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.

Resumo Objetivo: O balanço de massa tem sido aplicado recentemente na aquicultura brasileira. Em relação à truticultura, poucos trabalhos têm utilizado essa metodologia como indicador ambiental, notadamente quando se considera cada fase de desenvolvimento. O balanço de massa diário permite a estimativa da descarga de nutrientes, pois o esforço amostral ao longo de 24 horas possibilita monitorar as oscilações ao longo do dia. O objetivo deste estudo foi identificar o setor de criação em truticultura (alevinos, juvenis e adultos) que contribui com o maior aporte de fósforo e nitrogênio no efluente. Métodos As concentrações de fósforo total (PT), ortofosfato (P-PO4), nitrogênio total (NT) e íon amônio (N-NH4) foram determinadas no afluente e nos efluentes do sistema de produção. Os indicadores ambientais foram calculados com base nos valores das cargas de nutrientes e por meio de quantificação da descarga diária de nutrientes pelo método de balanço de massa. Resultados No decorrer de 24 horas, a truticultura exportou em média 0,26 kg PT, 0,11 kg P-PO4, 3,11 kg NT e 0,18 kg N-NH4. A descarga de fósforo e nitrogênio no efluente foi mais elevada durante o período noturno, associada aos horários e frequência de arraçoamento e ao hábito noturno das trutas. O balanço de massa mostra que os setores de juvenis e adultos foram responsáveis pelo maior aporte desses nutrientes, relacionados à maior biomassa de peixes e metabolismo, corroborado pela taxa de conversão alimentar de 1,95:1 e 2,01:1, respectivamente. Conclusão Para reduzir as exportações de fósforo e nitrogênio há necessidade de adequar o manejo alimentar (frequência alimentar de duas a quatro vezes por dia considerando o estágio de desenvolvimento da truta; realizar alimentação em horários próximos ao crepúsculo devido ao hábito noturno da espécie; reduzir o excesso de ração oferecida e usar ração de boa qualidade considerando as exigências nutricionais distintas de cada estágio de desenvolvimento da truta). Além do balanço de massa, a taxa de conversão alimentar também é ferramenta eficiente para detectar a eficiência de utilização da ração. Portanto, propõe-se a sua utilização como indicador ambiental, visando à sustentabilidade ambiental da aquicultura.

Abstract Aim: The mass balance has recently been applied in Brazilian aquaculture. In relation to trout farming, few studies have used this methodology as environmental indicator, especially when considering each development stage of fish. The daily mass balance allows an estimate of nutrients discharge, because the sampling effort over 24 hours enables to monitor the variations throughout the day. This study aimed to identify the breeding sector (fingerlings, juveniles and adults) in trout farming contributes with the great discharge of phosphorus and nitrogen in the effluent. Methods The concentrations of total phosphorus (TP), orthophosphate (PO4-P), total nitrogen (TN) and ammonium (NH4-N) were determined in affluent and effluents of the production system. The environmental indicators were calculated based on the values of nutrients loads and by quantifying the daily discharge of nutrients from the mass balance method. Results Over the 24 hours, the trout farming exported an average of 0.26 kg TP, 0.11 kg PO4-P, 3.11 kg TN and 0.18 kg NH4-N. The discharge of phosphorus and nitrogen in the effluent was higher at night associated to feeding management (hours and feeding frequency) and the nocturnal habits of trout. The juvenile and adult sectors accounted for the greatest contribution of these nutrients, related the largest fish biomass and metabolism, supported by the feed conversion ratio of 1.95:1 and 2.01:1, respectively. Conclusion In order to reduce exports of phosphorus and nitrogen there is a need to adequate the feeding management (feeding frequency from two to four times per day according to the trout development stage; carry out feeding in times close at twilight due to the nocturnal habits of this specie; reduce excess of ration offered and use good quality ration considering the distinct nutritional requirements of each trout stage of development). Besides the mass balance, the feed conversion ratio is also an efficient tool to detect the efficiency of feed utilization; therefore, it is proposed its use as environmental indicator, aiming the aquaculture environmental sustainability.

Cem exemplares adultos de tilápia, Oreochromis niloticus, foram inoculadas intraperitonealmente com 10(8) UFC de Mycobacterium marinum e outras 100 foram mantidas sem inoculação. Inicialmente, o sangue de 6 exemplares não inoculados foi colhido e considerado como "tempo zero". Do grupo dos inoculados foi retirado sangue de 6 animais por colheita, 1, 3, 7, 14, 21, 28, 35, 42, 49, 56 e 84 dias após inoculação. Os parâmetros hematológicos: hematócrito (Hct), taxa de hemoglobina (Hgb), contagem de eritrócitos (RBC), foram determinados e os índices hematológicos (VCM, HCM e CHCM), calculados. Foram determinados também o número de trombócitos e o número total e diferencial de leucócitos. Não ocorreram alterações nos valores de Hct, Hgb, HCM e CHCM. Entretanto houve diminuição dos valores de RBC e VCM. Os valores médios de RBC e Hct dos animais no "tempo zero" foram maiores e os de VCM e HCM, menores que os dos animais inoculados. Ocorreu neutrofilia e, após 3 dias de inoculação, ocorreram linfocitose e neutropenia nos animais. No 49º. dia após inoculação bacteriana, ocorreu monocitose.

A hundred adult of tilapia, Oreochromis niloticus, were inoculated intraperitoneally with 10(8) c.f.u. of Mycobacterium marinum. Other 100 speciemns were maintained without inoculation. Blood samples of six inoculated animals were collected at 01, 03, 07, 14, 21, 28, 35, 42, 49, 56 and 84 days after inoculation. Initially, six specimens were taken from the non inoculated group ("time zero"). The haematological parameters determined were: haematocrit (Hct), haemoglobin concentration (Hgb), total erythrocytes count (RBC), hematological indexes (MCV, MCH and MCHC), thrombocyte count (Tr), leukocyte count (WBC) and leukocyte differential count. There were no changes in Hct, Hgb, MCH and MCHC. However, the mean values for RBC and MCV decreased. The mean values for RBC and Hct of specimens from the "time zero" group were higher and the MCV and MCH lower than in inoculated animals. Occurred neutrophilia, and, at 72 h there was lymphocytosis and neutropenia. By the 49th day after bacterial inoculation, there was monocytosis.

This study involved 344 Mullets, Mugil platanus Günther, 1880, captured in the estuarine region of Cananeia, São Paulo, Brazil (25º00'S, 47º55'W). The following data were recorded for each fish: total weight, total length, haemoglobin ratio (Hb), haematocrit (Ht), erythrocyte count (Er), differential leucocyte count (lymphocytes, monocytes, neutrophils, basophils and "other cells") and haematometric indices; MCV, MCH, and MCHC. The sex and stage of gonadal maturity (undifferentiated, juvenile, resting, maturing, mature, and spent) were determined by macroscopical inspection of the gonads. Parasitological inspections revealed the following infestations: Gills - Trichodinidae, Monogenea, Copepoda, and Hirudinea. Liver: cysts of Digenea. Intestine: Nematoda, Digenea and Acanthocephala. Blood: Trypanosoma sp. and Haemogregarina sp. Analysis of variance was done to evaluate how far blood and gill parasitism had any effect on total length, total weight, the biological condition factor or the measured blood parameters. Significant differences were found for the haematocrit (infested versus noninfested by Trichodinidae) and for MCHC (infested versus noninfested by Trichodinidae and Copepoda). No differences were found with regard to leucocytes.