Antibiotics are widely used as feed additives in poultry industry
for purposes of improving health and performance [1].
However, the concerns about developing antibiotic resistant bacteria in human have led the European Union and the United
States to pass legislation to ban the usage of antibiotics as
growth promoter. Consequently, the research now has been
focused on natural products such as plants or their extracts
as possible alternative to antibiotics [2]. Plants and their
extracts are known to possess many bioactive components
such as tannin, alkaloids, and essential oils which have both
antimicrobial and antioxidant activities [3–5]. These bioactive
components exert their beneficial effects by manipulating the
intestinal microflora and improving digestibility. Furthermore,
many studies have indicated that plants and their bioactive
components can decrease intestinal pH thus favoring the
growth of beneficial bacteria such as lactobacilli and bifidobacteria
and reducing the number of the coliforms and Clostridium
perfringens in t