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1.
This study evaluated the effects of diets containing 0, 25, 50, 75 and 100 g kg?1 Spirulina platensis on proximate composition, fatty acid profile and lipid peroxidation of rainbow trout (Oncorhynchus mykiss). Supplementation of S. platensis did not change moisture and protein contents, but fish fed 50 and 100 g kg?1 S. platensis had lower muscle lipid content than those fed control diet (P < 0.05). Fish fed 100 g kg?1 of S. platensis contained lower percentages of saturated and monounsaturated fatty acid and a higher percentage of polyunsaturated fatty acid than those fed control diet (P < 0.05). The n‐3/n‐6 ratio of the fatty acid increased and muscle atherogenic and thrombogenic indices were significantly decreased as the dietary supplement of S. platensis increased. Furthermore, lipid peroxidation of the fillet significantly decreased with increasing dietary S. platensis at 4 °C and at ?20 °C (P < 0.05). The results of this study show that supplementation of S. platensis to the diet improves muscle quality of the rainbow trout.  相似文献   

2.
The crude ethanol, methanol and aqueous extracts of Spirulina (Spirulina platensis) have been investigated for antibacterial activity using disc diffusion assays against various strains of fish and shellfish pathogens e.g. Pseudomonas putida (ATCC 49128; PP1, PP2), Pseudomonas aeruginosa (ATCC 35032; PA1, PA2), Pseudomonas fluorescens (PF1, PF2), Aeromonas hydrophila (ATCC 49140; AH1, AH2, AH3, AH4), Vibrio alginolyticus (VA), Vibrio anguillarum (VAN), Vibrio fluvialis (VF), Vibrio parahaemolyticus (VP), Vibrio harveyi (VH), Vibrio fisheri (VFS), Edwardsiella tarda and animal isolates of Escherichia coli (O115, O1, O156, O164, O111 and O109). The minimum inhibitory concentrations (MIC) of crude extracts were determined using the tube dilution method. Ethanolic extract showed comparatively higher antibacterial activity (15.66 mm) than that of methanolic and aqueous extract of S. platensis along with their respective MIC values, ranging from 100 to 150 μg mL?1. The aqueous extract had no effective antibacterial activity against the test microorganism. The study suggested that S. platensis may have potential use in aqua feed as an antimicrobial agent of pharmaceutical interest.  相似文献   

3.
In this study, the influence of an agricultural liquid organic fertilizer on growth and biomass composition of Spirulina platensis Geitler was studied. In the first trial, five concentrations of organic fertilizer were arranged, e.g., 0.1, 0.25, 0.5, 1 and 2?ml/l, in which no other extra nutrients except bicarbonate were used. Maximum dry weight, chlorophyll a and specific growth rate were achieved in control group. In the second trial, initial fertilizer levels of the three groups were 0.1?ml/l and all groups contained sodium bicarbonate. One of the groups had 2.5?g/l NaNO3, while the other was supported with 0.1?ml/l fertilizer by two-day intervals to see the effect of nitrogen. In order to understand the effects of phosphate, 0.4?g K2HPO4 was added to the other group as well as 2.5?g NaNO3. Between the experimental groups, the highest chlorophyll a value was found in control group as 53.97?mg/l. The chlorophyll value at group II (37.65?mg/l) was lower than the control group. The maximum dry weight and crude protein recorded in control group were 1,330?mg/l and 60.17%, respectively, when compared with 1,256?mg/l and 59.92% in group II. No significant differences were observed in crude protein values of Spirulina grown in control and group II (P?<?0.05). Consequently, it was seen that commercial liquid organic fertilizers may be replaced by Zarrouk??s medium except for nitrate, phosphate and bicarbonate in S. platensis cultures in order to decrease the production costs.  相似文献   

4.
The effect of feeding Spirulina platensis on the growth, carcass composition, organoleptic quality, digestive enzyme activity and digestibility of common carp, Cyprinus carpio L., was studied through a culture trial lasting 120 days. Four experimental diets were employed by replacing fish meal protein from the standard diet at 25%, 50%, 75% and 100% through the incorporation of Spirulina. Another diet with Spirulina as the sole source of protein was also used. The final weight gain, specific growth rate, food conversion ratio and protein efficiency ratio of common carp were not affected by Spirulina supplementation. However, the diet with Spirulina as the sole source of protein resulted in better net protein retention. The muscle RNA:DNA ratio of fish fed Spirulina diets was higher than that of fish fed control diet. There was no significant difference in carcass moisture and protein content in the fish fed Spirulina diets as compared to fish-meal-based control diet. The carcass ash and fat contents were positively and negatively correlated with dietary Spirulina level, respectively. Organoleptic evaluation revealed no effect of Spirulina feeding on the quality of both raw and cooked fish. The gut digestive enzyme activity did not show any definite trend with respect to Spirulina supplementation. Spirulina improved the protein digestibility of the diets.  相似文献   

5.
This study investigated monthly changes of sedimentation and sediment properties in three different culture systems (ponds) – i.e. jellyfish Rhopilema esculenta monoculture (J), sea cucumber Apostichopus japonicus and jellyfish co‐culture (SJ) and sea cucumber monoculture (S) – to verify the feasibility of co‐culturing jellyfish and sea cucumbers. Results showed that jellyfish culture accelerated the settling velocity of total particulate matter (TPM). Average TPM settling velocities in the SJ (75.6 g m?2 day?1) and J (71.1 g m?2 day?1) ponds were significantly higher than that in the S pond (21.7 g m?2 day?1) from June to September during the jellyfish culture period. Average settling velocities of organic matter (OM), total organic carbon (TOC), total nitrogen (TN) and total phosphorus (TP) in the SJ pond increased significantly by 3.0, 2.9, 3.3 and 3.8 times, respectively, compared with those in the S pond. Sediment contents of OM, TOC, TN and TP in the SJ and J ponds were significantly higher than those in the S pond during the jellyfish culture season. The specific growth rate of sea cucumbers feeding on SJ sediment was significantly higher than that of those feeding on S sediment. Co‐culturing sea cucumbers with jellyfish may help alleviate benthic nutrient loading due to the jellyfish and provide a secondary cash crop.  相似文献   

6.
The aim of this study was to evaluate the effect of light limitation on the water quality, bacterial counts and performance of Litopenaeus vannamei postlarvae reared with biofloc at low salinity (≈9 g L?1). Two treatments were designed: T1 = culture with natural sunlight and T2 = culture in darkness. After 28 days, in both treatments, the final weight of shrimp was over 0.6 g with a specific growth rate over 7.4% d?1, and a survival rate over 70%. In both treatments, Vibrio sp. concentration presented low values (culture with natural sunlight = 0.1 to 9.9 × 102 CFU mL?1, culture in darkness = 0.4 to 11.7 × 102 CFU mL?1) and Bacillus sp. had high values (culture with natural sunlight = 0.7 to 66.0 × 104 CFU mL?1, culture in darkness = 0.7 to 65.8 × 104 CFU mL?1). All water quality parameters remained within the ranges suitable for shrimp culture, except for alkalinity during the first stage of the study. Although in some sampling periods some significant differences were found in bacterial counts and water quality parameters, shrimp productive performance under culture with biofloc at low salinity was not affected significantly by light limitation.  相似文献   

7.
Soybean molasses was evaluated as a partial replacement for sugarcane molasses as a carbon source for biofloc development in the superintensive culture of Pacific white shrimp (Litopenaeus vannamei). A 50‐day study was conducted with juvenile (3.2 g) shrimp stocked in 16 800 L tanks at a stocking density of 250 shrimp m?3. Control of total ammonia concentration was performed by the addition of combined mixtures of soybean and sugarcane molasses to the culture water. Three different molasses treatments were evaluated using different soybean‐to‐sugarcane molasses ratios: 15–85%, 38–62% and 60–40% respectively. The control group was treated only with sugarcane molasses. Water quality, chlorophyll a concentration, heterotrophic bacterial load, Vibrio spp. concentration and zootechnical indexes were all evaluated. Total ammonia concentration was controlled by heterotrophic and chemotrophic pathways. Biofloc formation, as quantified by measuring the total suspended solids, was not altered. The Vibrio spp. concentration showed a significant reduction in treatments with soybean‐to‐sugarcane molasses ratios of 38–62% and 60–40%. All combined mixtures of soybean and sugarcane molasses could maintain water quality and productivity in the superintensive culture of L. vannamei using the biofloc system. Thus, the potential use of a residue from agroindustry as a carbon source in a biofloc culture is demonstrated.  相似文献   

8.
Six iso‐nitrogenous (350 g protein kg?1) and iso‐caloric (4100 kcal kg?1) diets with or without probiotics supplementation namely T1 (Basal feed (BF) without probiotics; control), T2 (BF + Bacillus subtilis and Lactococcus lactis), T3 (BF + L. lactis and Saccharomyces cerevisiae), T4 (BF + B. subtilis and S. cerevisiae), T5 (BF + B. subtilis, L. lactis and S. cerevisiae) and T6 (BF + heat‐killed bacteria of B. subtilis, L. lactis and S. cerevisiae) were fed to Labeo rohita fingerlings (6.0 ± 0.06 g) for 60 days in triplicate tanks (30 fish per tank). In all probiotic‐supplemented diets, the probiotic concentration was maintained at 1011 cfu kg?1 feed. After 60 days of culture, the fish fed combination of three probiotics at equal proportion (T5) had higher (P < 0.05) growth, protein efficiency ratio, nutrient retention and digestibility and lower (P > 0.05) feed conversion ratio over other treatment groups. Total heterotrophic bacterial population in intestine was drastically reduced on 15th and 30th days of sampling than the initial value (0 day of sampling) for T3, T4 and T5 groups. Except T6, the gut colonization of respective probiotics, which were supplemented through the diets, was also increased up to 30 days of culture of fish and thereafter remained constant.  相似文献   

9.
By introducing recirculation aquaculture systems (RAS) in the nursery phase of the blue mussel (Mytilus edulis) (17–18 mm), we aimed at a similar growth and survival and a similar water quality compared to the commonly used flow‐through systems (FTS). To calculate water flow and size of the biofilter, a series of experiments were done to determine clearance rate (9.26 mL min?1), pseudo faeces threshold (60 000 cells Pavlova lutheri mL?1), nitrogen production (0.00065 mg TAN h?1 ind?1 and 1.6 × 10?5 mg NO2–N h?1 ind?1) and oxygen consumption (0.03 ± 0.01 mg O2 h?1 ind?1). RAS showed no significant differences in water quality (0.06 mg TAN L?1; 7.7 mg O2 L?1) and growth performance of mussel seed specific growth rate (SGR = 5% day?1) after the experimental period of 4 weeks compared with FTS. The low water refreshment, 10% per day, as well as the constant chlorophyll concentrations (9.76 ± 1.06 μg L?1), suggests the potential of RAS as culture system for mussel seed.  相似文献   

10.
An indoor trial was conducted for 42 days to evaluate water quality, Vibrio density and growth of Litopenaeus vannamei in an integrated biofloc system (IBS) with Gracilaria birdiae. Four treatments were used, each in triplicate: Control (monoculture shrimp); IBS 2.5 (L. vannamei and 2.5 kg wet weight seaweed m?3); IBS 5.0 (L. vannamei and 5.0 kg wet weight seaweed m?3) and IBS 7.5 (L. vannamei and 7.5 wet weight seaweed m?3). Shrimp individuals (0.34 ± 0.01 g) were stocked at a density of 500 shrimp m?3. No water exchange was carried out during the experimental period. Molasses was added once a day as an organic carbon source to maintain the C:N ratio at 12:1. The IBS significantly decreased (P < 0.05) dissolved inorganic nitrogen (DIN) ranging from 19% to 34% (3.12–3.83 mg L?1), NO3‐N ranging from 19% to 38% (2.40–3.16 mg L?1), Vibrio density ranging from by 8–83% (0.40–2.20 log 103 colony‐forming units mL?1), and FCR ranging from by 20–30% (1.20–1.37), as compared to the control (4.73 mg L?1, 3.93 mg L?1, 2.40 log 103 colony‐forming units mL?1, and 1.74 respectively). Moreover, the IBS significantly increased (P < 0.05) crude protein in whole body shrimp, ranging from 8% to 13% (13.2–13.7% wet weight basis); as well as final weight, ranging from 25% to 32% (3.90–4.12 g), weekly growth ranging from 25% to 34% (0.59–0.63 g), and shrimp yield by 22–39% (1.72–1.96 kg m?3), as compared to control (12.1% wet weight basis, 3.12 g, 0.47 g, and 1.41 kg m?3 respectively). It can thus be concluded that cultivating Gracilaria birdiae in an IBS with L. vannamei can contribute to DIN and NO3‐N removal, lower Vibrio density, increased crude protein in whole body shrimp, higher growth and yield parameters in shrimp culture.  相似文献   

11.
The objective of this study was to evaluate the effect of dietary and water supplementation of probiotic Streptococcus phocae PI80 on growth, immune response and feed utilization of tiger shrimp Penaeus monodon in earthen ponds. The probiotic bacterium S. phocae PI80 was cultured in large fermenter (50 L) by adding additional carbon source in the form of molasses and glucose along with yeast extract as nitrogen source to enrich S. phocae PI80 biomass. This enriched S. phocae PI80 was administered to shrimp in feed (6.5 × 1013 bacterial cells mL?1) as well as in pond water (5 L/pond). Shrimp growth performance was significantly improved (P < 0.05) in 120 days culture when the average body weight of treated molasses + yeast extract (MY) (28.41 ± 0.874 g), glucose + yeast extract (GY) (27.013 ± 0.698 g) was significantly higher than control (23.63 ± 0.684 g). Food conversion ratio FCR was also found to be reduced significantly in ponds treated with probiotics when compared with control pond (1.89 ± 0.09). Vibrio and luminescent bacteria were found to be lower in the treatment receiving MY group, and we hypothesize that this may lead to greater shrimp survival. Furthermore, fermentation product of S. phocae PI80 added to pond water and feed additives enhanced the shrimp immune system. The results indicated that total haemocytes count (THC), phenoloxidase (PO) activity, NBT reductase assay and phagocytic activity significantly increased in shrimps treated with S. phocae PI80. Our study demonstrates that administration of S. phocae PI80 in the water and feed at 6.5 × 1013 colony‐forming units (CFU) mL?1 bacterial cells induce immune modulation and enhances the immune ability of P. monodon in pond‐reared shrimp and increased the shrimp production.  相似文献   

12.
The nitrite toxicity was estimated in juveniles of L. vannamei. The 24, 48, 72 and 96 h LC50 of nitrite‐N on juveniles were 8.1, 7.9, 6.8 and 5.7 mg L?1 at 0.6 g L?1; 14.4, 9.6 8.3 and 7.0 mg L?1 at 1.0 g L?1; 19.4, 15.4, 13.4 and 12.4 mg L?1 at 2.0 g L?1 of salinity respectively. The tolerance of juveniles to nitrite decreased at 96 h of exposure by 18.6% and 54.0%, when salinity declined from 1.0 to 0.6 g L?1 and from 2.0 to 0.6 g L?1 respectively. The safe concentrations at salinities of 0.6, 1.0 and 2.0 g L?1 were 0.28, 0.35 and 0.62 mg L?1 nitrite‐N respectively. The relationship between LC50 (mg L?1), salinity (S) (g L?1) and exposure time (T) (h) was LC50 = 8.4688 + 5.6764S – 0.0762T for salinities from 0.6 to 2.0 g L?1 and for exposure times from 24 to 96 h; the relationship between survival (%) and nitrite‐N concentration (C) for salinity of 0.6–2.0 g L?1, nitrite‐N concentrations of 0–40 mg L?1 and exposure times from 0 to 96 h was as follows: survival (%) = 0.8442 + 0.1909S – 0.0038T – 0.0277C + 0.0008ST + 0.0001CT–0.0029SC, and the tentative equation for predicting the 96‐h LC50 to salinities from 0.6 to 35 g L?1 in L. vannamei juveniles (3.9–4.4 g) was 96‐h LC50 = 0.2127 S2 + 1.558S + 5.9868. For nitrite toxicity, it is shown that a small change in salinity of waters from 2.0 to 0.6 g L?1 is more critical for L. vannamei than when wider differences in salinity occur in brackish and marine waters (15–35 g L?1).  相似文献   

13.
The farming of abalone, Haliotis midae L., can be intensified in serial‐pass systems, but water re‐use increases the concentration of NH3 (free ammonia nitrogen, FAN) and reduces water pH. Changing the percentage dietary protein from 33% to 26% reduced the concentration of FAN (F42, 252 = 2.79; P < 0.0001) in a serial‐pass system and did not reduce weight gain (F1, 12 = 1.09; P = 0.31) or length gain (F1, 12 = 1.08; P = 0.31). Low water pH was the most important variable to contribute to a reduction in abalone growth (weight gain: F1, 19 = 64.5; P < 0.0001; r2 = 0.76; length gain: F1, 19 = 41.9; P < 0.0001; r2 = 0.67). In addition, supplemental oxygen (103% saturation) improved length gain (t = 3.45, P = 0.026) in abalone exposed to an average FAN concentration of 2.43 ± 1.1 μg L?1) and an average pH value of 7.6 ± 0.13, relative to a treatment with no oxygen supplementation. Thus, in an abalone serial‐use raceway with three passes, FAN was not the first growth‐limiting variable. It is suggested that future studies should examine the major causes of reduced water pH in serial‐use systems and their effect on the growth and health of H. midae.  相似文献   

14.
厌氧氨氧化和反硝化作用是底泥生物脱氮的主要过程,碳源是调控厌氧氨氧化和反硝化作用的关键因子。本研究以褐煤为对象,对褐煤的静态碳释情况及其对池塘底泥中脱氮作用的影响进行了研究。结果显示,褐煤在室温条件下的碳释放规律符合二级动力学方程,具备作为反硝化碳源的可行性;在脱氮实验中,发现褐煤对底泥上覆水体中的亚硝酸盐氮(NNO2--N)的去除具有促进作用,NNO2--N的去除率随褐煤浓度的增加而升高,当褐煤质量浓度为40 g/L时,N\${\rm{O}}_2^ - $\-N去除率最高达99.61%,此时硝酸盐氮(NO3--N)的浓度也最低;同时发现,水体中氨氮(NH4+-N)氧化的最适褐煤质量浓度为10 g/L,其去除率达99.39%;对底泥中的厌氧氨氧化菌群进行Illumina高通量测序发现,其中浮霉菌门占比最大(39.6%~71.8%),优势菌属为Candidatus Brocadia (13.9%~35.8%)和Desulfovibrio (17.1%~34.8%),添加褐煤组Candidatus Scalindua菌属比例高于未添加组;荧光定量PCR得出,随着褐煤质量浓度升高,底泥中的反硝化菌丰度呈增长趋势,而厌氧氨氧化菌丰度则低于无褐煤添加组,表明添加褐煤对底泥反硝化有促进作用,而对厌氧氨氧化有一定的抑制作用。研究表明,褐煤具备作为反硝化碳源的条件,可用于池塘养殖底泥脱氮作用。  相似文献   

15.
Marbled rabbitfish, Siganus rivulatus, is an economically valuable herbivorous fish and a potential candidate for warmwater aquaculture. This study was carried out to: (1) assess the effect of various oxygen concentrations on survival and behaviour of S. rivulatus fingerlings and (2) investigate the response of S. rivulatus to hypoxia and determine its critical oxygen tension (Pcrit). In the first experiment, groups of rabbitfish (15 fish per group) were maintained for 1 h in waters of various oxygen concentrations. They were then transferred to well‐aerated tanks and observed for 72 h. Survival was recorded, fish behaviour at low oxygen concentrations observed, and LC50 after 1‐h hypoxia and 72‐h recovery evaluated. In the second experiment, a series of stop‐flow respirometry experiments were performed during which dissolved oxygen was allowed to drop to 0.5 mg L?1 and respiration rate recorded at various oxygen concentrations. In the first experiment, all fish survived for 1 h at oxygen concentration of 1.44 mg L?1 and greater, but started dying at oxygen concentrations below 0.65 mg L?1 (16% survival). The LC50 of S. rivulatus fingerlings was 0.6 mg L?1. Results of the second experiment showed that S. rivulatus is an oxyregulator until Pcrit (1.7 mg L?1 O2) is reached, becoming an oxyconformer below this concentration. Findings allow for a better understanding of environmental oxygen tolerances and minimum acceptable oxygen concentration in rabbitfish aquaculture.  相似文献   

16.
This study was aimed at construction of reference (physiological) value intervals determined by lower 2.5% and upper 97.5% quantiles for total plasma protein (TPP) in farmed rainbow trout, Oncorhychus mykiss (Kamloops strain), aged 10–12 months (n=755). Total plasma protein in male trout from raceway culture was found to be significantly greater (38–58.3 g L?1) relative to females (31–51.5 g L?1). Total plasma protein in trout from cage culture was significantly greater (32–54 g L?1) compared with the raceway culture (31–49 g L?1). Moderate product–moment correlations between TPP and cholesterol (r=0.8730), TPP and total calcium (r=0.8188), TPP and alanine aminotransferase (r=0.6200) and between TPP and aspartate aminotransferase (r=0.6430) were estimated. Proteinaemia was explained as a metabolic response to feed content, infections of bacterial or viral aetiology or to intoxications.  相似文献   

17.
Two Artemia culture experiments were conducted in a zero water exchange system at salinity 80 g L?1. In Experiment I, different carbon sources including molasses, glucose, sucrose and corn flour were given to supplement suboptimal feeding with the microalgae Dunaliella viridis, whereas the control was fed only D. viridis. In Experiment II, molasses was supplemented to the culture medium, as well as the bacteria Alkalibacterium sp. or the archaea Halobacterium sp., isolated from the brine in the local saltponds. The control groups were fed only with D. viridis or with D. viridis and molasses. Our study shows that in laboratory culture biofloc development can be stimulated under hypersaline conditions. Supplementation of carbon sources, bacteria and archaea benefited biofloc development, water quality in terms of nitrogen load and enhanced Artemia production. Denaturing gradient gel electrophoresis analysis on the bioflocs also indicates an increased biodiversity and richness of the microbial community in the culture medium. These results need to be confirmed for large scale Artemia pond production, in which case, we recommend molasses as carbon source.  相似文献   

18.
Edwardsiella tarda was isolated from naturally infected rainbow trout (Oncorhynchus mykiss) in raceway culture on a commercial fish farm where the fish were kept at a density of 110 kg m?3 and at a water temperature of 14°C and with a photoperiod of 13 h light:11 h dark. The clinical signs of diseased fish (150 ± 20 mm standard length) were anorexia and lethargy. The most striking lesions in the fish were in the liver. There were hyperaemia and haemorrhages; on histopathological examination, the liver displayed inflammatory infiltrate in portal area, focal necrosis, dilatation of blood sinus and activation of sinusoidal cells. Infection experiments, performed 2 years after isolation of the original culture of E. tarda, were carried out under laboratory conditions at water temperatures of 15, 18 or 24°C. All experimental fish (common carp, Prussian carp, tench), intraperitoneally injected with 8 × 106 cells, demonstrated a total resistance to E. tarda.  相似文献   

19.
Glucose, when measured in haemolymph, has been found to reflect a useful predictor of energetic investment. This study evaluated the pattern of glucose in the haemolymph, with an attempt to gain a better insight into the role of glucose as nutritional source of ovarian development and energy reserves during reproductive and non‐reproductive moulting cycles. The haemolymph of female giant freshwater prawn, Macrobrachium rosenbergii, was obtained at eight different moulting stages, and levels of glucose were determined using an enzymatic colorimetric glucose‐oxidase method in parallel with a histological examination of ovarian development. Glucose levels were relatively low (0.15 ± 0.02 mg mL?1) at D0 stage, an abrupt increase (0.52 ± 0.13 mg mL?1) during premoult D1 stage and declined (0.32 ± 0.10 and 0.31 ± 0.09 mg mL?1) during premoult D2 and D3 stages, respectively; thereafter, a slight increase (0.43 ± 0.09 mg mL?1) occurred at post‐moult A stage. The progression of ovarian growth, marked by an increasing gonadosomatic index (GSI) pattern during the reproductive moulting cycle (C0–D3 stages), was directly proportionate to fluctuations in glucose levels. GSI was significantly positively correlated with glucose (R = 0.40; P < 0.05). In contrast, glucose was notably higher at post‐moult A and premoult D2 stages during non‐reproductive moulting cycle, the period during which glucose is crucial for exoskeletal chitin synthesis. At this particular stage, a negative correlation between body weight and glucose (R = ?0.36; P < 0.05) was observed. The dynamics of glucose in the haemolymph of female M. rosenbergii correlated with ovarian growth, which signify that glucose as nutritional source for vitellogenesis, and affects the body weight of this species.  相似文献   

20.
Physiological (reference) value intervals determined by the lower 2.5% and upper 97.5% quantiles were calculated for blood plasma cholesterol (CHOL) and triacylglycerol (TGL) in farmed rainbow trout, Oncorhynchus mykiss, in raceway culture. The fish were given dry pelleted diets that contained 37–47% crude protein and 7–14% crude fat and were kept at a stocking density of 50 kg m?3 in tanks provided with running freshwater at an ambient temperature of 3–16°C and dissolved oxygen, 8.4–11.5 mg L?1. Blood was sampled between September and November at a photoperiod of 9:00–13:00 hours: 11:00–15:00 hours (light:dark). Cholesterol levels were significantly (P = 0.0001) greater in males (4.7–12.1 mmol L?1, n = 34, mean weight 406 ± 138 g) than immature females (3.2–9.7 mmol L?1, n = 386, mean weight 416 ± 147 g). Physiological range for TGL in immature females and males was 2.4–14.4 mmol L?1 (n = 249, mean weight 418 ± 149 g). The distribution and density of the quantiles in the tested reference group were made possible by the use of histograms, which showed normal distributions for CHOL in males and in females, but not for TGL, in which a sinistral asymmetry was found. Correlation and regression analyses indicated significant (P = 0.0000) dependence between the CHOL and total protein (r2 = 76.2%), CHOL and Fulton's condition factor (r2 = 43.3%) and CHOL and absolute weight of liver (r2 = 45.5%). Fluctuation in cholesterolaemia and triacylglycerolaemia, depending on nutrition and the aquaculture method is discussed below.  相似文献   

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