This work presents results of the research project "Technology Transfer for Commercial Aquaculture Development in Veracruz, Mexico", conducted during 2001-2006 and whose overall aim was to achieve a better understanding of the different processes involved in technology transfer and extension in Veracruz, and their role in tilapia culture development in terms of characteristics, intensity and direction. Data and information were collected by personal interviews and through participant-observation techniques. The most relevant regional initiatives that have promoted tilapia farming were analyzed, as well as the current key actors of aquaculture development and their roles. 142 tilapia farmers were also typified and closely monitored. Dissemination and adoption of technical information regarding tilapia culture were evaluated through the development and use of a Technology Level Index (TLI). Findings revealed that the tilapia sector in Veracruz is diverse and immersed in a rather complex arena, where policy and finance issues, and the role of demand, linked in with market chains and their functioning are major determinants of further expansion. Farm producers were sharply differentiated by production size, degree of commercialisation, experience in production, and access to assets. Most entrants were the result of social development interventions with significant level of subsidy, which often resulted in low levels of productivity and high abandonment rates. However, for the most vulnerable groups, tilapia culture apparently provided a way to diversify their livelihood portfolio. Availability of local knowledge and expertise appeared to enhance and stimulate the dissemination and adoption of tilapia farming technology, and hence human capital. Private sector and collective action are likely to play an increasing and decisive role in the direction of the industry, while people-oriented and participative approaches are likely to be the best way to deliver technical information to small-scale farmers, and maintain good equity of access and opportunity. Methodologically, TLIs proved to be useful in the quantification and evaluation of technological change. Moreover, the Sustainable Livelihoods framework provided an adequate platform for understanding the needs of specific groups, particularly in terms of vulnerability and policies, institutions and processes.

M.Sc. / The increase in industrialisation, mining and agricultural activity along rivers could have a detrimental effect on aquatic environments unless the dangers of pollutants are not taken notice of. Metal ions and industrial effluent have become a source of pollution in the watercourses of South Africa. Pollutants generally have negative effects on the physiology of aquatic biota in polluted waters. The effects of copper and industrial effluent by the exposure of the clawed toad, Xenopus laevis and Tilapia sparrmanii are presented in this study. An experimental static-renewal system with an exposure time of 96 hours was followed at 25±1°C. After copper and effluent exposure, several physiological changes occurred in the two aquatic organisms. The sublethal effects that occurred include changes in hatching, survival, behaviour, growth impairment and developmental limitations. The results of the present study suggest that lethal endpoints can be used as indicators in detecting and evaluating the effects of aquatic pollution, caused by copper and effluent. Individual variation, however, could hamper the conclusions made but the study of aquatic organisms is of practical importance when conducting experimental studies in a laboratory and does not have the same impact as during field studies. Apart from the exposure to sublethal concentrations of copper and effluent, computational derivations of LC50, NOEC values and 95% confidence limits were made. The obtained concentrations were used as assumptions that pollutants should not exceed for the protection of aquatic life. Statistically different differences were found between the chosen derived variables of control and experimental organisms. The advantages of FETAX solution over borehole water can be attributed to the bioavailability of pollutants, which appears to be much less in those solutions. The predicted NOEC values provide some information regarding the concentrations at which no effects will be observed and the Target Water Quality Ranges (TWGR) for water were used to determine if the diluent was correct.

Made available in DSpace on 2014-06-11T19:32:59Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-12-16Bitstream added on 2014-06-13T19:03:47Z : No. of bitstreams: 1 castro_cs_dr_botfmvz.pdf: 654156 bytes, checksum: b2f3127da65755bade64baa370654697 (MD5) / Três frequências alimentares (24, 48 e 96 refeições/dia) e três períodos de alimentação (diurno, noturno e diurno/noturno) foram avaliados neste experimento. Rãs-touro (Lithobates catesbeianus), com peso médio de 78,6±15,7g, foram distribuídas em 36 baias na densidade de 88 rãs/m2. As baias, com 0,7x0,7x0,15m confeccionadas em polipropileno e com piso de tela, foram instaladas dentro de tanques-rede de 1m3 distribuídos linearmente em um viveiro de 2000m2 com 5% de renovação de água. As rãs foram alimentadas diariamente com ração comercial extrudada para peixe carnívoro e a quantidade fornecida foi corrigida diariamente com base na estimativa do ganho de peso diário das rãs. O experimento teve duração de 90 dias, correspondendo ao outono e inverno. Frequência e período de alimentação interagiram sobre os valores de peso médio (PM) das rãs. Ao final do experimento, nos períodos diurno e diurno/noturno, não houve diferença nos valores de PM das rãs entre as frequências alimentares avaliadas; entretanto, no período noturno o PM das rãs foi maior na frequência de 48 refeições/dia, cujo valor médio foi de 273,80g. Separadamente, frequência e período de alimentação influenciaram o resultado de conversão alimentar aparente (CAA), que foi melhor na frequência de 96 refeições/dia, com valor médio de 2,13; e no período noturno com valor médio de 2,23. Não houve diferença entre os tratamentos sobre os coeficientes de digestibilidade aparente da matéria seca, proteína bruta e energia bruta. Os coeficientes de disponibilidade aparente de cálcio e fósforo foram maiores na frequência de 48 refeições/dia, independente do período alimentar. Os resultados indicaram que a rã-touro pode ser alimentada tanto durante o dia como a noite, e que maiores frequências alimentares melhoraram a CAA na produção dessa espécie. Recomenda-se, para a criação da rã-touro / Three feeding frequencies (24, 48 and 96 meals/day) and three periods (diurnal, nocturnal and diurnal/nocturnal) were evaluated in this trial. Bullfrogs (Lithobates catesbeianus), with average weight of 78.6±15.7g, were distributed into 36 pens with density of 88 frogs/m2. The pens with 0.7x0.7x0.15m, made of polypropylene with screened floor, were installed within 36 cages of 1m3 distributed linearly in one pond of 2000m2 with 5% water renewal. Frogs were fed daily, by automatic feeders, with commercial extruded diet for carnivorous fish and the amount of feed supplied was corrected daily based on estimate of daily weight gain. The experiment lasted 90 days, during autumn and winter. Frequency and feeding period showed interaction on values of mean weight (MW). At the end of the experiment, diurnal and diurnal/nocturnal periods, did not show difference in MW values between feeding frequencies evaluated; however for nocturnal period the frogs MW was higher for frequency of 48 meals/day, with average value of 273.08g. However, frequency and feeding period influenced, separately, results apparent feed conversion rate (FCR), which was better for frequency of 96 meals/day, with average of 2.13; and in nocturnal period, with a overage of 2.23. There was no difference between treatments for apparent digestibility of dry matter, crude protein and energy. Apparent availability of calcium and phosphorus were higher for frequency of 48 meals/day, regardless feeding period. The results indicate that bullfrogs can be fed both during the day and night, and the higher feeding frequencies improve FCR this species. It is recommended for bullfrog raised in cages, diurnal and diurnal/nocturnal feeding with frequency of 96 meals/day; and frequency of 48 meals/day for nocturnal period

Made available in DSpace on 2014-06-11T19:22:55Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-03-02Bitstream added on 2014-06-13T19:49:19Z : No. of bitstreams: 1 mendonca_fz_me_sjrp.pdf: 192853 bytes, checksum: e701dc40c659f62670e7e20d9f5901d0 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Machos dominantes de Oreochromis niloticus defendem território no substrato, onde escavam ninhos para a reprodução. Alguns sistemas de criação de tilápia do Nilo utilizam tanques sem substrato, assim, testamos se a privação da construção de ninho aumenta a agressividade e interfere no sucesso de acasalamento dos machos dominantes. Foram utilizados dois grupos formados por 2 machos e 3 fêmeas: um com substrato (COM: n = 9), onde o aquário (~140L) continha uma camada de 3 cm de substrato de pedrisco, e um grupo sem substrato (SEM: n = 11) onde os animais foram privados da construção de ninho. Os animais permaneceram agrupados por 10 dias e o comportamento agonístico do macho dominante foi registrado através de quatro sessões de filmagens (20 min cada), sendo a primeira, 24 horas após o agrupamento e as outras três, a cada 72 horas. A agressividade foi inferida pela freqüência total de unidades de alta intensidade (frontal, lateral, paralelo e ondulação) emitidas pelo macho dominante para o submisso e para as fêmeas. A agressividade foi maior no grupo SEM (97.73 l 31.77. 80 min-1) do que no COM (61.75 l 13.24. 80 min-1; Mann-Withney, p = 0.008). Foram analisados a Taxa de Crescimento Específico (TCE) e o Índice Hepatossomático (IHS) dos dominantes como indicador de gasto energético. A TCE e o IHS foram menores para os dominantes que construíram ninhos (TCE: COM 0.86 l 0.44%.10 dia-1; SEM 1.48 l 0.52% .10 dia-1; teste t, p = 0.10; IHS: COM 1.39 l 0.42% .10 dia-1; SEM 2.16 l 0.82% .10 dia-1; teste t, p = 0.10), o que é indicativo de que os machos dominantes gastam energia escavando ninho, diminuindo a energia disponível para os ataques de alta intensidade. Além disso, foram registrados a latência e a porcentagem de desova, sendo esses similares nos grupos COM e SEM. O índice gonadossomático foi também analisado e maior nos dominantes... / Dominant males of Nile tilapia, Oreochromis niloticus, defend territory on substrates where they dig mating nests. Because some kinds of rearing systems of Nile tilapia use tanks with no substrate inside, our aim was to test whether nest digging privation increases aggressiveness in that species. As we have observed spawning in such conditions, we also tested the effect of nesting privation on dominant s mating success. Two groups formed by 2 males and 3 females each were used: a substrate inside-group (INS; n = 9), whose glass aquaria (~140L) had a 3 cm-layer of gravel, and a non substrate-group (NOS; n = 11) where animals were unable to dig nests. Groups were kept by 10 days and the agonistic behavior of dominant male was video-recorded in 4 sessions (20 min each), the first after 24 hours from grouping and the other 3, every 72 hours. Aggressiveness was inferred by the total frequency of high aggression intensity units (nip, mouthfight, lateral fight and undulation) given by the dominant male in contests with females and subordinate males. The aggressiveness was higher in the NOS (97.73 l 31.77. 80 min-1) than in the INS group (61.75 l 13.24. 80 min-1; Mann-Withney, p = 0.008). We analyzed the Specific Growth Rate and Hepatosomatic Index of dominants as indicators of energy expenditure, whose were higher for dominants that dig nests (SGR: INS 0.86 l 0.44% .10 day-1; NOS 1.48 l 0.52% .10 day- 1; t test, p = 0.10; HIS: INS 1.39 l 0.42% .10 day-1; NOS 2.16 l 0.82% .10 day-1; t test, p = 0.10). Dominant males seem to spend much energy digging nests and deviate energy from high aggressive contests. Moreover, we registered the latency to spawn and the percentage of spawning, whose was similar among INS and NOS groups. Gonadosomatic Index was also analyzed and it was higher in dominant... (Complete abstract click electronic access below)

Made available in DSpace on 2016-06-02T19:28:59Z (GMT). No. of bitstreams: 1 TeseCSRMP.pdf: 1996119 bytes, checksum: e3d20d79ade645245302f68c4d73f873 (MD5) Previous issue date: 2006-05-29 / Three experiments were carried out at the Aquaculture Section of the Center for the Technological Development of Agribusiness in Pindamonhangaba, Sao Paulo, Brazil, whose objective was to test the use of low-volume cages in populated or not populated ponds, aiming for a better utilization of the flooded area, as well as to assess the productivity of tilapia strains. The experiments were brought to an end when the units from at least one treatment reached mean weight value of 500g (commercial size). The first experiment was carried out from March to July 2000 (fall/winter). Three cages populated with Thai tilapia (Oreochromis niloticus) male juveniles, and three cages populated with red tilapia Oreochromis urolepis hornorum x Oreochromis mossambicus) male juveniles, at densities of 200, 250 and 300 fish/m³ were placed in each pond. After 126 days of culture, final mean weight and mean biomass were the double for the Thai tilapia than for the red one at the studied densities. The red tilapia did not reach commercial size at any of the densities. Feed conversion ranged from 1.24 to 1.50:1 among the densities, and survival rate was over 90% for all the treatments. The studied abiotic variables, with the exception of temperature, exhibited suitable values for the culture of tilapia. The objective of the second experiment, carried out from February to April 2001 (summer/fall), was to assess the productivity of the Thai tilapia in cages (intensive culture) placed in populated (semiintensive culture) or not populated ponds. Six cages with Thai tilapia males, at densities of 200, 250 and 300 fish/m³ were placed in the two ponds (V1 and V2). V2 was also populated with 4800 free male units of the same species. After 76 days of culture, the tilapia from the cages in P1 reached mean weight higher than 500g. In V2, only the units kept at the density of 200 fish/m³ reached 500g.Apparent feed conversion was around 1.0:1 for the confined fish and 1.3:1 for the free ones; survival rate was over 90% for all the treatments. The net yield in V2 was 2.7 times higher than in V1.The third experiment, carried out between February and June 2002 (summer/fall), examined the productivity of the Thai tilapia, as well as the effect of the amount of cages on the pond carrying capacity. Two ponds (V1 and V2) were populated with 4800 Thai tilapia male units. Six cages with 250 units each were placed in V1, and twelve (also with 250 units each) were placed in V2. After 60 days, the mortality rate in V2 was 35% for the confined population and 15% for the free fish, due to a sharp decrease in the dissolved oxygen concentration, suggesting that the pond had reached its maximum carrying capacity. At the end of the experiment, after 120 days of culture, only the units from the cages placed in V1 reached commercial size. / Foram conduzidos três experimentos no Setor de Aqüicultura do Pólo Regional do Desenvolvimento Tecnológico dos Agronegócios em Pindamonhangaba SP, visando testar a utilização de tanques-rede de pequeno volume em viveiros de piscicultura povoados ou não, procurando melhor aproveitamento da área inundada, e avaliar o desempenho produtivo de linhagens de tilápia. Os experimentos foram encerrados quando os exemplares de pelo menos um dos tratamentos atingiram peso médio de 500g (porte comercial). O primeiro experimento foi conduzido de março a julho de 2000 (outono/inverno). Foram colocados, em cada viveiro, três tanques-rede com machos juvenis de tilápia tailandesa (Oreochromis niloticus) e três com os de tilápia vermelha (Oreochromis urolepis hornorum x Oreochromis mossambicus), nas densidades de 200, 250 e 300 peixes/m3. Após 126 dias de cultivo, o peso e a biomassa média final, nas densidades estudadas, para a linhagem tailandesa foram o dobro daqueles obtidos pela vermelha que em nenhuma das densidades atingiu o porte comercial. A conversão alimentar variou de 1,24 a 1,50:1 entre as densidades, e a taxa de sobrevivência foi superior a 90% para todos os tratamentos. As variáveis abióticas analisadas, exceto a temperatura, apresentaram valores adequados à tilapicultura. O segundo experimento, realizado de fevereiro a abril de 2001(verão/outono), visou avaliar o desempenho produtivo da tilápia tailandesa em tanques-rede (cultivo intensivo), instalados em viveiros povoados (cultivo semi-intensivo) ou não. Seis tanques-rede com machos de tailandesa nas densidades de 200, 250 e 300 peixes/m³, foram instalados nos dois viveiros (V1 e V2). O V2 foi povoado ainda com 4800 exemplares livres. Com 76 dias de cultivo as tilápias dos tanques-rede do V1 atingiram peso médio superior à 500g e no V2 somente as da densidade de 200peixes/m3. A conversão alimentar aparente foi ao redor de 1,0:1 para os peixes confinados e de 1,3:1 para os livres e a taxa de sobrevivência, superior a 90% para todos os tratamentos. A receita líquida no V2 foi 2,7 vezes superior a do V1. O terceiro experimento, realizado de fevereiro a junho de 2002 (verão/outono), verificou o desempenho produtivo da tilápia tailandesa e a capacidade do viveiro em suportar diferentes quantidades de tanques-rede. Em dois viveiros com 4800 machos de tailandesa foram instalados tanques-rede com 250 exemplares cada, sendo seis no viveiro V1 e doze no viveiro V2. Após 60 dias ocorreu a mortalidade de 35% da população confinada e de 15% dos peixes livres no V2, devido à queda brusca da concentração de oxigênio dissolvido sugerindo que este viveiro atingiu sua capacidade suporte. No final do experimento, com 120 dias de cultivo, apenas os exemplares dos tanques-rede instalados no V1 atingiram o porte comercial.

Orientador: Luiz Edivaldo Pezzato / Banca: Dalton José Carneiro / Banca: Wilson Massamitu Furuya / Banca: Wilson Rogerio Boscolo / Banca: Rose Meire Vidotti / Resumo: Esse estudo teve como objetivo determinar a digestibilidade de ingredientes utilizados em formulações de rações para a aqüicultura, a melhor relação proteína digestível / lisina digestível, e por meio do conceito de proteína ideal a exigência em proteína e energia digestível para juvenis de tilápia do Nilo. Os resultados estão apresentados em capítulos, redigidos na forma artigos científicos para publicação em periódicos especializados. Foi possível observar diferenças em relação aos valores digestíveis dos nutrientes e aminoácidos, e verificar que os valores de coeficientes de digestibilidade aparente da proteína não refletem o coeficiente de digestibilidade aparente dos aminoácidos para alguns alimentos. Com relação à determinação da exigência em proteína e lisina em rações para juvenis de tilápia do Nilo (11,0 a 98,0g), o nível de 26% PD não diferiu do nível de 32,0% PD em relação a ganho em peso, sendo estes superiores ao tratamento com 22,0% PD. As diferentes relações proteína digestível (PD) / lisina digestível demonstram que o aminoácido lisina, ainda que, em níveis elevados de inclusão não foi suficiente para a melhora do desempenho produtivo da tilápia do Nilo, quando utilizado em dietas com baixo valor protéico. Entretanto, a suplementação de 7,5% de lisina em relação à proteína digestível (PD) em rações com níveis acima de 26% PD promoveu melhores respostas de desempenho produtivo para a espécie. A determinação da melhor relação proteína digestível / lisina digestível possibilitou a determinação posterior da melhor relação proteína digestível / energia digestível em rações formuladas com base no conceito de proteína ideal. Os resultados demonstram que a energia digestível das rações não influencia o desempenho dos peixes, uma vez que, as rações foram formuladas com base em energia... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The utilization of energetic and protein feeds, highly digestible as well, becomes more and more necessary due to the quality of formulated rations, zootecnic response and relationship with the environment. Apparent digestibility coefficient (ADC) of dry matter, protein, energy, phosphorus, and amino acids of corn starch, corn, wheat, rice, soybean, and cottonseed meal, corn gluten and fish meal were determined for Nile tilapia. ADC was determined using a reference ration based on albumin, gelatin and corn starch, indicator with the inert chromium III oxide (Cr2O3). Each test ration was made up of 70% of reference ration and 30% of the diet being evaluated. Feces were collected in groups of 5 replicates for each treatment. ADC values for protein and average ADC of amino acids were as follows: corn 89.76 and 96.43%, rice meal 95.88 and 92.26%, wheat meal 93.54 and 84.41%, fish meal 82.59 and 86.36%, corn gluten 89.82 and 87.98%, soybean meal 94.13 and 91.93%, cotton meal 87.10 and 77.47%, respectively. The results reported in this study suggest that ADC of protein might not be a very reliable indicator of ADC values of amino acids, even more so for wheat meal, corn, and cotton meal. Among protein feeds, soybean meal was found to have the highest ADC for protein and amino acids, while corn was the energetic feed with the highest ADC (86.15%) for energy. / Doutor

Orientador: Claudio Angelo Agostinho / Banca: Margarida Maria Barros / Banca: José Roberto Sartori / Banca: Silvia Conceição Reis Pereira Mello / Banca: Rolandro Alfredo Mazzon Romero / Resumo: Três frequências alimentares (24, 48 e 96 refeições/dia) e três períodos de alimentação (diurno, noturno e diurno/noturno) foram avaliados neste experimento. Rãs-touro (Lithobates catesbeianus), com peso médio de 78,6±15,7g, foram distribuídas em 36 baias na densidade de 88 rãs/m2. As baias, com 0,7x0,7x0,15m confeccionadas em polipropileno e com piso de tela, foram instaladas dentro de tanques-rede de 1m3 distribuídos linearmente em um viveiro de 2000m2 com 5% de renovação de água. As rãs foram alimentadas diariamente com ração comercial extrudada para peixe carnívoro e a quantidade fornecida foi corrigida diariamente com base na estimativa do ganho de peso diário das rãs. O experimento teve duração de 90 dias, correspondendo ao outono e inverno. Frequência e período de alimentação interagiram sobre os valores de peso médio (PM) das rãs. Ao final do experimento, nos períodos diurno e diurno/noturno, não houve diferença nos valores de PM das rãs entre as frequências alimentares avaliadas; entretanto, no período noturno o PM das rãs foi maior na frequência de 48 refeições/dia, cujo valor médio foi de 273,80g. Separadamente, frequência e período de alimentação influenciaram o resultado de conversão alimentar aparente (CAA), que foi melhor na frequência de 96 refeições/dia, com valor médio de 2,13; e no período noturno com valor médio de 2,23. Não houve diferença entre os tratamentos sobre os coeficientes de digestibilidade aparente da matéria seca, proteína bruta e energia bruta. Os coeficientes de disponibilidade aparente de cálcio e fósforo foram maiores na frequência de 48 refeições/dia, independente do período alimentar. Os resultados indicaram que a rã-touro pode ser alimentada tanto durante o dia como a noite, e que maiores frequências alimentares melhoraram a CAA na produção dessa espécie. Recomenda-se, para a criação da rã-touro / Abstract: Three feeding frequencies (24, 48 and 96 meals/day) and three periods (diurnal, nocturnal and diurnal/nocturnal) were evaluated in this trial. Bullfrogs (Lithobates catesbeianus), with average weight of 78.6±15.7g, were distributed into 36 pens with density of 88 frogs/m2. The pens with 0.7x0.7x0.15m, made of polypropylene with screened floor, were installed within 36 cages of 1m3 distributed linearly in one pond of 2000m2 with 5% water renewal. Frogs were fed daily, by automatic feeders, with commercial extruded diet for carnivorous fish and the amount of feed supplied was corrected daily based on estimate of daily weight gain. The experiment lasted 90 days, during autumn and winter. Frequency and feeding period showed interaction on values of mean weight (MW). At the end of the experiment, diurnal and diurnal/nocturnal periods, did not show difference in MW values between feeding frequencies evaluated; however for nocturnal period the frogs MW was higher for frequency of 48 meals/day, with average value of 273.08g. However, frequency and feeding period influenced, separately, results apparent feed conversion rate (FCR), which was better for frequency of 96 meals/day, with average of 2.13; and in nocturnal period, with a overage of 2.23. There was no difference between treatments for apparent digestibility of dry matter, crude protein and energy. Apparent availability of calcium and phosphorus were higher for frequency of 48 meals/day, regardless feeding period. The results indicate that bullfrogs can be fed both during the day and night, and the higher feeding frequencies improve FCR this species. It is recommended for bullfrog raised in cages, diurnal and diurnal/nocturnal feeding with frequency of 96 meals/day; and frequency of 48 meals/day for nocturnal period / Doutor

Orientador: João Batista Kochenborger Fernandes / Banca: Sérgio Fonseca Zaiden / Banca: Giovani Sampaio Gonçalves / Resumo: Os minerais são essenciais para a reprodução dos peixes, no entanto, as exigências para as espécies tropicais de peixes ainda são pouco conhecidas. Portanto, o presente estudo teve como objetivo avaliar o desempenho reprodutivo, o diâmetro do ovo e a qualidade espermática de reprodutores de tilápia-do-nilo (Oreochromis niloticus) alimentadas com dietas suplementadas com selênio orgânico. Foram utilizados 80 peixes adultos, com peso médio de 121,7 g, previamente sexados e identificados. Os animais foram marcados individualmente e divididos em grupos de quatro peixes (3 fêmeas e 1 macho) e estocados em 20 tanques de 1500 litros. Os peixes foram alimentados com dietas isocalóricas e isoprotéicas contendo cinco diferentes níveis de suplementação com selênio orgânico (0,0; 0,25; 0,50; 0,75 e 1,0 mg/kg-1). Durante o período experimental (84 dias) as fêmeas de todas as unidades experimentais foram capturadas a cada três dias para coletar os ovos da boca e os machos capturados mensalmente para a coleta de sêmen. O delineamento experimental aplicado para o estudo do desempenho reprodutivo foi inteiramente casualizado com cinco tratamentos e quatro repetições. A análise estatística dos resultados foi realizada com a utilização do programa estatístico SAS 9.0. Ao final do período experimental foi observado que a suplementação com selênio orgânico nos níveis estudados não apresentou diferenças estatísticas (p>0,05) paro o desempenho reprodutivo, assim como, para a qualidade espermática e o diâmetro dos ovos / Abstract: The minerals are important for the fish reproduction. However, the requirements for tropical fish aren't defined. The aim of this study was evaluate the reproductive performance, the sperm quality and the diameters eggs of Nile tilápia broodstocks (Oreochromis niloticus) fed with supplemented diets contained differents levels of organic selenium. Were utilized eighty adult fishes of Nile tilapia with mean weight of 121,7 g, previously identified and sexed. The animals were marked individually and divided into groups of four fish (3 females and 1 male) and stocked in 20 tanks of 1500 liters. The fish were fed with isocaloric and isoproteic diets contained five differents levels of supplemented with organic selenium (0; 0,25; 0,5; 0,75 and 1,0 mg/kg). During the experimental period (84 days) the females of all tanks were caught the each three days to collect the egg and males captured monthly for the collect of semen. The experimental design was evaluated with experimental design entirely randomized, contained five treatments and four replicates. Statistical analysis of results was performed using the statistical program SAS 9.0. After 84 days it was observed that supplementation with organic selenium did not affect (p> 0.05) reproductive performance, the sperm quality and egg diameter. Based on these results can be concluded that supplementation with organic selenium not affects apparently the reproductive performance of Nile tilapia matrices / Mestre

The tilapias are a group of African and Middle Eastern cichlid fish that are widely cultured in developed and developing countries. With many different species and sub-species, and extensive use of interspecies hybrids, identification of tilapia species is of importance in aquaculture and in wild populations where introductions occur. This research set out to distinguish between tilapia species and sub-species by retrieving species-specific nuclear DNA markers (SNPs) using two approaches: (i) sequencing of the coding regions of the ADA gene; and (ii) next-generation sequencing, both standard RADseq and double-digest RADseq (ddRADseq). The mitochondrial DNA (mtDNA) marker cytochrome c oxidase subunit I (COI) was used to verify tilapia species status. ADA gene sequence analysis was partially successful, generating SNP markers that distinguished some species pairs. Most species could also be discriminated using the COI sequence. Reference based analysis (RBA: using only markers found in the O. niloticus genome sequence) of standard RADseq data identified 1,613 SNPs in 1,002 shared RAD loci among seven species. De novo based analysis (DBA: based on the entire data set) identified 1,358 SNPs in 825 loci and RBA detected 938 SNPs in 571 shared RAD loci from ddRADseq among 10 species. Phylogenetic trees based on shared SNP markers indicated similar patterns to most prior phylogenies based on other characteristics. The standard RADseq detected 677 species-specific SNP markers from the entire data set (seven species), while the ddRADseq retrieved 38 (among ten species). Furthermore, 37 such SNP markers were identified from ddRADseq data from a subset of four economically important species which are often involved in hybridization in aquaculture, and larger numbers of SNP markers distinguished between species pairs in this group. In summary, these SNPs are a valuable resource in further investigating hybridization and introgression in a range of captive and wild stocks of tilapias.

Anti-müllerian hormone (AMH) is expressed in male embryos and represses development of müllerian ducts during testis differentiation in mammals, birds and reptiles. Amh orthologues have been identified in teleosts despite them lacking müllerian ducts. Previously we found sexually dimorphic aromatase activity in tilapia brains before ovarian differentiation. This prompted us to search for further dimorphisms in tilapia brains during sex differentiation and see whether amh is expressed. We cloned the tilapia amh gene and found that it contains 7 exons but no spliced forms. The putative protein presents highest homologies with Amh proteins of pejerrey and medaka as compared to other Perciformes. We analysed amh expression in adult tissues and found elevated levels in testes, ovary and brain. Amh expression was dimorphic with higher levels in XY male brains at 10–15 dpf, when the gonads were still undifferentiated and gonadal amh was not dimorphic. Male brains had 2.7-fold higher amh expression than gonads. Thereafter, amh levels decreased in the brain while they were up-regulated in differentiating testes. Our study indicates that amh is transcribed in male brains already at 10 dpf, suggesting that sexual differentiation may be occurring earlier in tilapia brain than in gonads. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.