- Natural Growth Promoters
Natural Growth Promoters (NDPs) are feed additives for farm animals.
Different categories of feed additives for farm animals are referred to as Natural Growth Promoters (NGPs) or Non-
antibioticGrowth Promoters. They are commonly regarded as favorable alternatives to Antibiotic Growth Promoters (AGPs) in livestock production.
Categories of NGPs
NGPs include predominantly organic acids, probiotics, prebiotics, synbiotics, phytogenics, feed enzymes and immune stimulants. Since in the
European Unionthe use of AGP has been banned on January 2006, an ongoing search for alternatives has created a large variety of NGPs for pigs, poultry, ruminants and aquatic species.
General benefits of NGPs
The main advantage of NGPs over AGPs is that they do usually not bear any risk regarding bacterial resistance or undesired residues in animal products such as meat, milk or eggs. Addition of NGPs to feeds of farm animals may have a number of beneficial effects, including:
Mode of action of different NGPs
Acidifiers, such as organic acids or their salts, are used to prevent microbial degradation of raw materials or finished feeds, especially under poor storage conditions (e.g. high moisture content, high levels of contamination with molds). Moreover, acidifiers may improve growth performance through establishment of low gastrointestinal pH conditions which support endogenous digestive enzymes and reduce undesired gut
microorganisms. Many dietary acidifiers are based on propionic acid, formic acid, lactic acid and others, either as single components or in combination. Some acidifiers also contain inorganic acids (e.g. phosphoric acid). Probiotics
Probiotics are live microorganisms or viable spores which support the development of a beneficial gut
microflora. Probiotic bacteria (e.g. from the genera "Lactobacillus", "Bifidobacterium", "Enterococcus") counteract undesired microorganisms such as "Salmonella" or "E. coli" by blocking receptors on the gut wall, production of antimicrobial substances or activation of the immune system. Prebiotics
Prebiotics are carbohydrates which are indigestible for the host animal. On the other hand, they are selectively fermented by beneficial gut bacteria and, therefore, support a healthy gut microflora.
Combined administration of probiotics and prebiotics, referred to as synbiotics, is supposed to cause synergistic effects in terms of gut health and performance.
Phytogenics are derived from herbs, spices or aromatic plants and have shown antimicrobial, antifungal, antiviral, antioxidant or sedative properties. They are known for their appetizing effects, since they increase the palatability of the feed and stimulate endogenous digestive enzymes. Moreover, phytogenics have a pronounced impact on the gut microflora.
Functions of Feed Animal feeds contain varying levels of indigestible nutrients and undesired components such as fiber, phytate or proteins with antigenic effects. Different feed enzymes such as, carbohydrases, phytases or proteases, can be included in feeds to improve the utilization of energy and nutrients or to degrade several undesired components. Moreover, some enzymes (e.g. amylases, lipases) can be added to the feed of young animals in order to support the endogenous enzyme secretions.
Different feed additives may function as stimulator or modulator of immunity processes. Specific cell wall fragments from bacteria or yeasts or sea algae may induce activation of immune cells (e.g. macrophages, lymphocytes).
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*Foote, K. (2003) "The battle of the bugs and other alternatives to antibiotics in pork production." MB Swine Seminar 2003, vol. 17: pp. 1–17.
*Kelly, D. and King, T.P. (2001) "Luminal bacteria: regulation of gut function and immunity." In: "Gut environment of pigs." Edited by Piva, A., Bach Knudsen, K.E., Lindberg, J.E.: pp. 113–131. Nottingham University Press, Nottingham, UK.
*Pasteiner, S. (2006) "New natural concept for poultry gut health." "International Poultry Production" 14, 1: 17.
*Richards, J.D., Gong, J. and de Lange, C.F.M. (2005) "The gastrointestinal microbiota and its role in monogastric nutrition and health with an emphasis on pigs: Current understanding, possible modulations, and new technologies for ecological studies." "Canadian Journal of Animal Science" 85: 421–435.
*Steiner, T. (2006) "The potential benefits of Natural Growth Promoters." "Feed Tech" 10.2: 26–28.
* [http://ressources.ciheam.org/om/pdf/c37/99600009.pdf Possible alternatives to the use of antibiotics as growth promoters. New additives]
* [http://www.card.iastate.edu/publications/DBS/PDFFiles/03bp41.pdf Lessons from the Danish ban of feed-grade antibiotics]
* [http://www.biomin.net/homepage/biomin_en.nsf/fa6a5340ce9a4fbac1256de6006c774d/eed8ca95150227c4c12571a3003d9b73/$FILE/2006%20SPB%20Int.%20Poult.%20Prod.%20Gut%20health%20Poultry.pdf New natural concept for poultry gut health]
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