ABSTRACT. With the rise of world fish farming, the national scenario is favorable for using native fish for intensive farming. Among the catfish, the Amazonian Jundiá (Leiarius marmoratus) is a robust candidate, easy to grow and with good organoleptic characteristics in its flesh. For productive success in captivity, it is necessary to consider some questions about the species, such as genetic variability, which must have an acceptable level in a breeding stock, in order to maintain a good diversity; this reduces losses due to inbreeding and low diversity. Therefore, the objective of this study was to characterize the genetic variability of commercial stocks of L. marmoratus from the State of Mato Grosso through microsatellite molecular markers. We analyzed 143 individuals from three stocks. The mean heterozygosity and the inbreeding coefficients observed were 0.060; 0.084; 0.141; and 0.539; 0.562; 0.514, respectively, for the stocks of Campo Verde, Juína, and Nova Mutum. The Deviation in the Hardy-Weinberg equilibrium was observed in most of the loci in the three populations. Considering the genetic differentiation, it is concluded that the three populations are very close genetically, which requires introduction of new genetic material in the stocks to enrich them genetically for a later reproductive program.

Abstract This study evaluated the effect of including clove essential oil (EOcl) in Nile tilapia diets on animal performance and antioxidant power, lipid oxidation, gene expression, texture, pH, color and sensory analysis in fillets. Three levels of EOcl in the diets were evaluated (0.70, 1.05 and 1.40 g/kg), provided over three periods before slaughtering the animals (15, 45 and 60 days). The antioxidant power in the diets increased after including EOcl. There was an interaction effect between the level and period of inclusion of EOcl on the antioxidant power and lipid oxidation of fillets stored up to 14 days after slaughter. Lipid oxidation was reduced by 43.3% compared with the control group. EOcl inclusion in the diet, regardless of level and period, improved texture and promote less gene expression of catalase and glutathione synthetase. This demonstrates that the antioxidant in the tilapia diet acts against the oxidative stress process. Considering the results for the interactions and parameters evaluated, including 1.05 g/kg of clove essential oil in the rations for 15 days before slaughter is indicated because it contributes to a higher fillet quality.

Abstract The aim of this investigation was to evaluate the impact of multiple freezing and thawing cycles on the physicochemical properties of Nile tilapia fillets. For this purpose, 72 fresh Nile tilapia fillets were packed and stored in a freezer at -18 °C. The frozen samples were submitted to five freeze-thaw cycles; in each cycle, the freezer was switched off during 14 hours. The consecutive freeze-thaw cycles resulted in a fillet’s total weight loss of 9.48%, with a quadratic regression (P < 0.0001) for thaw loss, with a greater loss percentage in cycle 3 (2.68%). pH values differed between the cycles (P < 0.0001), being observed an increment in this parameter only from cycle 4. The lipid oxidation remained constant in cycles 1, 2, 4 and 5, however in cycle 3 the lowest value (P < 0.0002) was observed. The luminosity, and intensity of the red and yellow colours increased linearly (P < 0.0001) as the cycles increased. Thereby, the tilapia fillets’ quality were adversely affected by the freezing cycles. The unfavourable alterations included weight loss, lipid oxidation and elevated pH, as well as the increasingly augmentation of brightness and red and yellow colorations of fillets as the progressive cycles occurred.

Resumo: O objetivo deste trabalho foi obter, por via enzimática, um hidrolisado proteico de tilápia em pó, por dois métodos de secagem, e realizar uma caracterização físico-química dos produtos finais, bem como avaliar sua estabilidade térmica. Foram realizadas análises de composição proximal, aminograma, perfil de ácidos graxos, pH, cor, atividade da água e análises microbiológicas. A proteína bruta foi o componente proeminente, com 87% no pó obtido por secagem por aspersão e 89% no pó liofilizado, e não apresentou diferença estatística. As amostras não apresentaram crescimento bacteriano, o que pode estar associado à baixa atividade de água dos produtos. As amostras secas tiveram b* positivo, e as amostras secas por liofilização mostraram-se mais amareladas do que as obtidas por aspersão. A secagem em ambos os métodos promoveu luminosidades semelhantes, próximas à cor branca. Na análise térmica, as amostras apresentaram perda de massa de 26% a 200°C, e a degradação foi observada a temperaturas a partir de 290°C. A hidrólise enzimática é eficiente, e os hidrolisados proteicos de tilápia em pó contém todos os aminoácidos essenciais. O hidrolisado apresenta teor de proteína semelhante em amostras secas por aspersão e liofilizadas, e os produtos finais são estáveis em altas temperaturas.

Abstract: The objective of this work was to enzymatically obtain hydrolysate tilapia protein powder by two drying methods, and to perform a physicochemical characterization of the final products, as well as to evaluate their thermal stability. Proximal composition, aminogram, fatty acid profile, pH, color, water activity, and microbiological analyses were performed. Crude protein was the prominent component, with 87% in the spray-dried powder and 89% in the lyophilized powder, showing no statistical difference. The samples showed no bacterial growth, which may be associated with the low water activity in the products. Dry samples had b* positive, and the freeze-dried ones were more yellowish than the spray-dried ones. Both drying methods promoted similar luminosity near the white color. In the thermal analysis, samples showed 26% mass loss at 200°C, and degradation started at 290°C. Enzymatic hydrolysis is efficient, and the hydrolysate tilapia protein powder contains all essential amino acids. The hydrolysate shows similar protein content for both spray-dried and freeze-dried samples, and the final products are stable at high temperatures.

RESUMO Objetivou-se caracterizar a variabilidade genética de cinco grupos de Pseudoplatystoma reticulatum Mato Grosso I (MT-I), Mato Grosso II (MT-II), Mato Grosso III (MT-III), Mato Grosso do Sul I (MS-I) e Mato Grosso do Sul II (MS-II) pertencentes a um núcleo de melhoramento genético. Para determinação das medidas de frequências alélicas, heterozigosidade observada (HO), coeficientes de endogamia (FIS), teste do equilíbrio de Hardy-Weinberg (HW-p) e diferenciação genética foram selecionados oito loci polimórficos de microssatélites (Pcor01, Pcor05, Pcor08, Pcor10,Ppu01, Ppu04, Ppu09, pu10) nos quais observaram-se um total de 62 alelos nos indivíduos (n=211). A População MS-I apresentou o maior (Pcor08 alelo 83:0,5000) e menor (Pcor10 alelo 50: 0,1667) valor de frequência alélica média. Maiores (HO= 0,782; 0,782) e menores (FIS= 0,034; 0,061) foram verificados nos grupos MS-I e MT-III respectivamente e o HW-p exibiu que os cinco grupos apresentaram desvios para a maioria dos loci analisados. Por último, diferenciação genética apontou a formação de dois grandes grupos genéticos, um conformado pelos grupos provenientes do Mato grosso e outro pelos grupos do Mato grosso do Sul. Essas medidas podem auxiliar na seleção do programa de melhoramento, permitindo a manutenção da variabilidade genética.

ABSTRACT The aim of this study was to characterise genetic variability in five groups of Pseudoplatystoma reticulatum: Mato Grosso I (MT-I), Mato Grosso II (MT-II), Mato Grosso III (MT-III), Mato Grosso do Sul I (MS-I) and Mato Grosso do Sul II (MS-II), taken from a centre for genetic improvement. In order to determine the allelic frequency, observed heterozygosity (HO), inbreeding coefficients (FIS), Hardy-Weinberg equilibrium (HW-p) and genetic differentiation, eight polymorphic microsatellite loci (Pcor01, Pcor05, Pcor08, Pcor10, Ppu01, Ppu04, Ppu09 and Ppu10) were selected, in which a total of 62 alleles were observed in the individuals (n = 211). The MS-I population had the highest (Pcor08 allele 83: 0.5000) and lowest (Pcor10 allele 50: 0.1667) mean values for allele frequency. Higher (HO = 0.782; 0.782) and lower (FIS = 0.034; 0.061) values were found in groups MS-I and MT-III respectively. The HW-p showed that the five groups presented deviations for most of the loci under analysis. Finally, genetic differentiation pointed to the formation of two large genetic groups, one formed by the groups from Mato Grosso and the other by the groups from Mato Grosso do Sul. These measurements can help selection in a breeding program and maintain genetic variability.

Abstract We evaluated the effect of the length of stay out of water on stress, gene expression, pH variation, blood parameters, histological analysis and water holding capacity (WHC) in fillets of the Nile tilapia (Oreochromis niloticus) cultivated in net-tanks. For this purpose, the fishes were maintained out of water under different periods of anoxia. Three and 6 min of anoxia in the pre-slaughter period increased the blood levels and mRNA expression of heat shock protein 70 the Nile tilapia and produced fillets with a less firm texture (greater sarcomere length). The evaluated periods of anoxia did not markedly affect pH and WHC. These results demonstrate that a pre-slaughter period of acute stress of up to 6 min does not considerably affect the quality of meat. The fillets of fish slaughtered in the early evening had a higher WHC and lower plasma glucose level than those slaughtered at the other time periods (morning and afternoon).

ABSTRACT This study evaluated morphometric and ultrasound information of tilapia (O. niloticus) breeders through multivariate analysis. We applied correlation, clustering, and principal component analysis to a dataset composed of information from 222 male and female breeders of the improved GIFT strain. The body weight, objective of the breeding program, showed a high positive correlation with most of the morphometric parameters. The formation of clusters indicated characteristics responsible for muscle composition and carcass weight. Some characteristics showed a high correlation, such as body weight and fillet weight (0.98 and 0.94 for females and males, respectively), and a high contribution to the explanation of data variability; of the total characteristics evaluated for females, two explained 75% data variability and four explained 72% for males. We concluded that it is possible to reduce the number of characteristics measured, as well as use information of average daily weight gain and body weight to select female and male breeders, respectively, to drive genetic gains favoring more productive generations.

ABSTRACT: This study evaluated pre-slaughter stress and its influence on the stress indicators, quality characteristics and sensory characteristics of Nile tilapia fillets. To this end, two experiments were conducted: (1) two transportation times (60 and 240 min), with a density of 200 kg m−3, were compared to control treatment fish (in which the fish were removed from the net cage and immediately euthanized); and (2) two transportation densities (100 and 400 kg m−3), transported for 180 min, compared with control treatment fish. In experiment 1, the transportation time of 60 min resulted in higher levels of serum cortisol and plasma glucose compared to the transportation time of 240 min and the control. Fish fillets transported for 240 min had higher water-holding capacity, less water loss by pressure and higher levels of juiciness compared to fish transported for 60 min. Color, pH and water loss during cooking were not affected by transportation time. In experiment 2, transportation densities of 100 and 400 kg m−3 did not significantly affect the stress indicators nor the instrumental quality parameters of the fillets, but fish transported at 400 kg m−3 showed better visual acceptance by panellists.

RESUMO: A piracanjuba (Brycon orbignyanus) é um peixe de grande valor econômico que nos últimos anos tem apresentado uma redução drástica em suas populações naturais. Nesse contexto, estudos de variabilidade genética dos estoques naturais e nos programas de repovoamento são fundamentais para adoção de medidas conservacionistas. O objetivo do presente trabalho foi verificar a amplificação cruzada de primers heterologos em B. orbignyanus. Foram avaliados um total de 52 primers das espécies Brycon opalinus, Brycon hilarii, Brycon insignis, Prochilodus sp., Piaractus mesopotamicus, Colossoma macropomum e Oreochromis niloticus. Os primers com melhor reprodutibilidade foram aplicados a uma amostra de 20 indivíduos e os parâmetros genéticos foram calculados. Nove primers apresentaram resultados satisfatórios de amplificação cruzada com B. orbignyanus, sendo das espécies Brycon opalinus (BoM5 e BoM13), Brycon hilarii (Bh5, Bh6, Bh8, Bh13 e Bh16), Brycon insignis (Bc48-10) e Prochilodus argenteus (Par80). Os primers de Piaractus mesopotamicus, Colossoma macropomum e Oreochromis niloticus não apresentaram amplificação ou apresentaram inespecificidade. Os resultados revelaram a possibilidade da utilização de primers de diferentes espécies e gênero em B. orbignyanus, o que facilita a realização de estudos genéticos nessa espécie.

ABSTRACT: Brycon orbignyanus, popularly known in Brazil as piracanjuba, is a fish with great economic value but whose natural population drastically decreased in number during the last years. In this context, genetic variability studies of natural stocks and in restocking programs are fundamental for the adoption of conservation measures. Current analysis verifies the cross-amplification of heterologous primers in B. orbignyanus. Fifty-two primers of the species Brycon opalinus, Brycon hilarii, Brycon insignis, Prochilodus sp., Piaractus mesopotamicus, Colossoma macropomum and Oreochromis niloticus were tested. Primers with the best reproducibility were applied to a sample of 20 individuals and the genetic parameters were calculated. Nine primers provided good results for cross-amplification with B. orbignyanus, involving (BoM5 and BoM13) of Brycon opalinus, (Bh5, Bh6, Bh8, Bh13 and Bh16) of Brycon hilarii, (Bc48-10) of Brycon insignis and (Par80) of Prochilodus argenteus. Primers of Piaractus mesopotamicus, Colossoma macropomum and Oreochromis niloticus failed to provide amplification or provided non-specificity. Results demonstrated the possibility of using primers of different species and genera of B. orbignyanus, facilitating genetic studies on the species.

Abstract The study was carried out with the objective of evaluating the influence of pre-slaughter stress on meat quality of Nile tilapia (O. niloticus) for 10 days of storage in ice. 75 whole fish were used eviscerated, with average weight and length of 825.75 ± 101.59 g and 28.25 ± 0.81 cm, respectively. The treatments consisted of time in which the animals underwent pre-slaughter hypoxia, being 0, 3 and 6 minutes. Rigor mortis and muscle pH were assessed besides the application of the Quality Index Method and analysis of total protein and blood glucose. Rigor mortis did not differ among treatments during the storage period, and after three hours all animals were in rigor stage. The muscle pH values varied widely during the study period, observing higher values on the third day of storage. Sensory analysis showed that after 10 days the tilapia from the different treatments did not differ in the evaluated quality parameters similarly, there was no difference regarding the evaluated blood biochemical parameters Thus, hypoxia of 6 minutes pre-slaughter does not influence the rigor mortis, muscle pH, qualitative perception of the meat quality, total protein and blood glucose of Nile tilapia.

Abstract The present work aimed at studying the effect of different drying methods applied to tilapia byproducts (heads, viscera and carcasses) fed with flaxseed, verifying the contents of omega-3 fatty acids. Two diets were given to the tilapia: a control and a flaxseed formulation, over the course of 60 days. After this period, they were slaughtered and their byproducts (heads, viscera and carcasses) were collected. These fish parts were analyzed in natura, lyophilized and oven dried. Byproducts from tilapia fed with flaxseed presented docosapentaenoic, eicopentaenoic and docosahexanoic fatty acids as a result of the enzymatic metabolism of the fish. The byproducts from the oven drying process had lower levels of polyunsaturated fatty acids. In the multivariate analysis, the byproducts from fish fed with flaxseed had a greater composition of fatty acids. The addition of flaxseed in fish diets, as well as the utilization of their byproducts, may become a good business strategy. Additionally, the byproducts may be dried to facilitate transport and storage.

RESUMO. Estimação de componente de co(variância) e parâmetros genéticos foram obtidos para as características de desempenho e morfométricas de machos e fêmeas de tilápias do Nilo em diferentes períodos de cultivo, a fim de verificar a necessidade de programas de seleção distinto para os sexos. O conjunto de dados continha informações de 1.720 animais, coletadas em quatro biometrias e sistema de tanques rede. Realizaram-se análises bicarácter, utilizando a metodologia bayesiana e consideraram-se os registros de machos e fêmeas como características distintas. Os valores de variância genética aditiva, fenotípicas e herdabilidade foram maiores para as fêmeas nas estimavas para as características morfométricas e maiores para os machos nas características de desempenho. Nos machos, o ambiente comum de larvicultura apresentou maior importância relativa. No entanto, nas fêmeas, o ambiente que causou maior variação foi o de alevinagem. As reduções dos valores de correlação genética com o avanço do período de cultivo acentuaram as diferenças entre os sexos e indicaram a necessidade de tratar machos e fêmeas como características de seleções distintos.

ABSTRACT. Co(variance) components and genetic parameters were estimated for performance and morphometric traits in male and female Nile tilapia at different growth periods to verify the need for separate selection programs for the two genders. Data set contained information on 1,720 animals, collected in cage system. Two-trait analyses using Bayesian methodology were conducted and the records of males and females were considered distinct traits. Rates of additive genetic variance, phenotypic and heritability were higher for females in estimates for morphometric traits and higher for males in performance traits. Whereas common hatchery environment showed higher relative importance for males, the nursery caused greater variations in females. The reduction of the genetic correlation rates caused by growth increased the difference between genders and indicated the treatment of males and females as a distinct feature selection.

Resumo:O objetivo deste trabalho foi estimar parâmetros genéticos e valores genéticos das características peso à despesca e ganho de peso diário de tilápias-do-nilo (Oreochromis niloticus), avaliadas durante cinco anos de cultivo em tanques-rede. O conjunto de dados continha registros de 6.650 animais, com valores genéticos preditos de 8.590 animais na matriz de parentesco. O número de animais avaliados foi de 2.196 (33 famílias), em 2008; 1.721 (58 famílias), em 2009; e 2.733 (78 famílias), em 2010. Análises uni- e bicaracter do conjunto de dados foram realizadas com uso do método de inferência bayesiana, por meio do programa computacional MTGSAM. As estimativas de herdabilidade obtidas foram de média magnitude: 0,273, para ganho de peso diário; e 0,282, para peso à despesca. A participação dos efeitos de ambiente comum na variação total foi de 15% para larvicultura e de 5% para alevinagem. As correlações genéticas e fenotípicas foram de 95%, o que indica forte associação entre as características. O ganho genético foi de 3,8% por geração, com acumulado de 15% em quatro gerações. Houve progresso genético e mudanças, causadas pela seleção de tilápias-do-nilo, nas condições de cultivo avaliadas. A seleção quanto ao ganho de peso permite ganhos indiretos relacionados ao peso.

Abstract:The objective of this work was to estimate genetic parameters and breeding values for body weight at harvest and daily weight gain of Nile tilapia (Oreochromis niloticus), evaluated in cages for five years. The data set contained records of 6,650 animals, with predicted breeding values of 8,590 animals in the relationship matrix. The number of animals evaluated was 2,196 (33 families) in 2008; 1,721 (58 families) in 2009; and 2,733 (78 families) in 2010. Single and two-trait analyses from the data set were performed using Bayesian inference methodology by the computer program MTGSAM. The obtained heritability estimates were of medium magnitude, as follows: 0.273, for daily weight gain; and 0.282, for body weight at harvest. The participation of common environmental effects in the total variation was of 15% for larvae and 5% for nurseries. The genetic and phenotypic correlations were of 95%, indicating a strong association between the traits. Genetic gain was 3.8% per generation, with accumulated 15% over four generations. There were genetic progress and changes caused by the selection of Nile tilapia in the evaluated growing conditions. The selection for weight gain allows of indirect gains associated to weight.

Objetivou-se verificar a performance reprodutivas de fêmeas de tilápia do Nilo em diferentes classes de idade e ambientes reprodutivos. O conjunto de dados foi composto por 451 fêmeas avaliadas em dois ambientes na cidade de Maringá, Estado do Paraná (hapas de 10 m3 - Local 1 e hapas de 1 m3 - Local 2) e em um ambiente em Alfenas, Estado de Minas Gerais (Local 3 - hapas de 14 e 28 m³). As fêmeas foram divididas em três classes de idade, correspondendo a animais de até um (Idade 1), entre um e dois (Idade 2) e com mais de três anos (Idade 3). A verificação de desovas foi realizada uma vez por semana no período de outubro/2012 a março/2013, correspondendo a 23 semanas de avaliação. Realizaram as análises estatísticas utilizando o procedimento Proc Genmod do programa estatístico SAS. O Local 2 apresentou resultados inferiores aos demais locais para todas as características estudadas ao utilizar animais de Idade 2. Diferenças estatísticas não foram observadas entre Idade 1 e 2 para o mesmo local de avaliação, no entanto a Idade 3 presente no Local 3 apresentou resultados superiores ao comparar com fêmeas de Idade 2. Desta forma, evitar o uso de animais em hapas individuais (1 m³) e manter fêmeas mais velhas no plantel podem melhor os resultados reprodutivos.

Current assay verifies the reproductive performance of females of Nile tilapia in different age classes and reproductive environments. Four hundred and fifty-one females were evaluated in two different Brazilian environments, namely in Maringá, Paraná State, Brazil (Site 1 - hapas of 10 m3 and Site 2 - hapas of 1 m3) and in one environment in Alfenas, Minas Gerais State, Brazil (Site 3 - hapas of 14 and 28 m3). The females were divided into three age classes, corresponding to animals under one year (age 1); between one to two years (age 2); and over three years old (age 3). Spawning was verified once a week, from October 2012 to March 2013, corresponding to a 23-week assessment. The statistical analyses were performed with Proc Genmod from the statistical program SAS. Site 2 had the lowest results when compared to the other sites for multiple spawning, spawning frequency and volume of eggs/female for animals of age 2. Statistical differences were not detected between ages 1 and 2 for the same assessment site, although females at age 3 in Site 3 provided higher results than those at age 2. Results show that, precluding the use of animals in individual hapas (1 m³) and maintaining older females in the stock, may improve reproduction results.

Resumo:O objetivo deste trabalho foi estimar parâmetros genéticos e respostas direta e indireta à seleção de características de desempenho em tilápia-do-nilo (Oreochromis niloticus), bem como avaliar o impacto da seleção sobre o ganho genético. Foram utilizadas informações de tilápias-do-nilo, sob seleção em um programa de melhoramento genético, cultivadas em sistema de tanques-rede, de 2008 a 2010. Estimaram-se herdabilidades e correlações genéticas das características ganho em peso diário e, à despesca, peso, largura, altura e comprimento do tronco, além dos ganhos genéticos obtidos com as estimativas de tendências genéticas e das respostas à seleção dessas características. As estimativas de herdabilidade ficaram em torno de 30%. As estimativas de correlações genéticas e de postos foram de alta magnitude. O ganho genético direto para ganho em peso diário foi de 7,9, 5,18 e 9,43%, em 2008, 2009 e 2010, respectivamente. Os ganhos genéticos obtidos a partir das tendências genéticas foram de 6,36, 6,30, 1,62, 1,65 e 1,51%, respectivamente, para ganho em peso diário, peso, largura, altura e comprimento do tronco. O incremento na velocidade de crescimento por meio da seleção impacta positivamente características de desempenho em tilápia-do-nilo.

Abstract:The objective of this work was to estimate genetic parameters and direct and indirect responses to selection for performance traits in Nile tilapia (Oreochromis niloticus), as well as to evaluate the impact of selection on genetic gain. Information about Nile tilapia, under selection in a genetic improvement program, grown in a net-tank system, from 2008 to 2010, was used. Heritability and genetic correlations for the traits daily weight gain, and, immediately after catching, weight, width, height, and trunk length were estimated, besides the genetic gains obtained by the estimation of genetic tendencies and of the responses to selection for these traits. Heritability estimates were around 30%. The estimates of genetic and rank correlations had high magnitude. The direct genetic gain for daily weight gain was 7.9, 5.18, and 9.43% in 2008, 2009, and 2010, respectively. The genetic gains obtained from the genetic tendencies were 6.36, 6.30, 1.62, 1.65, and 1.51%, respectively, for daily weight gain, and trunk weight, width, height, and length. The increased growth rate through selection positively impacts performance traits in Nile tilapia.