Abstract This study evaluated the effects of NaCl added to water during silver catfish (Rhamdia quelen) transportation on stress and meat quality. Physiological indicators of stress (cortisol, glucose, circulating ions and liver glycogen) and meat quality parameters (rigor mortis, pH, instrumental color, psychotropic aerobic count and sensory analysis) were assessed. Adult silver catfish (n=380) were distributed in four experimental groups: T1: non-transported; T2: transported without NaCl water addition; T3: transported with 8.0-g NaCl L–1 water addition; T4: transported with 12.0-g NaCl L–1 water addition. The addition of NaCl was not effective at reducing blood cortisol in silver catfish (P>0.05). An osmotic imbalance was detected as an increase in sodium and calcium levels in the NaCl treatment groups. The 12.0-g NaCl L–1 treatment showed rigor mortis evolution in lesser time than the other treatments, and also presented redder meat color. The NaCl addition in transport water do not mitigate the stress in silver catfish, and in high concentrations (12.0-g L–1) was unfavorable for the homeostasis of fish and have negatively affected its meat quality.

O objetivo deste trabalho foi avaliar a substituição do óleo de peixe por óleo de soja em dietas, quanto ao efeito no desempenho e na composição corporal de juvenis de robalo-peva (Centropomus parallelus). O experimento foi realizado em delineamento de blocos ao acaso, com três tratamentos (fonte de lipídeos) e seis repetições, pelo período de 60 dias. Juvenis de robalo-peva (24,17±0,28 g) foram distribuídos em 18 tanques experimentais de 200 L cada um, equipados com sistemas de aeração e aquecimento, com renovação contínua da água (800% ao dia). Três dietas isoproteicas (44% PB) e isoenergéticas (4.635 kcal EB kg-1) foram formuladas para abranger três níveis de substituição (0, 50 e 100%) do óleo de peixe pelo óleo de soja. Realizaram-se avaliações biométricas quanto ao desempenho, e dois animais por repetição foram utilizados para análises de composição corporal. Os índices zootécnicos de ganho de peso (38,68±5,41 g), conversão alimentar (1,38±0,10) e taxa de crescimento específico a 1,70±0,18% do peso vivo por dia foram considerados satisfatórios. A substituição da fonte de lipídeo não afeta o desempenho nem a composição corporal de juvenis de robalo-peva, o que é uma indicação de que o óleo de soja pode substituir o óleo de peixe na formulação de dietas.

The objective of this work was to evaluate fish oil replacement by soybean oil in diets, as for the effects on the performance and body composition of juveniles of fat snook (Centropomus parallelus). The experiment was carried out in a randomized block design, with three treatments (lipid sources) and six replicates, in a 60-day period. Fat snook juveniles (24.17±0.28g) were distributed in 18 experimental tanks of 200 L each, equipped with aeration and heating systems, under continuous water renovation (800% per day). Three isoproteic (44% CP) and isoenergetic (4,635 kcal CE kg-1) diets were formulated to comprise three replacement rates (0, 50, and 100%) of fish oil by soybean oil. Biometric analyses were done to evaluate fish performance, and two entire specimens from each replicate were used for body composition analyses. The zootechnical indices of weight gain (38.68±5.41 g), feed conversion (1.38±0.10), and specific growth at 1.70±0.18% weight gain per day were considered satisfactory. Lipid source substitution does not affect the performance and body composition of fat snook juveniles, which suggests that soybean oil can replace fish oil in diet formulation.

O objetivo deste trabalho foi quantificar o crescimento de juvenis de robalo-peva (Centropomus parallelus) cultivados em diferentes temperaturas. Os peixes foram cultivados durante 49 dias, a 20, 23, 26 e 29ºC. A temperatura da água influenciou o ganho de peso. Os peixes criados a 26 e 29ºC apresentaram os maiores ganhos em peso e foram os mais eficientes na conversão alimentar. Os peixes cultivados a 29ºC também apresentaram melhores taxas de crescimento específico. O desempenho do robalo-peva é afetado a 20ºC, e a espécie deve ser cultivada em temperaturas superiores a 23ºC.

The objective of this work was to quantify the growth of juvenile fat snook (Centropomus parallelus) reared at different temperatures. The fish were cultured during 49 days at 20, 23, 26, and 29ºC. Water temperature influenced weight gain. Fish reared at 26 and 29ºC showed the greatest weight gains and were more efficient in feed conversion. Fish reared at 29ºC also showed the best specific growth rates. Fat snook performance is affected at 20ºC, and the species should be grown at temperatures above 23ºC.