This study is aimed at assessing the feeding frequency for tilapia fingerlings. 240 fishes were randomly distributed in 24 containers. The feeding consisted of six frequencies: 4 (F4), 5 (F5), 6 (F6), 7 (F7), 8 (F8), and 9 (F9) times a day. The weight gain was significantly higher in F5 and F6 when compared to F4 ( p = 0.0409 and 0.0306, respectively). Feed intake and apparent feed conversion did not differ between treatments ( p = 0.129 and p = 0.451 ). About water quality, the nitrogen levels in the water from the treatments differed between F4 and F5 ( p = 0.0478 ) and F4 and F6 ( p = 0.0283 ) and for P between F4 and F6 ( p = 0.0215 ) and F4 and F9 ( p = 0.0432 ). The x 2 test showed a dependence relationship between feed frequencies and the muscle fibers frequency ( p < 22 × 10 − 17 ), prevailing fibers between 10-20 micrometers in F4, F5, F6, and F7 and 30-40 in F8 and F9. The area of the hepatocytes differed only between F5 and F9, while the nucleus area did not. Partial net revenue differed in 10% between F5 and F4 ( p = 0.0812 ) and between F6 and F4 ( p = 0.0568 ). In conclusion, fingerlings fed 5 to 6 times a day have better zootechnical and partial recipes.
This study aimed to compare 5 feed processing for O. niloticus fingerlings: ME1: micro-extruded 1 mm; ED03: extruded and disintegrated 0.3 mm; ED06: extruded and disintegrated 0.6 mm; BF03: bran 0.3 mm and BF06: bran 0.6 mm. Feed conversion was lower in ME1 and ED06. The protein retention coefficient was statistically higher in ME1. The fish proximate composition did not differ among treatments. Although superior in ME1 weight gain did not differ statistically from ED06. ME1 resulted in nitrogen and phosphorus in water statistically lower. ME1, ED06 and BF06 obtained the highest partial net revenues. Thus, ME1 presented the best zootechnical indices, economic performance and reduced impact on water quality.
The present study aimed at evaluating histopathological changes in gills of Rhamdia quelenjuveniles submitted to different concentrations of ibuprofen (0.0; 0.5; 5.0 and 50.0 mg/L); concentrations were determined from LC50acute assays of 5.0mg/L(120h). For each concentration four replicates were made, with four copies each. The experiment had a total duration of 120 hours in a chronic toxicological trial. After completion, the animals were euthanized, laparotomized, and the gills were localized, isolated and fixed in 10% formaldehyde, preserved in 70% alcohol and subsequently submitted to histological routine technique for paraffin inclusion. Fivecuts (6μM) per specimen were made and stained with Hematoxylin and Eosin (H&E). The Average Alteration Score(AAS) and Histopathological Alteration Indices (HAI) were determined according to the degree of the lesion and then classified in stages I, II and III which produced respectively Lamellar derangement, Lamella’s epithelium rupture and aneurysm with more expressive alterations. For all concentrations the drug led to histological alterations for Rhamdia quelen, putting in evidence damages that go from moderate to severe in the gills of the analysed fishes. Ibuprofen caused branchial lesions in R.quelenwith a progressive effect in high concentrations, suggesting that the presence of this drug could cause abnormalities and favour mortality in this species.
A aquicultura é a produção de organismos que apresentam parcial ou total desenvolvimento na água, gerando um efluente rico em nutrientes. A utilização de alimentos artificiais é algo comum na produção aquícola, porém esses são altamente nutritivos em nitrogênio e fósforo. Tais nutrientes são fontes de energia para plantas aquáticas, como é o caso das macrófitas. O uso de macrófita para absorção de nutrientes é comum em alguns sistemas de tratamento, como os wetlands. Assim, este estudo traz uma revisão sistêmica e metanálise sobre a eficiência do uso de macrófitas flutuantes para o tratamento de efluente de aquicultura. As plataformas utilizadas foram Periódicos Capes, Scopus e Web of Science. Dos artigos encontrados foram coletados dados de autores, ano de publicação, periódico científico publicado, espécie da macrófita, características avaliadas no efluente e local de estudo. Médias e desvios padrões foram usadas na análise estatística, através da diferença média padronizada (DMP), método para a realização da metanálise. Apenas 24 artigos se enquadraram na revisão sistêmica, mas somente 9 artigos foram possíveis de extrair as informações necessárias para a realização da metanálise. Dentre as propriedades químicas, o pH foi a mais mensurada, estando presente em 21 artigos. Os gêneros de macrófitas mais encontrados foram Eichhornia, Pistia, Lemna, Salvinia e Azolla. Apenas a metanálise do ortofosfato não apresentou diferença estatística, enquanto que nitrogênio total, amônia, nitrito, nitrato, nitrogênio Kjeldahl total, nitrogênio inorgânico total, fósforo total e ortofosfato foram significantes. Pode-se observar que as macrófitas apresentam maior afinidade por determinados nutrientes.
The use of live food has been recommended in the larval stage of several species of fish, providing better survival and growth results when compared to those obtained with artificial diets. This study aims to evaluate the biomass and protein content of Daphnia magna submitted to three diets: Diet A (Scenedesmus acuminatus) at a concentration of 1.5x107 cells/mL per individual, diet B (cattle manure) at 6.5g/L, and diet C at the same diets and concentration as in diets A and B for a period of 21 days. The experiment was repeated three times, totaling 63 days of study with a completely randomized design, with three replicates in each treatment. The experimental unit consisted of polyethylene containers with 20L, containing 10 D. magna neonates. Every two days, temperature, pH, dissolved oxygen and saturation were measured. At the end of the experimental period, nutrient quantification of the culture water and diets (phosphorus, nitrate, ammoniacal nitrogen, total nitrogen, and organic nitrogen), determination of the final biomass and protein content of the individuals were performed. Diet C provided a higher mean biomass value, followed by diet A and B, with values of 344.12 g, 157.71 g and 81.93 g, respectively. The D. magna fed with diet B had a higher protein content, with 2.56%, followed by those fed diets C and A, with 2.17 and 1.32%, respectively. At the end of the experiment, it was found that the organisms fed diet C had a larger reproduction rate when compared to the other diets.
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