Nonruminant nutrition symposium on natural phytobiotics for health of young animals and poultry: mechanisms and application.

Newly weaned piglets and young poultry are highly susceptible to various stressors, such as bacterial diseases resulting in decreased growth and even death (Lecce, 1986; Hoerr, 1998). Supplementing antibiotics in swine and poultry diets at subtherapeutic levels has long been shown to increase the growth rate (Becker et al., 1955; Stahly et al., 1980; Cromwell, 2002). However, due to growing concerns over antibiotic resistance, the use of antibiotics as growth promoters in animal diets could be limited due to public or regulatory pressures. Thus, current research involving feed additives for diets of young animals is focused on searching for alternatives to antibiotics that would have at least similar growth-promoting effects of antibiotics without causing bacterial resistance. Phytobiotics is a term used to describe plant-derived natural bioactive compounds, which affect animal growth and health, and is often applied to essential oils, botanicals, and extracts derived from herbal plants. Some phytobiotics are known to have antimicrobial or antiviral activities (Sökmen et al., 2004; Piao et al., 2006; Friedman, 2007). Those selected herbs or phytobiotics have long been used as complementary or alternative medicine to improve human health or to cure human disease. Recent advances in science have allowed for the identification of active components from selected phytobiotics and investigation into the mechanisms of those components in the animal’s body. More recently, animal nutritionists have attempted to use some phytobiotics as alternatives to the use of antibiotics for young animals and birds (Mao