Phytobiotics as an alternative to antibiotic growth promoter for food animals
Sanjeev Kumar, TK Dutta, P Roychoudhury, Fatema Akter and PK Subudhi
Contd from previous issue
The protection of the gut environment is now known to play an important role in reducing disease in animals. Thyme and yarrow extracts are reported to have potential to reduce caecal counts of Clostridium perfringens,when incorporated in the broiler diets (Cross et al., 2004). The dietary supplementation of plant extracts containing capsaicin (1.98 g/100g), carvacol (4.95 g/100g) and cinnamic aldehyde (2.97 g/100g) reduced C. perfringens and Escherichia coli counts in colonic contents, wchih is comparable to birds treated with the antibiotic, avilamycin (Jamroz et al., 2003).
2. Antimicrobial effect
Antimicrobial action of phytobiotics is due to the presence of essential oils and phenolic compounds (thymol, carvacrol, phenylpropane, greaniol, etc.) (Yang et al., 2015).The antimicrobial activity (either bactericidal or bacteriostatic) of phytobiotic compounds has been investigated by several researchers against food borne organisms such as protozoa and fungi (Chao et al., 2000). The presence of the hydroxyl group and delocalized electrons are important elements for their anti microbial action (Lambert et al., 2001). They suggested that the ability of hydrophobic essential oils to intrude into the cell membrane of pathogens, consequently disintegrating their membrane structures and causing ion leakage as a possible explanation of the antimicrobial activity of PFA. Some of them have shown promising activities against Eimeria species after experimental challenge in poultry (Giannenas et al., 2003). Phytobiotics also help in improving the microbial hygiene of carcasses (Aksit et al.,2006).
3. Prevent binding of harmful bacteria
Phytobiotics promote the binding of commensal microflora to the mucosa of the gastro intestinal tract either by specific adhesion of pathogens through the ‘lectin–receptor’ mechanism (agglutination) or by blocking the adhesion of pathogens onto the mucosal layer of the intestine. The phosphorylated mannan oligosaccharides (MOS) from yeast cell walls are extensively studied for their property to prevent the binding of harmful bacteria to GIT mucosa (Spring et al.,2000).
4. Immuno stimulatory effects
Certain plant polysaccharides act as immuno stimulatory (adjuvant effect) substances (Chen et al.,2003). Immune enhancer polysaccharides were obtained by Guo et al. (2003) from two mushroom species; Lentinus endodes and Tremella fuciformis, and a herb, Astragalus membranaceus radix, used in chickens to activate both innate and adaptive immunity. The dietary supplementation of fructooligosaccharides residues in phytobiotics leads to upregulation of immunoglobulin A (IgA) secretion in murine Peyer’s patch cells in the intestinal mucosa (Hosono et al., 2003).
5. Antioxidant and anti inflammatory action
Antioxidant properties of phytobiotics are due to their ability to scavenge free radicals that may play an important role in preventing some diseases (Kamatou and Viljoen, 2010). (To be contd)