Anaesthetics are important in ¢sh culture to reduce handling stress and mortality. Eugenol is a promising anaesthetic because of its low cost, e⁄cacy, safety margin for ¢sh and lack of toxicity to humans. The goal of this study was to establish a protocol using eugenol as a ¢sh anaesthetic for tambaqui Colossoma macropomum (Cuvier), and provide information for regulating authorities on establishing safety dosage protocols for its use. Juvenile and sub-adult tambaqui were ¢rst individually exposed to doses of 35, 50, 65, 85, 100 or 135 mg L À 1 eugenol for 10 min. A second experiment examined the e¡ect of the duration of exposure to eugenol on the time required for recovery and survival of tambaqui. A eugenol dose of 65 mg L À1 was adequate to induce ¢sh of both sizes into a surgical anaesthetic state, and recovery time was similar for dosages up to 100 mg L À1 . Exposure to the ideal dose (65 mg L À 1 ) for up to 30 min did not cause ¢sh mortality. Fish blood glucose values were similar for all the tested eugenol doses as well as with the benzocaine control. The results show that eugenol is an e⁄cient and safe anaesthetic for tambaqui.
Resumo -O objetivo deste trabalho foi avaliar a tolerância de juvenis de pirarucu, Arapaima gigas, a concentrações crescentes de amônia na água. Oito peixes (2,6±0,4 kg e 70,5±4,1 cm de comprimento) foram distribuídos aleatoriamente em quatro tanques (0,8x0,9x2,6 m) com 410 L de água tamponada com Na 2 PO 4 e HCl, ambos a 0,1 M, onde ficaram por 33 dias. As concentrações de amônia no plasma sanguíneo dos peixes e na água foram determinadas pelo método do salicilato. A glicose plasmática e os níveis de amônia aumentaram proporcionalmente à concentração de amônia na água. Juvenis de pirarucu toleram altas concentrações de amônia na água.Termos para indexação: Arapaima gigas, fisiologia de peixes, piscicultura. Tolerance of pirarucu juveniles to increasing ammonia concentration in a closed environmentAbstract -The objective of this work was to evaluate the tolerance of pirarucu (Arapaima gigas) juveniles to increasing concentrations of ammonia in the water. Eight fish (2.6±0.4 kg and 70.5±4.1 cm length) were evenly distributed in four tanks (0.8x0.9x2.6 m) with 410 L of water buffered with Na 2 PO 4 (0.1 M) and HCl (0.1 M), where they were kept for 33 days. Ammonia concentrations in the fish blood plasma and in the water were determined by the salicilate method. Plasma glucose and ammonia levels increased proportionally to the concentration of ammonia in the water. Pirarucu juveniles tolerate high concentrations of ammonia in the water.
The quality of fish flesh depends on the skeletal muscle's energetic state and delaying energy depletion through diets supplementation could contribute to the preservation of muscle's quality traits and modulation of fish allergens. Food allergies represent a serious public health problem worldwide with fish being one of the top eight more allergenic foods. Parvalbumins, have been identified as the main fish allergen. In this study, we attempted to produce a low allergenic farmed fish with improved muscle quality in controlled artificial conditions by supplementing a commercial fish diet with different creatine percentages. The supplementation of fish diets with specific nutrients, aimed at reducing the expression of parvalbumin, can be considered of higher interest and beneficial in terms of food safety and human health. The effects of these supplemented diets on fish growth, physiological stress, fish muscle status, and parvalbumin modulation were investigated. Data from zootechnical parameters were used to evaluate fish growth, food conversion ratios and hepatosomatic index. Physiological stress responses were assessed by measuring cortisol releases and muscle quality analyzed by rigor mortis and pH. Parvalbumin, creatine, and glycogen concentrations in muscle were also determined. Comparative proteomics was used to look into changes in muscle and liver tissues at protein level. Our results suggest that the supplementation of commercial fish diets with creatine does not affect farmed fish productivity parameters, or either muscle quality. Additionally, the effect of higher concentrations of creatine supplementation revealed a minor influence in fish physiological welfare. Differences at the proteome level were detected among fish fed with different diets. Differential muscle proteins expression was identified as tropomyosins, beta enolase, and creatine kinase among others, whether in liver several proteins involved in the immune system, cellular processes, stress, and inflammation response were modulated. Regarding parvalbumin modulation, the tested creatine percentages added to the commercial diet had also no effect in the expression of this protein. The use of proteomics tools showed to be sensitive to infer about changes of the underlying molecular mechanisms regarding fish responses to external stimulus, providing a holistic and unbiased view on fish allergens and muscle quality.
RESUMOO objetivo deste trabalho foi avaliar a exigência protéica de juvenis de tambaqui (Colossoma macropomum) após a privação alimentar. Os peixes (50,3±0,26g) foram submetidos a quatro rações isoenergéticas com diferentes concentrações protéicas (28, 32, 36 e 40% proteína bruta) e dois regimes alimentares (com privação e sem privação) durante 60 dias. O delineamento experimental foi inteiramente casualizado, em esquema fatorial 4x2, em triplicata. Avaliaram-se os parâmetros de qualidade de água e de desempenho no 1º, 15 o e 60º dia de experimento. Os parâmetros da qualidade da água permaneceram dentro dos padrões de cultivo. Não houve mortalidade nos tratamentos testados. Foram observados diferenças entre os tratamentos para os índices de desempenho analisados: taxa de crescimento específico, eficiência alimentar, consumo diário de ração, consumo de proteína bruta, taxa de eficiência protéica e ganho de peso relativo, com exceção do índice hepatossomático. Houve hiperfagia, indicando a existência de crescimento compensatório. Os peixes realimentados com 36% proteína bruta tiveram incremento no teor de gordura visceral e maior deposição de proteína corporal. Estes resultados explicam uma melhora nos dados de ganho de peso, duração da hiperfagia, taxa de crescimento e eficiência alimentar. A privação alimentar não influencia a exigência protéica em juvenis de tambaqui. PALAVRAS-CHAVE: Colossoma macropomum; crescimento compensatório; nutrição de peixes; piscicultura Protein requirement of tambaqui juveniles (Colossoma macropomum) after feed deprivation ABSTRACTThe aim of this work was evaluate protein requirement of tambaqui (Colossoma macropomum) juveniles after feed deprivation. During 60 days, fish (50,3 ± 0,26 g) were fed on four isoenergetics diets with different protein content (28, 32, 36 and 40% crude protein) at two feeding regimes (with and without feed deprivation) under completely random factorial design (4x2) in triplicate. Water quality parameters and performance index were evaluated at 1º, 15 o and 60º days. Water quality parameters were kept at normal fish cultivation patterns. No mortality in the tested treatments. There were observed differences among treatments for performance indexes analyzed: growth rate, feed efficiency, daily feed consumption, crude protein consumption, efficiency protein rate and relative weight gain, except for hepatosomatic index. Hyperfagia was detected indicating the occurrence of compensatory growth. Fat content and body protein deposition increased in fishes refed on 36% of crude protein. These results explain some data observed belong the experiment like the increase of weight gain, of the hyperfagia time extension, of the growth rate and of the feed efficiency. Therefore those fish shows increase on weight gain, hyperfagia time, growth rate and feed efficiency. There is no influence of feed deprivation on protein requirement tambaqui juveniles.
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