Alternative Strategies to Antibiotic Growth Promoters - A review

Abstract

Antibiotic growth promoters and antibiotic resistance are closed related. The increased concern about the potential for antibiotic resistant strains of bacteria has compelled the researchers to utility of other non-therapeutic alternatives like enzymes, probiotics, prebiotics, herbs, essential oils, immunostimulants and organic acids as feed additives in animal production. Organic acids are not antibiotics but, if used correctly along with nutritional, managerial and biosecurity measures, they can prove powerful in maintaining the health of the GI-tract of poultry, thus improving their zootechnical performances. Due to antimicrobial effect, organic acids result in inhibition of intestinal bacteria leading to the reduced bacterial competition with the host for available nutrients and diminution in the level of toxic bacterial metabolites as a result of lessened bacterial fermentation resulting in the improvement of protein and energy digestibility; thereby ameliorate the performance of bird. The increased villus height in the small intestines induced by organic acids increases the absorptive intestinal surface, facilitates the nutrient absorption and growth performance. They decrease the pH value in different segments of gastro-intestinal tract which is conducive for the growth of favourable bacteria simultaneously hampering the growth of pathogenic bacteria which grow at relatively higher pH. The acid anion has been shown to complex with calcium, phosphorus, magnesium and zinc, which improves the digestibility of these minerals. Reduction in gastric pH following organic acid feeding increases pepsin activity and the peptides arising from pepsin proteolysis trigger the release of hormones, including gastrin and cholecystokinin, which regulate the digestion and absorption of proteins.