Rhamdia quelen (Quoy & Gaimard, 1824), submitted to a stressful condition: effect of dietary addition of the essential oil of Lippia alba on metabolism, osmoregulation and endocrinology

Abstract

The aim of this study was to evaluate the effect of the essential oil of Lippia alba (EOLA) as a feed additive on ionoregulatory and metabolic parameters and pituitary hormones expression in silver catfish, Rhamdia quelen, submitted to a stressful condition (stocking density of 10.6 kg m -3 and limited space). Fish were fed with different concentrations of EOLA (0.0 -control, 0.25 and 0.50 mL kg food -1 ) for 20 days. Metabolic parameters were not affected by the diet, with the exception of alanine aminotransferase, which was higher in the liver of fish fed 0.50 mL EOLA kg food -1. Plasma ions and activity of H + -ATPase did not change, but fish fed 0.25 mL EOLA kg food -1 presented higher Na + /K + -ATPase activity. Somatolactin expression in the pituitary was higher in the fish fed 0.25 mL EOLA kg food, but the expression of growth hormone and prolactin did not change. Therefore, dietary EOLA does not exert a protective effect in R. quelen submitted to a stressful situation because it did not alter most measured parameters. The use of 0.25 mL EOLA kg food -1 seems to be more suitable than 0.50 mL EOLA kg food -1 since the latter may be related to liver damage.O objetivo deste estudo foi avaliar o efeito do óleo essencial de Lippia alba (OELA) como aditivo em rações na ionoregulação, parâmetros metabólicos e expressão de hormônios hipofisários em jundiás, Rhamdia quelen, submetidos a uma situação estressante (densidade de estocagem de 10,6 kg m -3 e espaço limitado). Os peixes foram alimentados com diferentes concentrações de OELA (0,0 -controle, 0,25 e 0,50 mL kg de ração -1 ) durante 20 dias. Parâmetros metabólicos não foram afetados pela dieta, com a exceção da alanina aminotransferase, que foi mais elevada no fígado dos peixes alimentados com 0,50 mL de OELA kg de ração -1. Íons plasmáticos e a atividade da H + -ATPase não apresentaram nenhuma alteração, mas os peixes alimentados com 0,25 mL OELA kg de ração -1 apresentaram maior atividade da Na + / K + -ATPase. A expressão da somatolactina na hipófise de peixes alimentados com 0,25 mL OELA kg de ração -1 aumentou, porém a expressão do hormônio de crescimento e da prolactina não mudou. Portanto, a adição do OELA na ração não tem um efeito protetor em jundiás submetidos a uma situação estressante, pois não influiu na maioria dos parâmetros medidos. O uso de 0,25 mL OELA kg de ração -1 parece ser mais adequado que 0,50 mL OELA kg de ração -1, uma vez que este nível de inclusão pode estar relacionado a danos hepáticos.

Plant essential oils as fish diet additives: benefits on fish health and stability in feed

“…Different methods of adding the EOs to fish diets are reported in the literature such as mixing the EOs with an organic diluent (Dairiki et al 2013;Ribeiro et al 2016;Brum et al 2017), phosphate-buffered saline (PBS) (Navarrete et al 2010) or incorporation with some ingredients of the diet, such as defatted rice bran (Zheng et al 2009). In most of the recent studies using natural EOs in fish diets (Saccol et al 2013;Volpatti et al 2013;Ferreira et al 2014;Souza et al 2015;Diler et al 2016;Hassaan & Soltan 2016;Sutili et al 2016;Zeppenfeld et al 2016a,b), the EOs are generally used as a blend with a carrier oil or combined with other oils in the feed, commonly the lipidic fraction of the diet (i.e. fish oil, soybean oil, sunflower oil and canola oil).…”

Physiological responses of Rhamdia quelen (Siluriformes: Heptapteridae) to anesthesia with essential oils from two different chemotypes of Lippia alba

“…This analysis was previously validated (Souza et al, 2015). Absorbance was measured in a spectrophotometer at 450 nm, and intraand inter-assay coefficients of variation were 6.3% and 5.2%, respectively.…”

Citrus x aurantiumessential oil as feed additive improved growth performance, survival, metabolic, and oxidative parameters of silver catfish (Rhamdia quelen)

“…As a result, there has been a growing interest in alternatives to improve production without affecting the environment. The use of medicinal plants and their major compounds as dietary additives has attracted much attention worldwide and has been the subject of several studies, assisting in the control of diseases, improving growth, and as immunostimulant (Bandeira Jr. et al, ; Pês et al, ; Saccol et al, ; Souza et al, ; Zeppenfeld et al, ).…”

“…Essential oils (EOs) are a mixture of organic compounds extracted from plants and can be used as food preservatives (Ruberto & Baratta, ; Veeck et al, ). The EOs are also natural antioxidants and antimicrobials that can improve fish performance and the immune system, thus reducing production costs (Pês et al, , b; Saccol et al, ; Souza et al, ; Zeppenfeld et al, ; Zheng et al, ). These properties could be useful in aquaculture because aquaculture practices often trigger stress in the animal, interfering in their physiology and behaviour.…”