RESUMO
This study attempts to describe the effects of different administration periods of dietary ß-glucan and Vit C on the non-specific immune response, physiological parameters and disease resistance of Nile tilapia against Aeromonas hydrophila infection. Therefore, a feeding trial (288 fish) was conducted to determine the best administration period (7, 15, 30 and 45 days) for a Nile tilapia diet supplemented with 0.1% ß-glucan and 600 mg Vit C/kg diet. After the administration period, three different groups of 96 fish were exposed to one of the following three stresses: cold-induced stress, transport-induced stress, and A. hydrophila challenge. Hematological, biochemical and immunological responses were analyzed before and/or after stress. Cold-induced stress increased cortisol levels and reduced the leukocyte count in fish fed the test diet for seven days compared with the other periods. After transport-induced stress, fish fed the test diet for seven days required more hours to return to the baseline levels of cortisol and neutrophils. Moreover, independently of the administration period, fish needed 24 h for leukocyte and glucose levels to return to the initial values. The lowest survival after bacterial infection was observed in fish test diet for seven days. Based on fish hematological and biochemical responses, diet supplemented with 0.1% of ß-glucan and 600 mg of Vit C/kg fed for at least 15 days is recommended for Nile tilapia especially when fish are likely to encounter transport-induced stress, and this stress was more severe than cold-induced stress or bacterial challenge.
Assuntos
Aeromonas hydrophila , Ácido Ascórbico/farmacologia , Ciclídeos , Doenças dos Peixes/imunologia , Doenças dos Peixes/microbiologia , Infecções por Bactérias Gram-Negativas/veterinária , beta-Glucanas/farmacologia , Análise de Variância , Criação de Animais Domésticos/métodos , Animais , Aquicultura/métodos , Ácido Ascórbico/administração & dosagem , Brasil , Temperatura Baixa , Suplementos Nutricionais , Resistência à Doença/efeitos dos fármacos , Resistência à Doença/imunologia , Infecções por Bactérias Gram-Negativas/imunologia , Estresse Fisiológico/efeitos dos fármacos , beta-Glucanas/administração & dosagemRESUMO
Objetivou-se avaliar os parâmetros hematológicos da tilápia-do-nilo alimentada com dietas suplementadas com níveis de levedura autolisada e zinco, anterior e posterior ao estímulo pelo frio. As dietas foram formuladas para conter 32,0% PD e 3.240 kcal ED/kg com adição de levedura autolisada (%) e zinco (mg/kg): 0,0:0,0; 0,0:79,5; 2,0:0,0; 0,795:79,5; 2,0:200; 4,0:400; 6,0:600; 12,0:1200 e 14,0:1400. Na fase I, 135 alevinos foram distribuídos em 27 aquários de 50L e alimentados quatro vezes/dia por 128 dias (26ºC). Posteriormente, iniciou-se a fase II. Nove peixes/tratamento foram transferidos para 27 aquários de 40L (três/aquário) e submetidos à baixa temperatura (13,0ºC) por sete dias. Antes e após o estímulo pelo frio avaliaramse: o número de eritrócitos, a porcentagem de hematócrito, a taxa de hemoglobina, o volume corpuscular médio, a concentração dehemoglobina corpuscular média, a proteína plasmática e leucócitos totais, a porcentagem de linfócitos, neutrófilos e monócitos. O número de eritrócitos foi influenciado (p<0,05) pela adição de levedura autolisada e zinco nas dietas. Após o estímulo pelo frio o maior prejuízo na eritropoiese ocorreu nos peixes que receberam dietas 0,795:79,50 (Lev:Zn) e 14:1.400 (Lev:Zn). A ausência dos nutrientes-testes determinou queda significativa no hematócrito, leucócitos e proteína plasmática total. O estresse pelo frio determina leucopenia, linfopenia, neutrofilia e monopenia.(AU)
Hematological parameters of Nile tilapia fed diets supplemented with increasing levels of autolised yeast and zinc, before and after cold stress, were analyzed. The diets were formulated to contain 32.0% DP and 3,240 kcal/kg DE with increasing levels of autolised yeast (%) and zinc (mg/kg), as: 0.0:0.0; 0.0:79.5; 2.0:0.0; 0.795:79.5; 2.0:200; 4.0:400; 6.0:600; 12.0:1.200; 14.0:1400 . In phase I, 135 fingerlings were distributed into 27 50l-aquaria and fed ad libitum four times a day during 128 days (26ºC). After that, phase II began and nine fish from each treatment were transferred to 27 40l-aquaria (three/aquarium) and submitted to cold temperature (13.0ºC) during seven days. Before and after cold stress, the following parameters were evaluated: erythrocytes number, hematocrit, hemoglobin, corpuscular volume, mean corpuscular volume, total plasmatic protein, total leucocytes, lymphocytes, neutrophils and monocytes percentage. The number of erythrocytes was significantly influenced by the addition of autolised yeast and zinc to the diets. After cold stress, fish fed diets supplemented with 0.795:79.50 (Lev:Zn) and 14:1400 (Lev:Zn) presented impaired erythrocyte synthesis. Absence of test nutrients determined significant decrease in hematocrit, total leukocyte and total plasmatic protein. Cold stress determines leukopenia, lymphopenia, neutrophylia and monopenia(AU)
Assuntos
Animais , Hematologia/instrumentação , Ciclídeos/classificação , Dieta/métodos , Zinco/administração & dosagem , Leveduras/crescimento & desenvolvimento , Clima Frio/efeitos adversos , Eritrócitos/metabolismo , Eritropoese/fisiologiaRESUMO
Objetivou-se avaliar os parâmetros hematológicos da tilápia-do-nilo alimentada com dietas suplementadas com níveis de levedura autolisada e zinco, anterior e posterior ao estímulo pelo frio. As dietas foram formuladas para conter 32,0% PD e 3.240 kcal ED/kg com adição de levedura autolisada (%) e zinco (mg/kg): 0,0:0,0; 0,0:79,5; 2,0:0,0; 0,795:79,5; 2,0:200; 4,0:400; 6,0:600; 12,0:1200 e 14,0:1400. Na fase I, 135 alevinos foram distribuídos em 27 aquários de 50L e alimentados quatro vezes/dia por 128 dias (26ºC). Posteriormente, iniciou-se a fase II. Nove peixes/tratamento foram transferidos para 27 aquários de 40L (três/aquário) e submetidos à baixa temperatura (13,0ºC) por sete dias. Antes e após o estímulo pelo frio avaliaramse: o número de eritrócitos, a porcentagem de hematócrito, a taxa de hemoglobina, o volume corpuscular médio, a concentração dehemoglobina corpuscular média, a proteína plasmática e leucócitos totais, a porcentagem de linfócitos, neutrófilos e monócitos. O número de eritrócitos foi influenciado (p<0,05) pela adição de levedura autolisada e zinco nas dietas. Após o estímulo pelo frio o maior prejuízo na eritropoiese ocorreu nos peixes que receberam dietas 0,795:79,50 (Lev:Zn) e 14:1.400 (Lev:Zn). A ausência dos nutrientes-testes determinou queda significativa no hematócrito, leucócitos e proteína plasmática total. O estresse pelo frio determina leucopenia, linfopenia, neutrofilia e monopenia.
Hematological parameters of Nile tilapia fed diets supplemented with increasing levels of autolised yeast and zinc, before and after cold stress, were analyzed. The diets were formulated to contain 32.0% DP and 3,240 kcal/kg DE with increasing levels of autolised yeast (%) and zinc (mg/kg), as: 0.0:0.0; 0.0:79.5; 2.0:0.0; 0.795:79.5; 2.0:200; 4.0:400; 6.0:600; 12.0:1.200; 14.0:1400 . In phase I, 135 fingerlings were distributed into 27 50l-aquaria and fed ad libitum four times a day during 128 days (26ºC). After that, phase II began and nine fish from each treatment were transferred to 27 40l-aquaria (three/aquarium) and submitted to cold temperature (13.0ºC) during seven days. Before and after cold stress, the following parameters were evaluated: erythrocytes number, hematocrit, hemoglobin, corpuscular volume, mean corpuscular volume, total plasmatic protein, total leucocytes, lymphocytes, neutrophils and monocytes percentage. The number of erythrocytes was significantly influenced by the addition of autolised yeast and zinc to the diets. After cold stress, fish fed diets supplemented with 0.795:79.50 (Lev:Zn) and 14:1400 (Lev:Zn) presented impaired erythrocyte synthesis. Absence of test nutrients determined significant decrease in hematocrit, total leukocyte and total plasmatic protein. Cold stress determines leukopenia, lymphopenia, neutrophylia and monopenia