Prebiotic effects of Vernonia amygdalina and Ocimum gratissimum aqueous leaf extracts in rabbit (Oryctolagus cuniculus)
The prebiotic potentials of crude extracts of Vernonia amygdalina and Ocimum gratissimum in rabbit (Oryctolagus cuniculus) were studied. The aqueous leaf extracts of both plants, taken orally, were evaluated for their effects on the composition and relative abundance of the rabbit gastrointestinal microflora as well as their protective roles against gastrointestinal infection by selected test organisms. The crude extracts were administered to eight-week old rabbits with average weight of 0.85 ± 0.14 kg, at a dosage of 0.1 g/day. Species of Corynebacterium, Enterococcus, Bacteroides, Lactobacillus and Actinomyces were identified as resident bacteria in the rabbit gastrointestinal tract (GIT). Consumption of Vernonia amygdalina extract selectively and significantly (p < 0.05) increased the numbers of Enterococcus and Actinomyces species recovered from the animals faecal specimens, while O. gratissimum increased only the Actinomyces species. In contrast, the numbers of Bacteriodes species were significantly decreased by both extracts. Consumption of V. amygdalina extract also reduced colonization and damage of the animals GIT by Escherichia coli and Staphylococcus aureus as evidenced by restricted shedding of the organisms in faeces and histopathological examination of colon tissues. The results from this study showed that the V. amygdalina leaf extract has prebiotic effects in the rabbit GIT including protection of the animals against some GIT pathogens.
Key words: Prebiotics, Vernonia amygdalina, Ocimum gratissimum, gastrointestinal tract, rabbit.