Effects of Microbial Fermented Feed on Growth and Development of Farmed Crayfish

Microbial fermented feed possesses a natural fermentation flavor and exhibits good palatability.It is not only easily digestible and absorbable by livestock but also non-toxic.Additionally,it has the capacity to inhibit the proliferation of pathogenic bacteria,facilitate the growth and development of animals,and enhance their immune response,disease resistance,and overall production performance.This paper summarizes the selection of common feed materials and microbial strains used in fermented feed,as well as their effects on the growth performance,muscle quality,antioxidant capacity,and immune function of crayfish.The aim of this study is to provide a reference for the further popularization and application ofmicrobialfermented feed in crayfishaquaculture.

Preliminary Results of Crayfish Distribution and Diseases in Latvia

A lot of water reservoirs offer good natural conditions for crayfish breeding. Today there are four crayfish species present in Latvia--the European species noble crayfish （Astacus astacus）, narrow-clawed crayfish （Astacus leptodactylus）, the North American signal crayfish （Pacifastacus leniusculus） and spiny-cheek crayfish （Orconectes limosus）. In general, crayfish were found in 258 localities--lakes （175）, rivers and streams （66）, reservoirs, ponds and gravel-pits （17）. A. astacus in Latvia is the dominant crayfish species distributed in all regions. Narrow-clawed crayfish was registered since 1960s. North American signal crayfish was introduced due to its resistance to diseases, but spiny-cheek crayfish arrived from Lithuania waters spontaneously. The main threat for crayfish population is crayfish plague, initiated by mucus Aphanomyces astaci. Astacus astacus was more susceptible species in comparison with Pacifastacus leniusculus and Orconectes limosus. Though the North American signal crayfish and spiny-cheek crayfish were not only resistant, they were the carriers of this disease. The physical habitat alterations, pollution and overfishing are significant during the first year breeding period. Crayfish might serve as bacteria carriers and can cause substantial fish diseases （such as aeromonosis, flavobacteriosis）.

Technical Standards for Lotus Root-Redswamp Crayfish Integrated Farming

Lotus root-redswamp crayfish integrated farming is a kind of ecologicalgrow mode on the basis of paddy field, which is an innovated mode for agricultural structure adjustment and special agriculture with high efficiency. In order to regulate producing technology of this mode, the essay puts forward some technical require- ments, stressing on cultivar selection, field works, farming technology and product quality, which aims at providing technical support for agricultural production.

Clinical characteristics of patients with Haff disease after eating crayfish

BACKGROUND: The study aimed to explore the clinical presentations, laboratory findings, treatments and prognosis of patients with Haff disease after eating crayfi sh. METHODS: Sixteen patients with Haff disease after eating crayfish were admitted to the Emergency Department of Beijing Chao-yang Hospital between June 2013 and August 2017. Clinical data was retrospectively analyzed. RESULTS: Alcohol consumption and exercise were found to be most commonly associated with the onset of rhabdomyolysis after consuming crayfi sh. Most patients were young adults and the symptoms mostly occurred within 24 hours of consumption of crayfi sh. Clinical symptoms included myalgia (100%), fatigue (87.5%), nausea (43.8%), dizziness (62.5%), chest distress (37.5%) and fever (18.8%). Also found after laboratory testing was elevations in the levels of creatine kinase (11,376±5,535 U/L), myoglobin (350±158 ng/mL), lactate dehydrogenase (6,539±3,180 U/L), alanine transaminase (174±71 U/L) and aspartate aminase (348±100 U/L). The incidence of renal dysfunction was low (6.25%), and all 16 patients had a good prognosis. CONCLUSION: Patients with Haff disease exhibited typical symptoms after consuming crayfish, and laboratory findings gave highly accurate diagnostic results. The development of rhabdomyolysis was considered to be associated with alcohol consumption and exercise, but further studies are needed to demonstrate its relationship with crayfi sh consumption. Compared with other causes of rhabdomyolysis, rhabdomyolysis after crayfi sh consumption has fewer complications and better prognosis.

Sustainability of the rice-crayfish farming model in waterlogged land:A case study in Qianjiang County, Hubei Province, China

The rice-crayfish farming model has been rapidly developed and become an economically viable method to supply food in China in recent years.However,its environmental and economic sustainability has not been thoroughly investigated.This study uses a survey in 2016 and a field experiment in 2017 in Qianjiang,Hubei Province,China to assess the relative economics of concurrent rice-wheat(RW),rice-crayfish(RC),and crayfish monoculture(CM)models in waterlogged land areas.Thefield survey indicated that the RC model had a higher benefit-cost ratio(3.5:1)than the RW(2.0:1)and CM(3.1:1)models and the RC model protected farmers’enthusiasm for grain production facing unfavourable weather conditions.The field experiment aimed to explore nitrogen management strategies in RC fields.In the experiment,four levels of nitrogen concentration gradient-0 kg N ha^(-1)(0 N),75 kg N ha^(-1)(75 N),150 kg N ha^(-1)(150 N)and 225 kg N ha^(-1)(225 N),were set in a 2-year-old rice-crayfish(RC2)field,an 8-year-old rice-crayfish(RC8)field,and a RWfield as a control.Thefield experiment results suggested that the peak rice yield in RW,RC2,and RC8 occurred when 225 N,150 N and 75 N were used,respectively.In RC2 and RC8,however,residual feed-nitrogen that was not used by crayfish was utilized by rice plants.Thus,an optimal amount of nitrogen in RCfields was proposed to improve the nitrogen use efficiency and reduce environmental pollution by nitrogen fertilizer.Farmers use less nitrogen but have higher net income in RC than in RW and CM.It is necessary to sustainably develop integrated farming technologies(i.e.,properfield configurations for ricefields)to effectively sustain rice production.The results also showed that the RC farming model was a viable diversification option for rice farmers in waterlogged land.

In vivo neutralization assays by monoclonal antibodies against white spot syndrome virus in crayfish (Cambarus proclarkii)

The neutralizing activities of eight monoclonal antibodies （MAbs） against white spot syndrome virus （WSSV） （2D2, 2B2,1D2, 1D5, 1C2, 4A1, 6A4 and 6B4） were analyzed by in vivo experiments. Gills from WSSV-infected shrimp were homogenized and ten-fold serially diluted by PBS, and then incubated with MAbs （hybridoma culture supernatant）, respectively. The mixture of WSSV and MAbs were injected into crayfish （Procambarus clarkii）. After challenge, the death rates of crayfish were counted to determine the neutralizing activities of MAbs. At the same time, the mixture of myeloma culture supernatant and WSSV or PBS was served as positive or negative control, respectively. The results showed that, at each virus dilution, the mean time to death of the crayfish injected with MAb-treated virus was significantly longer than that in the positive control, though they all showed 100% mortality within 25 d, and meanwhile, few crayfish died in the negative control. Among the eight MAbs, 2D2, 2B2, 1D2 and 1D5, especially the former two, delayed the mortality significantly, and 1 C2, 4A1 and 6A4 delayed the mortality as well but not so efficiently, while MAb 6IM was efficient only when the virus concentration increased. The results indicated that the anti-WSSV MAbs can neutralize WSSV in different virus dilutions.

Characterization of Specific Spoilage Bacteria and Volatile Flavor Compounds of Flavored Crayfish

It is a common issue in the processing industry of crayfish that flavored crayfish stored at room temperature is perishable.In order to establish an effective putrid prediction mechanism,high-throughput sequencing and solid phase microextraction gas chromatography-mass spectrometry(SPME-GCMS)were used to analyse the microbial community structure and volatile flavor compounds of normal and putrid crayfish.The results showed that Aeromonas(57%),Macrococcus(7.7%),Vibrio sp.(6.6%),Acinetobacter(5%),Citrobacter(4.9%)and Enterobacter(1.49%)were the main bacterial genus in the refrigerated fresh crayfish(HNA).And Staphylococcus(17.04%),Aeromonas(4.46%),Xanthomonas(4.16%),Streptococcus(4.62%)and Enterococcus(2.77%)were the main bacterial genus in the marinated and refrigerated crayfish(HND).With the spoilage of samples(HNE and HNC),the diversity of bacteria decreased,and the specific spoilage bacteria grew rapidly,mainly Enterococcus,Bacillus,Lactobacillus,Leuconostoc,Weissella.Meanwhile,the volatile compounds in non-spoilage sample(HNA and HND)were mainly alkane compounds,aldehydes compound and esters compounds;and the volatile compounds in spoilage samples were mainly alcohols,acids,benzene compounds,terpenoids,N-containing compounds,S-containing compounds and ethers.This indicated that the contents and types of volatile compounds changed with the sample spoilage and deterioration.Correlation analysis results showed that Enterococcus,Lactobacillus and Bacillus were significantly positively correlated with alcohols,acids,benzene,terpenoids,N-containing compounds,S-containing compounds and ether compounds,while Aeromonas,Megasphaera,Acinetobacter,Citrobacter and Vibrio were significantly positively correlated with alkane compounds and esters compounds,and Leuconostoc were significantly positively correlated with alcohol compounds.These results can provide a theoretical guidance for the storage of cooked flavor crayfish at room temperature.

Crayfish Shell Waste as Safe Biosorbent for Removal of Cu^(2+)and Pb^(2+)from Synthetic Wastewater

Crayfish shell is an abundant natural waste and is also a potential biosorbent for pollutants,especially,heavy metals.In this study,the safety of the use of crayfish shell as a biosorbent was first assessed by release experiments involving primary heavy metal ions,such as Cu^(2+),Zn^(2+),and Cr^(3+),in aqueous solution under different environmental conditions.The release concentrations of heavy metals were dependent on pH,ionic strength,and humic acid;and the maximum release concentrations of heavy metals were still lower than the national standard.Specifically,Cu^(2+) and Pb^(2+) removal by crayfish shell in synthetic wastewater was investigated.The removal process involved biosorption,precipitation,and complexation,and the results indicate that crayfish shell is an excellent biosorbent for Cu^(2+) and Pb^(2+) removal.The precipitation step is particularly dependent on Ca species,pH,and temperature.The maximum removal capacities of Pb^(2+) and Cu^(2+) were 676.20 and 119.98 mg/g,respectively.The related precipitates and the generated complex products include Cu_(2)CO_(3)(OH)_(2),Ca_(2)CuO_(3),CuCO_(3),Pb_(2)CO_(3)(OH)_(2),CaPb_(3)O_(4),and PbCO_(3).

Nutritional and Sensory Evaluation of Rice-Based <i>Masa</i>Enriched with Soybean and Crayfish

Masa is a cereal based snack made from rice, maize or millet. It is popularly consumed in the northern regions of Nigeria. The objective of this work was to assess the nutritional and sensory properties of the rice-Masa, enriched with soybean and crayfish. The enriched rice-Masa produced were labelled sample A (100% rice), sample B (rice: soybean blend (80:20), sample C (rice: crayfish blend (80:20) and sample D (rice: soybean: crayfish (80:10:10). The proximate and mineral composition was evaluated according to standard methods. Anti-nutrient content was also determined. Sensory evaluation was carried out to assess the acceptability of the enriched rice-Masa. The chemical analysis showed that protein, fibre, iron, zinc and vitamin A and beta carotene contents were highest in sample D with values 8.35 (±0.08) g/100g, 1.08 (±0.02) g/100g, 2.82 (±0.03) mg/100g, 4.20 (±0.03) mg/100g, 602.3 (±1.28) μg/100g and 420.2 (±0.98) μg/100g respectively, while calcium was highest in sample C with a value of 27.34 (±0.06) mg/100g. Moisture and ash contents increased from 47.4 (±0.50) g/100g to 50.9 (±0.80) g/100g and 0.40 (±0.01) g/100g to 1.15 (±0.01) g/100g respectively, while carbohydrate and energy contents decreased from 28.1 (±0.03) g/100g to 21.9 (±0.04) g/100g and 308.42 kcal/100g to 285.64 kcal/100g respectively. The sensory evaluation showed that with regards to taste, aroma, texture and overall acceptability, the sample enriched with soybean was more preferred to that enriched with crayfish, or a combination of both. Enrichment of Masa could contribute to improvement of nutritional status if promoted as a nutritious, healthy indigenous snack not only where Masa is already widely consumed, but also in other parts of Nigeria where it has not found wide acceptance.

Crayfish Robot That Generates Flow Field to Enhance Chemical Reception

This paper describes a wheeled underwater robot developed for locating chemical sources autonomously under stagnant flow conditions. In still water, the released chemical stays in the immediate vicinity of the source location. The search for chemical sources under such conditions is extremely laborious since the presence of a chemical source cannot be detected from a distant place. The chemical sensors on the robot show no response unless a chemical substance released from the source arrives at the sensors. Crayfish in search of food are known to actively generate water currents by waving their small appendages with a fan-like shape. It is considered that the generated water currents help their olfactory search. The smell of food is carried to their olfactory organs from the surroundings by the generated flow, and then is perceived. The robot presented in this paper employs arms mimicking the maxillipeds of a crayfish to generate water currents and to draw chemicals to its sensors. By waving the arms vertically, a three-dimensional flow field is generated and water samples are drawn from a wide angular range. The direction of a chemical source can be determined by comparing the responses of four laterally aligned electrochemical sensors. Experimental results show that the flow field generated by the maxilliped arms is more effective in collecting chemical samples onto the sensors than that generated by a pump. The robot equipped with the maxilliped arms can detect the presence of a chemical source even if the source is placed off the trajectory of the robot.

Heart and ventilatory measures in crayfish during copulation

Monitoring heart rate (HR) and ventilatory rate (VR) during defined sensory stimuli and during aggressive and submissive social interactions has provided additional information of a crayfish's physiological state which is not achieved by behavioral observations. In this study, the HR and VR of crayfish were monitored before, during and after the act of copulation in both heterosexual partners. The female crayfish abruptly reduces HR and VR during copulation but the male maintains HR and VR. After separation from copulation the female HR and VR are elevated, potentially paying back the O2 debt. The tight relationship with HR and VR in direction of change indicates a potential neural coupling. These physiological changes in cardiac and respiratory systems suggest an autonomic-like regulation of HR and VR. How these neuronal functions are driven and regulated remains to be determined. Olfactory cues from the female to the male during copulation may be reduced by the reduction in VR in the female. These studies offer experimental paradigms for future neuronal and pharmacological investigations into autonomic regulation of HR and VR as well as the neural circuitry involved.

Dietary Intake, Carcinogenic and Non-Carcinogenic Risk Potentials of Lead, Cadmium, Mercury and Arsenic Exposure via Consumption of Dried Crayfish in Calabar, Nigeria

Intense pressure from both onshore and offshore oil exploration and exploitation activities, together with the accompanying urbanization and industrialization has resulted in massive contamination of land and water resources in Niger Delta, Nigeria. Whereas crayfish is very sensitive to contaminant in the aquatic environment and constitute an important part of human diet, its quality and safety from environmental pollutant is of serious health concern. Evaluation of dietary intake, potential carcinogenic and non-carcinogenic risk of lead, cadmium, mercury and arsenic exposure via consumption of dried crayfish purchased from major markets in Calabar, Nigeria was carried out between June and August 2021. Thirty-six composite samples of dried crayfish purchased from 180 vendors were used for the study. Heavy metals concentrations were determined using Atomic Absorption Spectrophotometer (Model AA-6800, Japan) after wet digestion. Metals concentrations (Mg/kg) were of the ranges 0.02 - 0.24, 0.14 - 0.86, 0.32 - 0.72, 0.04 - 0.19 for Pb, Cd, Hg and As respectively. The mean content of cadmium and mercury exceeded FAO/ WHO and Commission of European Communities maximum levels for crustaceans. Average Estimated Daily Intake for each of the metals was found to be above the recommended daily intake level except for arsenic. The average estimated daily intake values for Cd and Hg were also above the tolerable upper intake level. Average Target Hazard Quotient of all the metals and Hazard Index of all the markets were below 1.00. The Incremental Lifetime Cancer Risk of the metals was greater than the standard tolerable regulatory risk (10-4) for carcinogens. Consumption of crayfish purchased from major markets in Calabar could pose a range of carcinogenic and non-carcinogenic human health risks.

Study on the Effect of "Crayfish-Rice Continuous Cropping" on Grain Production:A Case Study of Hubei Province

Taking Hubei Province as an example,starting with the present situation and existing problems of grain production,this paper expounds the great significance of"crayfish-rice continuous cropping"model in improving grain quality,and analyzes the beneficial influence of"crayfish-rice continuous cropping"on grain production and the difficulties it faces.This paper also puts forward some measures and suggestions for the further popularization of"crayfish-rice continuous cropping"in order to maintain food security.

Morphology and molecular phylogeny of four epibiotic ciliates(Ciliophora,Peritrichia)from farmed red swamp crayfish Procambarus clarkii Girard,1852,with notes on the geographic distributions of related taxa

Aquaculture of red swamp crayfish Procambarus clarkii is an emerging farming industry in China.As shown recently,one of the most significant diseases affecting the red swamp crayfish is caused by overabundance of epibiotic peritrichs,a group of ciliated protists that are commonly found living as epibionts on aquatic animals.Nevertheless,few studies focusing on this issue have been performed.As part of a faunal study carried out in the Lake Weishan Wetland,China,four colonial sessilid peritrichs,namely Epicarchesium granulatum,Epistylis bimarginata,Epistylis semiciculus,and Zoothamnium procerius,attached to P.clarkii are documented.For each species,redescriptions and improved diagnoses are supplied.As a further aid to identification,14 new rDNA sequences of these four and a closely related species were obtained.In addition,as an aid for future studies on epibiotic ciliates,we supply a list and information about recent integrative studies that document the geographic distributions of related taxa.

自然发酵虾酱中屎肠球菌的分离、鉴定及体外益生特性分析

从自然发酵的小龙虾酱中筛选出8株产酸菌,通过生理生化试验和16S rDNA序列分析对菌种进行鉴定,并根据发酵特性分析选取产酸能力最高的菌株LX12-2和LX18-9进行抑菌、抗氧化、体外益生特性分析及安全性评价。结果表明,有7株菌为乳酸菌,隶属肠球菌属,其中5株为粪肠球菌(Enterococcus faecalis)、2株为屎肠球菌(Enterococcus faecium);屎肠球菌LX18-9的产酸能力最高,具有广谱的抗菌活性和较高的抗氧化能力。其对单增李斯特菌生长的抑制作用最强,抑菌圈直径可达20.85 mm,对DPPH自由基的清除率达76.77%;该菌株对pH 2.0的酸性条件、0.5%胆盐以及人工胃肠液均具有良好耐受性,且不产组胺,无溶血性,安全性高。综上,该研究筛选的屎肠球菌LX18-9安全性高、且具有良好的抗菌、抗氧化及益生特性,在饲料发酵生产与水产养殖益生产品的开发中具有潜在应用价值。

Morphological variation in fossil crayfish of the Jehol biota,Liaoning Province,China and its texonomic discrimination

Twelve morphological characteristics in 61 fossil crayfish specimens, which came from the Upper Jurassic Yixian Formation, are discussed respectively in the present paper. A study of these new and better preserved materials allows us to add to and revise the original description for Family Cricoidoscelosidae. In our collection, no modifications of the second pleopod of the males have yet been noted. This would be a crucial factor for the diagnosis of the family. Based on the presence of annulus ventralis in both Cricoidoscelosus and Palaeocambarus, they would appear to be very closely allied to those characteristics of the Family Cambaridae. In regard to the family Protastacidae, we seriously doubt it is actually crayfish, in light of the lack of any apomorphies identifiable within the Astacida, and their marine habitat.

A review on conversion of crayfish-shell derivatives to functional materials and their environmental applications

As a new research focus in the field of biological resources,crayfish shells have great potential for development and utilization.In this review,the typical methods and research progress of separating the primary components such as chitosan,protein,and astaxanthin from crayfish shells and converting crayfish shells into functional carbon-based materials are introduced in detail.Then,the application of crayfish shell and typically modified crayfish-shell biochar in adsorption,antibacterial,electrochemical,etc.is reviewed.Finally,the future research outlook is proposed.This review can provide some perspectives on the development of the application of crayfish shells and crayfish-shell derivatives.

Effects of transport stress on immune response, physiological state, and WSSV concentration in the red swamp crayfish Procambarus clarkii

Transport is an essential part of the aquaculture and research of the main freshwater aquaculture crayfish Procambarus clarkii in China.However,transport is often accompanied by a low survival rate.Assessing the physiological state of P.clarkii before and after transport may discover the cause of this high mortality rate.In this study,ice-cold and exposed-to-air transport methods were compared using an array of parameters,including relative expression level of heat shock protein 70(HSP70),content of serum glucose and cortisol,immune parameters(enzyme and immune-related genes),and white spot syndrome virus(WSSV)concentration were investigated to understand the physiological state of P.clarkii before and after transport,as well as the cause of dying crayfish on days 5 and 7 after transport stress.Histological sections of hepatopancreas,gills,and intestines reflected pathological changes.The survival rate of crayfish with ice-cold transport was significantly higher than that with exposed-to-air transport,and mortality peaked at 3-9 days after transport stress.A prolonged response to oxidative stress and short-term immunosuppression was present after transport,and the trend of the WSSV concentration in the hepatopancreas was similar to the mortality rate of P.clarkii.The contents of serum glucose and cortisol,antioxidant enzymes and immune-related indexes,and the concentration of WSSV in hepatopancreas of dying crayfish were significantly higher than those of vibrant crayfish on the 5th and 7th days after transport.The hepatopancreas,intestines,and gills of dying crayfish had varying degrees of damage,and the hepatopancreas and intestines were severely damaged.The results suggested that the death of P.clarkii after transport stress is caused by oxidative stress,the imbalance of reactive oxygen species regulation,and decreased WSSV resistance,which eventually led to irreversible tissue damage.The increase of WSSV in the body of crayfish might be the direct cause of crayfish death.

Non-enzymatic browning path analysis of ready-to-eat crayfish(Promcambarus clarkii)tails during thermal treatment and storage

This study was carried out to reveal the browning path of ready-to-eat(RTE)crayfish tails during thermal treatment and storage using path analysis.Maillard reactions,lipid oxidation,and phenol oxidation were evaluated in combination with free radical content and FTIR analysis,and direct path coefficients as well as determination coefficients were obtained based on these parameters,such as the absorbance at 294 nm(A294),5-hydroxymethylfurfural(5-HMF),thiobarbituric acid-reactive substances(TBARS),and total phenols(TP).The result showed that the browning of seasoned RTE crayfish tails was ascribe to the synergistic effect of Maillard reaction and lipid oxidation by the order of determination coefficient.After the crayfish hepatopancreas were removed,the content of A294,5-HMF,TBARS,and TP declined more than 30%,specifically affecting the direct pathway from lipid oxidation to Maillard reaction and alleviating the browning.However,no significant change of color was observed in the group without thirteen-spices,while TBARS and free radical content increased by at least 16.7%.The removal of hepatopancreas and the control of Maillard reaction were deemed to be a good measure for inhibiting the non-enzymatic browning of RTE crayfish tails.

Antibacterial properties of extracts of Solidago canadensis and their potential use as dietary supplements in red swamp crayfish(Procambarus clarkii)

Canadian goldenrod(Solidago canadensis)is one of the most destructive invasive weeds in Southeastern China.To evaluate its potential application as dietary supplement in red swamp crayfish(Procambarus clarkii),the antibacterial properties of aqueous and ethanol extracts of this plant against three major pathogenic bacteria in crayfish aquaculture were examined.Inhibition zone tests and determination of minimum inhibitory concentration revealed that the extracts had lower antibacterial activity than extracts from two traditional medicinal plants that possess antibacterial properties,garlic(Allium sativum)and cortex phellodendri(Phellodendron chinense).However,they did exhibit greater antibacterial effects than extracts from another widely used medicinal plant,Sophora flavescens,and an aquatic weed,Alternanthera philoxeroides.Aqueous extracts of Canadian goldenrod gave greater inhibition than the ethanol extracts.Crayfish fed a diet with 2%these aqueous extracts exhibited significantly higher enzyme activity of alkaline phosphatase,catalase and phenoloxidase(P<0.05).Based on the results of this study,we conclude that aqueous extracts of Canadian goldenrod are highly promising for the development of new dietary supplement for use in crayfish aquaculture.