Respiratory and muscular effort during pre-slaughter stress affect Nile tilapia fillet quality.

Nile Tilapia (Oreochromis niloticus) management procedures are directly linked to the final quality of the product. The aim of this study was to evaluate the effect of pre-slaughter density and different stunning methods on biochemical, respiratory and muscle injury parameters associated with quality and sensory characteristics of Nile tilapia fillets. Fish with an average weight of 762±105 g were used, first collected called the control group. The experiment was conducted in a 2 × 2 factorial scheme, with two densities (50 and 300 kg of live weight m-3) and two stunning methods thus totaling four treatments, with 15 repetitions per treatment totaling 75 fish sampled. Blood gas analysis, evaluation of biochemical parameters, analysis of meat quality and sensory analysis were carried out. For blood gas, biochemical and enzymatic parameters, the highest values were obtained for the density of 300 kg m-3 and asphyxia method: partial pressures of CO2; glucose and lactate, the highest values presented were 268.98 and 11.33 mg dL-1 respectively. As well as enzymatic activities, Creatinine kinase (CPK); Creatinine kinase isoenzyme (CKMB) showed higher values (768.93 and 1078.98 mg dL-1 respectively) in the higher density and asphyxia method. Conversely, when evaluating the quality parameters, the highest values were observed for lower density and thermonarcosis. High depuration density (300 kg m-3), combined with the asphyxiation stunning method, promotes changes in respiratory dynamics and provides greater stress, less firm fillet texture and greater weight loss due to cooking, as well as changes in creatine kinase (CK) and its CK-MB isoenzyme, demonstrating greater muscle damage. On the other hand, the density of 50 kg m-3 during pre-slaughter, combined with the method of stunning by thermonarcosis, provide a longer period of permanence in pre rigor mortis, which will result in fillets with a better sensory profile.

Characterization and Strength Quality of the Oryctolagus cuniculus Leather Compared to Oreochromis niloticus Leather.

This study aimed to compare the resistance of the Oryctolagus cuniculus L. (rabbit) and Oreochromis niloticus L. (Nile tilapia) skins, as well as to observe the design of the flower of these skins and the morphology of the dermis. Tilapia and rabbit skins were placed inside the same equipment (tannery machine) for the chromium salt tanning process. The flower design of the fish leather distinguishes it from the rabbit leather, the latter being constituted by the opening of the hair follicles and pores, while the fish leather is constituted by the presence of protective lamellae and insertion of the scales. The dermis of rabbit skin consists of thick bundles of collagen fibers arranged in all directions, which differs from the morphology observed in the dermis of fish skin. However, in the Nile tilapia skin dermis, overlapping and parallel layers of longitudinal collagen fiber bundles are observed, these layers are interspersed with fiber bundles crossing the sking surface (transversely), tying the fibers together and providing greater strength, which can be proven by the strength test. The fish leathers, despite having less thickness (1.0 mm), demonstrated significantly greater tensile strength (13.52 ± 1.86 N mm-2) and tear strength (53.85 ± 6.66 N mm-2) than rabbit leathers, that is, (8.98 ± 2.67 N mm-2) and (24.25 ± 4.34 N mm-2). However, rabbit leather demonstrated higher elasticity (109.97 ± 13.52%) compared to Nile tilapia leather (78.97 ± 8.40%). It can be concluded that although the rabbit leather is thicker due to the histological architecture of the dermis (thick bundles of collagen fibers arranged in all directions with no pattern of organization of collagen fibers), it shows less resistance than Nile tilapia leather, which demonstrates an organization of overlapping and parallel layers and intercalating collagen fiber bundles transversally to the surface, functioning as tendons for the swimming process. It is recommended to use a piece of fabric (lining) together with the fleshy side of the rabbit leather, to increase resistance when used in clothing and footwear, as these products require greater tensile strength. Thus, it minimizes this restriction for the use of rabbit leather in the aforementioned purposes.

Effects of transportation stress on quality and sensory profiles of Nile tilapia fillets

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 m3, 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 m3), 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 m3 did not significantly affect the stress indicators nor the instrumental quality parameters of the fillets, but fish transported at 400 kg m3 showed better visual acceptance by panellists.

Effects of transportation stress on quality and sensory profiles of Nile tilapia fillets

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 m3, 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 m3), 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 m3 did not significantly affect the stress indicators nor the instrumental quality parameters of the fillets, but fish transported at 400 kg m3 showed better visual acceptance by panellists.

Genetic characteristics of Tambaqui broodstocks in the state of Rondônia, Brazil: implications on production and conservation / Caracterização genética de estoques de Tambaqui do Estado de Rondônia (Brasil): implicações na produção e na conservação

In recent years, the genetic monitoring of broodstocks in fish farming has been greatly highlighted due to its importance in the management and improvement of their production and conservation. Current study evaluates the genetic diversity of four Tambaqui broodstocks (Colossoma macropomum) in the state of Rondônia (Brazil) and discusses activities towards the species´s correct production management and conservation. Nine primers were employed to analyze 94 specimens from four fish farms in the municipalities of Ji-Paraná (JP), Ouro Preto do Oeste (OP), Presidente Médici (PM) and Rolim de Moura (RM). Differences in the frequency of 38 fragments, with an exclusive fragment in JP and OP, were reported. High polymorphism (52.40 to 64.60%) and Shannon Index (0.313 to 0.382) rates were observed. The analysis of molecular variance (AMOVA) demonstrated that most variation is within each stock. The identity and genetic distance between the groups ranged between 0.927 and 0.954 and between 0.047 and 0.076 respectively, with shortest distance between the OPxPM and JPxRM groups. Genetic differentiation ranged from moderate to high (Fst = 0.081 to 0.179) and the number of migrants per generation was moderate (Nm = 3.83 to 6.24). As a rule, stocks showed high genetic variability and moderate / high differentiation and genetic distance between them. The results allowed direct conservation pr

Nos últimos anos, o monitoramento genético de estoques na piscicultura tem recebido grande destaque devido a sua importância no gerenciamento e melhora da sua produção e conservação. Dessa forma, o objetivo deste estudo foi avaliar de forma inédita a diversidade genética de quatro estoques de reprodutores Tambaqui (Colossoma macropomum) do estado de Rondônia (Brasil) e através dela, discutir ações que contribuam com o correto manejo produtivo e conservação dessa espécie. Utilizaram-se nove iniciadores para analisar 94 indivíduos de quatro pisciculturas dos municípios Ji-Paraná (JP), Ouro Preto do Oeste (OP), Presidente Medici (PM) e Rolim de Moura (RM). Foram encontradas diferenças nas frequências de 38 fragmentos, com um fragmento exclusivo em JP e OP. Altos valores de polimorfismo (52,40 a 64,60%) e índice de Shannon (0,313 a 0,382) foram observados. A análise de variância molecular (AMOVA) demostrou que a maior parte da variação está dentro de cada estoque. A identidade e distância genética entre os agrupamentos variou de 0,927 a 0,954 e 0,047 a 0,076, respectivamente, com menor distância entre os agrupamentos OPxPM e JPxRM. A diferenciação genética variou de moderada a alta (Fst = 0,081 a 0,179) e o número de migrantes por geração foi moderado (Nm = 3,83 a 6,24). De forma geral, os estoques apresentaram alta variabilidade genética e moderada/alta diferenciação e distancia g

Genetic variability of wild populations of Leporinus elongatus in the São Domingos River - MS Brazil: a preliminary view on the construction of the hydroelectric plant / Variabilidade genética de populações naturais de Leporinus elongatus do rio São Domingos, MS - Brasil: uma visão preliminar à construção da usina hidrelétrica

Most of the electricity used in Brazil comes from hydroelectric plants, mainly due to the great availability of its water resources. However, the construction of these plants denotes serious problems related to migration of native fish and the genetic conservation of stocks. Current study evaluates two wild population of Leporinus elongatus (piapara) located downstream (Population A - PopA) and upstream (Population B - PopB) of the Cachoeira Branca before the construction of the São Domingos hydroelectric plant (HPP) in the Mato Grosso do Sul State, Brazil. Thirty samples from caudal fins were collected and analyzed for each population. Eighty-nine fragments, including 72 polymorphic ones (80.9%), were analyzed. Low fragments (less than 0.100) in both populations (PopA = 2 and PopB = 3) were identified. Nine fixed fragments (frequency 1.000) (PopA = 3 and PopB = 6), and four exclusive fragments (PopA = 3 and PopB = 1) were also reported. The genetic variability within populations, calculated by Shannon Index and by percentage of polymorphic fragments, indicated high rates of intrapopulation variability (PopA = 0.309 and 61.80% and PopB = 0.392 and 71.90%, respectively). Genetic distance and identity rates (0.089 and 0.915, respectively) were different between populations, whilst AMOVA showed that most variations lie within the populations and not between them. Fst and Nm rates

A maior parte da energia elétrica utilizada no Brasil provém de usinas hidrelétricas, devido principalmente à grande disponibilidade de recursos hídricos. Contudo, a construção dessas usinas pode representar graves problemas relacionados com a migração de peixes nativos e com a conservação genética dessas populações. O objetivo do presente trabalho foi avaliar duas populações naturais de Piapara (Leporinus elongatus) localizadas à jusante (População A - PopA) e montante (População B - PopB) da Cachoeira Branca no período anterior à construção da usina hidrelétrica (UHE) São Domingos, Mato Grosso do Sul - Brasil. Trinta amostras de nadadeira caudal foram coletadas e analisadas para cada população. No total, foram observados 89 fragmentos dos quais 72 foram polimórficos (80,9%). Foram identificados fragmentos de baixa frequência (menor que 0,100) em ambas as populações (PopA = 2 e PopB = 3). Nove fragmentos fixados (frequência de 1,000) (PopA = 6 e PopB = 3) e quatro fragmentos exclusivos (PopA = 3 e PopB = 1) também foram observados. A variabilidade genética dentro das populações, calculada através do índice de Shannon e pela porcentagem de fragmentos polimórficos mostrou altos valores de variabilidade intra-populacional (PopA= 0,309 e 61,80% e PopB = 0,392 e 71,90%, respectivamente). Os valores de distância e a identidade genética (0,089 e 0,915, respectivamente) mostraram dife

Genetic variability of wild populations of Leporinus elongatus in the São Domingos River - MS Brazil: a preliminary view on the construction of the hydroelectric plant / Variabilidade genética de populações naturais de Leporinus elongatus do rio São Domingos, MS - Brasil: uma visão preliminar à construção da usina hidrelétrica

Most of the electricity used in Brazil comes from hydroelectric plants, mainly due to the great availability of its water resources. However, the construction of these plants denotes serious problems related to migration of native fish and the genetic conservation of stocks. Current study evaluates two wild population of Leporinus elongatus (piapara) located downstream (Population A - PopA) and upstream (Population B - PopB) of the Cachoeira Branca before the construction of the São Domingos hydroelectric plant (HPP) in the Mato Grosso do Sul State, Brazil. Thirty samples from caudal fins were collected and analyzed for each population. Eighty-nine fragments, including 72 polymorphic ones (80.9%), were analyzed. Low fragments (less than 0.100) in both populations (PopA = 2 and PopB = 3) were identified. Nine fixed fragments (frequency 1.000) (PopA = 3 and PopB = 6), and four exclusive fragments (PopA = 3 and PopB = 1) were also reported. The genetic variability within populations, calculated by Shannon Index and by percentage of polymorphic fragments, indicated high rates of intrapopulation variability (PopA = 0.309 and 61.80% and PopB = 0.392 and 71.90%, respectively). Genetic distance and identity rates (0.089 and 0.915, respectively) were different between populations, whilst AMOVA showed that most variations lie within the populations and not between them. Fst and Nm rates

A maior parte da energia elétrica utilizada no Brasil provém de usinas hidrelétricas, devido principalmente à grande disponibilidade de recursos hídricos. Contudo, a construção dessas usinas pode representar graves problemas relacionados com a migração de peixes nativos e com a conservação genética dessas populações. O objetivo do presente trabalho foi avaliar duas populações naturais de Piapara (Leporinus elongatus) localizadas à jusante (População A - PopA) e montante (População B - PopB) da Cachoeira Branca no período anterior à construção da usina hidrelétrica (UHE) São Domingos, Mato Grosso do Sul - Brasil. Trinta amostras de nadadeira caudal foram coletadas e analisadas para cada população. No total, foram observados 89 fragmentos dos quais 72 foram polimórficos (80,9%). Foram identificados fragmentos de baixa frequência (menor que 0,100) em ambas as populações (PopA = 2 e PopB = 3). Nove fragmentos fixados (frequência de 1,000) (PopA = 6 e PopB = 3) e quatro fragmentos exclusivos (PopA = 3 e PopB = 1) também foram observados. A variabilidade genética dentro das populações, calculada através do índice de Shannon e pela porcentagem de fragmentos polimórficos mostrou altos valores de variabilidade intra-populacional (PopA= 0,309 e 61,80% e PopB = 0,392 e 71,90%, respectivamente). Os valores de distância e a identidade genética (0,089 e 0,915, respectivamente) mostraram dife

Genetic characteristics of Tambaqui broodstocks in the state of Rondônia, Brazil: implications on production and conservation / Caracterização genética de estoques de Tambaqui do Estado de Rondônia (Brasil): implicações na produção e na conservação

In recent years, the genetic monitoring of broodstocks in fish farming has been greatly highlighted due to its importance in the management and improvement of their production and conservation. Current study evaluates the genetic diversity of four Tambaqui broodstocks (Colossoma macropomum) in the state of Rondônia (Brazil) and discusses activities towards the species´s correct production management and conservation. Nine primers were employed to analyze 94 specimens from four fish farms in the municipalities of Ji-Paraná (JP), Ouro Preto do Oeste (OP), Presidente Médici (PM) and Rolim de Moura (RM). Differences in the frequency of 38 fragments, with an exclusive fragment in JP and OP, were reported. High polymorphism (52.40 to 64.60%) and Shannon Index (0.313 to 0.382) rates were observed. The analysis of molecular variance (AMOVA) demonstrated that most variation is within each stock. The identity and genetic distance between the groups ranged between 0.927 and 0.954 and between 0.047 and 0.076 respectively, with shortest distance between the OPxPM and JPxRM groups. Genetic differentiation ranged from moderate to high (Fst = 0.081 to 0.179) and the number of migrants per generation was moderate (Nm = 3.83 to 6.24). As a rule, stocks showed high genetic variability and moderate / high differentiation and genetic distance between them. The results allowed direct conservation pr

Nos últimos anos, o monitoramento genético de estoques na piscicultura tem recebido grande destaque devido a sua importância no gerenciamento e melhora da sua produção e conservação. Dessa forma, o objetivo deste estudo foi avaliar de forma inédita a diversidade genética de quatro estoques de reprodutores Tambaqui (Colossoma macropomum) do estado de Rondônia (Brasil) e através dela, discutir ações que contribuam com o correto manejo produtivo e conservação dessa espécie. Utilizaram-se nove iniciadores para analisar 94 indivíduos de quatro pisciculturas dos municípios Ji-Paraná (JP), Ouro Preto do Oeste (OP), Presidente Medici (PM) e Rolim de Moura (RM). Foram encontradas diferenças nas frequências de 38 fragmentos, com um fragmento exclusivo em JP e OP. Altos valores de polimorfismo (52,40 a 64,60%) e índice de Shannon (0,313 a 0,382) foram observados. A análise de variância molecular (AMOVA) demostrou que a maior parte da variação está dentro de cada estoque. A identidade e distância genética entre os agrupamentos variou de 0,927 a 0,954 e 0,047 a 0,076, respectivamente, com menor distância entre os agrupamentos OPxPM e JPxRM. A diferenciação genética variou de moderada a alta (Fst = 0,081 a 0,179) e o número de migrantes por geração foi moderado (Nm = 3,83 a 6,24). De forma geral, os estoques apresentaram alta variabilidade genética e moderada/alta diferenciação e distancia g