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1.
The tolerance of Litopenaeus vannamei larvae to increasing concentrations of total ammonia nitrogen (TAN) using a short‐term static renewal method at 26°C, 34 g L?1 salinity and pH 8.5 was assessed. The median lethal concentration (24 h LC50) for TAN in zoea (1‐2‐3), mysis (1‐2‐3) and postlarvae 1 were, respectively, 4.2‐9.9‐16.0; 19.0‐17.3‐17.5 and 13.2 mg L?1TAN (0.6‐1.5‐2.4; 2.8‐2.5‐2.6 and 1.9 mg L?1 NH3‐N). The LC50 values obtained in this study suggest that zoeal and post‐larval stages are more sensitive to 24 h ammonia exposure than the mysis stage of L. vannamei larvae. On the basis of the ammonia toxicity level (24 h LC50) at zoea 1, we recommend that this level does not exceed 0.42 mg L?1 TAN – equivalent to 0.06 mg L?1 NH3‐N – to reduce ammonia toxicity during the rearing of L. vannamei larvae.  相似文献   

2.
In a Biofloc Technology System (BFT), there is constant biofloc formation and suspended solids accumulation, leading to effects on water quality parameters that may affect the growth performance of cultured shrimp. This study aimed to analyse during biofloc formation the effect of different total suspended solids (TSS) levels on water quality and the growth performance of Litopenaeus vannamei shrimp in a BFT system. A 42‐day trial was conducted with treatments of three ranges of TSS: 100–300 mg L?1 as low (TL), 300–600 as medium (TM) and 600–1000 as high (TH). The initial concentrations of 100 (TL), 300 (TM) and 600 mg L?1 (TH) were achieved by fertilization before starting the experiment. Litopenaeus  vannamei juveniles with an average weight of 4.54 ± 1.19 g were stocked at a density of 372 shrimp m?3. Physical and chemical water parameters and shrimp growth performance were analysed. After 6 weeks, TSS mean concentrations were 306.37, 532.43 and 745.2 mg L?1 for, respectively, TL, TM and TH treatments. Significant differences (P < 0.05) were observed in TSS, settleable solids, pH, alkalinity and nitrite, especially between the TL and TH treatments. Similarly, differences (P < 0.05) were observed in the growth performance parameters, specifically final weight, survival, feed conversion and productivity. The water quality parameters at lower range of total suspended solids concentration (TL) treatment resulted in a better performance of L. vannamei in the BFT system. The maintenance at range of 100–300 mg L?1 TSS is thus important to the success of shrimp culture.  相似文献   

3.
In this study, we tested the lower salinity tolerance of juvenile shrimps (Litopenaeus vannamei) at a relatively low temperature (20 °C). In the first of two laboratory experiments, we first abruptly transferred shrimps (6.91 ± 0.05 g wet weight, mean ± SE) from the rearing salinity (35 000 mg L?1) to salinities of 5000, 15 000, 25 000, 35 000 (control) and 40 000 mg L?1 at 20 °C. The survival of L. vannamei juvenile was not affected by salinities from 15 000 to 40 000 mg L?1 during the 96‐h exposure periods. Shrimps exposed to 5000 mg L?1 were significantly affected by salinity, with a survival of 12.5% after 96 h. The 24‐, 48‐ and 96‐h lethal salinity for 50% (LS50) were 7020, 8510 and 9540 mg L?1 respectively. In the second experiment, shrimps (5.47 ± 0.09 g wet weight, mean ± SE) were acclimatized to the different salinity levels (5000, 15 000, 25 000, 35 000 and 40 000 mg L?1) and then maintained for 30 days at 20 °C. Results showed that the survival was significantly lower at 5000 mg L?1 than at other salinity levels, but the final wet weight under 5000 mg L?1 treatment was significantly higher than those under other treatments (P<0.05). Feed intake (FI) of shrimp under 5000 mg L?1 was significantly lower than those of shrimp under 150 00–40 000 mg L?1; food conversion efficiency (FCE), however, showed a contrasting change (P<0.05). Furthermore, salinity significantly influenced the oxygen consumption rates, ammonia‐N excretion rates and the O/N ratio of test shrimps (P<0.05). The results obtained in our work provide evidence that L. vannamei juveniles have limited capacity to tolerate salinities <10 000 mg L?1 at a relatively low temperature (20 °C). Results also show that L. vannamei juvenile can recover from the abrupt salinity change between 15 000 and 40 000 mg L?1 within 24 h.  相似文献   

4.
Lack of information on the daily activity patterns of Litopenaeus vannamei (Boone 1931) might result in inadequate feed management strategies in shrimp farms. In order to provide information to improve feed management in shrimp farms, the daily activity of juvenile shrimp reared in glass aquaria was studied, using L. vannamei (7.57±1.01 g), equivalent to 33 shrimp m?2. Thirty‐two shrimp were observed, half in light and half in dark phase, over 280 h in 15 min h?1 windows. Feed was provided once a day, at 10% of tank biomass. Swimming, exploration of substrate, inactivity and cleaning were recorded through instantaneous focal sampling. During the dark phase, swimming was predominant and alternated with exploration. In the light phase, inactivity was predominant, and again alternated with exploration. Cleaning occurred evenly in both the light and the dark. Substrate exploration, which characterizes the search for food, occurred in both dark and light phases, with a most intense peak 7 h after light phase onset, indicating this as the optimal feed offer.  相似文献   

5.
A 40‐day experiment was conducted to investigate the effects of different Ca2+ concentration fluctuation on the moulting, growth and energy budget of juvenile Litopenaeus vannamei with an initial wet body weight of (1.20±0.01) g. The Ca2+ concentration of the control group C385 was 385 mg L?1 throughout the experiment, while the Ca2+ concentration of the C591, C803, C1155 and C2380 groups periodically fluctuated from 385 to 591, 803, 1155 and 2380 mg L?1 respectively. The moulting frequency (MF) of the shrimp in the Ca2+ concentration fluctuating groups was significantly higher than those in the control group (P<0.05). The specific growth rates (SGRd) and feed intake of the shrimp in the C591 and C803 groups were significantly higher than those in other groups (P<0.05), but no significant differences in feed efficiency were found among all groups (P>0.05). The shrimp in C591 and C803 groups spent significantly less energy in respiration, while depositing significantly more energy for growth than those in other three groups (P<0.05). These results showed that proper Ca2+ concentration fluctuation could increase the MF and growth rate of the juvenile L. vannamei, and according to the regression formula made using SGRd and range of Ca2+ concentration fluctuation, periodically enhanced Ca2+ concentration of 295 mg L?1 in the seawater was suggested to be used in shrimp culture.  相似文献   

6.
Effect of different carbon sources on nursery performance of Pacific white shrimp (Litopenaeus vannamei) cultivated in biofloc system was investigated. Shrimp postlarvae (98.47 ± 8.6 mg) were fed for 32 days in tanks with water volume of 130 L and density of 1 individual L?1. One control treatment and four biofloc treatments (BFT1, BFT2, BFT3 and BFT4) with adding different carbon sources including molasses, starch, wheat flour and mixture of them, respectively, were considered at equal weight ratios. According to the results, salinity, dissolved oxygen and pH were not significantly different among the biofloc treatments (P > 0.05). Maximum pH (8.27) and maximum dissolved oxygen (6.35 mg L?1) were recorded in the control. Maximum (0.43 mg L?1) and minimum (0.09 mg L?1) ammonia were recorded in the control and BFT2, respectively (P < 0.05). Using simple carbohydrates (molasses and starch) lowered the ammonia concentration significantly. The highest increase in body weight (1640.43 ± 231.28 mg), growth rate, specific growth rate (8.97 ± 0.42% per day) and biomass (190.29 ± 26.83 mg) were found in BFT1 and the highest survival (90 ± 0.77%) was found in BFT4. The highest feed conversion (1.52 ± 0.23) and the lowest feed efficiency (66.81 ± 7.95) were observed in the control (P < 0.05). The proximate composition analysis revealed an increase in lipid and ash in biofloc treatments. Results indicated that using biofloc technology with zero‐water exchange system and adding carbon sources could help to recycle waste and improve the water quality. Moreover, the type of carbonaceous organic matter as a substrate for heterotrophic bacteria would be effective in degradation and metabolization of ammonia and nitrite.  相似文献   

7.
The experiment was conducted to determine the leucine requirement of juvenile Pacific white shrimp Litopenaeus vannamei (Boone) in low‐salinity water (0.50–1.20 g L?1). Six diets were formulated to contain 410 g kg?1 crude protein with fish meal, peanut meal and precoated crystalline amino acids with different concentration of l ‐leucine (16.72, 19.60, 22.06, 24.79, 27.28 and 30.16 g kg?1 dry diet). Each diet was randomly assigned to triplicate groups of 30 shrimps (0.38 ± 0.002 g), and the feed trial lasted for 8 weeks. The results indicated that the maximum weight gain was observed at 24.95 g kg?1 dietary leucine group, whereas the diets containing higher leucine concentration conversely reduced the growth performance (P < 0.05). Moreover, the highest body protein content and body protein deposition and the lowest haemolymph AST and ALT activities were also found at 24.95 g kg?1 dietary leucine group. With the increase in leucine in diets, a dose‐dependent increase was found in body lipid content and haemolymph urea concentration. The polynomial regression calculated using weight gain, feed efficiency and body protein deposition indicated that the optimal dietary leucine requirement for L. vannamei reared in low‐salinity water was 23.73 g kg?1 leucine of dry diet, correspondingly 57.88 g kg?1 of dietary protein.  相似文献   

8.
Infectious hypodermal and haematopoietic necrosis virus (IHHNV) was first noted in blue shrimp Litopenaeus stylirostris (Stimpson) in mid-1981. Since that time, at least 12 species of penaeoid shrimp have been reported to be infected with IHHNV. Pacific white shrimp Litopenaeus vannamei (Boone) represents a shrimp species highly refractory to the disease, whereas L. stylirostris was highly susceptible to the disease. Since the beginning of the shrimp farming industry in Ecuador, viral diseases have been observed in L. vannamei and L. stylirostris. Of these, L. vannamei represents ≈ 80% of cultured shrimp. Histopathology, ultrastructure and in situ DNA hybridization confirm the presence and assess the prevalence of IHHNV in pond-reared shrimp, and especially in abnormally small animals of both species. Although IHHNV may be considered enzootic in cultured L. vannamei in Ecuador, we did not find high prevalence (Cowdry A bodies) in specimens of diseased pond shrimp before 1996. From that time to 1998, a higher prevalence of IHHNV has been observed in both species. The epizootic of the IHHNV disease has been related to the oceanographic and climatological conditions caused by El Niño. In addition, it has been suggested that large quantities of wild shrimp post-larvae of both species that were stocked in shrimp farms, infected as latent carriers in 1997, from which the virus could spread to a larger population of these shrimp in 1998.  相似文献   

9.
The effects of salinity fluctuation on the growth, intermoult period and energy budget of juvenile Litopenaeus vannamei were investigated. Salinity fluctuation regimes were set in different frequencies of 2, 4 and 8 days and different amplitudes of ±2, ±5 and ±10 g L?1 from a control salinity of 20 g L?1. After a 48‐day feeding trial, the intermoult period of shrimp became shorter with increasing amplitude and frequency of salinity fluctuation (P<0.05). Both the frequency and the amplitude of salinity fluctuation had a significant effect on the growth rate of L. vannamei juveniles (P<0.05). At the frequency of 4 days, the highest growth rates occurred at amplitudes of 5–10 g L?1, whereas the growth rate was the lowest at 10 g L?1 when the frequency was reduced to 2 days. Feed intake (FI) and assimilation efficiency (AE) of shrimp were also significantly affected by the salinity fluctuation (P<0.05) and matched the growth rate response. The energy expenditures for growth (G), respiration (R), excretion (U) and exuviae (E) to the energy consumed as food (C) were not affected by salinity fluctuation. However, salinity fluctuation significantly affected the percentage of C as faeces (F), with the lowest value occurring at salinity amplitudes of 5–10 g L?1 and frequencies of 4–8 days. Therefore, salinity fluctuations (every 4 days by ±5–10 g L?1) result in higher growth rates than constant salinity conditions (20 g L?1) through greater FI, enhanced feed assimilation and reduced faecal energy loss.  相似文献   

10.
A 10‐week feeding experiment was conducted to evaluate the effect of different protein to energy ratios on growth and body composition of juvenile Litopenaeus vannamei (initial average weight of 0.09 ± 0.002 g, mean ± SE). Twelve practical test diets were formulated to contain four protein levels (300, 340, 380 and 420 g kg?1) and three lipid levels (50, 75 and 100 g kg?1). Each diet was randomly fed to triplicate groups of 30 shrimps per tank (260 L). The water temperature was 28.5 ± 2 °C and the salinity was 28 ± 1 g L?1 during the experimental period. The results showed that the growth was significantly (P < 0.05) affected by dietary treatments. Shrimps fed the diets containing 300 g kg?1 protein showed the poorest growth. However, shrimp fed the 75 g kg?1 lipid diets had only slightly higher growth than that fed 50 g kg?1 lipid diets at the same dietary protein level, and even a little decline in growth with the further increase of dietary lipid to 100 g kg?1. Shrimp fed the diet with 420 g kg?1protein and 75 g kg?1 lipid had the highest specific growth rate. However, shrimp fed the diet with 340 g kg?1 protein and 75 g kg?1 lipid showed comparable growth, and had the highest protein efficiency ratio, energy retention and feed efficiency ratio among dietary treatments. Triglycerides and total cholesterol in the serum of shrimp increased with increasing dietary lipid level at the same dietary protein level. Body lipid and energy increased with increasing dietary lipid level irrespective of dietary protein. Results of the present study showed that the diet containing 340 g kg?1 protein and 75 g kg?1 lipid with digestible protein/digestible energy of 21.1 mg kJ?1 is optimum for L. vannamei, and the increase of dietary lipid level has not efficient protein‐sparing effect.  相似文献   

11.
In this study, we evaluated the production potential of the polyculture of Freshwater Angelfish (Pterophyllum scalare, Cichlidae) and Pacific white shrimp (Litopenaeus vannamei). Two experimental trials were set up. The first trial entailed the use of a randomized design to investigate three treatments options: angelfish monoculture, shrimp monoculture, and fish and shrimp polyculture in 12 experimental 15 m2 ponds. In the second trial, we investigated two treatments (polyculture of caged fish and uncaged fish) in 10 experimental units. In trial 1, polyculture negatively affected fish growth and survival. However, fish did not affect shrimp growth and the greatest profit was achieved in polyculture. In trial 2, caging fish improve the growth of both fish and shrimp. An economic analysis showed the greatest profit and benefit cost ratio for caged fish compared with uncaged fish. We conclude that growing P. scalare and L. vannamei together is a better strategy than shrimp monoculture in low‐salinity water. The use of caged fish in such a polyculture operation would enhance productivity and profitability.  相似文献   

12.
The effect of Streptomyces strains RL8 and N7 on the growth, survival and histological structure of the hepatopancreas of Litopenaeus vannamei was determined. Shrimp post‐larvae of 0.02 ± 0.01 g were fed with diets supplemented with Streptomyces spp. RL8 and N7 at 108 CFU g?1 of feed for 30 days, followed by challenge with Vibrio parahaemolyticus. Toxicity was also assessed by recording the mortality associated with the use of 1‐100 g/L of cell mass and 108‐1010 CFU/g of feed of these strains in Artemia salina and L. vannamei, respectively. The group treated with Streptomyces sp. RL8 had significantly better weight gain (0.62 ± 0.18 g) and survival rates (84.44 ± 5.7%) after challenge, whereas the one fed with Streptomyces sp. N7 showed significantly higher survival rate (57.77 ± 6.8%) than the control group (0.55 ± 0.20 g and 11.11 ± 9.0%, respectively). The hepatopancreas of Streptomyces‐fed shrimps showed better histological integrity with significantly lower degree of atrophy and necrotic tubules than their unfed counterpart. No toxicity associated with these strains was found. Consequently, they can be excellent probiotic candidates to improve the physiological status and prevent infectious diseases of cultured L. vannamei.  相似文献   

13.
A research was designed to explore the effect of ibuprofen (IBU) as an intervening agent for prostaglandin biosynthesis on male and female reproduction of three species of Litopenaeus. Ovarian maturation was studied in L. stylirostris and L. vannamei injected periodically with IBU at 0.01 and 0.1 μg g?1 body weight (b.w.) and treated for unilateral eyestalk ablation. IBU at 0.1 μg induced a statistically (P < 0.05) higher rate of L. vannamei females with developing ovaries (45 ± 19%) as compared with controls (12 ± 8%) during 5 weeks; L. stylirostris did not activate vitellogenesis under this experimental protocol. IBU was also evaluated for male sexuality in L. occidentalis, L. stylirostris and L. vannamei. Periodic injections of IBU had no effect on sperm counts and spermatophore weights; however, sperm abnormalities in IBU 0.1 μg treated L. occidentalis and L. stylirostris were very low. In L. stylirostris, the renovation of normal spermatophores was remarkably improved in IBU treated males as compared with controls, but in L. vannamei spermatophore deterioration was not affected. The findings of this research support the hypothesis that prostaglandins are involved in penaeid reproduction playing a negative physiological role; however, altered steroidogenic pathways could also be involved.  相似文献   

14.
This work evaluated the performance of Litopenaeus vannamei to low fish meal diets supplemented with 2‐hydroxy‐4‐(methylthio)butanoic acid (HMTBa). A basal diet with 150.0 g kg?1 of anchovy fish meal was designed. Two positive control diets were formulated to reduce fish meal at 50% and 100% with 1.0 and 2.0 g kg?1 of MERA? MetCa (calcium salt with 84% HMTBa activity), respectively. Two nearly equivalent diets acted as negative controls, without HMTBa supplementation. A total of 50 clear‐water tanks of 500 L were stocked with 2.22 ± 0.19 g shrimp under 70 animals m?2. Shrimp survival (92.3 ± 5.1% and 81.4 ± 8.0%), yield (808 ± 12 and 946 ± 17 g m?2) and FCR (2.17 ± 0.19 and 3.12 ± 0.37) showed no differences among diets after 72 or 96 days, respectively. A significantly higher shrimp body weight and weekly growth were observed for those fed with the basal diet or diets supplemented with HMTBa compared with non‐supplemented ones. This study has shown that L. vannamei growth, body weight, survival, yield and FCR were supported by HMTBa supplementation when 150.0 g kg?1 of fish meal was replaced by soybean meal and other ingredients, at 50% and 100%.  相似文献   

15.
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   

16.
The potential of water hyacinth leaf protein concentrate (WHLPC) as an alternative protein source to soybean meal in formulated diets for the white shrimp Litopenaeus vannamei (Boone) postlarvae, was assessed. Isonitrogenous and isolipidic diets were formulated containing 40% protein and 8% lipid. WHLPC replaced 0%, 25%, 50% and 75% of soybean meal protein in the formulated diets. Twenty postlarval Litopenaeus vannamei weighing 5.0 ± 0.00032 mg were randomly assigned to twelve 30‐L aquarium tanks and were fed experimental diets for 70 days. Results show that the overall biological performance of shrimp in terms of specific growth rate (SGR), protein efficiency ratio (PER), feed efficiency (FE) and survival in treatment receiving the 25% WHLPC replacement is comparable to that of the control diet. Replacement levels beyond 25% exhibited significant depression in terms of growth performance of the shrimp. Collectively, these findings indicate that WHLPC can replace 25% of soybean meal protein in the formulated diets of L. vannamei.  相似文献   

17.
Shrimp farms in India had average yields (pond surface basis) of 7.86 ± 1.04 (SE) m.t./ha/yr for Litopenaeus vannamei (n = 89) and 3.88 m.t./ha/yr for Penaeus monodon (n = 11). Average feed conversion ratio was 1.48 ± 0.04 for L. vannamei and 1.24 ± 0.12 for P. monodon. Land use for production ponds, supporting area, and feed ingredients averaged 0.634 ± 0.053 ha/m.t. for L. vannamei and 0.716 ± 0.087 ha/m.t. for P. monodon. Saline water volume used at farms without water exchange was 18,522 ± 4065 m3/m.t. for L. vannamei and 9528 m3/m.t. for P. monodon. Farms exchanging water used 149,188 m3/m.t. for L. vannamei and 191,500 m3/m.t. for P. monodon. Freshwater embodied in feed was 1678 ± 508 m3/m.t. for L. vannamei and 1401 ± 137 m3/m.t. for P. monodon. Average energy use for farm construction and repair, farm operations, and embodied in feed and liming materials was 82.14 ± 9.08 GJ/m.t. for L. vannamei and 59.03 ± 24.92 GJ/m.t. for P. monodon. Wildfish used to make fishmeal included in feed was 1209 kg/m.t. for L. vannamei and 1611 kg/m.t. for P. monodon. Farm infrastructure, pond management methods, yields, and resource use in India were similar to those previously reported for shrimp farms in Thailand and Vietnam.  相似文献   

18.
The influence of protein and energy levels on growth rate, survival, pre- and post-prandial oxygen consumption, ammonia excretion, haemolymph glucose (HG), glycogen in digestive gland and osmotic pressure (OP) in white shrimp Litopenaeus vannamei (Boone) and L. setiferus (Linne) juveniles was studied. Diets containing a high-quality protein at a protein/energy (P/E) ratio of 16, 26, 31 and 36 mg kJ−1 were fed at 20% of shrimp body weight of two sizes: < 1 g and > 1 g. Both species showed a optimum P/E ratio of 36 mg kJ−1 (33–44% protein and 6–23% carbohydrate) in juveniles < 1 g. For shrimp > 1 g, L. setiferus showed a higher growth rate in the diet with 16 mg kJ−1 (27% protein; 32% carbohydrate) and L. vannamei between 26 and 36 mg kJ−1 (33–44% protein and 6–23% carbohydrate). In both experiments, the growth rate of L. vannamei was 2–3 times that observed in L. setiferus. Routine oxygen consumption and apparent heat increment (AHI) of L. setiferus juveniles was two times higher than that observed in L. vannamei juveniles, which could indicate that L. setiferus has a higher metabolic rate. The O/N ratio varied according to protein level, with higher values (O/N = 180) with a 16-mg kJ−1 diet and lower values (O/N = 73) with a 36-mg kJ−1 diet in L. setiferus juveniles. A similar variation in O/N ratio was obtained in L. vannamei fed with all diets with an interval between 22 and 50. An inverse relation between ammonia excretion and HG, and digestive gland glycogen (DGG) in relation to an increase in the P/E ratio indicate that both shrimp species are well adapted to use carbohydrates and/or proteins from their diet. The higher values of hyper-osmotic capacity (hyper-OC) were observed in L. setiferus < 1 g fed with 36 mg kJ−1 and the lowest in L. vannamei < 1 g fed with 31 mg kJ−1. Intermediate values of hyper-OC were observed in both species fed all diets indicating that osmotic factors of juveniles < 1 g of both species are more affected by the P/E ratio than juveniles > 1 g. All results showed that juveniles > 1 g of both species are less dependent of P/E ratio than juveniles < 1 g. Litopenaeus vannamei is a most tolerant shrimp species with a high capacity to use a wide range of dietary P/E ratios for growth, which may be due to its lower energy requirements. Litopenaeus setiferus showed a lower capacity to accept different P/E ratios but the optimum P/E ratio obtained with this species shows that L. setiferus accept diets with a high carbohydrate level as well. These results demonstrate that there are nutritional and physiological differences that explain the differences that have been observed when both species were cultured in commercial ponds.  相似文献   

19.
Litopenaeus vannamei were stocked in 25 clear‐water 500‐L tanks at 100 shrimp m?2 and in 25 green‐water 1000‐L tanks at 60 animals m?2. Four diets were formulated to include krill meal at 10, 50 or 110 g kg?1; or krill oil at 25 g kg?1 by replacing fish meal, fish oil, soybean lecithin and cholesterol. Diets had similar levels of crude protein, total energy and essential amino acids. After 72 days, shrimp reared in clear and green water showed no differences in performance among diets. In clear water, shrimp attained 13.1 ± 0.59 g body weight, 1.00 ± 0.06 g week?1 growth, 81.4 ± 7.3% survival, 780 ± 118 g m?2 yield, 16.9 ± 1.8 g shrimp?1 apparent feed intake (AFI), and 2.18 ± 0.29 food conversion ratio (FCR). In green water, shrimp attained 14.3 ± 0.81 g body weight, 1.04 ± 0.09 g week?1 growth, 91.4 ± 5.4% survival, 569 ± 69 g m?2 yield, 20.9 ± 3.2 g shrimp?1 AFI, and 2.22 ± 0.34 FCR. Diets containing krill meal or krill oil were able to fully replace the protein and lipid value of fish meal, fish oil, soybean lecithin and cholesterol at no cost to performance.  相似文献   

20.
Growth rate, soluble protein content, osmotic stress and digestive enzyme activity were studied in early Litopenaeus schmitti postlarvae under different feeding regimens, by partially or completely replacing Artemia nauplii with Moina micrura. Growth was significantly higher in the postlarvae fed with a mixture of M. micrura, Artemia nauplii and algae (0.030 mg dry weight (dw) larva?1 day?1, 17.4 ± 2.1% day?1), together with the postlarvae fed on Artemia nauplii and algae (0.027 mg dw larva?1 day?1, 18.3 ± 1.9% day?1). Complete replacement of Artemia nauplii by M. micrura produced the lowest growth rate (0.018 mg dw larva?1 day?1, 14.3 ± 1.6% day?1) and induced the highest protease and α‐amylase activities and lower soluble protein contents. No significant difference among the treatments could be detected in postlarval resistance to osmotic stress. Based on the growth results, soluble protein content, enzymatic activity and osmotic stress resistance, we determined that the partial replacement of Artemia nauplii by M. micrura did not affect the growth, the soluble protein content and the nutritional state in the postlarvae of L. schmitti. To our knowledge, this is the first reported use of M.micrura as feed for early postlarvae of L. schmitti.  相似文献   

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