Hematologia de tilápia-do-nilo alimentada com suplemento à base de algas frente a desafios de estresse agudo e crônico

Avaliou-se o efeito da suplementação com produto à base de algas, ergosan, em dietas para tilápias Oreochromis niloticus, submetidas ao desafio de estresse agudo e crônico sobre as características hematológicas. O ensaio foi realizado com tilápias jovens (15g) em caixas de 500L de capacidade de estocagem, em sistema com recirculação da água, com fluxo constante, na densidade de 35 peixes por caixa. Os peixes foram alimentados com as dietas-teste durante 10 dias e, ao final deste período, voltaram a receber dieta isenta de ergosan, quando foram submetidos aos desafios de estresses agudo e crônico. Utilizou-se o delineamento inteiramente ao acaso (DIC), em esquema fatorial 4x2, sendo testados: quatro porcentagens do suplemento 0; 0,25; 0,5 e 1% de ergosan na ração em dois tipos de estresse, agudo e crônico. Os resultados permitem concluir que os estímulos de estresse aplicados foram capazes de provocar alterações fisiológicas nos peixes, incluindo redução no número de eritrócitos, eritroblastos e leucócitos e aumento do volume corpuscular médio dos eritrócitos. A administração oral de 1% de suplemento durante 10 dias para juvenis de tilápia-do-nilo, em condição de estresse agudo, induz o incremento de 69% no número de trombócitos circulantes

The Potential Of Periphyton-based Cage Culture Of Nile Tilapia In A Brazilian Reservoir

In land-based pond cultures, periphyton is considered to be a complementary food source for cultured fish. In cage aquaculture, studies on the use of periphyton are scarce and do not support the viability of periphyton-based cage culture. The aim of this study was to evaluate the potential of periphyton-based cage culture of Nile tilapia in a hydroelectric reservoir in Brazil at three stocking densities and two feeding regimes. Sex-reversed male Nile tilapia Oreochromis niloticus (46.56 ± 2.53 g) were placed in 21 cages (6 m3 - 2 × 2 × 1.5 m each) with or without bamboo substrates for periphyton growth. A completely randomized design with three replicates per treatment was used to test the effect of substrate inclusion in the three stocking densities (80, 60, 40 kg of fish/m3) associated with two feeding regimes (100% and 50% of daily ration). Three cages without bamboo substrates were included in the experimental design as control group (CTRL) (80 kg/m3 and 100% of daily ration). The study demonstrates the efficiency of using substrates for Nile tilapia in cages in the reservoir. The presence of bamboo substrates improved the weight gain of fish but reduced the carrying capacity of the cage at the highest density. The concentration of dissolved oxygen in the cages was improved by the presence of substrate between 50 and 140 days of the trial and reduced after 155 days of culture. The inclusion of bamboo substrates inside the cages allows producing up to 52 kg/m3 of Nile tilapia using 32% less diet in a period almost 20% shorter than in the CTRL group. If farmers prefer to produce 80 kg/m3, they can use 30% less diet but the production period would be 20% longer. Statement of relevance: This study has high relevance to the general field of commercial aquaculture because the experiment was carried out at a commercial fish farm, under real environmental conditions and management. Presented results are promising because show that bamboo substrates in cages improve the efficiency of the system up to 52 kg/m3. This production model may be an efficient alternative for family farmers. © 2016 Elsevier B.V.46422923

Alternative treatment for

The present work, studied the effect of 0, 1,000, 1,500 and 2,000 mg of garlic powder/kg dry ration for Piaractus mesopotamicus (Osteichthyes: Characidae), weighting 73.6 ± 39.4 g and measuring 15.0 ± 2.7 cm, fed for a period of 15, 30 and 45 days. Fifteen days after treatment with 1,000 and 2,000 mg of garlic/kg dry ration, significant reduction of Anacanthorus penilabiatus (Monogenea: Dactylogyridae) in the gills was related. Nevertheless, the addition of garlic to the ration caused significant increase in the erythrocyte number and in the thrombocyte percentage in the circulating blood. However, a decrease in the lymphocyte percentage was also observed. After 45 days, fish fed with garlic showed significant increase in the erythrocyte number, leucocyte, haemoglobin rate, hematocrit and thrombocyte

Alternative treatment for Anacanthorus penilabiatus (Monogenea: Dactylogyridae) infection in cultivated pacu, Piaractus mesopotamicus (Osteichthyes: Characidae) in Brazil and its haematological effects

The present work, studied the effect of 0, 1,000, 1,500 and 2,000 mg of garlic powder/kg dry ration for Piaractus mesopotamicus (Osteichthyes: Characidae), weighting 73.6 ± 39.4 g and measuring 15.0 ± 2.7 cm, fed for a period of 15, 30 and 45 days. Fifteen days after treatment with 1,000 and 2,000 mg of garlic/kg dry ration, significant reduction of Anacanthorus penilabiatus (Monogenea: Dactylogyridae) in the gills was related. Nevertheless, the addition of garlic to the ration caused significant increase in the erythrocyte number and in the thrombocyte percentage in the circulating blood. However, a decrease in the lymphocyte percentage was also observed. After 45 days, fish fed with garlic showed significant increase in the erythrocyte number, leucocyte, haemoglobin rate, hematocrit and thrombocyte

Experimental infection in Notodiaptomus sp. (Crustacea: Calanoida) with larvae of Camallanus sp. (Nematoda: Camallanidae) Infecção experimental em Notodiaptomus sp. (Crustacea: Calanoida) com larvas de Camallanus sp. (Nematoda: Camallanidae)

This trial registered the experimental infection viability with nematode larvae Camallanus sp. in Notodiaptomus sp., a crustacean, which can be an intermediate host. Adult females of nematode were dissected from the intestines of Xiphophorus maculatus (Osteichthyes: Poeciliidae), at a fish farm in the State of São Paulo. Females were slightly compressed for larvae release, collected with Pasteur pipette and separated on Petri dishes with 9ml filtered water at 28.1ºC, from zooplankton culture. Treatments consisted of Petri dishes with 60 and 105 copepods, in which 120, 150 and 210 larvae of nematode were added in four replications. Twenty-four and 36h after exposition to the larvae, the copepods were fixed in 70% alcohol to record the amount of fixed larvae. Twenty four hours after exposition, 60 copepods group with 120 larvae showed significantly higher prevalence (46.5%) when compared to 105 copepods and 120 larvae (33.2%). Thus, these answers suggested that 120 larvae were enough for a successful infectivity. Experimental infection was available and so, it was used as a pattern to life cycle studies of camallanid nematodes and hosts susceptibility tests.<br>A viabilidade da infecção experimental com larvas do nematóide Camallanus sp. em Notodiaptomus sp., crustáceo com potencial para hospedeiro intermediário foi avaliada. Fêmeas adultas do nematóide foram extraídas de Xiphophorus maculatus (Osteichthyes: Poeciliidae), provenientes de piscicultura de peixes ornamentais no estado de São Paulo. As fêmeas foram ligeiramente pressionadas para liberar as larvas, coletadas com pipeta Pasteur e separadas em placas de Petri contendo 9ml de água filtrada a 28,1ºC do próprio cultivo de zooplâncton. Os tratamentos consistiram de placas contendo 60 e 105 copépodes onde se adicionou 120, 150 e 210 larvas de nematóides em quatro repetições. Nos tempos de 24 e 36h após a exposição às larvas, os copépodes foram fixados em álcool 70% para quantificação de larvas. Após 24h de exposição, o grupo com 60 copépodes na presença de 120 larvas apresentou maior prevalência (46,5%) do que 105 copépodes com 120 larvas (33,2%). Sugere-se que 120 larvas foram suficientes para o sucesso da infecção. A infecção experimental mostrou-se viável, servindo de modelo para o estudo do ciclo de vida de camalanídeos e testes de susceptibilidade de hospedeiros