phytase was either included at 250, 500, 1,000 or 4,000 U Phy kg−1 diet or the SPC was pre-treated prior to making diets using 250, 500 or 1,000 U Phy kg−1 SPC. Fish were fed the experimental diets for 12 weeks, and there were no differences in survival among treatments nor were
there differences in growth performance between the phytase-pre-treated SPC diets. Feed intake and weight gain were significantly
lower for diets supplemented below 1,000 U Phy kg−1 compared to all other diets. Apparent digestibility (AD) of phosphorus was significantly lower without the use of phytase
(45.43 ± 2.06%) than for all other treatments. AD phosphorus increased from 55.70 ± 1.81% at the lowest phytase supplementation
(250 U Phy kg−1) to 80.87 ± 2.12% at the highest (4,000 U Phy kg−1). There was no difference in AD phosphorus between the diet with the highest supplementation (4,000 U Phy kg−1) and the pre-treated diets. There were no differences in whole-body dry material, crude protein or total lipid, whereas bone
ash was significantly lower for diets supplemented below 1,000 U Phy kg−1. Ash and phosphorus in the whole body and bone increased with increasing added phytase. At and above an inclusion of 1,000 U
Phy kg−1, bone ash (51.26 ± 0.12% bone weight) and bone phosphorus (11.21 ± 0.04% bone weight) reached concentrations that were no
different to the pre-treated diets. In conclusion, phytase improved Atlantic salmon’s growth performance fed low fishmeal
diets containing SPC, and at least 1,000 U Phy kg−1 diet was required to have the same effect as pre-treatment of SPC with 250 U Phy kg−1 SPC. 相似文献
6.
The effects of dietary mannan oligosaccharides (MOS) on the survival and growth of Astacus leptodactylus juveniles were evaluated. Experimental diets were prepared by using supplementation of 0 (Control), 1.5, 3.0, and 4.5 g MOS
kg−1 commercial trout larvae diet containing 43 g kg−1 protein and 15.74 g kg−1 lipid. A. leptodactylus juvenile with an average total length of 3.6 ± 0.46 cm (TL) and average weight of 1.25 ± 0.43 g was stocked in 0.2-m2 aquariums at a rate of 50 crayfish/m2 and reared for 60 days at 22.8°C. The experiment consisted of four treatments with three replicates each. Each aquarium contained
ten crayfish. Crayfish juvenile fed with 0, 1.5, 3.0, and 4.5 MOS attained 6.15 ± 0.49, 5.94 ± 0.29, 7.34 ± 0.39, and 5.94 ± 0.27 cm
final total length and 50, 56.67, 46.67, and 50% survival rates, respectively. Moreover, molting frequencies in 0, 1.5, 3.0,
and 4.5 g kg−1 MOS groups were detected as 44.44, 61.11, 83.33, and 38.88%, respectively. At the end of the experiment, a general enhanced
growth performance (P < 0.05) and feed conversion ratio were observed in crayfish fed on the diet containing 3.0 g kg−1. Crayfish juveniles fed with 3.0 g kg−1 MOS had the highest final length (7.34 ± 0.39 cm), although their survival was the lowest (46.67%) compared to other treatments
but not significant. Specific growth rates were significantly different (P < 0.05) among the treatment groups at the end of the 60-day experiment. There were no significant differences (P > 0.05) in percentage moisture, protein, and ash (wet-weight basis) in the tail meat of A. leptodactylus juvenile among treatments (diet) that averaged 82.3, 16.1, and 1.2%, respectively. However, lipid value was significantly
different among the diets P < 0.05), with values between 0.13 and 0.32. From the current results, it could be advised to use MOS at the rate of 3.0 g kg−1 in A. leptodactylus juvenile diets. 相似文献
7.
Tohya Yasuda Kazuyoshi Komeyama Keitaro Kato Yasushi Mitsunaga 《Fisheries Science》2012,78(2):229-235
We investigated the usefulness of acceleration loggers in aquaculture by examining net-cage use and metabolic rates in red
sea bream, Pagrus major. First, the fish’s metabolic rate (mg O2 kg−1 min−1) was measured with the logger in a swim tunnel at designated water velocities. We found that metabolic rate could be expressed
by using a linear regression model of the activity rate index (unitless min−1) derived from acceleration data. Using this equation, the field metabolic rates of three fish in a net cage were monitored
and were estimated at 14.1–15.0 kcal kg−1 day−1. The results suggested that 15–19% of energy from satiation feeding ration was consumed for metabolism and activity in the
net cage. The loggers showed orderly net-cage use by the fish. Tagged individuals used the whole cage from surface to bottom,
but individual fish that preferred the surface area rarely used the bottom, and vice versa. Metabolic rate increased significantly
with distance of the fish from their preferred depths. The logger provided information on the physiological and behavioral
responses of fish in a given breeding system, and its use should contribute to the design of practical aquaculture systems. 相似文献
8.
Azadeh Hatef Hamid Niksirat Sayyed Mohammad Hadi Alavi 《Fish physiology and biochemistry》2009,35(4):695-700
In this study, ovarian fluid composition and its effects on the motility and fertilizing ability of sperm were studied in
endangered Caspian brown trout, Salmo trutta caspius, and were compared with a saline activation medium (125 mM NaCl, 30 mM Glycine, 20 mM Tris–HCl, pH = 9.0) and freshwater
as the control. The ovarian fluid was composed of sodium 164.4 ± 4.4 mM l−1, potassium 1.8 ± 0.1 mM l−1, calcium 0.6 ± 0.1 mM l−1, magnesium 0.4 ± 0.02 mM l−1, chloride 127.4 ± 5.9 mM l−1, total protein 389.5 ± 89.6 mg 100 ml−1, cholesterol 9.3 ± 1.2 mg dl−1, and glucose 3.3 ± 0.2 mM l−1. The percentage of motile spermatozoa and the duration of sperm motility were significantly higher in ovarian fluid (62 ± 3%,
74.6 ± 0.8 s) than freshwater (35 ± 4%, 44 ± 1 s), but they did not differ significantly from saline medium (56 ± 3%, 74.3 ± 0.7 s)
(P > 0.05). Higher eyeing rates were observed after the activation of sperm in ovarian fluid and saline solution than freshwater
when 35,000 or 350,000 spermatozoa per egg were added into the activation media. However, no significant differences were
observed at higher concentrations of spermatozoa per egg (730,000) (P > 0.05). Also, this study showed that the ovarian fluid composition can be considered as a species-specific character among
salmonid fishes. As a conclusion, the results of this study recommend the use of ovarian fluid or the saline solution as an
activation medium in the artificial reproduction of Caspian brown trout. 相似文献
9.
B. Mickowska 《Fish physiology and biochemistry》2009,35(2):231-240
The main serine proteinase inhibitors of rainbow trout (Oncorhynchuss mykiss) and common carp (Cyprinus carpio) blood plasma were isolated and purified. The investigated inhibitors, α1-proteinase inhibitor (α1-PI) and antithrombin III (AT III), act by forming stable complexes with target proteinases. The association rate constants
k
on for the interaction of fish plasma inhibitors with several serine proteinases have been determined: k
on for both carp and rainbow trout α1-PI were >107 M−1 s−1 for human neutrophil elastase, and in the case of bovine trypsin and chymotrypsin k
on values were 2.0–5.2 × 106 M−1 s−1. Association rate constants k
on for the interaction of carp and rainbow trout AT III with bovine trypsin and thrombin were about 1.3 × 104–7.9 × 105 M−1 s−1 without and >107 M−1 s−1 in presence of heparin; so antithrombins require the presence of heparin to become effective proteinase inhibitors. The high
degree of homology of the estimated amino acid sequences of fish inhibitors reactive site loops confirms their similarity
with other proteinase inhibitors from the serpin family. 相似文献
10.
P. Domingues S. Garcia I. Hachero-Cruzado N. Lopez C. Rosas 《Aquaculture International》2010,18(3):487-499
The effects of two alternative prey (crayfish and hake) were tested on growth and survival of both juveniles and adults of
Octopus vulgaris in two experiments. Octopuses fed the control (squid) were larger (3.0 ± 0.7 kg) than those fed crayfish (2.4 ± 0.6 kg) at
the end of experiment I. Similarly, overall growth rates were higher for octopuses fed squid (1.7 ± 0.3 and 1.2 ± 0.2 %BW day−1, respectively). Average feeding rates for the experiment were not different, being 6.5 ± 0.9 and 7.5 ± 0.9 %BW day−1, respectively, for octopuses fed either squid or crayfish. Nevertheless, food conversions for the experiment were higher
(42.4 ± 2.7%) for octopuses fed squid compared to the ones fed crayfish (23.9 ± 1.9 g). For experiment II, hake and crayfish
were compared to squid; the final weight of octopuses fed squid, hake or crayfish was 1,183.0 ± 242.7 g, 1,175.6 ± 240.1 g
and 922.3 ± 160.1 g, respectively. Overall growth rates for the experiment were 1.9 ± 0.2 %BW day−1, 1.9 ± 0.3 %BW day−1 and 1.1 ± 0.3 g, respectively. Final weight and growth rates were never different (P > 0.05) between octopuses fed squid and hake, but were always higher (P < 0.05) compared to the ones fed crayfish. Average feeding rates for experiment II were similar for the three diets, and
of 4.6 ± 1.5, 4.2 ± 1.3 %BW day−1 and 5.1 ± 0.9 %BW day−1, respectively, for octopuses fed squid, hake or crayfish. Food conversions for experiment II were of 41.0 ± 9.6%, 40.5 ± 9.9%
and 21.3 ± 7.4 g, respectively, for octopuses fed squid, hake or crayfish, and were always higher for octopuses fed squid
and hake compared to crayfish. The results indicate that crayfish is not an adequate replacement for the usual prey to fatten
octopus, even considering its much lower market price. 相似文献
11.
Chenying Guo Shin‐ichi Ito Nicholas C. Wegner Laura N. Frank Emmanis Dorval Kathryn A. Dickson Dane H. Klinger 《Fisheries Oceanography》2020,29(3):215-226
As a crucial step in developing a bioenergetics model for Pacific Chub Mackerel Scomber japonicus (hereafter chub mackerel), parameters related to metabolism, the largest dissipation term in bioenergetics modelling, were estimated. Swimming energetics and metabolic data for nine chub mackerel were collected at 14°C, a low temperature within the typical thermal range of this species, using variable‐speed swim‐tunnel respirometry. These new data were combined with previous speed‐dependent metabolic data at 18 and 24°C and single‐speed (1 fork length per second: FL/s) metabolic data at 15 and 20°C to estimate respiration parameters for model development. Based on the combined data, the optimal swimming speed (the swimming speed with the minimum cost of transport, Uopt) was 42.5 cm/s (1.5–3.0 FL/s or 2.1 ± 0.4 FL/s) and showed no significant dependence on temperature or fish size. The daily mass‐specific oxygen consumption rate (R, g O2 g fish?1 day?1) was expressed as a function of fish mass (W), temperature (T) and swimming speed (U): R = 0.0103W?0.490 e(0.0457T) e(0.0235U). Compared to other small pelagic fishes such as Pacific Herring Clupea harengus pallasii, Pacific Sardine Sardinops sagax and various anchovy species, chub mackerel respiration showed a lower dependence on fish mass, temperature and swimming speed, suggesting a greater swimming ability and lower sensitivity to environmental temperature variation. 相似文献
12.
K. L. Worrall C. G. Carter R. J. Wilkinson M. J. R. Porter 《Aquaculture International》2011,19(6):1075-1082
The efficacy of photoperiod manipulation to influence growth and developmental processes is well documented in a range of
temperate aquaculture species. However, the application of such techniques with tropical species requires further investigation.
This preliminary 20-day study investigated the influence of continuous photoperiod on growth of barramundi (Lates calcarifer). In addition, diel plasma melatonin profiles provided a physiological measure of how the endocrine system of barramundi
responded to continuous photoperiod. Juvenile barramundi (1.33 ± 0.02 g) were held in recirculation systems under 12-h light:
12-h dark (12L:12D) or 24-h light (24L:0D) with a light intensity of 1,000 lux throughout the water column. Fish from both
treatments grew to more than 14 times their original weight, with final weight (24L:0D = 21.59 ± 0.85 g; 12L:12D = 19.12 ± 0.55 g),
total length (24L:0D = 12.67 ± 0.14 cm; 12L:12D = 11.96 ± 0.13 cm) and specific growth rate (24L:0D = 9.60 ± 0.05% bw day−1; 12L:12D = 9.14 ± 0.06% bw day−1) being significantly higher for fish grown on 24L:0D compared with 12L:12D. There were no significant differences in feed
intake (24L:0D = 226.46 ± 6.27 g; 12L:12D = 219.02 ± 5.73 g) or feed conversion ratio (24L:0D = 0.71 ± 0.06; 12L:12D = 0.80 ± 0.07)
between light treatments. Barramundi held under 12L:12D exhibited diel melatonin secretion, which peaked mid-dark phase (171.83 ± 4.81 pg ml−1) followed by a gradual decrease in base levels at the onset of illumination (68.61 ± 8.77 pg ml−1). When juvenile barramundi were subjected to 24L:0D, the amplitude of peak melatonin secretion was significantly suppressed
during the subjective mid-dark phase (129.71 ± 2.36 pg ml−1). This preliminary study confirmed that barramundi respond to photoperiod manipulation in a similar manner to many temperate
fish species, thus demonstrating the future potential use of artificial lighting to improve growth in this species commercially. 相似文献
13.
Wirat Jiwyam 《Aquaculture International》2011,19(5):987-997
Asian river catfish (Pangasius
bocourti Sauvage, 1880) were cultured at five different stocking densities in cages (submerged volume 1 m3) suspended in a dugout pond from August to November 2009. Pangasius
bocourti fingerlings (mean weight 27.09 ± 0.54 g) were stocked at densities of 12, 25, 50, 100, and 200 fish m−3. At the end of 3 months, the harvest weights (gross yields) were, respectively, 2.05 ± 0.30, 5.20 ± 0.31, 10.60 ± 0.42, 19.98 ± 0.78,
and 42.37 ± 0.41 kg m−3. The mean fish weights among the stocking densities of 25, 50, 100, and 200 fish m−3 were not significantly different, but were significantly higher than that of the 12 fish m−3 density. The specific growth rates among high stocking densities of 50, 100, and 200 fish m−3 were not significantly different; however, they were significantly higher than those of the low stocking densities of 12
and 25 fish m−3. Asian river catfish performed poorly at the lowest density. The results indicate an initial lower stocking threshold for
Asian river catfish of above 5.20 kg m−3. The Asian river catfish cultured in small cages placed in a pond reached the desirable market size (>200 g) within a 90-day
grow-out period. The results show that the maximum yield for Asian river catfish during a 3-month production cycle was not
reached. 相似文献
14.
The effects of irradiance and photoperiod on the biomass and fatty acid (FA) composition of Chlorella vulgaris were examined in the exponential growth phase. Results indicated significant differences in biomass and FA at different intensities
and photoperiods. Maximum biomass (2.05 ± 0.1 g l−1) was at 62.5 μmol photons m−2 s−1 and 16:8 h light/dark photoperiod. FA composition changed considerably in different light regimes; the maximum percentage
of total saturated (SFA) (33.38%) was recorded at 100 μmol photons m−2 s−1 and 16:8 h photoperiod, while monounsaturated (MUFA) and polyunsaturated (PUFA) fatty acids decreased with increasing irradiance
and light duration. The maximum percentage of total MUFA (15.93%) and PUFA (27.40%) was recorded at 37.5 μmol photons m−2 s−1 and 8:16 h photoperiod. 相似文献
15.
The effect of prebiotic xylooligosaccharides (XOS) on the growth performance and digestive enzyme activities of the allogynogenetic
crucian carp, Carassius auratus gibelio, was investigated. XOS was added to fish basal semi-purified diets at three concentrations by dry feed weight: diet 1, 50 mg kg−1; diet 2, 100 mg kg−1; diet 3, 200 mg kg−1, respectively. Twelve aquaria (n = 20) with three replicates for each treatment group (diets 1–3) and control treated without XOS were used. Weights of all
collected carp from each aquarium were determined at the initial phase and at the end of the experiment, and the carp survival
was also determined by counting the individuals in each aquarium. After 45 days, there were significant differences (P < 0.05) in the relative gain rate (RGR), and daily weight gain (DWG) of diets 1–3 were compared with the control. However,
the survival rate was not affected (P > 0.05) by the dietary treatments. For enzymatic analysis, dissection produced a crude mixture of intestine and hepatopancreas
of each segment to measure. The protease activity in the intestine and hepatopancreas content of fish in diet 2 (487.37 ± 20.58 U g−1 and 20.52 ± 1.93 U g−1) were significantly different (P < 0.05) from that in the control (428.13 ± 23.26 U g−1 and 12.81 ± 1.52 U g−1) and diet 3 (428.00 ± 23.78 U g−1 and 14.04 ± 1.59 U g−1). Amylase activity in the intestine was significantly higher for diet 2 compared to diet 1 and the control. As for amylase
in the hepatopancreas, assays showed higher activity in diet 2 (P < 0.05) compared to the rest. 相似文献
16.
The effects of culture density and bottom areas on cuttlefish (Sepia officinalis) culture were studied. Cuttle fish were cultured under three experimental combinations of culture density and bottom area:
(1) high density and small bottom surface area; (2) low density and large bottom area; (3) high density and large bottom
area. Each experimental protocol was repeated in triplicate. Average weights at the end of the experiment were of 65.8 ± 5.8,
87.1 ± 5.6 and 78.7 ± 5.9 g for cuttlefish cultured under the conditions of protocol 1, 2, and 3, respectively; these differences
were significant between each of the three groups. Total biomass increased faster (up to 7.5 kg per tank) under the high density/large
bottom area conditions (protocol 3) due to the larger number of animals and low mortality in those tanks. Growth rates (%bw day−1) were different between protocols, with growth rates of 2.1 ± 0.1, 3.0 ± 0.2, and 2.5 ± 0.1%bw day−1 obtained for cuttlefish cultured according to protocol 1, 2, or 3, respectively. Average feeding rates were similar for the
three groups—10.7 ± 0.8, 9.7 ± 2.0, and 9.6 ± 1.1%bw day−1 for cuttlefish cultured according to protocols 1, 2, and 3, respectively, while food conversions (%) were different—21.5 ± 3.2,
32.4 ± 2.5, and 27.0 ± 1.1%bw day−1, respectively. Total mortality was high in the high density/small bottom area tanks, 30%, while it was very low for the groups
cultured under conditions of low and high density/large bottom area, 4%. Based on these results, we conclude that culture
conditions that provide large bottom areas also provide good survival conditions and promote growth in comparison those with
small bottom areas, even under conditions of lower culture densities. 相似文献
17.
Fatih Basaran Huseyin Ozbilgin & Yeliz Doganyilmaz Ozbilgin 《Aquaculture Research》2007,38(8):870-876
The critical swimming speed (Ucrit, cm s−1) value of normal juvenile sea bass (Dicentrarchus labrax) (64.7±6.33) was significantly higher than that of fish with lordosis (60.3±6.66) (P<0.05). Both normal fish and those with lordosis showed increased endurance with increasing length during exercise at a fixed water velocity of 50 cm s−1. This speed was used to investigate the separation possibility of deformed specimen from the normal developed fish based on their swimming performance, and 28% separation was achieved without losing any normal fish by the end of the 10th minute. To achieve a better separation of the deformities from the normal, first grading of the juveniles and then a swimming endurance test is advised. 相似文献
18.
Y. Durmaz M. Donato M. Monteiro L. Gouveia M. L. Nunes T. Gama Pereira Ş. Gökpınar N. M. Bandarra 《Aquaculture International》2009,17(4):391-399
Diacronema vlkianum was grown in polyethylene bags at two different temperatures (18 and 26°C) in the laboratory. The biochemical composition
level decreased when the temperature increased from 18 to 26°C. The maximum cell number at 18°C was 11.9 × 106 cells ml−1, while maximum cell number at 26°C was 1.6 × 106 cells ml−1. The maximum level of α-tocopherol was 257.7 ± 21.6 μg g−1 dry weight (DW) at 18°C. The highest total carotenoids and chlorophylls were 6.5 mg g−1 DW and 4.3 mg g−1 DW, respectively, and the main pigments were determined as astaxanthin and lutein. Polyunsaturated fatty acids were found
to be the predominant group, reaching 39.5% of the total fatty acids at 18°C. This comprised 20:5(n − 3) as the main polyunsaturated
fatty acids (20.4%, at 18°C) followed by 22:6(n − 3) (4.8%, at 18°C). The results suggest that D. vlkianum can be successfully used as feed in shellfish hatcheries or aquaculture hatcheries, either as a substitute or in association
with other microalgae, when this algae is cultured at 18°C. 相似文献
19.
The effects of ration levels on growth, conversion efficiencies and body composition of fingerling Heteropneustes fossilis (6.8 ± 0.04 cm, 5.0 ± 0.02 g) were studied by feeding isonitrogenous (40% crude protein) and isocaloric (19.06 MJ kg−1 gross energy) diets representing 1, 3, 5, 7 and 9% of the body weight (BW) day−1 to triplicate groups of fish . Growth performance of the fish fed at the various ration levels was evaluated on the basis
of live weight gain percentage (LWG%), feed conversion ratio (FCR), specific growth rate percentage (SGR%), protein retention
efficiency (PRE%) and energy retention efficiency (ERE%) data. Maximum LWG% and SGR were obtained at a feeding rate of 7% BW day−1, whereas best FCR (1.6), PRE% and ERE% were recorded at a feeding rate of 5% BW day−1. Maximum body protein was also obtained for the group receiving the diet representing 5% of their body weight. However, a
linear increase in fat content was noted with the increase in ration levels up to 7% BW day−1. The SGR, FCR, PRE and ERE data were also analyzed using second-degree polynomial regression analysis to obtain more precise
information on ration level, with the results showing that the optimal ration for these parameters was 6.8, 6.1, 5.9 and 6.2% BW day−1, respectively. Based on the above second-degree polynomial regression analysis, the optimum ration level for better growth,
conversion efficiencies and body composition of fingerling H. fossilis was found to be in the range of 5.9–6.8% of the BW day−1, corresponding to 2.36–2.72 g protein and 88.20–101.66 MJ digestible energy kg−1 diet day−1. 相似文献
20.
Tailiang Liu Hua Wen Ming Jiang Danning Yuan Pan Gao Yujiang Zhao Fan Wu Wei Liu 《Fish physiology and biochemistry》2010,36(3):565-572
An experiment was conducted to investigate the effect of dietary chromium picolinate supplement on growth and haematology
parameters of grass carp, Ctenopharyngodon idellus. Six diets with increasing dietary chromium picolinate levels 0, 0.2, 0.4, 0.8, 1.6 and 3.2 mg kg−1 were fed to triplicate groups of 20 fish (initial weight of 12.78 ± 1.16 g, mean ± SD) in a flow water system for 10 weeks.
Fish fed the diet supplemented with 0.8 mg Cr kg−1 had significantly improved weight gain (WG), feed efficiency ratio (FER), protein efficiency ratio (PER) and protein retention
(PR). Fish fed high-chromium diets exhibited lower whole-body crude lipid contents than fish fed low-chromium diets. Liver
glycogen concentrations for fish fed the diet with 0.2 mg Cr kg−1 was the highest (77.67 mg g−1). Fish fed the diet supplemented with 1.6 and 3.2 mg Cr kg−1 had significantly lower liver glycogen concentrations than other groups (P < 0.05). The highest serum insulin concentrations were observed in fish fed the diet supplemented with 0.8 mg Cr kg−1, but serum insulin concentrations decreased (P < 0.05) when dietary supplementation of chromium was higher than 0.8 mg Cr kg−1. Cholesterol concentrations decreased in direct proportion to dietary chromium level and achieved the lowest level when the
fish were fed the 0.8 mg Cr kg−1 diet, but increased when the fish were fed the diet with more than 0.8 mg Cr kg−1 (P < 0.05). Fish fed the diet supplemented with 0.8 mg Cr kg−1 had higher triglyceride and high-density lipoprotein cholesterol (HDL-C) concentrations compared to other treatments. The
results of the present study suggested that chromium picolinate could modify serum carbohydrate and lipid metabolism profile,
and that the optimal dietary chromium level was 0.8 mg kg−1 for grass carp according to growth. 相似文献