Phytogenic substances show a clear antimicrobial activity in vivo (e.g., Okitoi
et al., 2007). In the same way anticoccidial effects of phytobiotics are described
(Giannenas and Kyriazakis, 2009). The observed effects are probably caused by
the potential of hydrophobic essential oils to intrude the bacterial cell membrane,
to disintegrate membrane structure and to cause ion leakage (Windisch et al.,
2009). Nevertheless, more research is needed to clearify this specific action of
phytobiotics.
Effects on gut morphology are obviously twofold. On the one side phytobiotics
irritate intestinal tissues leading to shortage of intestinal surface and on the
other side change the microbial population to a more favourable composition.
Furthermore, they result in an enhanced secretion of digestive enzymes resulting
in an improved gut functioning (Windisch et al., 2009).