Respostas imune inatas de pacus (Piaractus mesopotamicus) alimentados com dieta suplementada com β-glucano em protocolos de alimentação pulsada e desafiados com LPS
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Data
2022-07-29
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Universidade Estadual Paulista (Unesp)
Resumo
A procura por uma alimentação mais saudável influencia o crescimento do cultivo de peixes. O pacu (Piaractus mesopotamicus), uma espécie nativa de peixes redondos, é um dos mais vendidos no mercado nacional. O cultivo de peixes em cativeiro capacita a criação de um número maior de animais em menor espaço, o que por si só é estressante, e, somado aos manejos diários, pode resultar em imunossupressão e maior susceptibilidade a doenças. Por isso indica-se o uso de imunoestimulantes para aumentar a resistência dos peixes às doenças, tais como o β-glucano que é capaz de melhorar a resposta imune dos animais. Por isso, o presente estudo avaliou protocolos de administração do imunoestimulante, na dose 0,1%, adicionado a ração comercial. Os tratamentos foram: 1- alimentação contínua com ração comercial por 28 dias; 2- alimentação contínua com ração suplementada com β-glucano por 28 dias; 3- alimentação alternada / uma semana com β-glucano e uma semana sem; 4- alimentação alternada / uma semana sem e semana com; 5-duas semanas seguidas com imunoestimulante e duas últimas sem; 6- alimentação alternada / duas semanas sem e duas com. Ao final do período experimental, os peixes foram amostrados para coleta de sangue e tecidos e determinação de indicadores do estresse (cortisol plasmático e glicose), indicadores da imunidade inata (atividade sérica da lisozima, atividade sérica do sistema complemento, atividade respiratória de leucócitos) e metabólicos (colesterol, triglicerídeos e gordura). Após uma amostragem (inicial), os peixes foram inoculados com injeção intraperitoneal com 1,5 mg kg-1 de LPS (E. coli) e amostrados 3, 6 e 24 horas depois. Os resultados mostraram que os protocolos e o β-glucano não modificaram os níveis de glicose no sangue, mas apenas a inoculação aumentou estes níveis, 6 h depois. Os níveis de cortisol oscilaram sem um padrão definido, mas tenderam a diminuir, em geral, 24 h após o LPS. As oscilações observadas nos indicadores imunológicos não apresentam padrão claro ou definido. Houve leucopenia e linfopenia após inoculação do LPS, bem como aumento nos valores de triglicerídeos e colesterol circulantes. A oferta de β glucano nos diferentes protocolos, seguindo um padrão pulsado não mostrou vantagem de nenhum deles.
The demand for a healthier diet influences the growth of fish farming. Pacu (Piaractus mesopotamicus), a native species of round fish, is one of the most important in the national market. The farming of fish enables a larger number of animals in a smaller space, which is stressful, and, in addition to daily management, can result in immunosuppression and greater susceptibility to diseases. Therefore, it is indicated the use of immunostimulants to increase the resistance of fish to diseases, such as the β-glucan which can improve the immune response of animals. Thus, the present study evaluated protocols of immunostimulant administration (0.1%) added to the commercial feed. The treatments were: 1- continuous feeding with commercial feed for 28 days; 2- continuous feeding with feed supplemented with β-glucan for 28 days; 3- alternating feeding / one week with β-glucan and one week without; 4- Alternating feeding/ one week without and week with; 5-two weeks in a row with immunostimulant and last two without; 6- Alternate feeding / two weeks without and two with. At the end of the experimental period, the fish were sampled for collection of blood and tissues and determination of stress indicators (plasma cortisol and glucose), indicators of innate immunity (serum lysozyme activity, serum activity of the complement system, respiratory activity of leukocytes) and metabolic (cholesterol, triglycerides and fat). After sampling (initial), the fish were inoculated with intraperitoneal injection with 1.5 mg kg-1 of LPS (E. coli) and sampled 3, 6 and 24 h after. The results showed that the protocols and the βglucan did not modify blood glucose levels, but only inoculation increased the levels 6 h later. The cortisol levels fluctuated without a clear pattern, but they tended to decrease in general 24 h after LPS. The oscillations observed in the immunological indicators did not show a clear or defined pattern. There was leukopenia and lymphopenia after LPS inoculation, as well as an increase in circulating triglyceride s and cholesterol values. The supply of β-glucan in the different protocols, following a pulsed pattern showed no advantage of any of them.
The demand for a healthier diet influences the growth of fish farming. Pacu (Piaractus mesopotamicus), a native species of round fish, is one of the most important in the national market. The farming of fish enables a larger number of animals in a smaller space, which is stressful, and, in addition to daily management, can result in immunosuppression and greater susceptibility to diseases. Therefore, it is indicated the use of immunostimulants to increase the resistance of fish to diseases, such as the β-glucan which can improve the immune response of animals. Thus, the present study evaluated protocols of immunostimulant administration (0.1%) added to the commercial feed. The treatments were: 1- continuous feeding with commercial feed for 28 days; 2- continuous feeding with feed supplemented with β-glucan for 28 days; 3- alternating feeding / one week with β-glucan and one week without; 4- Alternating feeding/ one week without and week with; 5-two weeks in a row with immunostimulant and last two without; 6- Alternate feeding / two weeks without and two with. At the end of the experimental period, the fish were sampled for collection of blood and tissues and determination of stress indicators (plasma cortisol and glucose), indicators of innate immunity (serum lysozyme activity, serum activity of the complement system, respiratory activity of leukocytes) and metabolic (cholesterol, triglycerides and fat). After sampling (initial), the fish were inoculated with intraperitoneal injection with 1.5 mg kg-1 of LPS (E. coli) and sampled 3, 6 and 24 h after. The results showed that the protocols and the βglucan did not modify blood glucose levels, but only inoculation increased the levels 6 h later. The cortisol levels fluctuated without a clear pattern, but they tended to decrease in general 24 h after LPS. The oscillations observed in the immunological indicators did not show a clear or defined pattern. There was leukopenia and lymphopenia after LPS inoculation, as well as an increase in circulating triglyceride s and cholesterol values. The supply of β-glucan in the different protocols, following a pulsed pattern showed no advantage of any of them.
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Aquicultura, Peixe, Piaractus mesopotamicus