Desempenho produtivo e caracterização da resposta hemato-imunológica induzida por nucleotídeo em tilápia-do-Nilo desafiada com Streptococcus agalactiae sorotipo não tipável
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Data
2022-02-24
Autores
Moro, Evandro Bilha [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Este estudo objetivou avaliar a suplementação de RNA, como fonte de nucleotídeos dietético, incluído antes e após a extrusão na dieta da tilápia-do-Nilo e seu efeito nos parâmetros hematológico, bioquímico e imunológico antes e após o desafio contra Streptococcus agalactiae não tipável. O estudo foi conduzido em três etapas. No primeiro experimento foi avaliada a incorporação de 0, 37, 75 e 150 mg kg-1 de RNA na ração antes da extrusão. Os peixes foram alimentados por 30 dias com as dietas e realizadas biometrias em 0, 15 e 30 dias. Ao final do período experimental, oito peixes de cada unidade experimental foram realocados em uma unidade para inoculação da bactéria inativada. Os demais peixes foram desafiados com cepa de S. agalactiae viva. Os resultados deste primeiro experimento não foram promissores, pois a porcentagem de nucleotídeos disponíveis na dieta foi inferior ao recomendado para suprir a demanda pelos peixes, portanto, novos estudos foram realizados. No segundo experimento, foram preparadas dietas contendo 0, 250, 500 e 1.000 mg kg-1 de nucleotídeo, incorporado na dieta de dois modos, antes da extrusão e após a extrusão por coating utilizando-se CMC. Os peixes foram alimentados por 90 dias com essas dietas e as coletas foram realizadas em 0, 30, 60 e 90 dias. Ao final do período experimental, nove peixes de cada grupo experimental foram realocados para uma unidade para inoculação da bactéria inativada. Os demais peixes foram desafiados com cepa S. agalactiae viva. A suplementação dietética de nucleotídeo em ambos os métodos de incorporação foi promissora durante os 90 dias de alimentação, todavia, após o desafio o imunomodulador pode ter apresentado efeito adverso (sobrecarga) ao sistema imune devido a exposição prolongada à dieta suplementada. No terceiro experimento, foram utilizadas as mesmas dietas do segundo experimento. Os peixes foram alimentados por 30 dias com as dietas experimentais e o desempenho produtivo avaliado. Ao final dos 30 dias, os peixes foram desafiados com S. agalactiae vivo. Os peixes alimentados com a dieta contendo 1.000 mg kg-1 de RNA como fonte de nucleotídeos dietéticos apresentaram melhor desempenho produtivo em crescimento e ganho em peso, contudo, os níveis de inclusão e métodos não apresentaram diferença significativa para sobrevivência após o desafio bacteriano. A suplementação dietética de nucleotídeo está intimamente relacionada com a fase de vida e tempo de administração na dieta para peixes. A inclusão de 500 a 1.000 mg kg-1 de nucleotídeo antes ou após a extrusão ocasiona melhora no desempenho produtivo e na resposta imunológica da tilápia-do-Nilo, desde que não seja administrado por período superior a 90 dias.
This study aimed to evaluate RNA supplementation, as a source of dietary nucleotides, included before and after extrusion in the diet of Nile tilapia and its effect on hematological, biochemical and immunological parameters before and after challenge against non-typeable Streptococcus agalactiae. The study was conducted in three stages. In the first experiment, the incorporation of 0, 37, 75 and 150 mg kg-1 of RNA in the feed before extrusion was evaluated. The fish were fed for 30 days with the diets and biometrics were performed at 0, 15 and 30 days. At the end of the experimental period, eight fish from each experimental unit were relocated to a unit for inoculation of the inactivated bacteria. The other fish were challenged with a live strain of S. agalactiae. The results of this first experiment were not promising, as the percentage of nucleotides available in the diet was lower than recommended to meet the demand for fish, therefore, new studies were carried out. In the second experiment, diets containing 0, 250, 500 and 1,000 mg kg-1 of nucleotide were prepared, incorporated into the diet in two ways, before extrusion and after extrusion by coating using CMC. The fish were fed for 90 days with these diets and collections were performed at 0, 30, 60 and 90 days. At the end of the experimental period, nine fish from each experimental group were relocated to a unit for inoculation of the inactivated bacteria. The remaining fish were challenged with a live S. agalactiae strain. Dietary nucleotide supplementation in both incorporation methods was promising during the 90 days of feeding, however, after the challenge, the immunomodulator may have had an adverse effect (overload) on the immune system due to prolonged exposure to the supplemented diet. In the third experiment, the same diets as in the second experiment were used. The fish were fed for 30 days with the experimental diets and the productive performance was evaluated. At the end of the 30 days, the fish were challenged with live S. agalactiae. Fish fed with a diet containing 1,000 mg kg-1 of RNA as a source of dietary nucleotides showed better productive performance in terms of growth and weight gain, however, the inclusion levels and methods did not present a significant difference for survival after the bacterial challenge. Dietary nucleotide supplementation is closely related to the life stage and time of administration in the diet for fish. The inclusion of 500 to 1,000 mg kg-1 of nucleotide before or after extrusion causes an improvement in the productive performance and in the immune response of Nile tilapia, as long as it is not administered for a period longer than 90 days.
This study aimed to evaluate RNA supplementation, as a source of dietary nucleotides, included before and after extrusion in the diet of Nile tilapia and its effect on hematological, biochemical and immunological parameters before and after challenge against non-typeable Streptococcus agalactiae. The study was conducted in three stages. In the first experiment, the incorporation of 0, 37, 75 and 150 mg kg-1 of RNA in the feed before extrusion was evaluated. The fish were fed for 30 days with the diets and biometrics were performed at 0, 15 and 30 days. At the end of the experimental period, eight fish from each experimental unit were relocated to a unit for inoculation of the inactivated bacteria. The other fish were challenged with a live strain of S. agalactiae. The results of this first experiment were not promising, as the percentage of nucleotides available in the diet was lower than recommended to meet the demand for fish, therefore, new studies were carried out. In the second experiment, diets containing 0, 250, 500 and 1,000 mg kg-1 of nucleotide were prepared, incorporated into the diet in two ways, before extrusion and after extrusion by coating using CMC. The fish were fed for 90 days with these diets and collections were performed at 0, 30, 60 and 90 days. At the end of the experimental period, nine fish from each experimental group were relocated to a unit for inoculation of the inactivated bacteria. The remaining fish were challenged with a live S. agalactiae strain. Dietary nucleotide supplementation in both incorporation methods was promising during the 90 days of feeding, however, after the challenge, the immunomodulator may have had an adverse effect (overload) on the immune system due to prolonged exposure to the supplemented diet. In the third experiment, the same diets as in the second experiment were used. The fish were fed for 30 days with the experimental diets and the productive performance was evaluated. At the end of the 30 days, the fish were challenged with live S. agalactiae. Fish fed with a diet containing 1,000 mg kg-1 of RNA as a source of dietary nucleotides showed better productive performance in terms of growth and weight gain, however, the inclusion levels and methods did not present a significant difference for survival after the bacterial challenge. Dietary nucleotide supplementation is closely related to the life stage and time of administration in the diet for fish. The inclusion of 500 to 1,000 mg kg-1 of nucleotide before or after extrusion causes an improvement in the productive performance and in the immune response of Nile tilapia, as long as it is not administered for a period longer than 90 days.
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Palavras-chave
Aquicultura, Imunidade Inata, Peixe, RNA, Bacterioses