This study investigated the effects of essential oil extracted from Daniellia oliveri leaf
(DOLE) on immune function, oxidative stress markers, semen quality, and caecal
microbial and fermentation characteristics in male rabbits. Animals were randomly
assigned to three dietary treatments: a control group fed a basal diet, and two test
groups receiving the basal diet supplemented with DOLE at two different inclusion
levels. Blood, semen, and caecal samples were collected and analyzed at the end of
the trial. Rabbits supplemented with DOLE showed improved immune responses, as
indicated by higher levels of immunoglobulins and antioxidant enzymes than the
control group. Levels of oxidative stress markers, such as malondialdehyde and
cortisol, were significantly reduced in DOLE-supplemented groups. Semen
characteristics—including ejaculatory volume, motility, and sperm concentration—
were enhanced with DOLE supplementation, while sperm abnormalities and reaction
time were lower compared to the control. Semen color and pH remained consistent
across all groups. Microbial analysis revealed a reduction in harmful bacteria, such as
Escherichia coli, coliforms, and Streptococcus species, in rabbits fed DOLE supplemented
diets, alongside an increased beneficial Lactobacillus species. Caecal pH
remained stable across treatments. Ammonia nitrogen levels were reduced in rabbits
receiving the higher dose of DOLE. Additionally, total volatile fatty acids increased
with DOLE supplementation, while the concentrations of acetic acid was highest in
the control group, the butyric, and propionic acids showed significant increase in
animals supplemented DOLE. In conclusion, DOLE supplementation enhanced
immune function, mitigated oxidative stress, improved reproductive traits, and
positively influenced gut microbial ecology in rabbits. The higher inclusion level of
DOLE demonstrated the most pronounced benefits, suggesting its potential as an
effective natural dietary additive for improving overall health and productivity in
small mammals.
Keywords: Rabbit bucks, tropical phytogenics, oxidative stress indices, semen, ceacal microbes and fermentation
