| dc.description.abstract | Stress on Nile tilapia (Oreochromis niloticus) can impact growth and overall health
during sensitive circumstances. This study overviews the different lines of fish
defenses and illustrates other elements involved in innate and specific immune
responses, which various factors (e.g., stressors or environmental aspects of
natural origin) could influence. The study has been conducted to evaluate the
effect of a vitamin solution on the growth, health, post-injection stress, and
resistance of tilapia that were challenged with Streptococcus agalactiae, which has
not been investigated before. White blood cells were evaluated to determine stress
in the fish at different time intervals following placebo vaccination (saline solution)
before challenging Streptococcus agalactiae. Here, fish in treatment Vi 10 were
applied at 10 mL/kg of a vitamin solution top coated on commercial feed pellets
and no saline injection during 3 weeks of the trial, while fish in Vi 10-Saline
treatment was fed similarly but with saline injection on the seventh day to compare
sampled cortisol levels as an indication of the stress response. Besides, a Control
treatment in which no product application nor injection was included in the
experimental design. Finally, 30 fish of each replication per treatment were
challenged with S. agalactiae on day 22, and the mortality was followed up for 7
days. There were no significant differences in weight gain, feed intake, and feed
efficiency ratio between the three treatments. The hematological parameters and
blood cell counts recorded in fish fed with and without a vitamin diet had similar
results. The results indicated that adding vitamin solution is essential for tilapia to
maintain relative cortisol levels in stressful conditions and potentially improve
survival after a pathogenic challenge. Further studies are recommended to
optimize the vitamin supplementation regime and rearing conditions for better
influence on growth performance. | en_US |
