科研之友
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摘要
This study verified the optimum dietary salt level for the growth and ion regulation of silver catfish juveniles at different water pH levels (5.5, 7.0 and 9.0). The control diet was supplemented with NaCl to yield experimental diets with 0.5, 1.0 and 2.0% NaCl. Juveniles were collected at 15 and 35 days after the beginning of experiment for analyses of Na+ net fluxes. Exposure of silver catfish juveniles to alkaline or acidic water did not affect their survival. Fish fed with diets without NaCl supplementation and exposed to pH 7.0 showed significantly higher weight, length, specific growth rate and biomass per tank than those exposed to pH 5.5. Ionoregulatory disturbances of silver catfish maintained at all pH are less pronounced when fed higher dietary salt supplementation (1.0-2.0%NaCl). The increase of dietary NaCl reduced body Na+ loss and protected against the impact of acidic water on growth. Este estudo verificou o melhor n赤vel de dieta de sal para o crescimento e regula o i nica de juvenis de jundi芍 em diferentes n赤veis de pH da 芍gua (5,5; 7,0 e 9,0). A dieta controle foi suplementada com 0,5; 1,0 e 2,0% de NaCl. Juvenis foram coletados aos 15 e 35 dias de experimento para an芍lise dos fluxos l赤quidos de Na+. A exposi o de juvenis de jundi芍 para 芍guas 芍cidas ou alcalinas n o afetou sua sobreviv那ncia. Exemplares alimentados com dietas sem adi o de NaCl e expostos em pH 7,0 mostraram peso, comprimento, taxade crescimento espec赤fico e biomassa/tanque significativamente maiores que aqueles expostos em pH 5,5. Dist迆rbios ionorregulat車rios em jundi芍s mantidos em todos os pH s o menos pronunciados quando em exemplares alimentados com dietas com maior suplmenta o de sal (1,0-2,0% NaCl). O aumento de NaCl na dieta reduziu a perda de Na+corporal e protegeu contra o impacto da acidez da 芍gua no crescimento dos juvenis.
