Hematoimmunological responses of Nile tilapia juvenile with dietary supplementation of immunomodulators and different levels of vitamins after acute and physical stress

Abstract

The study analyzed the hematoimmunological effects of the joint dietary supplementation of immunomodulators (β-glucans-nucleotides) and different levels of vitamins for Nile tilapia after physical and acute stress. Four treatments with different experimental diets were used: diets with indicated vitamin levels (Vit ind); Vit ind + 0.5% immunomodulator (Vit ind+Immune); rations with a high level of vitamins (Vit high); Vit high + 0.5% immunomodulator (Vit high+Immune). The experiment included 560 fish (3.0 ± 0.68 g of initial weight and 5.33 ± 0.66 cm of initial length), in 28 tanks and 25 fish/tank, with 7 replicates. After 60 days of supplementation, the animals had a weight of 33.30 ± 7.6 g and a length of 11.97 ± 0.94 cm. The water temperature was set at 20°C and two complete biometrics were performed. Subsequently, the animals were conditioned to two stress factors: physical (I), temperature oscillations: 20ºC to 30ºC/30ºC to 20ºC/20ºC to 30ºC; (II), the same animals were placed in plastic bags with dechlorinated water and shaken for 5 minutes and returned to their respective tanks. For hematoimmunological data, 140 animals were used after stress. Antimicrobial title and total plasma protein were significantly higher in fish that did not receive an immunomodulator. Differently, the binder title increased in fish fed with lower levels of vitamins, while immunoglobulin showed immunomodulatory interaction x level of vitamins. In summary, the inclusion of immunomodulators increased the animals' resistance to physical and acute stress, and improved hematoimmunological parameters, and the high level of vitamins did not modulate immune responses.