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1.
Genetic parameters and genotype by rearing density interactions for growth traits and survival were investigated in Litopenaeus vannamei. A total of 3626 shrimps from 40 families in two densities (low density, 80 shrimps m?2; high density, 160 shrimps m?2) were measured for four growth traits, body length, body weight, cephalothorax length and abdominal segment length. Variance components and genetic parameters for growth and survival were estimated using a two‐trait animal model or a threshold (probit) sire and dam model. The common environment effect was excluded because it could not be partitioned effectively, likely because of high heritability. The heritability for growth traits varied from 0.21 to 0.44, indicating a moderate level. For survival, the back‐transformed heritability () was 0.36 ± 0.06 and 0.22 ± 0.04 for the low and high densities respectively. There were no significant differences in heritability for growth traits and survival between the two densities (P > 0.05). High genetic correlations (0.94–0.98) between the two densities for growth traits indicated a low genotype by density interaction and ranking effect across the environments, which suggested that these traits were controlled mostly by the same genes over the two densities. Therefore, selection in a low‐density environment should produce desired correlated responses for growth at a high density. Genetic correlation (0.77 ± 0.09) between the two densities for survival was moderate and significant, which indicated that the genotype by density interaction effect was moderate and low for survival under the two densities. Our results provide crucial information for use in L. vannamei breeding programmes in China.  相似文献   

2.
Studies on chronic or acute toxicity of nitrogen species on fish in recirculating aquaculture systems (RAS) usually focused on adverse effects of total ammonia nitrogen (TAN: sum of NH3 + NH4+) and nitrite (), while underestimating the potential effects of high nitrate accumulation on growth and health status of fish. In our study, Nile tilapia (Oreochromis niloticus) were exposed to five different nitrate concentrations (0, 10, 100, 500 and 1000 mg L?1 ‐N) over 30 days. Growth parameters (feed conversion ratio (FCR), specific growth rate (SGR), hepatosomatic index (HSI)), blood samples (concentrations of haemoglobin, methaemoglobin, plasma /) and the histology of the gills were studied to evaluate growth and health status of the fish. At the highest nitrate concentration, the fish showed significantly reduced growth and impaired health status (SGR, FCR, plasma /, haemoglobin and methaemoglobin concentration), demonstrating that too high nitrate concentrations can negatively influence tilapia production in RAS. Here, we recommend not exceeding concentrations of 500 mg L?1 ‐N in juvenile tilapia culture to ensure an optimal health and growth status of the fish, as below that concentration no effects on the tilapia have been observed.  相似文献   

3.
A field campaign was conducted around salmon cages, using a combination of a towed ADCP and a free‐fall multi‐parameter profiler, in order to investigate flow structures and the possible distribution of effluent materials. Two transect observations showed that hydrographic conditions changed dramatically within 5 days, from highly stratified open water conditions to weak stratification. Three‐dimensional observation revealed that flow was blocked behind the cages and that the blockage was reduced as the distance from the cages increased. The flow speed was positively correlated with the intensity of the backscattering signal. The R2 value was high immediately behind the cages and decreased with distance from the cages. The flow time series behind the cages exhibited a k–2 power law spectrum that was consistent with a typical internal wave spectrum. This suggests that eddies shed from the cages were highly influenced by stratification. We estimated the rate of kinetic energy dissipation, , from YODA Profiler data based on the Thorpe scale approach. We also estimated the eddy diffusivity coefficient, . Both and followed a lognormal probability density function. The mean was consistent with a one‐dimensional diffusion model assessed from the R2 values of flow speed and backscatter intensity.  相似文献   

4.
The effect of temperature (10, 13, 16, 19 and 22°C) on hatching, development and survival of yolk‐sac larvae of European hake, Merluccius merluccius, was studied. At 22°C the experiment was suspended because all eggs died a few hours after incubation. Five morphological indicators of larval development (standard length – SL, yolk‐sac volume – YSV, oil globule diameter – OD, body height – BH and body wet weight – BW) were analysed. SL, YSV, OD and BW of newly hatched larvae were biggest in size and weight at low temperatures (P < 0.05). Throughout the experiments, the rates of changes in SL, YSV and OD varied with temperature (P < 0.05). By contrast, BH and BW remained constant and did not show significant relationship with the effect of temperature (P > 0.05). The potential model showed that the SL growth rate varied from 0.05 to 0.08 mm day?1 from 10.5 to 19.5°C respectively. However, at all temperatures two growth phases were identified: a rapid growth phase followed by a slow one. Rapid growth rate in length and depletion in yolk‐sac and oil globule occurred at high temperatures. After total YSV and OD consumption (death by starvation), larvae died between 8 and 14 days at 19.5 and 10.5°C respectively, reaching a maximum length of 4.3 mm at 10.5°C. Metabolic indices such as: lowest threshold temperature (T0); effective larval development (); cumulative thermal units (TC) to complete larval development; the temperature coefficient on growth rate in length (Q10) and the condition factor (K) were also studied.  相似文献   

5.
A novel marine origin Bacillus subtilis strain H1 isolated from a shrimp culture pond effectively removed NH4+‐N, ‐N and ‐N, with a maximum ammonium, nitrite and nitrate removal rate of 2.35 mg NH4+‐N L?1 hr?1 per OD, 9.64 mg ‐N L?1 hr?1 per OD and 0.75 mg ‐N L?1 hr?1 respectively. The gas chromatography–isotope ratio mass spectrometry results indicated that N2O was emitted when 15NH4Cl, Na15NO2 or Na15NO3 was used. Additionally, N2 was also produced when Na15NO2 was used. Single‐factor experiments suggested that the optimal conditions for NH4+‐N and ‐N removal were glucose as a carbon source, C/N 15, initial pH 7.5, 30 g/L NaCl, 28°C and a shaking speed of 160 rpm. Orthogonal tests showed that the optimal conditions for NH4+‐N removal were C/N 15, pH 9, 10 g/L NaCl and shaking speed 160 rpm when ammonium chloride was used as the substrate. The optimal conditions for ‐N removal were C/N 10, pH 6, 10 g/L NaCl and a shaking speed of 160 rpm when sodium nitrite was used as the substrate. In summary, B. subtilis strain H1 had highly efficient aerobic nitrifying–denitrifying ability and high adaptability, suggesting that it is potentially valuable to marine aquaculture.  相似文献   

6.
Under controlled conditions of food density and temperature, larval performances (ingestion, growth, survival and settlement success) of the flat oyster, Ostrea edulis, were investigated using a flow‐through rearing system. In the first experiment, oyster larvae were reared at five different phytoplankton densities (70, 500, 1500, 2500 and 3500 μm3 μL?1: ≈1, 8, 25, 42 and 58 cells μL?1 equivalent TCg), and in the second, larvae were grown at four different temperatures (15, 20, 25 and 30°C). Overall, larvae survived a wide range of food density and temperature, with high survival recorded at the end of the experiments. Microalgae concentration and temperature both impacted significantly larval development and settlement success. A mixed diet of Chaetoceros neogracile and Tisochrysis lutea (1:1 cell volume) maintained throughout the whole larval life at a concentration of 1500 μm3 μL?1 allowed the best larval development of O. edulis at 25°C with high survival (98%), good growth (16 μm day?1) and high settlement success (68%). In addition, optimum larval development (survival ≥97%; growth ≥17 μm day?1) and settlement (≥78%) were achieved at 25 and 30°C, at microalgae concentrations of 1500 μm3 μL?1. In contrast, temperature of 20°C led to lower development (≤10 μm day?1) and weaker settlement (≤27%), whereas at 15°C, no settlement occurred. The design experiments allowed the estimation of the maximum surface‐area‐specific ingestion rate  = 120 ± 4 μm3 day?1 μm?2, the half saturation coefficient {XK} = 537 ± 142 μm3 μL?1 and the Arrhenius temperature TA = 8355 K. This contribution put a tangible basis for a future O. edulis Dynamic Energy Budget (DEB) larval growth model.  相似文献   

7.
The Channel Catfish Ictalurus punctatus is an important ecological, recreational and aquaculture species. In both natural and pond culture systems, Channel Catfish are periodically exposed to acute increase in temperature, especially in the summer, which may induce a stress response. With the effects of global climate change, the impact of rising temperatures on aquatic systems is expected to be exacerbated in the future. Hence, there is the need to understand the physiological mechanisms controlling the thermal stress response in fish. Acid–base, haematological, osmotic and metabolic regulations were investigated following acute temperature increase from 28°C to either 32°C or 36°C at a rate of 2°C/hr to assess the physiological response of Channel Catfish to temperature increase. Blood was sampled 1 hr after treatment temperatures were reached. When temperature increased from 28 to 32°C, blood bicarbonate () decreased while cortisol, partial pressure of carbon dioxide (pCO2) and glucose increased. When temperature increased from 28 to 36°C, blood pH, , chloride, total proteins and mean corpuscular haemoglobin concentration decreased while cortisol, pCO2, haematocrit, haemoglobin, glucose, lactate, mean corpuscular volume and mean corpuscular haemoglobin all increased. The changes observed are characteristic of acute stress responses in fish and suggest that acute temperature increases to both 32 and 36°C are physiologically stressful to Channel Catfish.  相似文献   

8.
The pharmacokinetic of minocycline was studied after a single intravenous as well as oral dose (5 mg/kg body weight) in crucian carp (Carassius auratus) reared in freshwater at 10°C. Plasma samples were randomly collected from six fish at each sampling time. Plasma concentrations were determined by high‐performance liquid chromatography and further subjected to noncompartmental analysis. Initial concentration of minocycline just after intravenous administration was calculated as 7.320 μg/ml, while the other parameters after intravenous injection were determined as flows: apparent elimination rate constant (λz) of 0.064 per hr, apparent elimination half‐life () of 10.82 hr, total body clearance (Cl) of 142.72 ml/hr/kg, volume of distribution (Vz) of 2,227.38 ml/kg and volume of distribution at steady‐state (Vss) of 1,937.08 ml/kg. While after oral administration, the λz, , mean absorption time (MAT), absorption half‐life (t1/2ka) and bioavailability were determined as 0.059 per hr, 11.74, 5.55, 3.84 hr, and 81.98%, respectively, and the peak concentration was observed as 1.474 ± 0.362 μg/ml at 8 hr. It was shown that minocycline was slowly but relatively completely absorbed, extensively distributed, and slowly eliminated in crucian carp. Based on the ratios of AUC0–24 hr/MIC90, a minocycline dosage of 5 mg/kg body weight administered intravenously or orally would be only effective to successfully treat crucian carp infected by bacterium with MIC values ≤0.25 μg/ml.  相似文献   

9.
A physiological study was performed to explore the effects in Sphoeroides annulatus (Jenyns 1842) juveniles of exposure to different salinities 10, 17, 23, 29, 35 and 41‰ on oxygen consumption rate (OCR), ammonium excretion rate (AER), the oxygen‐nitrogen atomic ratio (O:N), osmoregulation and Na+/K+‐ATPase expression. The OCR values ranged from 27.9 to 30.9 mg O2 h?1 kg?1, displaying a Type 1 response pattern Kinne (1977). AER ranged from 0.60 to 0.69 mg h?1 kg?1, and O:N values were from 53.12 to 59.26, indicating that the puffers use proteins and lipids as an energy‐substrate. Osmoregulation in S. annulatus was hyposmotic in salinities of 23, 29, 35 and 41‰ and hyperosmotic in a salinity of 10‰. The isosmotic point of the bullseye puffer was 356 mmol kg?1 (10.5‰). The enzyme expression analysis indicates that the fish acclimated to 41‰ had the highest Na+/K+‐ATPase expression level, whereas, the lowest expression level was found close to the isosmotic point. Na+/K+‐ATPase expression in the gills was found to have a U‐shaped relationship with environmental salinity. We conclude that the bullseye puffer is strongly euryhaline and can be cultivated in a wide range of environments that has important economic implications.  相似文献   

10.
Hypnea musciformis that are harvested from natural beds and introduced Kappaphycus alvarezii are the two main sources of raw material for the production of carrageenan in Brazil. The daily growth rate (DGR) and carrageenan yield (CY) of both species were evaluated in vitro and in the sea to assess the feasibility of cultivating H. musciformis as a complement or as an alternative to the production of K. alvarezii. The DGR of H. musciformis (10.8 ± 0.6% day?1) was higher than the DGR of K. alvarezii (5.6 ± 0.3% day?1) in vitro, and the CY extracted using NaOH (62.3 ± 0.15%) was better than using KOH (32.0 ± 0.3%). In eutrophic medium, the DGR of H. musciformis (9.4 ± 2.1% day?1) was higher than that of K. alvarezii (5.0 ± 1.2% day?1). However, in this condition, the CY was similar for both species (50.2 ± 3.5%), and both species were effective in removing nutrients (30% NH4+, 18% NO2? and 2.4% ). H. musciformis did not survive when cultivated in the sea, neither in monospecific nor in multispecific cultivation. Moreover, K. alvarezii grew better in monospecific cultivation throughout the year (from 1.73 to 5.15% day?1) except during the wet period and the CY was high in both cultivation types (33.7–50.8%). We conclude that the cultivation of H. musciformis is not an alternative to K. alvarezii on the Brazilian southeastern coast. However, the results in vitro suggested its use as a complementary source of carrageenan or as a biological filter.  相似文献   

11.
Nan Bai  Min Gu 《Aquaculture Research》2017,48(4):1856-1865
This study investigated the attenuate effects of zinc (Zn) and selenium (Se) on lipopolysaccharide (LPS)‐induced oxidative stress in sea cucumber Apostichopus japonicus coelomocytes in vitro. Coelomocytes were first treated with different concentrations of Zn (0.12, 0.48 and 1.2 mM) and Se (0.06, 0.24 and 0.6 mM) for 12 h and the optimal concentrations of Zn and Se as antioxidants for A. japonicus coelomocytes were selected based on antioxidant parameters including total antioxidant capacity (T‐AOC) and activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione‐S‐transferase (GST) and concentration of reduced glutathione (GSH). Next, coelomocytes were pretreated with 0 (control), 0.12 mM Zn or 0.24 mM Se for 12 h, and then were treated with LPS (100 μg mL?1) for 6 h. Se completely inhibited LPS‐induced increase in superoxide anion () production and lipid peroxidation (LPO) and effectively prevented the LPS‐induced decreases of T‐AOC, activities of SOD, CAT, GPx and GST and concentration of GSH. Zn alleviated the LPS‐induced oxidative stress but the protective effects were not as effective as Se. The present work also proved that suboptimal amount of Zn and Se could impair the antioxidant system of A. japonicus coelomoytes. In conclusion, the present work demonstrated that both Zn and Se, especially Se, have the potentials to be the effective antioxidants for A. japonicus. Further work will be conducted for their optimal administration concentrations in vivo.  相似文献   

12.
Nitrogen and Phosphorus are the major end products of fish feed loading and affect the water environment as a whole. A magnetic stirrer was used to simulate the intensity of water flow by using different stirring strengths (0, 600, 1,200 rpm), and kinetic experiments on nutrients release from different fish feed (0.2500 and 0.5000 g) were performed. Results have shown that total phosphorus (TP) increase rapidly and become stable in about 96 hr, while orthophosphate ( ), total nitrogen (TN) and ammonia nitrogen ( ) increase relatively slowly and gradually reach stable from 200, 300 and 300 hr respectively. Both released contents of unit weight fish feed (i.e. released nutrients contents) and released nutrients concentrations in the condition of stirring were higher than those in the static condition. All of the pseudo‐first‐order, pseudo‐second‐order and Elovich kinetic models can be used to describe variations of released TP, , TN and contents with time, while the pseudo‐first‐order kinetic and Elovich kinetic models give better results with R2 = .66–.99 and R2 = .57–.99 respectively. Variance analysis showed that both stirring strength and fish feed type have significant effects on released TP, TN and contents (p < .05), while fish feed dosage has no significant effects (p > .05). In addition, only the fish feed type does have significant effects on contents (p < .05). In sum, the release kinetics and the factors related to the release of nutrients from fish feed are essential in planning strategies of nutrient management and pollution control.  相似文献   

13.
Three‐year classes of Atlantic cod Gadus morhua were studied throughout their rearing in the eastern coast of Iceland from 2004 to 2011. The growth and status of maturity were recorded during the rearing. For one of the year classes, genetic parameters for body weight and maturity status were estimated from 757 individuals, which were the offspring of 40 dams and 20 sires. The estimate for heritability of body weight was h2 = 0.34 at the average weight of 630 g, and heritability for proportion of maturity was h2 = 0.17 given the same weight. The relationship between body weight and the proportion of mature individuals at first winter revealed a strong genetic correlation of rG = 0.90. The phenotypic relationship between body weight and proportion of maturity was estimated with a Bayesian logistic regression as P(yi = 1(mature)) = Φ(β0 + β1weight + β2sex). The best fit yielded β0 = ?2.9320 with a 95% interval between ?3.2807 and ?2.5394, β1weight = 0.0041 with a 95% interval ranging from 0.0035 to 0.0046 and β1sex = ?0.0201 with a 95% interval from ?0.2003 to 0.1445. The gender had no notable effect. This strong phenotypic and genetic correlation in body weight and maturation suggests that an increased growth rate will consequently lead to a higher proportion of mature individuals in the population. As a consequence, genetic manipulations to simultaneously increase growth and delay maturation may present a challenge.  相似文献   

14.
This study assessed the effect of cyclical feeding on compensatory growth, nitrogen (N) and phosphorus (P) budgets of juvenile Litopenaeus vannamei. A 36‐day growth trial was performed with four different feeding protocols. The control group (S0) was fed to satiation twice every day during the whole experimental period; treatment groups S1, S2 and S3 were fed by the 9, 5 and 3 cycles of 1:3, 2:5 and 3:9 (fasting days:feeding days) respectively. Fasting in S1, S2 and S3 groups did not change the specific growth rate in wet weight (SGRw), but the feed conversion efficiency (FCE) and protein efficiency ratio (PER) were significantly increased (P < 0.05) in comparison with control. The N and P consumed per unit wet weight gain of shrimp in S1, S2, S3 groups were significantly lower (P < 0.05) than control group by 15.39%, 15.96%, 19.33% for N, and 15.16%, 15.98%, 19.26% for P respectively. The total discharge of N and P (including N and P discharged by faeces (FN/P), non‐faecal excretions (UN/P) and exuviations (EN/P); ) was significantly lower (P < 0.05) in the experiment groups by 19.91–22.07% for N and 18.68–26.37% for P respectively. Overall, the results suggest that the L. vannamei can reach completely compensatory growth, and the total discharge of N and P per unit wet weight gain of L. vannamei significantly decreased by cyclical feeding, which could have a positive effect on the reduced of environmental N and P loading due to the cultured of L. vannamei.  相似文献   

15.
Herbivorous fish can have strong effects on stream ecosystem function by consuming primary producers and excreting limiting nutrients, but it is unclear whether they are resource limited. Thus, understanding factors regulating abundance of these fish might help predict ecosystem function. We used stream mesocosms to test whether populations of central stoneroller Campostoma anomalum exhibit density dependence across a range of typical densities and resource abundance found in Great Plains streams. We predicted that incrementally increasing stocking biomass from 3·7 to 24·9 g·m?2 would reduce standing stocks of resources resulting in lower growth of stocked fish. Fish growth (over 41 days) was compared to initial stocking biomass and primary production as well as standing stocks of algae and invertebrates using regression analysis. Mean growth of individuals was negatively associated with stocking biomass ( = 0·55; P = 0·02), as predicted. Contrary to our prediction, increases in fish biomass led to increased primary productivity ( = 0·31, P = 0·07), but resulted in no relationship among algal filament lengths ( = 0·00; P = 0·34), algal biomass ( = 0·12; P = 0·19) or invertebrate biomass ( = 0·03; P = 0·30). Thus, density dependence occurred without an apparent reduction in food resources. We hypothesised that stoneroller growth was possibly limited by competition for high‐quality algae or invertebrates, or behavioural interactions causing interference competition.  相似文献   

16.
This study established a pilot‐scale recirculating treatment system that coupled an ecological process with a biological process to achieve adequate water quality and to minimize the water consumption for intensive marine culture. The recirculating treatment system consisted of a settling cell, a biofilter tank, a bivalve tank and gravel beds. The toxic pollutants, threatening the growth of bivalves, were reduced by the settling cell and the biofilter tank, so that the polyculture of shrimp and bivalves could be achieved. The living bivalve tank could function well as a remover of remaining small suspended solids (SS), and other pollutants. As the SS was reduced to a very low level by bivalve tank before the water flowing into the gravel beds, the risk of clogging was prevented. The studies suggested that the system maintained high removal efficiencies of SS, ammonium nitrogen () and nitrite nitrogen () and could contribute to the increase in shrimp yield.  相似文献   

17.
Cannibalism is frequently observed in larviculture of orange‐spotted grouper Epinephelus coioides. Previously, based on measurements of morphometric characters, a linear equation of total length (TL) of prey to cannibals was proposed: TLprey = 0.80 TLcannibal – 1.50. To verify the reliability of the equation, experiments were performed with pairs of fish with different TLs. Cannibalism occurred only when the cannibal‐prey size ratios were equal to or larger than that predicted by the equation. To predict the probability of cannibalism among the grouper of known TLs, a logistic regression model was proposed. The logistic regression model is: The logistic regression model showed the following: when either TLprey or TLcannibal is constant, the probability of cannibalism increases with increase in the cannibal‐prey size ratios; if given a constant cannibal‐prey size ratio, probability of cannibalism is lower in early stages than in later stages. The prediction contrasts with that calculated from the linear equation where the minimum cannibal‐prey size ratios decrease with size of the cannibal. However, the prediction matches observed rearing experiences: cannibals prefer smaller prey to larger ones and the cannibalism rate declines as fry age.  相似文献   

18.
The effects of body and meals sizes on gastric evacuation (GE) of the endangered Siberian sturgeon (Acipenser baerii) were parameterized (at temperatures ranging from 16.8 to 17.6°C) using radiography technique. GE experiments were performed using different body sizes A. baerii ranged from 1.5 kg to 5 kg fed on meal sizes of 4.6 g to 47.6 g composed of either commercial pellets or live food (fish prey, whiting). The commercial pellets used in these experiments had barium sulphate at concentrations of 20%, while the same amount was injected into the body of live food for radiography technique monitoring. The course of GE in A. baerii was best described by the square root model independently of meal size. The effects of body mass and temperature on GE rates were described by power model and simple exponential model respectively. GE rates of A. baerii fed on live food could be summarized by (g/hr), while for commercial pellets, where St is the stomach contents mass (g), W is fish wet weight (cm), T is temperature (°C), and t is time (hr). These summarized models could estimate the time required for a meal to be evacuated from the stomach of A. baerii or determine the stomach fullness at postprandial time t. These results will assess the planning of feeding regime for A. baerii to avoid their overfeeding and underfeeding.  相似文献   

19.
Arctic charr, Salvelinus alpinus, were obtained as eggs from two North American sources, an eastern (Fraser River, Canada) and a western (Bristol Bay, Alaska, USA) stock. Fish were pit tagged (eastern , western ) and stocked communally into three replicated 7‐m3 tanks at a density of 7.6 ± 1.2 kg/m3. Each tank was supplied with 2 ppt salinity water from a recirculating biological filtration system. Fish were fed a commercial diet (48%P, 20%F) from automatic feeders. Fish were harvested approximately 24 mo after hatching at a final tank density of 56.2 ± 1.3 kg/m3. Mean daily water temperature was 10.4 C with a range of 5.9–12.6 C and mean dissolved oxygen was 12.6 mg/L with a range of 9.7 (91% of saturation) to 17.8 mg/L (149% of saturation). Individual fish were evaluated for total, carcass, and fillet weight, sex, stage of sexual maturity, fillet fat, fillet color, and gonad weight. The western stock fish grew faster and were significantly larger ( ) (P < 0.0001) than the eastern stock ( ). Heritabilities were low for all traits and ranged from 0.08 ± 0.06 to 0.28 ± 0.09. Genetic correlations for body size traits were highly positive and significant (0.99–1.00). Genetic correlations of fillet color and body size traits were positive, but not significant. Genetic correlations of fillet fat with body size traits were negative, but not significant. Genetic correlation of fillet fat and fillet color was positive and significant (0.55 ± 0.27). Random genetic variation was assessed from microsatellite variability on 30 fish from each stock (eastern and western) and 32 fish from a third commercial source of unknown origin for comparison. The amount of variation detected in the western stock was higher than the eastern and commercial stocks. The eastern stock was composed of an admixture of two sources, the commercial stock was composed by three different sources, and the western stock was composed by three to four source populations. Data will be used to calculate breeding values on a separate group of captive sibling adult broodfish and a line selected for carcass weight and maturity at 3 yr will be developed.  相似文献   

20.
We studied the feeding and growth rates, feed efficiency and nutritional composition of subadult octopuses (689 ± 77 g) fed low‐lipid diets with two different protein/energy ratios (P/E): Medium P/E diet (30.5 g protein MJ?1, 662 g kg?1 protein dry weight (dw)) or High P/E diet (36.8 g protein MJ?1, 843 g kg?1 protein dw). Survival was 100% for the Medium P/E and 87.5% for the High P/E diet. The specific feeding rates were 1.91% and 1.67% body weight day?1 for the Medium P/E and High P/E diet, respectively (P < 0.05). The specific growth rates (0.92% and 1.25% body weight day?1), feed efficiency indices (47.3% and 72.7%), productive protein value (23.9% and 29.1%) and digestive gland index (5.6% and 6.4%) were significantly better in animals fed the High P/E than the Medium P/E diet (P < 0.05). The proximate composition of the digestive gland was similar for both diets, but the total lipid content of carcass was higher in animals fed the Medium P/E diet (P < 0.05). Our results suggest that the protein content of the feed could be a factor regulating feeding rates in octopus.  相似文献   

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