Estratégias alimentares na larvicultura do peixe ornamental amazônico acará-severo (Heros severus) (Heckel, 1840) / Feeding strategies on larval rearing of severum (Heros severus) (Heckel, 1840), Amazonian ornamental fish

Com o presente estudo, objetivou-se avaliar o tempo de fornecimento de náuplios de artêmia e o período de transição alimentar para pós-larvas de acará-severo (Heros severus). Foram utilizadas 450 pós-larvas de acará-severo, distribuídas em 45 aquários, em delineamento inteiramente ao acaso, em esquema fatorial 3x5, com três repetições. Foram avaliados três períodos de fornecimento de náuplios de artêmia: zero, cinco e 10 dias. Além disso, foram testados cinco períodos de transição alimentar: um, dois, três, quatro e cinco dias, quando os animais receberam alimentação conjunta de náuplios de artêmia e dieta farelada. Ao final do experimento, os peixes foram contados, pesados e fotografados, para avaliação do desempenho produtivo e das variáveis morfométricas. Para todos os parâmetros avaliados, não foi constatada interação entre o tempo de fornecimento de artêmia e o período de transição alimentar. Os animais alimentados por 10 dias com náuplios de artêmia apresentaram os melhores resultados de desempenho e as maiores variáveis morfométricas. Os peixes que receberam alimentação conjunta por três dias apresentaram desenvolvimento satisfatório. Dessa forma, recomendam-se 10 dias de fornecimento de náuplios de artêmia e três dias de transição alimentar, antes de se iniciar o fornecimento exclusivo de dieta inerte para pós-larvas de acará-severo.(AU)

The aim of this study was to evaluate the supply time of artemia and the period of food transition to post-larvae of severum (Heros severus). A total of 450 post-larvae of severum were distributed in 45 aquaria, in a completely randomized design, in a 3x5 factorial scheme, with three replicates. Three feeding periods with artemia nauplii were evaluated: zero, five, and ten days. In addition, five feeding transitions were tested: one, two, three, four and five days, when the animals received joint feeding of artemia nauplii and dry diet. At the end of the experiment the fish were counted, weighed and photographed, to evaluate the productive performance and the morphometric variables. For all parameters evaluated, no interaction between the time of artemia supply and the feeding transition period was observed. Animals fed for 10 days with artemia nauplii showed the best performance results and the highest morphometric variables. The fish that received joint feeding for three days presented satisfactory development. Thus, 10 days of artemia nauplii supply and three days of feeding transition is recommended before starting the exclusive supply of diet inert to post-larvae of severum.(AU)

Bioencapsulation of probiotic Lactococcus lactis subsp. lactis on Artemia franciscana nauplii: Effects of encapsulation media on Nauplii survival and probiotic recovery

Aims: This study aimed to investigate the suitability and efficacy of various encapsulation media in bioencapsulating the probiotic Lactococcus lactis subsp. lactis in Artemia franciscana nauplii. The impact of the encapsulation media on nauplii survival and probiotic recovery was also determined. Methodology and results: Various encapsulation media (sodium alginate, palm oil, starch, gum Arabic and gelatin) were prepared by dissolving the respective media in artificial sea water. Each media was prepared in four different concentrations: 0.25, 0.5, 1.0 and 2.0 g/L. To determine the suitability of encapsulation media on the survivability of A. franciscana, survival rate (SR) of Artemia nauplii was determined after 8 hours post-encapsulation. Instar II stage Artemia nauplii at 1 nauplii per mL was used for each replicate. The result revealed that A. franciscana reached 100 % SR in the encapsulation media at ≤ 0.5 g/L. All media enabled > 23 % recovery of L. lactis subsp. lactis from encapsulated A. franciscana, which is similar (p > 0.05) to the recovery of free-cells (non-encapsulated) of L. lactis subsp. lactis. Noticeably in sodium alginate (E1) treatment, the total counts of L. lactis subsp. lactis in bioencapsulated A. franciscana were the highest among others, accounting for 2.44 × 107 CFU/mL per A. franciscana tissue homogenate. Conclusion, significance and impact of study: Artemia nauplii bioencapsulated with L. lactis subsp. lactis using 0.5 g/L sodium alginate as encapsulation medium has the highest SR for nauplii and bioencapsulation efficiency, respectively. This result provides a basic guideline for Artemia bioencapsulation in fish/shrimp larval culture.

Evaluation of antioxidant activity and cytotoxic potential of Cryptocoryne ciliata.

Cryptocoryne ciliata belonging to the Araceae family has been investigated for isolation of its secondary metabolites and evaluation of biological activities of the crude extractives with special emphasis to the antioxidant activity and brine shrimp lethality bioassay. The whole plant was extracted with methanol and concentrated extract was parti-tioned using petroleum ether, carbon tetrachloride and ethyl acetate. Aqueous soluble fraction of the methanolic extract showed the highest antioxidant activity. The carbon tetrachloride soluble fraction of the methanolic extract and the ethyl acetate soluble fraction of the methanolic extract showed moderate antioxidant activity as compared to free antioxidant activity of tert-butyl-1-hydroxytolunene. In the brine shrimp lethality bioassay, among all extracts of whole plant of C. ciliata, the carbon tetrachloride soluble fraction of the methanolic extract showed strong cytotoxic activity. Aqueous soluble fraction of the methanolic extract, methanolic crude and ethyl acetate soluble fraction of the methanolic extract showed mild cytotoxity as compared to that of vincristine sulphate. The study confirms the mild to moderate antioxidant and moderate potent cytotoxic activities of C. ciliata plant extract as compared to reference standards and therefore demands the isolation of active principles and thorough bioassay.

Evaluation of antioxidant activity and cytotoxic potential of Cryptocoryne ciliata.

Cryptocoryne ciliata belonging to the Araceae family has been investigated for isolation of its secondary metabolites and evaluation of biological activities of the crude extractives with special emphasis to the antioxidant activity and brine shrimp lethality bioassay. The whole plant was extracted with methanol and concentrated extract was parti-tioned using petroleum ether, carbon tetrachloride and ethyl acetate. Aqueous soluble fraction of the methanolic extract showed the highest antioxidant activity. The carbon tetrachloride soluble fraction of the methanolic extract and the ethyl acetate soluble fraction of the methanolic extract showed moderate antioxidant activity as compared to free antioxidant activity of tert-butyl-1-hydroxytolunene. In the brine shrimp lethality bioassay, among all extracts of whole plant of C. ciliata, the carbon tetrachloride soluble fraction of the methanolic extract showed strong cytotoxic activity. Aqueous soluble fraction of the methanolic extract, methanolic crude and ethyl acetate soluble fraction of the methanolic extract showed mild cytotoxity as compared to that of vincristine sulphate. The study confirms the mild to moderate antioxidant and moderate potent cytotoxic activities of C. ciliata plant extract as compared to reference standards and therefore demands the isolation of active principles and thorough bioassay.