Effect of beta 1,3 glucan in stress responses of the pencilfish (Nannostomus trifasciatus) during transport within the rio Negro basin

Abstract

We investigated the use of beta 1,3 glucan as an imunostimulant during a transport experiment to determine the effects upon the stress response of the pencilfish (Nannostomus trifasciatus). Pencilfish were fed for seven days with different concentrations of beta 1,3 glucan: 0.0% (control); 0.01%; 0.1% and 0.5% of beta 1,3 glucan per kg of feed -1 . Fish were then transported for 24 hours by boat from Barcelos to Manaus. The highest dose of beta 1,3 glucan in the food increased Na + influx after 12 hours of transport and 0.1 and 0.5% beta 1,3 glucan maintained the flux of both ions close to zero at 24 hours. All doses of beta 1,3 glucan reduced K + loss significantly in the beginning of the transport, but after 12 to 24 hours did not. No significant differences in whole body cortisol or survival were observed. Our results indicate that pencilfish had ionic alterations during transport from Barcelos to Manaus. The lack of significant differences in whole body cortisol and survival rate in addition to the maintenance of Na + and K + balance during transport reinforce the positive effects of beta 1,3 glucan immunostimulant on fish homeostasis. Therefore, we recommend its addition to food prior to transport.O objetivo deste trabalho foi verificar se o imunoestimulante beta 1,3 glicano, adicionado à ração fornecida dias antes do transporte, pode minimizar algumas respostas de estresse do peixe lápis (Nannostomus trifasciatus) capturado na natureza. Estes peixes foram alimentados por sete dias com diferentes concentrações de beta 1,3 glicano: 0,0% (controle); 0,01 %; 0,1% e 0,5 % de beta 1,3 glicano.kg de ração -1 . Após este período, as caçapas foram transportadas via barco de Barcelos para Manaus, com duração de 24 horas. Nos peixes alimentados com a maior concentração de beta 1,3 glicano na ração foi verificado aumento no influxo de Na + após 12 horas de transporte e nos peixes alimentados com 0,1 e 0,5% de beta 1,3 glicano, o fluxo destes íons foi mantido próximo de zero no final de 24 horas de transporte. Todas as doses de beta 1,3 glicano reduziram significativamente a perda de K + no início do transporte, mas, após 12 horas até o final do transporte houve efeito significativo no efluxo de K + . Não foram verificadas diferenças significativas entre tratamentos ou tempos de amostragem para os níveis de cortisol corpóreo. A taxa de sobrevivência não diferiu ao final do experimento. Nossos resultados indicam que o transporte entre Barcelos e Manaus promoveu alterações iônicas no peixe-lápis e a ausência de diferenças significativas no cortisol corpóreo e na taxa de sobrevivência aliada, à manutenção do equilíbrio de sódio e potássio durante o transporte, reforça o efeito positivo do imunoestimulante beta 1,3 glicano na homeostase dos peixes e sua adição à ração é recomendada.

Monitoring water quality changes and ornamental fish behaviour during commercial transport

“…Studies focusing on the effect of low water quality in ornamental fish welfare tend to focus on mortality or physiological response (Gonzalez et al, 1998;Brinn et al, 2012), however, here we show that water quality can also influence the behaviour of fishes. Future studies on the response of fishes to water quality should record behavioural changes as this may provide additional information (Abreu et al, 2014;Brinn et al, 2012). Other stress measures tested in this study did not vary between transport stages.…”

“…In addition to the lack of information on change in water quality during commercial transport, little is known about the cumulative effect of repeated transport and exposure to water of varying quality on the stress and welfare of ornamental fishes. Most studies assessing stress experienced in this context measure a range of stress indicators such as plasma cortisol, lactate and glucose levels (Ferreira et al, 2017;Inoue et al, 2005;Salbego et al, 2015) and the techniques involved are invasive (Abreu et al, 2014;Azambuja et al, 2011;Zanuzzo et al, 2017). However, in small ornamentals, taking a blood sample in order to measure these indicators of stress often requires sacrificing the fish.…”

Growth of Amazon ornamental fish Nannostomus beckfordi larvae (Steindachner, 1876) submitted to different stocking densities and feeding management in captivity conditions

“…In the first experiment, water quality parameters showed adequate values for Nannostomus beckfordi , not influencing the zootechnical parameters of the study (Abreu et al, ). The feeding frequency (two or four times per day) did not differ between treatments for the dependent variables measured.…”

The use of feed and water additives for live fish transport

“…Abreu et al . () fed wild‐caught pencilfish ( Nannostomus trifasciatus ) one of four experimental diets with 0%, 0.01%, 0.1% or 0.5% beta 1,3 glucan added for 7 days. The fish were then fasted and transported for 24 h. The addition of beta 1,3 glucan reduced the net loss of K + during the first 3 h of transport.…”

“…Silver pomfret were then transported in darkened plastic bags for 4 h. Diet supplementation with ascorbic acid significantly reduced serum cortisol and glucose levels as well as mortality, indicating that high ascorbic acid successfully reduced stress associated with transport. Abreu et al (2014) fed wild-caught pencilfish (Nannostomus trifasciatus) one of four experimental diets with 0%, 0.01%, 0.1% or 0.5% beta 1,3 glucan added for 7 days. The fish were then fasted and transported for 24 h. The addition of beta 1,3 glucan reduced the net loss of K + during the first 3 h of transport.…”