Alternatives for AGPs
As we all know AGPs are working very well to reduce harmful bacteria in the animals, hence having healthier animals and therefore better growth. As we are taking out these AGPs we are looking for alternatives to replace them. But unfortunately there is not a "AGP-out-product-B-in" principle. We need complete new feeding concepts.
There is done over the last 20 years done a lot of research, mainly in Europe (Sweden, Denmark, Netherlands as countries where AGP first were forbidden and where regulations are strictly controlled) to find alternatives for AGPs. This research resulted in a long list of alternatives that have a proven anti-microbial effect. The options given below are some of the most common measures used in AGP free countries. But this list is not a complete overview and many other alternatives exists and are still investigated. Which solution is the best depends various factors such as animal type (pigs, poultry) production (meat production, egg production), disease pressure (depending a lot on biosecurity and hygiene status), climate (in hot and humid climate bacteria grow faster), age of the animals (younger animals need more gut support than older animals where gut flora is already well established) and which raw materials are used in the feed.
The most well know alternative for antibiotic growth promoters are probably the acidifiers which decrease the pH in the feed and in the stomach and intestines and inhibits the growth of various harmful bacteria like E. coli and Salmonella. Acids have also shown a positive influence on digestion of Calcium and Phosphorus. Formic acid, fumaric acid, citric acid and lactic acid have shown the best positive effect on gut health. Often combinations of these acids (sometimes with propionic acid to reduce mould growth) are used. The downside is that there is a risk that many microorganisms show adaptation to acidic environments and can even contribute to the enhancement of virulence of Salmonella by increased acid tolerance. Also mixtures of short and medium chain fatty acids, which are important nutrient sources for the digestive bacteria are proven to have an very positive effect.
A second alternative are the probiotics and prebiotics. Probiotics are live microbials such as Lactobacilli and Bifidobacteria as a feed supplements which improve the intestinal health. Of course is it possible to stimulate the growth of the beneficial bacteria by giving them the right nutrients, called the prebiotics with are non-digestible food substances that improve health by stimulating the growth of beneficial bacteria, like fructo-oligosaccharides (FOS) or plant fibers (fructans).
Enzymes such as proteases, amylases, lipases helping in digestion can be used to decrease the undigested feed in the end gut that might be a nutrient for harmful bacteria. NPS (non-starch polysaccharides) can have the same characteristics.
Cell walls from bacteria and yeast have influence on the immune system by activating macrophage activity and the proliferation of lymphocytes. These cell wall must originate from non-pathogenic bacteria or yeast cells that are able to produce glycans. Some subtracts from sea algae called phycophytics, can also stimulate the immune system and as such reduce the disease pressure.
Phycobiotics originate from leaves, roots, tubers or fruits of herbs, spices and other plants. They may be available in solid, dried, and ground forms, or as extracts (essential oils). In simple terms, phytobiotics are products of plant origin, and preparations such as thyme, oregano, turmeric, cinnamon and garlic are gaining interest among researchers and pig and poultry producers. They also will improve the taste of the feed.
Some minerals such as zinc and copper function as an antibacterial and reduce diarrhea. Although strict regulations on the use of these are in place for various countries. The last couple of years we have seen an increasing interest in organic minerals as they are more biologically active and have a higher bio-availability. Organic mineral are generally more stable, do not react with other dietary nutrients and do not compete with other minerals for same uptake mechanism or site.
Of course good balanced feed, and in particular the protein and amino acid balance is extremely important to reduce the not digested protein and amino acids in the end gut. In feed formulation attention should be given in restricting the nutrients that might promote the growth of pathogenic bacteria and restricting the anti-nutritional ingredients such as lectin, tannins and protease inhibitors can inhibit the proliferation of pathogens, especially in the end gut.
Coarse grinding improves the structure of the feed. Bigger particles stimulate stomach and intestines which will develop better this way and keep animals healthy. However, to coarse grinding means incomplete digestion: the whole grain kernel is difficult to digest for younger animals and will be excreted almost undigested.
These are some of the possibilities and additives to replace antibiotic growth promotors. Once again, this is not an complete overview but is a list of the most used and important ones and the most suitable one or combination depends a lot the local situation.
For more of the article, please click here.
Article made possible through the contribution of Jan Cortenbach, MSc and Royal De Heus Animal Nutrition