河北省海水池塘底质生物修复菌的分离筛选

为了修复对虾养殖池塘的养殖环境。从昌黎、乐亭、黄骅等3地的对虾池塘中取底泥，共分离出215种细菌．通过其对对虾饵料和蛤蜊内降解能力的测定，筛选出9株虾池有机污染降解茵。这些菌株能以对虾饵料作为生长的唯一碳源和氮源。并且对对虾的配合饵料和蛤蜊肉具有较强的降解能力。通过7d的培养。有4株细菌对对虾的饵料的COD去除率约70％。对蛤蜊肉的COD去除率超过50％，其他5株细菌对对虾饵料及蛤蜊肉的COD去除率也在30％以上。结果表明。这些细菌能快速消除对虾池塘的有机污染，具有修复虾池环境的潜力。     

刺参池塘低温有机污染物降解细菌的分离筛选及其降解特性

利用刺参(Apostichopus japonicus)饵料培养基,在低温(16±1)℃下,从刺参养殖池塘环境中富集驯化分离有机污染物低温降解细菌;根据菌株生长情况、好氧性和生物安全性进行了初步筛选,然后在菌体接种密度1×106 CFU/mL、(16±1)℃、pH 8.0、160 r/min条件下,通过检测菌株对饵料中有机物(COD)和氨态氮(NH4+-N)成分的去除率来最终筛选获得优良低温有机污染物降解细菌,并对其降解特性进行研究。菌株筛选结果表明,从分离的17株低温细菌中共获得3株菌株DR7、DR8和DR11,它们能同时高效降低和去除饵料浸出物中COD和NH4+-N,5 d COD去除率分别为37.7%、50.0%和21.0%,NH4+-N去除率分别为95.0%、98.0%和99.8%。根据菌株的形态特征、生理生化特性以及16S rRNA序列分析,初步鉴定DR7和DR11属于假单胞菌属细菌(Pseudomonas sp.),DR8属于副球菌属细菌(Paracoccus sp.)。菌株降解特性研究结果表明,菌株培养时间对饵料降解有显著影响(P<0.05),在0～6 d内3菌株对饵料中有机物和氨态氮的去除过程明显,其中DR8降解力最强;各组合菌株的饵料降解效果差异显著(P<0.05),但并不完全优于对照单菌株,其中最佳组合为DR8-DR11。研究认为,筛选的3株低温有机污染物降解细菌为良好的菌种资源,在刺参养殖池塘污染环境调控及刺参微生态制剂的研制方面具有较好的潜在应用前景。     

白洋淀网箱养殖环境微生物原位修复技术研究

为了修复因白洋淀网箱养殖而污染的水环境,采集试验网箱底部、试验网箱周围、待用网箱及对照点四个泥样,经过富集培养,共分离到174种细菌,通过其对鱼饵料COD去除率的测定,筛选出10株有机污染降解菌,这些菌株能以鱼饵料作为生长的唯一碳源和氮源.1株细菌对鱼饵料的COD去除率约70%,5株菌的COD去除率超过60%,4株菌C...     

应用RFLP和DGGE技术分析工厂化养殖凡纳滨对虾肠道微生物群落特征

本研究应用PCR-RFLP(Polymerase Chain Reaction-Restriction Fragment Length Polymorphism)和PCR-DGGE(Polymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis)技术,对工厂化养殖的凡纳滨对虾肠道菌群进行多样性分析。RFLP结果显示,8月样品中不同的克隆子为5个,其中以不可培养细菌(Unculturable bacteria)为主要优势菌,其次为鲁杰氏菌属菌种Ruegeria spp.和Rhodobacterales spp.。依据微生物多样性的覆盖率分析结果表明,所构建16S rDNA克隆文库的覆盖率为97.5%。10月样品中克隆子为8个,其中以不可培养细菌、芽孢杆菌属Bacillus spp.和弧菌属Vibrio spp.为主要优势菌属,其次为Photobacterium spp.和Neptunomonas spp.;所构建16S rDNA克隆文库的覆盖率为90.8%。应用DGGE分析8月和10月对虾肠道样品,菌群以不可培养细菌和弧菌属为主,其次为Streptomyces spp.、Ruegeria spp.、Enterococcus spp.和Photobacterium damselae。     

鲤鱼肠道细菌及其淀粉酶对宿主消化的影响

本文就鲤鱼肠道细菌对其宿主的影响和细菌淀粉酶对宿主消化的影响作了探讨。从鲤鱼肠道筛选细菌菌株６３株，这上结细菌中淀粉酶产生菌分布较广，溶血毒素产生菌较少，且产毒素的６株菌无致病性。淀粉酶活力较高的ＣＣＩ１３９菌株的淀粉酶和鲤鱼肝胰淀粉酶的最适ｐＨ和反应产物都不相同。原位酶反应法显示鲤鱼肠道食物混合液及肠壁样品中均有细菌淀粉酶。本文结果证明了鲤鱼肠道不稳定的细菌群落，细菌淀粉酶对鲤鱼消化食物的淀粉起     

近江牡蛎养殖水体中细菌产酶能力的研究

为了解近江牡蛎养殖水体中细菌的产酶特性 ,筛选出有应用潜力的有益菌 ,本实验从近江牡蛎养殖水体中分离到 32株菌。革兰氏染色表明 ,10株为革兰氏阳性菌 ,2 2株革兰氏阴性菌。在此基础上研究了它们蛋白酶、脂肪酶、淀粉酶和纤维素酶的产酶能力。结果表明 ,6 1.9% ( 17株 )的菌株能分泌蛋白酶 ,71.9% ( 2 3株 )菌株能分泌脂肪酶或淀粉酶 ,34.4 % ( 11株 )的菌株产纤维素酶。这些产酶菌株均以革兰氏阴性菌为主。在这 32株菌中 ,产四种酶的有 5株菌 ,产三种酶的有 9株菌 ,产两种酶的有 9株菌 ,产一种酶的有 9株菌 ,也就是说 ,所有的菌株都能产酶。由此表明近江牡蛎养殖水体中细菌在该环境物质循环中的重要地位。     

凡纳滨对虾养殖体系中群体感应淬灭菌的筛选、安全性评估及发酵条件优化

从凡纳滨对虾(Litopenaeus vannamai)养殖体系中筛选得到具有群体感应淬灭(Quorum quenching, QQ)活性的潜在功能菌，并对菌株进行16S rDNA鉴定、安全性评估及发酵条件优化。采用根癌农杆菌(Agrobacterium tumefaciens) A136液体X-gal法进行活性菌株筛选，发现2株细菌(BDZ5和W1B)的发酵液对信号分子己酰基高丝氨酸内酯(C6-HSL)具有显著的降解作用，但经沸水浴处理后均丧失降解活性。经16S rDNA基因序列分析，菌株BDZ5和W1B分别被鉴定为芽孢杆菌属(Bacillus)和科贝特氏菌属(Cobetia)。安全性评估结果显示，菌株BDZ5和W1B均无溶血性，且对多数抗生素具有敏感性，注射2株活性菌未提高凡纳滨对虾死亡率，且对凡纳滨对虾血清免疫酶活性无显著影响。单因素条件优化结果显示，在起始pH为7.0、盐度为20、0.0005%的MnCl2条件下培养48 h后，菌株BDZ5达到最大生长量；在起始pH为6.0、盐度为40、0.05%的CaCl2条件下培养48 h，菌株W1B达到最大生长量。2株菌的最适信号分子C6-HSL降解条件与其生长条件有所不同，在起始pH为7.5、盐度为30、0.0005%的MnCl2条件下培养48 h，2株活性菌对信号分子C6-HSL的降解率达到最大值。研究表明，菌株BDZ5和W1B可作为益生菌应用于水产养殖，为基于QQ角度防治对虾细菌性病害提供优良菌种。     

凡纳滨对虾肠道内产消化酶益生菌的分离与筛选

为获得具有消化酶活性且安全的益生菌,从凡纳滨对虾肠道中初步分离得到576株细菌,对菌株进行产蛋白酶、淀粉酶和脂肪酶能力的定性及定量测试,筛选出产酶种类多且产酶能力强的菌株11株。对筛选出的11株菌进行了幼虾浸浴实验、药敏性实验和溶血性实验,以评价其生物安全性。将11株菌的菌悬液添加到凡纳滨对虾幼虾的养殖水体中进行浸浴实验,浸浴结束后用鳗弧菌进行刺激,测定不同浸浴组幼虾相关免疫基因的相对表达量,以确定其对幼虾的保护效果。综合消化酶活性、菌株对幼虾的保护效果及生物安全性,筛选得到4株效果较好的菌株。菌株的16S r DNA分子鉴定结果表明,细菌1号、2号和4号分别与芽孢杆菌(Bacillus sp.PCSAS2-38,GQ284495.1)、蜡样芽孢杆菌(B.cereus strain N419,JN400121.1)及苏云金芽孢杆菌(B.thuringiensis strain EA26.1,KC758847.1)的相似性均为100%,9号菌株与荚膜红细菌(Rhodobacter capsulatus strain PSB-03,FJ866782.1)相似性达到99%,为后续益生菌制剂的开发奠定了前期基础。     

防治对虾幼体“长毛”的方法

1.单胞藻治疗法。在单胞藻繁殖旺盛足够对虾幼体摄食的前提下,不投饵料。单胞藻生物群落繁殖旺盛能够抑制细菌的繁殖,对虾幼体食用天然饵料营养丰富长得快,可以正常脱皮,不用饵料使水质清澈,一般2天就可以治愈对虾幼体“长毛”。 2.突然升温法。在操作规程规定温度的基础上,一次升温2—3℃,促使对虾幼体脱皮,一般1—2天就可以治愈,尔后再把温度调整到该生长期的适宜温度。     

一株海洋产电菌产碱性蛋白酶的初步研究

从浙江省舟山海域潮间带中得到一株产电细菌M2,经过16SrRNA分子鉴定及生理生化试验,初步鉴定该菌为Shewanella属细菌,并命名为Shewanellasp.M2。菌株M2在脱脂奶平板上能产生明显且较大的水解透明圈,通过Folin-酚法进行酶活测定,初始蛋白酶酶活为110U/mL,对其进行紫外诱变处理,最终得到酶活为205U/mL的突变株,酶活提高了86.4%,传代试验结果显示该菌株具有较好的遗传稳定性能。     

In vitro and in vivo selection of probiotic purple nonsulphur bacteria with an ability to inhibit shrimp pathogens: acute hepatopancreatic necrosis disease‐causing Vibrio parahaemolyticus and other vibrios

Shrimp cultivation has been faced with huge losses in productivity caused by infectious shrimp pathogenic vibrios, especially Vibrio parahaemolyticus that causes acute hepatopancreatic necrosis disease (AHPND). Hence, purple nonsulphur bacteria (PNSB) were isolated from shrimp ponds for investigating their abilities to control shrimp pathogenic Vibrio spp. and their use as probiotics for sustainable shrimp cultivation. Based on their probiotic properties, strains S3W10 and SS15 were selected because of their strong abilities to produce amylase, gelatinase and vitamin B12. However, only three PNSB strains (SS15, TKW17 and STW181) strongly inhibited V. harveyi_KSAAHRC and V. vulnificus_KSAAHRC including V. parahaemolyticusAHPND strains by secreting antivibrio compounds. Four selected PNSB also grew in the presence of pancreatic enzymes, and they were identified as Rhodobacter sphaeroides for strains S3W10, SS15 and TKW17 and Afifella marina for strain STW181. The effects of a mixed culture were also investigated as follows: T1 (S3W10 + SS15), T2 (S3W10 + TKW17) and T3 (S3W10 + STW181) on postlarval white shrimp (Litopenaeus vannamei) for 60 days by comparison with a control. All three probiotic PNSB sets significantly improved the digestive enzyme activities and shrimp growth with their proliferation in shrimp gastrointestinal tract although the shrimp survival was not significantly different. They also significantly reduced the cumulative mortality of shrimp exposed to a virulent AHPND strain (V. parahaemolyticusSR2). This is the first to conclude that selected probiotic PNSB strains have great potential to be used for shrimp cultivation to control vibrios including AHPND strains.     

Effect of the addition of diatoms (Navicula spp.) and rotifers (Brachionus plicatilis) on water quality and growth of the Litopenaeus vannamei postlarvae reared in a biofloc system

The aim of this study was to evaluate the effect of the addition of Navicula spp. and Brachionus plicatilis on water quality and growth of postlarvae shrimp Litopenaeus vannamei reared in a biofloc system. Four treatments were considered: a control (biofloc system – BFT); BFT with the addition of Navicula spp. (BFT‐N); BFT with the addition of Brachionus plicatilis (BFT‐B) and BFT with the addition of Navicula spp. and Brachionus plicatilis (BFT‐NB), each in triplicate. Shrimp (16.2 ± 0.03 mg) were stocked at a density of 2500 shrimp m^?3 and plankton were added on days 1, 5, 10, 15, 20, 25 and 30 at a density of 5 × 10⁴ cells mL^?1 (Navicula spp.) and 30 organisms L^?1 (Brachionus plicatilis). The shrimp were fed a formulated feed in four daily rations composed of 40% crude protein and 8% lipids. Significant differences between treatments were observed for final weight, yield, feed conversion ratio, specific growth rate, protein efficiency ratio and protein content of the shrimp. The combined plankton addition of Navicula spp. and B. plicatilis had better performance parameters, indicating their benefit as natural food sources for postlarvae L. vannamei in biofloc systems.     

Manufacturing Different Diet Sizes and Its Effect on Pellet Water Stability and Growth of Three Size Classes of Pacific White Shrimp,Litopenaeus vannamei

Abstract

A feed manufacturing method involving the production of large pellets followed by crumbling to desired diet sizes was used to produce six shrimp diets to determine its effect on growth of three size classes of Pacific white shrimp, Litopenaeus vannamei. The six diets containing 45% protein were 0.7 mm crumble, 1.2 mm crumble, 1.7 mm crumble, 2.2 mm crumble, 2.6 mm crumble, and 3.0 mm pellet. These diets were fed to three size classes of shrimp subjected to a four-week growth trial under indoor laboratory conditions. Stocking density was 12 shrimp/aquarium for size class 1 (1.13iö.01 g), 9 shrimp/aquarium for size class 2 (7.31iö.06 g), and 6 shrimp/aquarium for size class 3 (13.12iö. 10 g). Shrimp were fed three times daily and were evaluated for live weight, growth rate, feed conversion ratio (FCR), and survival. Results for shrimp growth appeared to be affected by diet size and pellet water stability. The effects of diet size, however, were more evident on smaller sized shrimp. Weekly growth rates for class 1 and class 2 shrimp indicated significant responses (P < 0.05) to the effects of diet size, while the class 3 shrimp did not show any significant result. The growth rates for both class 1 and class 2 shrimp were lowest at the smallest diet size (0.7 mm crumble) but differed with respect to highest growth rates. The largest diet (3.0 mm pellets) yielded the highest growth rates for class 1 shrimp, while medium sized feed (2.2 mm crumble) produced the best growth for class 2 shrimp. This could be partly attributed to pellet water stability, which had a direct correlation to diet size (r = 0.97). Smaller diet sizes resulting from crumbling larger pellets tend to have lower water stability. The water stability decreased from 82.5% to 76.3% as the 3.0 mm pellets were reduced to 0.7 mm crumbles. Stress cracks are created during crumbling, and surface area to volume ratio are increased as larger particles are reduced to crumbles. These would make smaller diet particles more susceptible to disintegration and nutrient leaching. For class 3 shrimp, the largest pellets produced the highest growth rate. This high growth value, however, was not significantly different (P > 0.05) from growth results produced by the crumbled feed sizes. This observation suggests that diet sizes ranging from 0.7 mm crumble to 3.0 mm pellet could be used for a 13 g shrimp, although preference would be given to larger pellets due to higher growth performance and better pellet water stability. Results for shrimp live weights were similar to results obtained for weekly growth rates. FCR and survival of all shrimp sizes did not show any significant response from the effects of various diet sizes. However, larger shrimp were less efficient in their diet utilization than smaller shrimp.     

Feed management and stocking density of the endangered wild zebra pleco: Implications for captive breeding

Due to the economic potential of Hypancistrus zebra in the ornamental fish market and its current classification as an endangered species in its natural occurrence sites, the present study sought to determine a suitable feed management strategy and stocking density to allow for an adequate captivity maintenance of this fish species. Three experiments were conducted as follows: (1) feed preference (artemia Artemia sp., shrimp Litopenaeus vannamei, fish Cynoscion spp. or mussel Perna perna); (2) determination of feeding rate (5% and 10% live weight day^?1) and frequency (1, 2 or 3 meals. Day^?1); and (3) evaluation of stocking density (0.25, 0.50, 1.00 and 2.00 g/L). Zebra pleco did not present the characteristic buccal scraping behaviour on the feed, commonly seen in other Loricariids. Artemia was the preferred diet followed by fish, shrimp and mussels. The frequency of two daily meals and the feeding rate of 10% live weight day^?1 allowed for an improved zootechnical performance. Zebra pleco showed enhanced specific growth rate at the density of 2 g/L. Our results suggest that, to improve the zebra pleco rearing conditions, it should be maintained at a density of 2 g/L, fed two daily meals at a feeding rate of 10% live weight day^?1. These findings correspond to useful information for an adequate management of this species and could assist in the supply of healthy specimens to the ornamental fish market as well for the restocking of declining wild populations.     

Effect of microencapsulated thyme essential oil on white spot virus-infected <Emphasis Type="Italic">Litopenaeus vannamei</Emphasis>

The present work was performed to investigate if feeding Litopenaeus vannamei with microencapsulated thyme essential oil (TEM, 1.05 g thyme essential oil per 100-g powder) adsorbed on commercial pellet feed was able to protect shrimps against white spot syndrome virus (WSSV) disease. Five treatments were tested: uninfected shrimp fed with commercial pelleted feed (T_C, negative control), WSSV-infected shrimp fed with commercial pelleted feed (T₁, positive control), WSSV-infected shrimp fed with commercial pelleted feed with 0.1% TEM (T₂), WSSV-infected shrimp fed with commercial pelleted feed with 0.5% TEM (T₃), and WSSV-infected shrimp fed with commercial pelleted feed with 1% TEM (T₄). At 72 h post infection, phenoloxidase activity of shrimps treated with 1% TEM did not show significant differences with T_C values but it was significantly higher than that of the other treatments (T₁, T₂, and T₃). Moreover, shrimps treated with T₄ presented absence of clinical signs of WSSV infection and their survival rate was significantly higher than that of T₁, T₂, and T₃ treatments. Therefore, 1% TEM seemed to protect shrimps against WSSV symptoms. Using microencapsulated thyme essential oil may help to fight against WSSV in shrimp farms.     

Some effects of oral doses of oxytetracycline on growth,survival and disease in Penaeus aztecus

Two size groups of brown shrimp (Penaeus aztecus) were fed a formulated feed containing 0, 100, 1 000 or 5 000 mg of oxytetracycline/kg of feed. Growth and survival were measured after a 3-week drug consumption period. The shrimp were then inoculated with Vibrio alginolyticus, and survival was monitored during the following 24 h.At all three concentrations of oxytetracycline, small shrimp (mean initial wet weight 143.4 mg) consumed approximately one-third the amount of feed consumed by those fed the control diet with no oxytetracycline, yet growth was more rapid with diets containing 100 and 1 000 mg of oxytetracycline/kg of food than with the control diet. Larger shrimp (mean initial wet weight 458.1 mg) receiving oxytetracycline consumed about one-fourth the feed consumed by those on the oxytetracycline-free diet. Some growth inhibition was apparent in these shrimp at all oxytetracycline concentrations. Maximum drug consumption rate, based on actual feed intake, was approximately 1 300 mg oxytetracycline per kg body weight per day for small shrimp, but only 370 mg per kg body weight per day for larger shrimp.All shrimp fed 0, 100 or 1 000 mg of oxytetracycline/kg of feed died within 24 h following inoculation with a standard dose (70% light transmission at 520–540 nm) of Vibrio alginolyticus. All the small shrimp and 70% of the large shrimp fed at the 5 000-mg drug level died, but death generally took place later in the 24-h period than with those fed at the lower drug concentrations. All shrimp fed 5 000 mg oxytetracycline/kg of feed and inoculated with a 1 : 100 dilution of the standard dose of Vibrio alginolyticus survived. All small shrimp and 90% of the large shrimp survived injection of sterile saline.     

Shrimp Yields and Economic Potential of Intensive Round Pond Systems

Three intensive growout trials using Penaeus vunnumei were conducted in round ponds in Hawaii in 1987. A 337 m² experimental pond was stocked at 100 shrimp/m² for two trials; a 2,000 m² commercial prototype pond was stocked at 75/m² for one trial. In the experimental pond trials, shrimp survival averaged 88 ± 10% (SE) and feed conversion averaged 2.2 ± 0.2. Growth averaged 1.5 ± 0.3 g/week, yielding 18.2 ± 1.7 gram shrimp in 80 ± 5.5 days. Combined production in the experimental trials was 32,272 kg/ha in 174 days (from stocking of trial 1 to harvest of trial 2). Comparing these results to 1986 results (Wyban and Sweeney 1988), it was concluded that shrimp growth is not affected and production is doubled by increasing stocking density from 45/m² to 100/m². Pooling data from 1986 and 1987, a significant linear regression was obtained when weekly growth of shrimp above four grams individual size was regressed on mean weekly pond temperature: growth = 0.37 * temperature - 8.44, (r²= 0.41; P < 0.01). Multiple regression to examine effects of shrimp size, pond biomass, and shrimp age on the temperature-growth relationship was not significant. In the commercial prototype pond trial, survival was 67% and feed conversion was 2.0. Growth averaged 1.4 g/week, yielding 18.1 gram shrimp in 88 days. Production was 9,120 kg/ha. Individual shrimp size distribution at harvest in the commercial pond was similar to experimental pond results, indicating that shrimp growth in the two systems was comparable. Financial characteristics of a hypothetical 24 pond shrimp farm using these results were determined using an electronic spreadsheet model (hung and Rowland 1987). Feed costs were 40% of total operating costs while postlarvae and labor were 14% and 16% of total operating costs, respectively. Breakeven price (BEP) was far more sensitive to changes in revenuedetermining inputs such as survival and growth than to comparable changes in costdetermining inputs such as feed and postlarvae costs. Together these results suggest that commercial scale round pond production mimics experimental scale production and that round pond technology has commercial potential.     

Probiotic characteristics and aflatoxin B1 binding ability of Debaryomyces hansenii and Kazaschtania exigua from rainbow trout environment

The aim of this study was to evaluate probiotic properties and the aflatoxin B₁ adsorption ability of yeasts isolated from rainbow trout intestine and fish feed to assess their use in the formulation of feed additives. Growth at pH 2, bacterial pathogens inhibition, bacterial pathogens co‐aggregation, autoaggregation, homologous and heterologous inhibition against lactic acid bacteria were evaluated. Moreover, aflatoxin B₁ adsorption was tested. All strains were able to maintain viable (10⁷ cells/ml) at pH 2. All strains isolated from intestine were identified as Kazaschtania exigua, while strains isolated from feed were all identified as Debaryomyces hansenii. Kazaschtania exigua RC035 and RC037 showed the strongest antimicrobial activity while K. exigua RC037 and RC038 were the most efficient co‐aggregating bacterial pathogens. All strains exhibited strong autoaggregation. None of the tested yeast strains showed homologous inhibition towards other yeasts and heterologous inhibition towards lactic acid bacteria strains. Debaryomyces hansenii RC031 demonstrated aflatoxin B₁ adsorption capacity (21%). The results of the present study indicate that select strains of Kazaschtania exigua and D. hansenii showed potential to improve the health of rainbow trout by inhibiting pathogens and binding AFB₁ and their use as probiotics may improve the production of rainbow trout in aquaculture systems.     

Feed preference and growth response of juvenile Litopenaeus vannamei to supplementation of marine chemoattractants in a fishmeal‐challenged diet

This study compared the feed preference and growth response of Litopenaeus vannamei to chemoattractants. A diet with 3% fishmeal was supplemented with either 3% salmon meal (POS), 3% soy protein concentrate (NEG), 3% krill meal (KRM), 3% squid meal (SQM), 3% shrimp head meal (SHM), 3% shrimp meal (SM), 3% squid liver meal (SLM), or 5% liquid sardine hydrolysate (SAH). Shrimp with a body weight (BW) of 0.99 ± 0.08 g were stocked at 100 animals/m² in 56 tanks of 1 m³ and fed 10 times daily for 74 days. Feed preference was evaluated by feeding shrimp of 10.87 ± 1.82 g in excess twice a day for 10 days in two separate feeding trays allocated in 50 tanks of 0.5 m³. Survival reached 93.3 ± 5.80% and was unaffected by supplementation. Final BW was the highest for shrimp fed the KRM‐supplemented diet (11.97 ± 0.93 g), followed by POS (11.11 ± 0.77 g) and SQM (11.01 ± 1.17 g). Diets SHM, SM, SLM, and NEG showed a lower shrimp BW than POS, but were not statistically different among them. Shrimp fed the SAH diet achieved the lowest BW (10.06 ± 1.02 g). The highest gained yield was obtained with diets KRM and POS. No statistical difference was observed in shrimp yield among other diets. The lowest feed conversion ratio (FCR) was achieved with shrimp fed KRM (1.31 ± 0.05) when compared to diets SHM (1.47 ± 0.05), SAH (1.47 ± 0.07), and SLM (1.45 ± 0.17). Two‐by‐two comparisons indicated that shrimp preferred SHM and KRM, except when these were compared to SQM and SLM. No difference in feed preference was found between diets with SQM and SLM. SAH was the least preferred raw material in all comparisons. Results indicated that KRM acts as a powerful feeding effector and growth enhancer in fishmeal‐challenged diets for whiteleg shrimp. A dietary supplementation with 3% KRM is more effective than the same dose of any other chemoattractant evaluated.     

The value of sea urchin,Lytechinus variegatus,egesta consumed by shrimp,Litopenaeus vannamei

Sea urchins produce high‐energy, membrane‐bound fecal pellets that contain residual nutrients and large quantities of microbiota. These egesta are readily consumed by the shrimp, Litopenaeus vannamei. Egesta of the sea urchin, Lytechinus variegatus, were evaluated as a feed supplement or total replacement for a commercial shrimp diet. Shrimp were stocked at 0.49 g ± 0.06 g initial body weight and housed individually in 2.8‐L tanks in a commercial recirculating zebrafish system. Shrimp were assigned to one of six diets: commercial shrimp feed, reference sea urchin feed, collected dried sea urchin egesta, collected wet sea urchin egesta, half ration of shrimp feed and half collected wet sea urchin egesta, and egesta naturally produced by two sea urchins in polyculture. Equivalent dry matter amounts of each diet were proffered to shrimp in each treatment twice daily, except for those that had complete access to natural egesta excreted by sea urchins in polyculture. Sea urchins were proffered a reference sea urchin feed at 2% body weight daily. After 27 days, shrimp proffered collected dried or wet egesta did not differ significantly in percent weight gain and showed the lowest weight gain. The percent weight gain of shrimp fed the commercial shrimp diet did not differ significantly from that of the shrimp fed half commercial shrimp diet and half egesta. The highest weight gain was recorded for those shrimp that consumed the untouched egesta produced by sea urchins in polyculture. These data suggest that consumed egesta have noteworthy nutritional value and therefore would be beneficial to the culture of extractive species in an integrated multitrophic aquaculture system.