No abstract

One way to develop broodstock fish diets is to determine the compositions of wild broodstock tissues and attempt to replicate these compositions in the eggs of farmed fish via dietary manipulation. We collected 30 wild and 30 farmed lambari females that were in the reproductive stage. The extraction and separation of polar and neutral fractions and the saponification and methylation of lipids were performed and analysed in the muscles, livers and ovaries to determine the compositions of the fatty acids via gas chromatography. Regardless of habitat, lambaris mobilize large amounts of fat to the ovaries during the reproductive period, in addition to highly unsaturated fatty acids, such as arachidonic, eicosapentaenoic and docosahexaenoic acids. The wild lambaris were observed to contain higher levels of various fatty acids, including linoleic acid, which is an essential fatty acid. The most abundant fatty acid that was observed in the commercial diet was linoleic acid, which was supplied in all fish farmed tissues. The commercial diet has low AA, EPA and DHA contents, and, higher levels of these fatty acids were recorded in the tissues of farmed lambari, which suggests that this species are able to elongate and desaturate precursors, linoleic and linolenic acids, into highly unsaturated fatty acids.

No abstract

The aim of this study was to evaluate the effect of replacing animal protein with vegetable protein sources on the productive performance of Astyanax altiparanae (lambari-do-rabo-amarelo). Five experimental diets were formulated with increasing replacement levels of animal protein by vegetable protein. A total of 9000 individuals (initial mean weight 1.18 ± 0.12 g, initial mean length 2.1 ± 0.3 cm) were distributed in 20 net cages (1 m 3) with a density of 450 ind. m-3. Cages were randomly placed in a pond (180 m 2 , 1.5 m deep, 10% water renewal per day). After 63 days of cultivation, total count and individual biometrics from 20% of each experimental unit were taken. Mean weight, total length, survival, feed conversion, biomass weight gain and proximate body composition were evaluated. The experimental design was completely randomized with five treatments and four replications. The reduction in the formulation cost achieved by increasing levels of vegetable protein compensated the slight decrease in biomass gain. Besides that, inclusion of vegetable protein resulted in greater fat deposition, suggesting future exploration of A. altiparanae as a functional food.

Para estudar o manejo alimentar de alevinos de tilápia do Nilo (Perciformes, Cichlidae) foram estocados 1680 exemplares dessa espécie, com aproximadamente 24 mm de comprimento médio e 0,30 g de peso médio. Esses foram distribuídos em 24 caixas de água com capacidade de 250 L cada. Foram alimentados com ração comercial, sendo a mesma oferecida quatro vezes ao dia. O experimento foi constituído por quatro tratamentos, com diferentes níveis de vitamina C, com seis repetições cada. Foram analisadas as seguintes variáveis físicas, químicas e biológicas: temperatura do ambiente e da água, transparência, oxigênio dissolvido, níveis de amônia e níveis de nitrito presentes na água, pH, biovolume de fitoplâncton e de zooplâncton, período do dia, número da coleta e efeito do tratamento. Conclui-se que o grau de repleção do estômago (GR) é influenciado pela temperatura do ar, período do dia, temperatura da água, pH, biovolume do fitoplâncton e número da coleta. Os maiores valores para o GR foram obtidos nos horários mais quentes do dia, demonstrando que o consumo de alimento ocorre, preferencialmente, em temperaturas mais elevadas, o que coincide com o período de maior luminosidade, caracterizando a espécie como diurna. O tipo de alimento preferencial foi o artificial, seguido pelo fitoplâncton, que é consumido constantemente, confirmando a tendência fitoplânctófoga e filtradora da espécie. Palavras-chave: tilápia do Nilo, grau de repleção do estômago, fitoplâncton, zooplâncton, hábito alimentar. ABSTRACT. Feeding management of fingerlings of Nile tilapia Oreochromis niloticus (L.) associated with physical, biological and chemical variables of the environment. Feed management of 1680 Nile tilapia fingerlings (Perciformes, Cichlidae) with approximately 24 mm of mean length and 0.30g of mean weight is provided. The fingerlings were distributed in 24 tanks with 250 liters each. capacity each one. They were feed on a commercial diet four times a day. Four treatments with different levels of vitamin C and six repetitions constituted the experiment. Data of physical-chemical and biological variables, environment and water temperature, water transparency, dissolved oxygen, ammonium and nitrite levels in water, pH, phytoplankton and zooplankton biovolume, period of day, number collect and effect of treatment were analyzed. Stomach repletion degree is influenced by water and environment temperature, period of day, pH, phytoplankton and zooplankton biovolume and number of collect. Highest values of RD were obtained in the hottest hours of the day, which shows that the feed intake occurs in the highest temperature, coinciding with the time of the most intense light species characterized as diurnal. Artificial diet was preferred, followed by phytoplankton. This confirms the phytoplanktivorous habit of the specie, its diet and filtered, non-visual predation.

This study aimed to evaluate the effect of manipulating hours of light and water temperature in some important reproductive parameters for Astyanax altiparanae fish farming during winter. The experiment was conducted from July 3 rd to August 28 th 2013 (57 days), and two groups of 32 couples of fish (G1 and G2) were used. On G1, hours of light and water temperature were not controlled; on G2, otherwise, these variables were manipulated in order to achieve similar conditions to those observed in spring. Every 14 days, eight couples of each group were hormonally induced with carp pituitary gland extract, and eggs were collected after semi-natural spawning. The percentage of females from G2 that spawned was higher than G1 (81.25 vs. 9.38%), the same trend was observed for a number of eggs produced per female (G1: 2,976.57 ± 1,085.71; G2: 8,471.14 ± 860.08). The G2 ovaries presented a higher incidence of primary growth oocytes and post-ovulatory follicles whereas G1 ovaries had more atretic follicles. Economic analysis showed that operational profit from eggs and larvae production on G2 was higher than on G1, as well as the gross margin. In conclusion, the results showed that environmental manipulation might improve reproduction management practices extending eggs and larvae production during the natural non-breeding season. Further studies are necessary to determine more appropriate facilities to be used by farmers in large scale, as well as management protocols to ensure the survival of post-larvae.

This work examines the economic advantages of probiotic use in the diet of Nile tilapia broodstock during the reproductive period. For this purpose, Bacillus subtilis was applied as a feed additive. The experimental design was completely randomized with three treatment groups: the T0 control (without probiotic), the T1 continuous probiotic intake, and the T2 alternate probiotic intake at a dose of 0.50 g kg-1 of feed (1010 CFU g-1) with four replicates. For the reproduction assay, 118 females and 48 males of Nile tilapia (proportion 4 males:9 females. hapa-1) (weight 527.65 g ± 185.98 g and length 30.16 cm ± 3.57 cm) were distributed into 12 hapas (3.5 × 2.0 × 1.5 m). Reproductive variables (spawning female percentage, egg production, and fry production) were used to calculate the economic feasibility indexes (total cost of nutrition [TcN], gross revenue [GR], and total operational profit [ToP]). The results show increasing values for spawning female number, collected eggs, and surviving fry in the probiotic groups. We recommend continuous intake of probiotic (feed with addition of probiotic) at a dose of 0.5 g kg-1 of feed (1010 CFU g-1) during the breeding season of Nile tilapia, due to the suitable reproductive indexes and profitability.

The objective of this study was to evaluate the effects of different oil sources and alpha-lipoic acid levels on pacus performance, chemical composition of fillets and histological changes in the liver. A total of 480 pacu juveniles (3.35 ± 0.78 g), distributed in 24 experimental units (n = 20), were used. Six treatments were delineated in a completely randomized design (CRD), in a 3 x 2 factorial scheme, with three sources of oil (soybean, sesame and linseed) and two levels of alpha-lipoic acid (0 and 0.1%), with four replications. Data were evaluated statistically by analysis of variance (ANOVA) and Tukey’s test (5%). Diets containing linseed oil as the only lipid source provided better indices of final body weight and individual weight gain in pacu juveniles. Crude protein content was higher in fish fillets that fed diets without alpha-lipoic acid. Liver histology was not affected by the experimental diets. In conclusion, linseed oil improved final body weight and individual weight gain on pacus, and alpha-lipoic acid did not affect the performance of the animals, however, its absence promoted higher levels of crude protein in fish fillets.