ABSTRACT. 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.

ABSTRACT 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 3rd to August 28th 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.

O objetivo desse trabalho foi avaliar o efeito da substituição de fontes de proteína animal por fontes proteicas vegetais no desempenho produtivo do Astyanax altiparanae (lambari-do-rabo-amarelo). Cinco dietas experimentais foram formuladas com níveis crescentes de substituição de proteína animal por proteína vegetal. Foi distribuído o total de 9.000 indivíduos (peso médio inicial 1,18 ± 0,12 g, comprimento médio inicial 2,1 ± 0,3 cm) em 20 tanques-rede (1 m³; 450 ind. m-3). Os tanques-rede foram aleatoriamente dispostos em um viveiro (180 m², profundidade: 1,5 m, renovação de água: 10% ao dia). Após 63 dias de cultivo, foi realizada a contagem total dos indivíduos e biometria individual de 20% de cada unidade experimental. Foram avaliados peso e comprimento médios, sobrevivência, conversão alimentar, ganho em biomassa e composição corporal. O delineamento experimental foi inteiramente casualizado, com cinco tratamentos e quatro repetições. A diminuição alcançada no custo de formulação pela inclusão de níveis crescentes de proteína de origem vegetal mais que compensou a ligeira diminuição no ganho em biomassa. Ademais, a inclusão de proteína vegetal resultou em maior deposição lipídica, sugerindo exploração futura de A. altiparanae como alimento funcional.

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 m³) with a density of 450 ind. m-3. Cages were randomly placed in a pond (180 m², 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.