Frog Farms Research Articles

Horizontal plasmid transfer promotes antibiotic resistance in selected bacteria in Chinese frog farms

The emergence and dissemination of antibiotic resistance genes (ARGs) in the ecosystem are global public health concerns. One Health emphasizes the interconnectivity between different habitats and seeks to optimize animal, human, and environmental health. However, information on the dissemination of antibiotic resistance genes (ARGs) within complex microbiomes in natural habitats is scarce. We investigated the prevalence of antibiotic resistant bacteria (ARB) and the spread of ARGs in intensive bullfrog (Rana catesbeiana) farms in the Shantou area of China. Antibiotic susceptibilities of 361 strains, combined with microbiome analyses, revealed Escherichia coli, Edwardsiella tarda, Citrobacter and Klebsiella sp. as prevalent multidrug resistant bacteria on these farms. Whole genome sequencing of 95 ARB identified 250 large plasmids that harbored a wide range of ARGs. Plasmid sequences and sediment metagenomes revealed an abundance of tetA, sul1, and aph(3″)-Ib ARGs. Notably, antibiotic resistance (against 15 antibiotics) highly correlated with plasmid-borne rather than chromosome-borne ARGs. Based on sequence similarities, most plasmids (62%) fell into 32 distinct groups, indicating a potential for horizontal plasmid transfer (HPT) within the frog farm microbiome. HPT was confirmed in inter- and intra-species conjugation experiments. Furthermore, identical mobile ARGs, flanked by mobile genetic elements (MGEs), were found in different locations on the same plasmid, or on different plasmids residing in the same or different hosts. Our results suggest a synergy between MGEs and HPT to facilitate ARGs dissemination in frog farms. Mining public databases retrieved similar plasmids from different bacterial species found in other environmental niches globally. Our findings underscore the importance of HPT in mediating the spread of ARGs in frog farms and other microbiomes of the ecosystem.

The Mechanism of Elizabethkingia miricola Infection of the Black Spotted Frog as Revealed by Multi-Omics Analysis

Elizabethkingia miricola (E. miricola) is a significant pathogen that causes the crooked head disease in black spotted frogs. This disease has plagued numerous frog farms in China and has resulted in substantial losses to the frog farming industry. Nonetheless, the exact mechanism that causes the disease in frogs remains unknown. In this study, transcriptomic and microbiomic analyses were conducted to analyze frog samples infected with E. miricola to reveal the infection mechanism of the pathogen. Liver transcriptomic analysis indicated that the livers of infected frogs had 1469 differentially expressed genes when compared with an uninfected group. These DEGs are mainly involved in immunity and metabolism, including neutrophil extracellular trap formation, the NOD-like receptor signaling pathway, leukocyte transendothelial migration, chemokine signaling pathway, Fc gamma R-mediated phagocytosis, and “metabolism”-related pathways such as the pentose phosphate pathway, carbon metabolism, glycerophospholipid metabolism, and glycerolipid metabolism. Similarly, 4737 DEGs were found in the kidney of infected frogs. These DEGs are mainly involved in immunity, including neutrophil extracellular trap formation, the NOD-like receptor signaling pathway, B cell receptor signaling pathway, C-type lectin receptor signaling pathway, complement and coagulation cascade, and Toll-like receptor signaling pathway. Ten immune-associated DEGs were screened in liver and kidney DEGs, respectively. And it was hypothesized that E. miricola infection could influence the host immune response. Microbiome analysis results showed that some opportunistic pathogens such as Citrobacter, Shigella, and Providencia were significantly elevated (p < 0.05) in infected frogs. Additionally, functional prediction confirmed that most of the microbiota in infected frogs were linked to metabolism-related KEGG pathways. In this study, the screened genes linked to immunity showed an association with the gut microbiome. The majority of these genes were found to be linked with the abundance of opportunistic pathogens. The results showed that E. miricola infection led to the downregulation of immune and metabolic-related genes, which led to the inhibition of immune function and metabolic disorder, and then increased the abundance of opportunistic pathogens in the gut microbiota. The findings of this study offer a preliminary foundation for comprehending the pathogenic processes of E. miricola infection in black spotted frogs.

Sex, health status and habitat alter the community composition and assembly processes of symbiotic bacteria in captive frogs

BackgroundFrogs are critical economic animals essential to agricultural ecosystem equilibrium. However, Meningitis-like Infectious Disease (MID) often affects them in agricultural settings. While frog-associated microbiota contribute to elemental cycling and immunity, the effects of frog sex and health on gut bacteria remain understudied, and the relationship between frog habitat and soil microbes is unclear. We aimed to determine how frog sex, health status and habitat influence symbiotic bacteria and community assembly mechanism to provide guidance for sustainable frog farming and conservation.ResultsWe employed 16S rRNA sequencing to investigate gut microbiota differences in relation to frog sex and health status. We also compared symbiotic communities in frog-aggregation, native and soybean soil on the farm. Results showed that gut bacterial β-diversity and taxonomy were markedly influenced by frog sex and health. Healthy frogs had more robust gut bacterial metabolism than frogs infected with MID. Cooccurrence network analysis revealed that healthy female frogs had more complex microbial network structure than males; however, diseased males showed the greatest network complexity. The assembly mechanism of gut bacteria in male frogs was dominated by deterministic processes, whereas in female frogs it was dominated by stochastic processes. Among symbiotic bacteria in frog habitat soils, deterministic processes predominantly shaped the community assembly of soybean soil. In particular, soybean soil was enriched in pathogens and nitrogen functions, whereas frog-aggregation soil was markedly increased in sulphur respiration and hydrocarbon degradation.ConclusionOur study reveals that sex mainly alters the interaction network and assembly mechanism of frog intestinal bacteria; MID infection significantly inhibits the metabolic functions of intestinal bacteria. Furthermore, diverse frog habitat soils could shape more symbiotic bacteria to benefit frog farming. Our findings provide new horizons for symbiotic bacteria among frogs, which could contribute to sustainable agriculture and ecological balance.

Bullfrog (Aquarana catesbeiana) farming in adapted water tanks from fall to spring in the state of Rio de Janeiro

Economically viable and readily accessible solutions are necessary for the sustainability of the economic endeavors of small-scale frog producers. An experiment was conducted with the objective of assessing the growth of post-metamorphosis frogs in adapted polyethylene water tanks in the period from fall to spring in the Southern Hemisphere. A total of 23 animals were employed, with a stocking density of 33 animals/m2, exhibiting an average weight of 17.39 g. The frogs were housed in a 500-L polyethylene water tank that was adapted to allow complete drainage at its outlet. The water was consistently replaced before each feeding, and the animals were provided with two daily feedings of commercial carnivorous fish food containing 400 g/kg of crude protein. Biometric measurements were conducted on 12 occasions, along with individual weighing of the frogs. The evaluated parameters included body growth (g), weight gain (g/day), feed intake (g), and feed conversion (g/g). Additionally, production costs were evaluated. Body weight (g) data were subjected to exponential regression analysis. The growth curve of the bullfrog adhered to the exponential regression model. Frog growth during the fall and winter seasons was sluggish, but, began to accelerate as spring emerged, closely associated with ambient temperature. Feed conversion rate stood at 1.89 g/g. The use of polyethylene water tanks shows promise as a viable environment for frog farming, particularly for small-scale producers.

Background color preference of Amphibian Rana dybowskii

Background color may affect the welfare of the brown frog Rana dybowskii in captivity. To evaluate the perching platform color and feeding platform color preferences of brown frogs at day and night, a total of 1200 brown frogs kept in 12 square plastic buckets (100 brown frogs per bucket) and eight plastic plates with different background colors (black, red, orange, yellow, green, baby blue, cyan, and blue) were used in this study, and the background color preference of brown frogs was measured by counting the number of frogs on the different colored plastic plates at different time points (7.5 min, 15 min, 30 min, 60 min, 120 min, 240 min, and 360 min) after replacing the square perching platforms with the experimental perching platforms and the control perching platform. The results show that brown frog counts on the plastic plates was significantly affected by the background color, daytime versus nighttime, and feeding versus not feeding (P < 0.05). In addition, brown frog counts on the black background was usually the largest, whether it was day or night, and regardless of whether there were mealworms (Tenebrio molitor) on the plastic plates, which indicated that brown frogs prefer the black backgrounds. It is reasonable to recommend using more black backgrounds for brown frogs R. dybowskii in captivity, which would provide a more suitable living environment for brown frogs, and undoubtedly have a positive role in promoting the brown frog farming industry.

Production techniques and environmental management in frog farming in Dong Thap province

This study surveyed 40 farmers on their production techniques and environmental management in frog farming in Cao Lanh and Thap Muoi district, Dong Thap province, and the results showed that frogs were cultured in tarpaulin tanks (82.5%), hapas in an earth pond (35%), and earth ponds (2.5%). Most of the farmers (82.5%) had a combination of breeding frogs and production frogs to be self-sufficient froglet. Stocking density is high with 146.3±92.3 individuals/m2 for production frogs and 51.6±35.7 individuals/m2 for breeding frogs. The culture duration of froglet was an average of 33.6±8.8 days/crop (9.3±2.4 crops/year) and production frogs was 64.7±9.7 days/crop (5.1±0.6 crops/year). Frogs were raised with a commercial pellet feed of many brands. The diseases occurred in tadpole and froglet phase (2-30 days), including septicemia diseases (57.5%), red thighs (45%), white bodies (35%), blindness (35%), digestive disorders (20%), and flatulence (15%). The disease causes were mainly due to poor water quality, weather change, feed, and high stocking density. However, few farmers had treated farming system (37.5%), supplemental water (27.5%), and monitored and controlled water quality. There were 60% of households to discharge wastewater directly into rivers and canals. Some farmers have used nutrient for wastewater from frogs with combining frog with fish (27.5%), or discharging wastewater into ditches gardens, fields (7.5%), settling pond (5%), which have helped to increase income and protect the environment. Therefore, farmers need to be supported with knowledge of farming technique and environmental management from the local government.

Co-infections of Klebsiella pneumoniae and Elizabethkingia miricola in black-spotted frogs (Pelophylax nigromaculatus)

Pelophylax nigromaculatus is a common commercial specie of frogs that generally cultured throughout China. With the application of high-density culture, P. nigromaculatus can be co-infected by two or more pathogens, which thereby induce synergistic influence on the virulence of the infection. In this study, two bacterial strains were simultaneously isolated from diseased frogs by incubating on Luria-Bertani (LB) agar. Isolates were identified as Klebsiella pneumoniae and Elizabethkingia miricola by morphological, physiological and biochemical features, as well as 16S rRNA sequencing and phylogenetic analysis. The whole genome of K. pneumoniae and E. miricola isolates consist single circular chromosome of 5,419,557 bp and 4,215,349 bp, respectively. The genomic sequence analysis further indicated that K. pneumoniae isolate conserved 172 virulent and 349 antibiotic-resistance genes, whereas E. miricola contained 24 virulent and 168 antibiotic resistance genes. In LB broth, both isolates could grow well at 0%-1% NaCl concentration and pH 5–7. Antibiotic susceptibility testing revealed that both K. pneumoniae and E. miricola were resistant to kanamycin, neomycin, ampicillin, piperacillin, carbenicillin, enrofloxacin, norfloxacin and sulfisoxazole. Histopathological studies showed that co-infection caused considerable lesions in the tissues of brain, eye, muscle, spleen, kidney and liver, including cell degeneration, necrosis, hemorrhage and inflammatory cell infiltration. The LD50 of K. pneumoniae and E. miricola isolates were 6.31 × 105 CFU/g and 3.98 × 105 CFU/g frog weight, respectively. Moreover, experimentally infected frogs exhibited quick and higher mortality under coinfection with K. pneumoniae and E. miricola than those single challenge of each bacterium. To date, no natural co-infection by these two bacteria has been reported from frogs and even amphibians. The results will not only shed light on the feature and pathogenesis of K. pneumoniae and E. miricola, but also highlight that co-infection of these two pathogen is a potential threat to black-spotted frog farming.

Numerous uncertainties in the multifaceted global trade in frogs’ legs with the EU as the major consumer

The commercial trade in frogs and their body parts is global, dynamic and occurs in extremely large volumes (in the thousands of tonnes/yr or billions of frogs/yr). The European Union (EU) remains the single largest importer of frogs’ legs, with most frogs still caught from the wild. Amongst the many drivers of species extinction or population decline (e.g. due to habitat loss, climate change, disease etc.), overexploitation is becoming increasingly more prominent. Due to global declines and extinctions, new attention is being focused on these markets, in part to try to ensure sustainability. While the trade is plagued by daunting realities of data deficiency and uncertainty and the conflicts of commercial interests associated with these data, it is clear is that EU countries are most responsible for the largest portion of the international trade in frogs’ legs of wild species. Over decades of exploitation, the EU imports have contributed to a decline in wild frog populations in an increasing number of supplying countries, such as India and Bangladesh, as well as Indonesia, Turkey and Albania more recently. However, there have been no concerted attempts by the EU and present export countries to ensure sustainability of this trade. Further work is needed to validate species identities, secure data on wild frog populations, establish reasonable monitored harvest/export quotas and disease surveillance and ensure data integrity, quality and security standards for frog farms. Herein, we call upon those countries and their representative governments to assume responsibility for the sustainability of the trade. The EU should take immediate action to channel all imports through a single centralised database and list sensitive species in the Annexes of the EU Wildlife Trade Regulation. Further, listing in CITES (the Convention on International Trade in Endangered Species of Wild Fauna and Flora) can enforce international trade restrictions. More joint efforts are needed to improve regional monitoring schemes before the commercial trade causes irreversible extinctions of populations and species of frogs.

The European Market Remains the Largest Consumer of Frogs’ Legs from Wild Species

The loss of biodiversity due to overexploitation is well known, but a review and regulation of species used in the frogs’ legs trade has yet to be accomplished. This problem relates to supply (the capture and trade of wild populations) and demand (the main consumer being the EU). The EU’s responsibility should not be ignored, since unsustainable imports of certain species drives population decline and increases risk of extinction. For most organisms, including frog species in the frogs’ legs trade, commercial international trade remains unregulated, includes species in extinction-threat categories on the IUCN Red List, and is not economically sustainable. With a tradition of frogs’ legs consumption anchored in western EU countries, demand for many species from the principal supplying countries (Indonesia, Vietnam, Turkey, Albania) has resulted in the overexploitation of the regional populations of many species. Unfortunately, legal trade takes place in the midst of numerous uncertainties, including unresolved taxonomic status for many frogs, no database or regulation of trade-relevant species, unknown population status, and no health standards for the animals involved in the trade. In addition, regional overharvest may increase the use of pesticides, there is uncertain but likely spread of disease along the trade chain, and certification schemes for frog farming operations are both not standardised and can lead to exotic invasive species escaping into naïve ecosystems. Mechanisms to help make the international trade in frogs’ legs sustainable are essential, and require international agreement and targeted efforts, ideally financed by the trade sector itself.

Diagnóstico produtivo da ranicultura no estado do Rio de Janeiro

ABSTRACT Brazilian frog farming has a history of production that began in the state of Rio de Janeiro in 1935. Over the years, this activity has spread throughout Brazil, with technological advances that have improved the productivity and health of enterprises. However, structuring the production chain has presented moments of growth and decline, culminating in low production compared with other aquaculture activities. Despite efforts focused on restructuring the chain, data on enterprises and their actors remain scarce. To obtain information on the current scenario of frog farming in the state of Rio de Janeiro, in this study, an online survey of data on frog producers in Rio de Janeiro was conducted. In general, frog farming in Rio de Janeiro has not shown substantial improvements in terms of structuring. Its dynamics are still linked to lowproduction, family run enterprises, little insertion into the market, and not being formalized, encompassing aspects related to fiscal, environmental, and health issues. Therefore, the restructuring process of the frog chain in the state depends on overcoming the bottlenecks mentioned in this study. These predominantly refer to the availability of information on the relevant aspects of management and regularization of production.

Ova kurbağası, Pelophylax ridibundus'un (Pallas, 1771) bacak tüketiminden elde edilen eser element biyobirikimi ve sağlık riski değerlendirmesi

Amphibians, which can live in aquatic and terrestrial environments, are a good indicator of pollution in these areas. Although frog leg is not consumed frequently in some cuisines, including Turkey, it is important in terms of evaluating metal accumulation since it is preferred as human food in many European countries. In this study, the quantities of trace elements (Cd, Pb, Cu, Zn, As, Co, Cr, Ni, Mn, V) were measured in the edible tissues (muscles) of an amphibian species by sampling from two frog farms in Turkey. It was aimed to assess possible health hazards for humans by frog legs consumption comparing with the toxicological limit values, including provisional tolerable weekly intake (PTWI), target hazard quotient (THQ), and Hazard Index (HI). In general, the average values (µg kg−1) of trace elements were Zn (3.437.62)&gt; Pb (69.22)&gt; Cu (66.72)&gt; Mn (35.07)&gt; As (24.24)&gt; Cr (11.47)&gt; Ni (6.94)&gt; Cd (6.51)&gt; Co (2.97)&gt; V (&lt;0.001). The results indicated that concentrations of the analyzed trace elements were determined below the European Commission’s permitted levels and edible tissues of the marsh frog posed no carcinogenic health risk to humans.

Rapid and sensitive detection of pathogenic Elizabethkingia miricola in black spotted frog by RPA-LFD and fluorescent probe-based RPA

Elizabethkingia miricola is a highly infectious pathogen, which causes high mortality rate in frog farming. Therefore, it is urgent to develop a rapid and sensitive detection method. In this study, two rapid and specific methods including recombinase polymerase amplification combined with lateral flow dipstick (RPA-LFD) and fluorescent probe-based recombinase polymerase amplification (exo RPA) were established to effectively detect E. miricola, which can accomplish the examination at 38 °C within 30 min. The limiting sensitivity of RPA-LFD and exo RPA (102 copies/μL) was ten-fold higher than that in generic PCR assay. The specificities of the two methods were verified by detecting multiple DNA samples (E. miricola, Staphylococcus aureus, Aeromonas hydrophila, Aeromonas veronii, CyHV-2 and Edwardsiella ictaluri), and the result showed that the single band was displayed in E. miricola DNA only. By tissue bacterial load and qRT-PCR assays, brain is the most sensitive tissue. Random 24 black spotted frog brain samples from farms were tested by generic PCR, basic RPA, RPA-LFD and exo RPA assays, and the results showed that RPA-LFD and exo RPA methods were able to detect E. miricola accurately and rapidly. In summary, the methods of RPA-LFD and exo RPA were able to detect E. miricola conveniently, rapidly, accurately and sensitively. This study provides prospective methods to detect E. miricola infection in frog culture.

Histological Comparison of the Edible Water Frog (Pelophylax ridibundus Pallas, 1771) Gonads Before and After Reproduction

In this study, testicular and ovarian structures of economically important edible Pelophylax ridibundus (Pallas, 1771) were histologically examined before and after reproduction in male and female individuals. Fourty eight (24 ♀, 24 ♂) adult frogs were collected from Gölbaşı Lake in Hatay. The average weight and length values of female frogs collected from nature were found to be 56.61±19.59 g and 79.54±7.07 mm; while, the average weight and length values of male frogs were 36.63±12.84 g and 69.29±9.15 mm, respectively. Frogs were brought to the frog farm established in Aydıncık and placed in breeding ponds with a width of 1m2. Frogs in the ponds were brought to the laboratory of Iskenderun Technical University in different periods, before breeding (March) and after breeding (June). Then, histological samples were taken from ovary and testis. The female frogs were determined ready for reproduction. Moreover, a large number of mature oocytes in the before breeding ovaries in vitellogenic stage, while after reproduction oocytes in primary structure and oocytes which have atresia status observed. Also, increase in the thickness of the theca layer was determined. In the male frog seminiferous tubules containing a large number of spermatogonia, spermatocyte, spermatid and a small number of spermatozoons including sperm bundles and leydig cells were found before reproduction. After the reproduciton, the density of spermatogonia, spermatocyte and spermatids were decreased; while, the density of spermatozoon and sperm bundle were increased in the seminiferous tubules. This study will contribute to the determination of mating and spawning in frog breeding by revealing the histological status of the gonad structure of P. ridibundus in the breeding process.

Assessing the performance of Alphitobius piceus (Oliver, 1792) as novel feeder insect species for small sized postmetamorphic frogs

One of the major difficulties of frog farming is providing adequate food in the first few weeks after the metamorphosis. This is a critical time frame, with rapid growth and high mortality. The established feeder insect species used throughout this delicate stage (cricket and mealworm larvae, adult fruit flies) are suitable from a trophic perspective, but present challenges and difficulties that influence the production costs. The aim of this study is to assess the performance of an alternative feeder species - Alphitobius piceus - with a simpler production technology and a lower production cost. Two species of feeder insect were used: the conventionally used Acheta domestica larvae as control species, and Alphitobius piceus larvae as experimental species. As model anuran we used the European common frog, Rana temporaria. The experimental insect species was easily accepted and produced a strong feeding response in the post-metamophic frogs. There were no significant differences between the control and experimental groups in terms of body condition index and mortality, however survival was better in the experimental group. This similarity indicates a high potential of Alphitobius piceus as feeder species for the newly metamorphosed frogs and also a good economic opportunity for frog farms.

Genome-Wide SNP Analysis of Male and Female Rice Field Frogs, Hoplobatrachus rugulosus, Supports a Non-Genetic Sex Determination System

Sex determination systems (SDSs) in anurans are diverse and have undergone independent evolutionary transitions among species. The mode of sexual reproduction of the rice field frog (Hoplobatrachus rugulosus)—an economically viable, edible amphibian species—is not well known. Previous studies have proposed that threshold temperature conditions may determine sex in these frogs. To elucidate the SDS in H. rugulosus, we karyotyped 10 male and 12 female frogs, and performed fluorescence in situ hybridization combined with sequencing analyses using DArTseq™. Our results revealed a highly conserved karyotype with no sex chromosome heteromorphism, and the sequencing analyses did not identify any consistent sex-linked loci, supporting the hypothesis of temperature-dependent sex determination. The results of this study, and others, on SDSs in the rice field frog and related species also provide support for the theory that heteromorphic sex chromosomes may lead to an evolutionary trap that prevents variable SDSs. These findings add important information to the body of knowledge on H. rugulosus and are likely to have a significant impact on the productivity and economic success of rice field frog farming.

Changes in morphological and physiological parameters of adult marsh frogs at different phases of their feeding and breeding technology

The article discusses the possibility of keeping a marsh frog in a farm on the territory of central Russia to obtain delicious meat. For this, at different stages of keeping and after spawning, body weight and length, as well as hematological parameters, were studied. During the study, marsh frogs were kept in different conditions, depending on the season of the year, and fed on different foods. During the summer and early autumn, when kept in a summer enclosure in the air temperature range from 15 to 23 °C, when fed with natural food (live invertebrates) and fed with cultivated cockroaches and flour beetle, a positive increase and an increase in weight was observed. Hematological indices were slightly below the conditional norm, but the number of segmented neutrophils and eosinophils in frogs in the aviary turned out to be quite high, since the natural food they consumed could activate antiparasitic immunity. When the frogs were kept in an aquarium at an air temperature of 22 °C and fed only with cultivated food, the distribution of weight gain and plumb weight was approximately equal. After hibernation at 4 °C, the frogs lost a lot of weight and were placed in a special spawning pool. After hormonal stimulation of frogs with a mixture of drugs “chorionic gonadotropin” and “surfagon”, successful spawning was observed with 100% fertilization of eggs, while the plumb line was small and more uniform. A low number of red blood cells and a low hemoglobin were found in the blood. The total number of neutrophils in frogs kept in the pool decreased, and the number of monocytes increased by 3 times, exceeding the conditional norm by half, which may indicate a monocytic-macrophage reaction necessary for the resorption of remnants of reproductive products. There was also a rapid development of a conditioned reflex in frogs to feeding on a floating feeder, which is an important link in the mechanization of frog farms.

Evaluation of nutritional composition and technological functionality of whole American Bullfrog (Lithobates catesbeianus), its skin, and its legs as potential food ingredients

Frog farming systems do not take advantage of their byproducts, which represents health risks and environmental pollution. The present study aimed to evaluate the proximate composition, amino acid, and fatty acid profile of American Bullfrog byproducts (whole frogs (WF), legs (LF), and skin (SF)) and their technological functionality. Results showed that WF, LF, and SF protein content was 47.6, 88.4, and 91.1% dry base (d.b.), correspondingly. Fat content resulted in 34.6, 3.2, and 4.2% (d.b.), respectively. Moreover, byproducts contain all the essential amino acids (23.8–46.6%), and the unsaturated fatty acids predominated the saturated fats. Samples showed water and oil absorption capacities of 1.8–2.6% and 1.8–4.0%, respectively, while oil and water emulsion capacities were 76.7–98.3% and 36.1–85.6%, correspondingly. Additionally, SF presented a gelling capacity in a 5% concentration. These results showed that frogs' byproducts have adequate nutritional and functional capacities, compared to other vegetable and animal flours used in the industry.

Drugs and chemicals use in frog farming in Dong Thap province

The study was conducted to investigate the use of chemicals, drugs, and disease occurrence from frog farming in Dong Thap province. Data were collected through a questionnaire from a random sample of 30 frog farmers from January to April 2020. The results showed that the common diseases were pus in liver (66.7%), hemorrhage (66.7%), and digestive tract problems (flatulence, abdominal intestine, 40%). Farmers used antibiotics to treat diseases and chemicals to treat parasitic infection without knowledge on pathogens. Commonly used antibiotics were oxytetracycline (53.3%), doxycycline (63.3%), amoxicillin (53.3%), florfenicol (36.7%), and sulfamethoxazole/trimethoprim (46.7%). In addition, other antibiotics such as tetracycline, enrofloxacin, ciprofloxacin, rifampicin were used in some households. Farmers used iodine (26.7%), copper sulfate (20%), and BKC (16.7%) as disinfectants. There was no antibiotic residues test prior to sell to traders. It is necessary to support farmers in knowledge on diseases, drugs/chemicals use, and safety in the use of drugs and chemicals.

TECHNICAL AND FINANCIAL ANALYSIS OF FROG CULTURE (Rana tigerina) AT TRA VINH PROVINCE

This study was conducted through the direct interview of 90 households applying the alternative system of culturing frogs in Tra Vinh Province from 9/2020 to 3/2020. The study aimed to determine current status of frog farming. The collected data includes the technical and financial aspect of culturing frogs. The results showedthat there are two models of frog farming: culturing frogs in canvas (65.56% of households), and culturing frogs in cages (34.44% of households); Both models applied the same average farming area of 36.27 m2 with stocking density of 115 inds/m2. After 2.6 months of culturing, the average frog size was 257 g. The average frogyield produced 21,024 kg/1,000 m2/crop and the net income of 100 million VND/1,000 m2/crop was achieved. The result indicated that it is easy to raise frogs because the households can take advantage of the surrounding area of their houses for raising frogs and therefore the farmers’ could improve by this method.

Microbiomic and transcriptomic insight into the pathogenesis of meningitis-like disease in cultured Pelophylax nigromaculatus

In recent years, a deadly infectious disease named frog meningitis (or cataract and torticollis) raged the frog farms in China. Diseased frogs manifested torticollis, cataract, edema, and finally died. Yet, the molecular pathogenesis of this disease has not been studied. In this study, the etiologic factor of frog meningitis broken in a black-spotted frog (Pelophylax nigromaculatus) farm was investigated by comparative microbiomics (brain, eyeball, and intestine). And the pathogenesis of two major types of symptomatic frogs (individuals with both torticollis and cataract and individuals with only torticollis) were investigated by histopathological section and comparative transcriptomics of brain, liver, and muscle. Our results indicated that Elizabethkingia bacteria had increased proportions in the brain and eyeball microbiomes (but not intestine microbiomes) of both types of symptomatic frogs, and E. miricola was dominant in the eyeball and brain microbiomes of most torticollis-cataract frogs. In the torticollis-only individuals, vascular congestion and reduced hepatic fat can be detected in their leptomeninges vessels and liver, respectively. While in the torticollis-cataract ones, we observed additional leukocyte extravasation in their leptomeninges vessel, and neurologic damage in their brain and spiral cord. Transcriptional analyses suggested that frogs could be well divided into asymptomatic, torticollis-only, and torticollis-cataract groups by the variation of their brain transcriptomes. The upregulated brain genes in symptomatic frogs were mainly enriched in immune-related pathways. And the Toll-like receptor and NOD-like receptor signaling pathways, inflammation, and adaptive humoral immunity were activated in response to E. miricola infection. Torticollis-only and torticollis-cataract individuals differed in the level of immune gene expression remarkably, and the emerge of cataract symptom indicated the onset of strong innate immune and inflammatory responses. Overall, our results suggested that E. miricola was likely the etiologic factor of meningitis emerged in this farm. In regards to pathological stages, the infection progressed to leptomeninges invasion in torticollis-only individuals, while it had caused meningitis in torticollis-cataract ones. Correspondingly, the torticollis symptom was likely due to leptomeninges infection, and the cataract was likely a concomitant symptom of meningitis due to disruption of vascular permeability during excessive inflammation. Our results provided a first molecular insight into the pathogenesis of frog meningitis.