Maria Clara Miguel Libanori

This study aimed to evaluate the effects of a probiotic mix composed of Bacillus spp. and benzoic acid, all together and separately, in intestinal microbiology, liver, and intestinal histology, as well as in the composition of the intestinal microbiota by high-throughput sequencing analysis of juvenile Nile tilapias Oreochromis niloticus. Three hundred and twenty fish were divided into four experimental groups with four replicates. They were fed for 54 days: control (no supplementation), 0.1% benzoic acid (BA0.1%), mix of Bacillus spp. (Bacillus), and feed supplemented with Bacillus spp. and 0.1% benzoic acid (B+BA0.1%). Classical microbiological analysis showed that B+BA0.1% increased the concentration of total heterotrophic bacteria (4.94 ± 0.77) compared to the control group (4.43 ± 0.90). The results showed significant liver changes such as ballooning, congestion of large vessels, and pancreatic congestion between treatments B+BA0.1% and BA0.1%, the latter resulting in less (15.91 ± 16.61) pancreatic congestion than the other treatments. Vacuolation in the intestine was greater in supplemented animals with BA0.1%, B+BA0.1%, and Bacillus spp. than in the control group. The width of the villi was greater in the group supplemented with B+BA0.1% (22.19 ± 10.91) than in the Bacillus group. The abundance of Firmicutes and Bacteroidetes was higher in the B+BA0.1% group. Cetobacterium somerae was more abundant in the Bacillus and B+BA0.1% groups in the diversity index. Notably, joint supplementation with the probiotic mixture Bacillus spp. and 0.1% benzoic acid had a synergistic effect on the intestines of tilapia, positively modulating the intestinal microbiota.

In this study, we analyzed the hematoimmunological effects of dietary supplementation with immunomodulators (β-glucans + nucleotides) and different levels of vitamins on Nile tilapia (Oreochromis niloticus) after exposure to physical stress. The following four diet treatments were used: diets with indicated vitamin levels (Vitind), diets with Vitind + immunomodulator (Vitind + Immune), diets with high vitamin content (Vithigh), and those with Vithigh + immunomodulator (Vithigh + Immune). The experiment included 560 fish in 28 tanks (20 fish tank-1), with seven replicates per treatment. After 60 days of supplementation, the water temperature was set at 20 °C, and complete biometrics were performed. The animals were then subjected to physical stress with temperature oscillations of 20 °C to 30 °C/30 °C to 20 °C/20 °C to 30 °C. Hematoimmunological data from 140 animals were collected poststress. Antimicrobial titer and total plasma protein levels were significantly higher in fish not receiving immunomodulator-supplemented diets (2.88 ± 0.43 log2 and 26.81 ± 4.01 mg∙mL-1, respectively) than in those that did. Conversely, the agglutination titer increased in fish fed with lower vitamin levels (3.33 ± 0.66 log2) compared to those with higher vitamin levels. Increased immunoglobulin levels were observed in fish fed diets co-supplemented with vitamins and immunomodulators, revealing an interaction between immunomodulators and dietary vitamin levels. In summary, the inclusion of immunomodulators in the diet enhanced the animals’ resistance to physical stress and improved hematoimmunological parameters. Additionally, a high vitamin content in the diet did not modulate the immune responses in the animals. Neste estudo analisamos os efeitos hematoimunológicos da suplementação dietética com imunomoduladores (β-glucanos+nucleotídeos) e diferentes níveis de vitaminas na tilápia do Nilo (Oreochromis niloticus) após exposição ao estresse físico. Foram utilizados quatro tratamentos: dietas com níveis indicados de vitaminas (Vitind), dietas com Vitind + imunomodulador (Vitind+Immune), dietas com alto teor de vitaminas (Vithigh) e dietas com Vithigh + imunomodulador (Vithigh+Immune). O experimento incluiu 560 peixes em 28 tanques (20 peixes tanques-1), com sete repetições por tratamento. Após 60 dias de suplementação, a temperatura da água foi fixada em 20 °C e realizada biometria completa. Os animais foram submetidos a estresse físico com oscilações de temperatura de 20 °C a 30 °C/30 °C a 20 °C/20 °C a 30 °C. Dados hematoimunológicos de 140 animais foram coletados pós-estresse. O título antimicrobiano e os níveis de proteína plasmática total foram significativamente maiores em peixes que não receberam dietas com imunomodulador (2,88±0,43 log2 e 26,81±4,01 mg∙mL-1) do que naqueles que receberam. Por outro lado, o título de aglutinação aumentou em peixes alimentados com níveis mais baixos de vitaminas (3,33±0,66 log2) comparado àqueles com níveis mais elevados. Níveis aumentados de imunoglobulinas foram observados em peixes alimentados com dietas co-suplementadas com vitaminas e imunomoduladores, revelando interação entre imunomoduladores e níveis de vitaminas na dieta. Em resumo, a inclusão de imunomoduladores na dieta aumentou a resistência dos animais ao estresse físico e melhorou os parâmetros hematoimunológicos. Além disso, o alto teor de vitaminas na dieta não modulou as respostas imunológicas dos animais.

The essential oil of alfavaca (Ocimum gratissimum) contains important compounds, such as 1.8-cineol and eugenol. This study evaluated the effects of diets containing alfavaca essential oil on the zootechnical performance, plasma glucose, leukocyte respiratory activity, haematology, and intestinal histomorphometry in “cachara” (Pseudoplatystoma reticulatum) challenged with Aeromonas hydrophila. A total of 300 juvenile fish, with an average total length of 14.98 ± 0.28 cm and average weight of 18.84 ± 1.22 g, distributed in 20 tanks of 80 L, were fed twice a day with a diet containing essential oil at 0.5, 1.0, or 1.5% or without its inclusion in five replicates. After 45 days, blood collection and mid-intestinal bowel were sampled, before a challenge with Aeromonas hydrophila was performed. The fish supplemented with 1.0% of essential oil presented better weight gain, mean corpuscular volume, concentration of thrombotic and neutrophils, respiratory activity of leukocytes, and height of villi (p < 0.05) when compared to other groups. The cumulative mortality response was lower for fish fed 1.5% essential oil of alfavaca diets. Thus, the use of alfavaca essential oil is recommended in the diet of cachara catfish (P. reticulatum) at the level of up to 1.0% for 45 days for improvements in the zootechnical, haematological, and intestinal histomorphometric parameters.