对虾环保型饲料在养殖上的应用

文章探讨了无公害健康养殖与环保饲料营养的关系以及环保饲料的应用,对环保饲料的营养饲料源、添加剂的质量要求、研制环保饲料的重要性,对食品安全和养殖安全的关系,以及环保饲料在无公害健康养殖的应用技术进行分析。     

The growth and apparent digestibility of white shrimp,Litopenaeus vannamei,are increased with the probiotic,Bacillus subtilis

The aims of this study were to evaluate the probiotic efficiency of Bacillus subtilis E20 (10⁹ colony‐forming units kg^?1) on the growth and apparent digestibility coefficients (ADCs) of dry matter (DM), crude protein (CP), amino acids (AAs), and crude lipids (CLs) of the white shrimp, Litopenaeus vannamei. A control diet without probiotic supplementation was used. Shrimp exhibited significant increases in growth performance and feed utilization after being fed the test diet for 56 days. Shrimp were then used to evaluate the apparent nutrient digestibility using 0.1% Cr₂O₃ in the diet as an indicator. During the trial, faeces was collected from triplicate groups of shrimp twice daily. ADCs of CP and DM in the test diet significantly increased compared to those of the control diet. Although the ADCs of CLs did not significantly differ between the control and probiotic group, the ADC of CLs was higher in the probiotic group than in the control group. In addition, ADCs of most AAs in the test diet were significantly higher compared to those of the control diet. These results suggest that shrimp in the test group had significantly better growth performance, which was due to increases in nutrient digestibility and absorption.     

Dominant sources of dietary carbon and nitrogen for shrimp reared in extensive rice-shrimp ponds

Stable isotope analysis was used to determine the sources of dietary nitrogen (N) and carbon (C) for shrimp during the rearing phase in extensive rice‐shrimp ponds in My Xuyen and Gia Rai districts, Vietnam. Farm‐made feed was added as a food source in shrimp ponds in My Xuyen district, and based on stable isotope analyses, was generally a poor dietary source. The commercial formulated feed used in Gia Rai also appeared to contribute little directly to the nutritional needs of the shrimp. In contrast, the natural biota in all ponds appeared to contribute substantially. In particular, biota from beam trawls and benthic organic matter were the most likely sources of nutrition in My Xuyen ponds, while benthic organic matter was the main source in Gia Rai ponds. δ¹⁵N ratios in the natural biota in My Xuyen farms decreased over the growing season, suggesting increased N fixation in the case of the benthic organic matter reaching values as low as 1‰. This suggests N‐limitation in the ponds and that natural biota become increasingly dependent on N fixed by algae and/or other microorganisms. There is the potential to promote the growth of the plankton and hence, the other natural biota, by the judicious addition of fertilizer.     

Inclusion of Amazonian Mauritia flexuosa fruit pulp as functional feed in the diet for the juvenile Pacific white shrimp Litopenaeus vannamei

This study investigated the effects of the inclusion of Mauritia flexuosa fruit pulp in the diet on the growth performance, economic benefit, muscle composition, total contents of carotenoids and flavonoids, chromaticity parameters, total antioxidant capacity, and lipid peroxidation in the hepatopancreas and muscle of the juvenile shrimp Litopenaeus vannamei (weighing 1.26 ± 0.023 g). Five diets (37% protein, 10% lipid) consisting of 0 (control), 1.25%, 2.50%, 5.00% and 10.00% (w/w) M. flexuosa fruit pulp were formulated and provided to the shrimps (n = 50 per tank, treatments in triplicate) for 31 days. Results showed that there were no significant differences between the treatments in terms of the growth capacity, chromaticity parameters, muscle composition and total flavonoid content of shrimps (p > .05). However, the carotenoid content in the muscle and hepatopancreas of the shrimps was significantly increased due to the dietary carotenoids present in M. flexuosa fruit pulp (p < .05). This increase in the carotenoid content directly favoured the increase in the antioxidant capacity in the hepatopancreas and muscle of the shrimps (R² = 0.99 and R² = 0.97 respectively; p < .05). There was also a direct relationship between the carotenoid content and the decrease in lipid peroxidation in the hepatopancreas (R² = 0.90; p < .05). The feed cost kg^?1 in terms of weight gain and protein production decreased with the inclusion of high levels of M. flexuosa fruit pulp, reaching 8.11% and 18.76% of cost reduction, respectively, with the addition of 5.00% of M. flexuosa fruit pulp. Therefore, the inclusion of M. flexuosa fruit pulp in the diets of shrimp can increase the carotenoid content and the antioxidant capacity in the hepatopancreas and muscle, reduce lipid peroxidation in the hepatopancreas, and probably provide economic benefits for the rearing of juvenile shrimps.     

虾池有机污染物降解细菌的筛选

在实验室条件下对612株海洋细菌和10株海水驯化淡水菌进行筛选,检测其快速降解水体中富营养有机物的能力。利用对虾饵料培养基、BOD仪、胞外酶检测等方法进行筛选,最后筛选到10株对富营养有机物具有 较高降解性能的细菌。所有的细菌均能产生明胶酶和脂酶（Tween-80),其中9株细菌能产生淀粉酶,8株产生卵磷脂酶,2株产生酪蛋白酶,1株产生褐藻胶酶。通过测量BOD来衡量10株细菌利用对虾饵料的效果,2天时能消化46.6%-59.5%的对虾饵料,5天时能消化50.8%-70.2%的对虾饵料。用常规生理生化方法将细菌鉴定到属,其中3株为弧菌属细菌（Vibrio spp.),3株为假单胞菌属细菌（Pseudomonas spp.),2株为发光杆菌属细菌（Photobacterium spp.),1株为气单胞菌属细菌（Aeromonas spp.),1株为枯草杆菌（Bacillus subtilis)。     

Effects of feed processing method (extrusion and expansion-compression pelleting) on water quality and growth of rainbow trout in a commercial setting

To determine the effects of feed processing method (extrusion or expansion followed by compression pelleting) on feed physicochemical characteristics, fecal stability, water quality, and growth performance in rainbow trout, three types of feed pellets (expanded sinking [EpS], extruded sinking [ExS], extruded floating [ExF]) were prepared, analyzed, and fed to juvenile rainbow trout (initial weight = 285.8 ± 15.2 g) at three feeding rates based on feeding rate curves developed at Snake River Farm (Buhl, Idaho, USA) (median rates [%BW] for feeding rate 1: 0.85; feeding rate 2: 0.95; feeding rate 3: 1.05) for 124 days. Results showed that all feeds had similar chemical composition, but the degree of starch gelatinization (as % of starch) was significantly higher in ExS (90.01 ± 0.26) and ExF (84.82 ± 0.63) than in the EpS (9.09 ± 0.41) feed, which led to extruded feeds having much higher water stability, fecal durability, and lower phosphorus discharge. The ExF feed produced better growth (% increase; 154.4 ± 18.5) and feed conversion (1.06 ± 0.06) compared to EpS (126.3 ± 12.4 and 1.26 ± 0.14) and ExS (121.7 ± 7.8 and 1.22 ± 0.04) in rainbow trout. Growth (% increase) improved as feeding rate increased (feeding rate 1: 125.6 ± 10.3; feeding rate 2: 140.8 ± 16.0), but further improvements were not observed at the highest feeding rate (feeding rate 3: 135.9 ± 22.8). The present study is the first to show that the extrusion process not only produces pellets having better quality than the expansion-compressed pelleting method but also improves fecal size and durability in water, and therefore, use of extruded feeds has the potential to improve waste collection and removal and reduce contribution to pollution in effluent.     

Toxicity of chlorine to different sizes of black tiger shrimp (Penaeus monodon) in low-salinity shrimp pond water

An experiment was conducted, in a dark room with controlled temperature (27.3–28.4 °C), to determine the acute toxicity of chlorine concentration to black tiger shrimp (Penaeus monodon fabicus) of sizes 0.02 g, 2.75 g, 8.47 g and 23.65 g. Toxicity tests on each of these shrimp sizes were run in triplicate in glass jars under static conditions without media renewal. The concentration of active chlorine that killed 50% of the shrimp of each size after 24‐h exposure (LC₅₀‐24 h) was used as an indicator of acute toxicity. Chlorine concentrations applied in the shrimp toxicity test ranged from 2.0 to 14.5 mg L^?1 in shrimp pond water. As the test water contained total suspended solids of 22.0–85.0 mg L^?1 and total ammonia nitrogen of 0.18–0.40 mg L^?1, the resultant concentrations of combined residual chlorine ranged from 0.6 to 3.5 mg L^?1, which were the effective doses causing shrimp mortality. The test results showed that 24‐h LC₅₀ for average shrimp size at 0.02, 2.75, 8.47 and 23.65 g occurred in water containing combined residual chlorine at a concentration of 0.91, 1.39, 1.74 and 1.98 mg L^?1, for which the original application doses were 6.96, 2.05 11.50 and 13.34 mg L^?1 respectively.     

Comparison of Ulva clathrata and the kelps Macrocystis pyrifera and Ascophyllum nodosum as ingredients in shrimp feeds

Three experimental diets were formulated to contain 33 g kg⁻¹ seaweed meals, made of wild brown algae (kelps) Macrocystis pyrifera (MAC) and Ascophyllum nodosum (ASC) or of a cultivated green alga Ulva clathrata (ULVA). The diets were fed to juvenile white shrimp Litopenaeus vannamei (1.6 g) for 28 days. Loss of dry matter (LDM) and loss of protein (LP) after 1 hour immersion in seawater, and distilled water absorption (WA) were analyzed in the pelleted diets, as well as shrimp weight gain, feed intake, feed conversion ratio (FCR), survival, protein efficiency ratio (PER) and body pigmentation. Feed intake, FCR and PER were corrected for nutrients preprandial losses in seawater. ULVA diet resulted in lower LDM, but a higher LP and also higher WA, indicating a modification of the pellet physical quality (better hydro stability). No significant differences in feed consumption and survival were found, but ULVA diet resulted in a slightly higher final weight (4.8 for ULVA versus 4.6 and 4.3 g for ASC and MAC), and better FCR (1.7 versus 1.9 and 2.1) and PER (2.0 versus 1.7 and 1.5), the differences with MAC diet being significant (Duncan, α = 0.05). Red color after cooking was markedly darker in the ULVA fed shrimp.     

Incentive for shifts in water management systems by shrimp culturists in southern Thailand

ABSTRACT:   Water management systems and other business situations of shrimp culturists were surveyed in two districts in southern Thailand. There were three types of water management systems in southern Thailand, namely closed, semiclosed and open systems, categorized by the frequency of exchange of pond water. Shrimp culturists in those districts tended to shift their system from the open system to the closed system of their own accord, and the average net income ratio decreased due to the change of water management system in a district from more than 2 to less than 1. The reason for this shift, in spite of the decrease in the profit rate, was prevention of infectious disease caused by water exchange. In conclusion, it was proven that independent shrimp culturists, such as medium and small scale shrimp pond owners in southern Thailand, would accept short-term decreases in profit rate in order to stabilize production.     

Effects of dietary moisture content of extruded diets on physical feed quality and nutritional response in Atlantic salmon (Salmo salar)

Feeds in modern aquaculture must be of high physical quality to withstand mechanical impacts. However, physical quality of feed has been shown to affect nutritional responses. In this study, different physical feed qualities were created using different drying time. Effects on physical feed quality, feed intake, nutrient digestibility and growth in Atlantic salmon were investigated. Different drying times of four commercial‐like diets resulted in dry matter contents of 95.9%, 94.1%, 92.3% and 90.8%. A fifth diet containing 70% dry matter was made by soaking pellets. Triplicate groups of Atlantic salmon (961 ± 12.1 g ind^?1, mean ± SEM) were first fed ad libitum and thereafter a restricted ration. The diets differed significantly in bulk density, DORIS durability, hardness, water stability after 60 and 120 min, but not in water stability after 240 min. Feed intake and growth were not affected by physical quality of the dry diets, whereas soaking had a positive effect on feed intake. Restricted compared with ad libitum feeding increased nutrient digestibility, but digestibility was not affected by varying drying time among diets. However, soaking resulted in slightly reduced digestibility of starch. Most methods used to analyse physical quality did not correlate with feed intake and growth; only long‐term water stability affected feed intake.     

Dietary arginine requirement of juvenile kuruma shrimp Marsupenaeus japonicus (Bate)

The requirements for essential amino acids by kuruma shrimp, Marsupenaeus japonicus (Bate) have not yet been determined using the dose–response method due to poor utilization of crystalline amino acids (CAA). In a previous study, we produced coated CAA that could be used to retard leaching losses. Therefore, to determine the arginine requirement of juvenile kuruma shrimp, a growth study was conducted using test diets containing six levels of coated arginine (from 1.20% to 3.19% of diet) for 42 days. Crystalline amino acids was supplemented to correspond to the amino acid pattern in the whole body protein of the kuruma shrimp except for arginine. To reduce leaching losses, CAA were coated with carboxymethylcellulose (CMC) and diets were further bound with CMC and k‐carrageenan. Test diets were fed to triplicate groups of juveniles (0.25±0.02 g) twice a day. Proximate composition and the amino acid composition of shrimp whole bodies were analysed at the end of the feeding trial. Percent body weight gain (WG), specific growth rate, feed intake, feed efficiency ratio and protein retention efficiency were significantly affected by the dietary arginine concentrations. Estimating the arginine requirement of kuruma shrimp using broken‐line analysis of percent WG resulted in a value of 2.66% of diet or 5.32% of protein. After correcting for leaching of arginine from the diets, the optimum dietary value of arginine for kuruma shrimp was a little lower than the estimated value.     

Thermal challenge of the Indian shrimp Penaeus indicus

This study investigated short‐term effects of increasing water temperature from 27 to 41°C on survival and feed consumption of Penaeus indicus at three different ages: PL₂₅ (postlarvae 25 days old), PL₅₀ and PL₉₀. For each age group, water temperature was maintained at 27°C in the control, but increased to 32, 35, 38 and 41°C at a rate of 1°C every eight hours. The temperature was then kept stable until the end of the 7‐day experiment. Results showed that increasing water temperature affected both survival and feed consumption of the experimental shrimps (p < .01). Survival was highest at 32 and 35°C ranging from 93.8% to 100%, but significantly reduced to 40.0%–81.6% at 38°C. No shrimp survived the 41°C treatment. PL₂₅ were more tolerant to 38–41°C than PL₅₀ and PL₉₀ in terms of survival. Increasing water temperature had no effects on feed consumption of PL₂₅ (p > .05). For PL₅₀ and PL_90, feed consumption significantly increased at 38 and 41°C (p < .01) and was similar within the range of 27–35°C. This study suggests that P. indicus in tropical areas can tolerate water temperatures of at least 35°C and should be considered for farming during the summer time.     

Effects of Particle Size and Processing Variables on the Properties of an Extruded Catfish Feed

Abstract

A catfish feed was extruded to determine how particle size, moisture content and screw speed affected the pellet durability, water stability index, and buoyancy. Increasing moisture content from 250 to 300 g/kg required less die pressure, specific mechanical energy and product temperature to produce durable pellets that were stable in water. Increasing screw speed from 200 to 400 rpm also lowered die pressure, due to a lower filled length of the extruder screw channels, but increased specific mechanical energy and product temperature; the resulting pellets had a lower apparent bulk density, but a higher degree of starch gelatinization and water stability index. Reducing particle size from 1200 to 700 m decreased die pressure and apparent bulk density, but increased product temperature, degree of starch gelatinization, pellet durability index and water stability index.     

Preliminary evaluation of the seaweed Gracilaria cervicornis (Rhodophyta) as a partial substitute for the industrial feeds used in shrimp (Litopenaeus vannamei) farming

The aim of this study was to evaluate the use of Gracilaria cervicornis meal as a partial substitute for the industrial feeds used in shrimp (Litopenaeus vannamei) farming. A total of 90 L. vannamei juveniles (0.34 g) were assigned randomly into nine experimental units at a stocking density of 10 shrimp tank⁻¹ and fed a commercial shrimp feed (CSF; 35% crude protein) as a control treatment, a feed made entirely of G. cervicornis (GCM), and a mixture of equal parts of the commercial shrimp feed and the Gracilaria meal (MIX) for 30 days. Over the first 2 weeks of the experiment, the survival was high (100%) in all dietary treatments. However, at the termination of the feeding trial survival decreased to 40% in shrimp fed GCM, significantly lower (P<0.05) than survival of shrimp fed the commercial diet control (CSF) or MIX treatments (100%). The highest growth performance was obtained in the CSF or MIX treatment groups. The absolute growth increase in these groups was significantly higher than for shrimp fed GCM. Similarly, the specific growth rates (SGRs) of shrimp given feeds containing CSF (5.11% day⁻¹) and MIX (4.71% day⁻¹) were significantly greater (P<0.05) than that of shrimp fed GCM pellets (0.44% day⁻¹). The feed efficiency ratios (FERs) were 64 for CSF, 54.3 for MIX and 3.3 for GCM. The results obtained in this study indicated the effectiveness of using G. cervicornis as a partial substitute for shrimp feeds. To our knowledge, this is the first time that the concept that macroalgae can partially substitute for the industrial feeds used in shrimp (L. vannamei) farming has been demonstrated.     

The effects of various binders and moisture content on pellet stability of research diets for freshwater crayfish

Two experiments were conducted to assess the water stability of a practical research diet manufactured with various binders and differing levels of moisture. In the first experiment the binders – agar, gelatine, carrageenan, and carboxymethylcellulose (CMC) were included at both 3 and 5% of total ingredient weight. All binders were tested with equal ingredient weight to water volume, and additionally carrageenan was tested in a diet with double the water volume. The dry matter remaining following immersion for up to 180 min was calculated and the rate of pellet decay was modelled using the Weibull distribution. The analysis revealed that the rate of dry matter loss decreased with time, and that carrageenan and CMC binders were significantly better (P < 0.001) binders than the agar and gelatine. The 5% binder concentration slowed the decay rate by as much as 62% as compared with the 3% binder concentration. The second experiment compared the binding performance of carrageenan and sodium alginate in both 50% moisture and 10% moisture pellets. The same analysis revealed that 10% moisture alginate‐bound pellets were more water stable than the others. A discussion of the use of moist diets for crayfish research is included.     

Evaluation of different concentrations of adult live Artemia (Artemia franciscana,Kellogs 1906) as natural exogenous feed on the water quality and production parameters of Litopenaeus vannamei (Boone 1931) pre-grown intensively

A 7-week experimental study was performed to evaluate the effect of five concentrations of adult live Artemia (0, 1, 2, 3 and 4 L⁻¹) as exogenous natural feed on the water quality and production parameters of juvenile (0.2 ± 0.01 g) shrimp (Litopenaeus vannamei) pre-grown intensively (125 organism m⁻²) under laboratory conditions (80 L plastic tanks). No significant differences were observed in the environmental variables among treatments. Total ammonium nitrogen, nitrates and phosphates recorded higher concentrations in all the treatments using artemia, as compared with the treatment without Artemia. In all the cases, the levels remained within or close to the ranges considered necessary for the farming of the species. The highest weight gain and biomass were obtained in the treatments with 3 and 4 Artemia L⁻¹. The best feed conversion ratio were recorded using 2 Artemia L⁻¹ and the highest with 0 Artemia L⁻¹. No differences in survival were detected among treatments. The greatest concentrations of nitrogenous metabolites achieved at the highest densities of Artemia were lower than the LC₅₀ for penaied shrimp and no negative effect was observed on the survival of the shrimp. These results clearly indicate that the use of adult live Artemia as exogenous natural feed significantly increased the production parameters of the Pacific white shrimp.     

对虾海水高密度养殖后期水质因子的昼夜变化规律

2008年7月5～6日,对广东汕尾红海湾对虾养殖场养殖87～88d的海水高密度半封闭养殖虾池水质进行每4h监测分析,旨在了解养殖后期昼夜水质变化状况,为合理和即时调控养殖后期水质提供相关理论数据。结果显示,24h内水质指标除化学需氧量（COD）和无机氮（DIN）基本稳定外,其他因子均有较大波动。其中氨氮（NH4＋-N）在3：00达到高峰,5：00落至低谷,9：00又达到高峰;亚硝酸盐氮（NO2--N）的变化却相反,在3：00落至低谷,5：00达到高峰,9：00又落至低谷;pH和溶解氧（DO）均在5：00降至最低,13：00上升到最高。结果表明,3：00～9：00是虾池水质变动的关键时期,应留意水质变化,适时采取合理增氧措施并投洒相应水质调节剂以提高ρ（DO）,减少NH4＋-N和NO2--N产生及降低其毒性。     

Protein and lipid requirement for the growth and reproduction of the peppermint shrimp Lysmata wurdemanni

The effect of dietary protein and lipid level on growth and reproductive efficiency of the pepermint shrimp Lysmata wurdemanni was evaluated over a 90‐day period. The percentage of protein and lipid (%P/L) in the experimental diets varied as follows: 34/7, 34/8, 34/9, 37/7, 37/8, 37/9, 40/7, 40/8 and 40/9, and a commercial diet was used as control (35/7‐Silver Cup^®). Fifteen shrimps per treatment and three replicates were used. The number of moults, survival, and growth, number of ovigerous females as well as protein and carbon content of fertilized eggs were evaluated. The shrimps fed experimental diets 37/7 and 40/9 exhibited a survival of 100%, whilst the survival of shrimp fed diet 40/7 was 73%, without significant differences being observed among the treatment groups. The weight gained (g) by shrimps fed diets 37/9 and 40/8 was significantly greater than the control group. The greatest percentage of ovigerous females was observed in those fed 34/7 and 37/9 diets, and the lowest in the control group. The greatest content of protein/carbon in the eggs was found in females fed the 40/8 diet. The results indicated that a P/L relationship of 34/7% promote efficient growth; however, during the reproductive phase it is necessary to increase the P/L to 40/8% to improve the quality and viability of the eggs.     

虾池浮游微藻与养殖水环境调控的研究概况

在对虾养殖过程中,虾池中的浮游微藻群落结构和对虾的健康养殖有着密切关系,一些有益微藻能调节水体溶氧量（DO）和酸碱度（pH）,吸收氨氮（NH4-N）和亚硝氮（NO2-N）等有害物质,有效地调控养殖环境。但一些能分泌毒素的微藻也会给对虾的健康生长带来危害。数量和生物量占微藻总量比例均较高的浮游微藻优势种对整个虾池微藻群落结构的稳定起着重要作用,主导着微藻群落的功能发挥。不同养殖模式、养殖季节、养殖地域以及养殖阶段虾池中浮游微藻的优势种类分布、多样性等群落特征有差异。浮游微藻群落中优势种的变动规律和虾池中各种环境因子的动态密切相关,环境因子的变动会影响浮游微藻群落结构的变动。文章综述了对虾养殖生产实践中浮游微藻群落结构和生态调控特征的研究概况,并对在养殖中构建优良微藻藻相的方法进行了探讨。