Body colouration in tilapia is an important trait affecting consumer preference. In the Nile tilapia (Oreochromis niloticus), there are three colour variants which are normal (wild type), red and blond. In some countries, the red variant is important and reaches higher prices in the market. However, one major problem regarding red tilapia culture is their body colouration which is often associated with blotching (mainly black but also red) which is undesirable for the consumer. The overall aim of this work was to expand knowledge on various aspects of body colouration in Nile tilapia using genetic approaches. The results of this research are presented as four different manuscripts. The manuscripts (here referred as Papers) have either been published (Paper IV) or are to be submitted (Paper I, II and III) in relevant peer reviewed journals. Paper I and II investigated the inheritance of black blotching and other body colour components of the red body colour. Specifically, Paper I consisted of two preliminary trials (Trial 1 and 2), to look at the ontogeny of black blotching and body colour components over a period of six months. Trial 1 investigated the effect of tank background colour (light vs dark) on black blotching and other body colour components and was carried out using a fully inbred (all female) clonal red line. Trial 2 was carried out using mixed sex fish and was aimed to investigate the association of black blotching with the sex of the fish. The results from this study were used to guide the experiment described in Paper II. Sixteen red sires with various levels of black and red blotching were crossed to clonal females and the inheritance of blotching and other body colour components were investigated using parent-offspring regressions. The results showed no significant heritability for black blotching and body redness, but a significant correlation for body redness and black blotching was found in female offspring at one sampling point suggesting that attempts to increase body redness may increase black blotching, as had been hypothesized. Paper III was divided into two parts. The first objective was to map the blond locus onto the tilapia linkage map and the second was to investigate the interaction of the blond and red genes on black blotching using the blond-linked markers to distinguish different blond genotypes in heterozygous red fish (i.e. RrBlbl or Rrblbl). In the blond fish, the formation of melanin is almost blocked via much reduced melanophores and this feature may be able to help reducing the black blotching in red tilapia. Two intraspecific families (O. niloticus) and one interspecific family (O. aureus and O. niloticus) were used as mapping families and the blond locus was located in LG5. Four out of eight markers were successfully used to assess the interaction of blond on red blotched fish. The blond gene did not significantly reduce the area of blotching but did reduce the saturation (paler blotching) and enhanced the redness of body colour in the Rrblbl fish compared to the RrBlbl group. Finally, Paper IV aimed to find out the effect of male colouration on reproductive success in Nile tilapia. A choice of one wild type male and one red male was presented to red or wild type females and these fish were allowed to spawn under semi-natural spawning conditions. Eggs were collected from the female’s mouth after spawning and paternity was assessed using microsatellite genotyping and phenotype scoring. No significant departures from equal mating success were observed between the red and wild type males, however there was a significant difference between the red and wild type females in the frequency of secondary paternal contribution to egg batches. The results suggest that mating success of wild type and red tilapia is approximately equal. The results from this research help to broaden our knowledge and understanding on the aspects of body colouration in Nile tilapia and provide fundamental information for further research.

Os resíduos de pescado são descartados, em sua maioria, gerando um alto impacto ao ambiente; ou subutilizados em co-produtos de baixo valor agregado. O presente estudo objetivou a obtenção de hidrolisados proteicos a partir de resíduos sólidos oriundos do processamento industrial de tilápia vermelha (Oreochromis niloticus var.), avaliando sua capacidade antioxidante e eficiência como fonte suplementar de nitrogênio para o crescimento de bactérias e leveduras. Um total de 30 carcaças inteiras não evisceradas, sem filé e pele, com peso médio de 741,53g, foram mecanicamente homogeneizadas. A composição centesimal apresentou 54,34±0,31g/100 g de umidade, 8,46±0,72 g/100 g de cinza, 27,03±2,94 g/100 g de proteína e 10,17±0,65 g/100 g de lipídeos, assim como a carga microbiana do homogeneizado estava dentro dos limites de tolerância preconizados pela legislação vigente para consumo humano. Foram otimizadas as condições de hidrólise proteica quanto à concentração de substrato, enzima e tempo de hidrólise, dos resíduos sólidos de tilápia vermelha, resultando na obtenção de modelos preditivos para o grau de hidrólise (GH) produzido tanto pelas enzimas endógenas como pelas enzimas comerciais neutrase e papaína. OGH diminuiu significativamente (p < 0,05) com o incremento da concentração de substrato, exceto na hidrólise produzida pelas enzimas endógenas sob condições ótimas para papaína. Não obstante, o GH produzido pelas enzimas endógenas aumentou significativamente (p < 0,05) com o incremento do tempo de hidrólise, enquanto que o incremento na concentração de papaína também aumentou significativamente (p <0,05) o GH nos resíduos. Rendimento de 80,95 ± 3,12%, e GH de 45,33 % foram alcançados sob condições ótimas para neutrase (22 g substrato/100 mL e 0,277 g enzima/100 g proteína durante 3 min), enquanto que a papaína teve um rendimento de 82 ± 2,21% e GH de 42,37% sob condições ótimas (18,5 g substrato/100 mL e 0,570 g enzima/100 g proteína durante 3 min). As peptonas produzidas apresentaram atividade antioxidante quanto à capacidade de sequestro dos radicais livres ABTS e DPPH, sendo esta incrementada significativamente (p < 0,05) com o aumento da concentração de peptona. As peptonas também foram altamente eficientes para o crescimento das bactérias Escherichia coli, Listeria monocytogenes e Staphylococcus aureus, e para a levedura Saccharomyces cerevisiae, sendo similares ou mesmo superiores quando comparadas às três peptonas comerciais. Os resultados obtidos no presente trabalho demonstraram, portanto, que os hidrolisados proteicos obtidos a partir de resíduos sólidos de tilápia vermelha podem ser uma fonte alternativa de antioxidantes e de nitrogênio para crescimento de microrganismos. / Fish wastes are mostly discarded in Brazil, causing a high environmental impact, or underused in low-valuable coproducts. The present study aimed to obtain protein hydrolysates from solid wastes of red tilapia (Oreochromis niloticus var.), evaluating their antioxidant activity as well as their efficiency as supplemental source of nitrogen for the growth of bacteria and yeasts. Thirty carcasses with viscera of red tilapia (i.e. tilapia without fillet and skin), with an average weight of 741.53 g, were mechanically homogenized. Proximate composition and microbial quality were determined, containing 54.34±0,31g/100 g of moisture, of ash, 27.03±2,94 g/100 g of protein and 10.17±0,65 g/100 g of lipids, as well as microbial levels in concordance with the legal limits in force. Conditions for the proteolysis of solid wastes of red tilapia (concentration of substrate, concentration of enzyme and time of hydrolysis) were optimized. Predictive models for the degree of hydrolysis (DH) generated by both endogen enzymes and thecommercial enzymes neutrase and papain were obtained. DH decreased significantly (p < 0.05) with the increase of the concentration of substrate, except in the hydrolysis caused by the endogen enzymes under optimal conditions for papain. However, DH produced by the endogen enzymes increased significantly (p < 0.05) with the increment of the time of hydrolysis. Meanwhile, DH increase significantly (p < 0.05) with the increase of the concentration of papain. A yield of 80.95 ± 3.12% and a DH of 45.33 % were achieved under optimized conditions for neutrase (i.e. 22 g substrate/100 mL and 0.277 g enzyme/100 g protein for 3 min). Moreover, proteolysis with papain reached a yield of 82 ± 2.21% and a DH of 42.37% under optimized conditions (i.e. 18.5 g substrate/100 mL and 0.570 g enzyme/100 g protein for 3 min). Obtained peptones showed antioxidant activity in terms of inhibition of free radicals of ABTS and DPPH, being increased significantly (p < 0.05) with the increment of the concentration of peptone. Peptones also had a high efficiency for the growth of Escherichia coli, Listeria monocytogenes, Staphylococcus aureus and Saccharomyces cerevisiae, being comparatively similar or higher than commercial peptones. Therefore, results obtained in the present study demonstrated that protein hydrolysates from solid wastes of red tilapia could be an alternative source of antioxidants and nitrogen for the use in bioprocess.

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.

Os resíduos de pescado são descartados, em sua maioria, gerando um alto impacto ao ambiente; ou subutilizados em co-produtos de baixo valor agregado. O presente estudo objetivou a obtenção de hidrolisados proteicos a partir de resíduos sólidos oriundos do processamento industrial de tilápia vermelha (Oreochromis niloticus var.), avaliando sua capacidade antioxidante e eficiência como fonte suplementar de nitrogênio para o crescimento de bactérias e leveduras. Um total de 30 carcaças inteiras não evisceradas, sem filé e pele, com peso médio de 741,53g, foram mecanicamente homogeneizadas. A composição centesimal apresentou 54,34±0,31g/100 g de umidade, 8,46±0,72 g/100 g de cinza, 27,03±2,94 g/100 g de proteína e 10,17±0,65 g/100 g de lipídeos, assim como a carga microbiana do homogeneizado estava dentro dos limites de tolerância preconizados pela legislação vigente para consumo humano. Foram otimizadas as condições de hidrólise proteica quanto à concentração de substrato, enzima e tempo de hidrólise, dos resíduos sólidos de tilápia vermelha, resultando na obtenção de modelos preditivos para o grau de hidrólise (GH) produzido tanto pelas enzimas endógenas como pelas enzimas comerciais neutrase e papaína. OGH diminuiu significativamente (p < 0,05) com o incremento da concentração de substrato, exceto na hidrólise produzida pelas enzimas endógenas sob condições ótimas para papaína. Não obstante, o GH produzido pelas enzimas endógenas aumentou significativamente (p < 0,05) com o incremento do tempo de hidrólise, enquanto que o incremento na concentração de papaína também aumentou significativamente (p <0,05) o GH nos resíduos. Rendimento de 80,95 ± 3,12%, e GH de 45,33 % foram alcançados sob condições ótimas para neutrase (22 g substrato/100 mL e 0,277 g enzima/100 g proteína durante 3 min), enquanto que a papaína teve um rendimento de 82 ± 2,21% e GH de 42,37% sob condições ótimas (18,5 g substrato/100 mL e 0,570 g enzima/100 g proteína durante 3 min). As peptonas produzidas apresentaram atividade antioxidante quanto à capacidade de sequestro dos radicais livres ABTS e DPPH, sendo esta incrementada significativamente (p < 0,05) com o aumento da concentração de peptona. As peptonas também foram altamente eficientes para o crescimento das bactérias Escherichia coli, Listeria monocytogenes e Staphylococcus aureus, e para a levedura Saccharomyces cerevisiae, sendo similares ou mesmo superiores quando comparadas às três peptonas comerciais. Os resultados obtidos no presente trabalho demonstraram, portanto, que os hidrolisados proteicos obtidos a partir de resíduos sólidos de tilápia vermelha podem ser uma fonte alternativa de antioxidantes e de nitrogênio para crescimento de microrganismos. / Fish wastes are mostly discarded in Brazil, causing a high environmental impact, or underused in low-valuable coproducts. The present study aimed to obtain protein hydrolysates from solid wastes of red tilapia (Oreochromis niloticus var.), evaluating their antioxidant activity as well as their efficiency as supplemental source of nitrogen for the growth of bacteria and yeasts. Thirty carcasses with viscera of red tilapia (i.e. tilapia without fillet and skin), with an average weight of 741.53 g, were mechanically homogenized. Proximate composition and microbial quality were determined, containing 54.34±0,31g/100 g of moisture, of ash, 27.03±2,94 g/100 g of protein and 10.17±0,65 g/100 g of lipids, as well as microbial levels in concordance with the legal limits in force. Conditions for the proteolysis of solid wastes of red tilapia (concentration of substrate, concentration of enzyme and time of hydrolysis) were optimized. Predictive models for the degree of hydrolysis (DH) generated by both endogen enzymes and thecommercial enzymes neutrase and papain were obtained. DH decreased significantly (p < 0.05) with the increase of the concentration of substrate, except in the hydrolysis caused by the endogen enzymes under optimal conditions for papain. However, DH produced by the endogen enzymes increased significantly (p < 0.05) with the increment of the time of hydrolysis. Meanwhile, DH increase significantly (p < 0.05) with the increase of the concentration of papain. A yield of 80.95 ± 3.12% and a DH of 45.33 % were achieved under optimized conditions for neutrase (i.e. 22 g substrate/100 mL and 0.277 g enzyme/100 g protein for 3 min). Moreover, proteolysis with papain reached a yield of 82 ± 2.21% and a DH of 42.37% under optimized conditions (i.e. 18.5 g substrate/100 mL and 0.570 g enzyme/100 g protein for 3 min). Obtained peptones showed antioxidant activity in terms of inhibition of free radicals of ABTS and DPPH, being increased significantly (p < 0.05) with the increment of the concentration of peptone. Peptones also had a high efficiency for the growth of Escherichia coli, Listeria monocytogenes, Staphylococcus aureus and Saccharomyces cerevisiae, being comparatively similar or higher than commercial peptones. Therefore, results obtained in the present study demonstrated that protein hydrolysates from solid wastes of red tilapia could be an alternative source of antioxidants and nitrogen for the use in bioprocess.