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.