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HOW DFM’S WORK www.performanceprobiotics.com Last Updated Nicola Brazier | March 2010 Performance Direct Fed Microbials (DFM’S) consists of 5 bacteria, 1 yeast and 3 enzymes, all of which perform specific roles within the digestive tract of the cow. Some of these act within the rumen, others act further down the digestive tract. To fully understand the actions of the individual components of DFM, we first need to understand the groups to which they belong. We need also accept that rarely do microorganisms act alone, but they often work together, providing each other with essential nutrients or enzymes and thus provide a multi layered benefit to the rumen and intestinal environment and to the host animal. Bacteria Bacteria are one of the most important groups in microbiology due to their vast numbers, their general ecological importance and their practical importance to humans and animals. Much of our understanding within science comes from research of bacteria. All bacteria are ‘procaryotic’ in that they have a very simple cell structure, however bacteria can vary tremendously in shape and size. The main shapes are cocci (spheres), either in single, chains or clusters, or rods (often called bacillus), again single or in chains, and with varying shapes at the end of the rod. Bacteria can be divided into two groups based on their response to the ‘Gram stain procedure’, whereby cells are stained with crystal violet dye, enhanced with iodine and then washed with ethanol or acetone. Gram Positive bacteria retain the crystal violet colour, while Gram Negative bacteria become colourless. The difference between the two comes about from the structure of their cell walls, with the cell wall of gram negative bacteria being much more complex. Bacteria have a variety of structures outside their cell walls, which are important in protection, attachment or movement. Capsules (well organised and stable), slime (easily washed away) and S Layers (floor-tile like stable structure) can offer protection, while capsules may also aid in attachment. Pili and fimbriae are short, fine, hair like structures, which often help attachment. Flagella are slender, rigid structures that extend from bacteria and are the way that motile bacteria move. They do not swim aimlessly, but have chemical receptors by which they are attracted to nutrients and repelled by harmful substances and waste products. Bacteria require carbohydrates (starch, sugar, fibre) to meet energy requirements, and in turn produce volatile fatty acids, which provide a large percentage of the host animals metabolisable energy. Additionally, they require amino acids for protein, and the bacteria themselves become protein for the host animal. Minerals and vitamins are also required for microbial growth, with certain vitamins also being produced by the bacteria. Fungi / Yeast The term fungus is used by biologists to describe eukaryotic (much more complicated cell structure that prokaryotes), spore-bearing organisms with absorptive nutrition and no chlorophyll. Fungi degrade complex compounds into simple organic compounds and inorganic molecules. In this way carbon, nitrogen, phosphorus and other molecules are released and made available. Like bacteria they can vary tremendously in size and shape, from tiny, single celled, microscopic yeasts through to moulds and mushrooms. Yeast is a unicellular fungus, usually larger than bacteria, and spherical or egg shaped. WE BUILD HEALTHY COWS Page 1 HOW DFM’S WORK www.performanceprobiotics.com Enzymes Enzymes are protein molecules that catalyse specific chemical reactions. They are specific to their substrates similar to a key being specific for a lock. Within the rumen, enzymes are most often released by bacteria, protozoa and yeast as part of their mode of operation. Direct Fed Microbials The original concept of introducing micro-organisms to animals involved feeding beneficial microbes to ill animals or when they were under stress. The term ‘Probiotic’ was employed, meaning ‘product for life’, but due to the implication of providing a ‘cure’ US regulations have brought about the term DFM. The use of DFM in dairy diets is much more common in the USA than it is in Australia, however their use here continues to grow. Performance DFM consists of the following micro-organisms: BACTERIA YEAST ENZYMES Lactobacillus acidophilus Saccharomyces cerevisiae Alpha-amylase Bifidobacterium thermophilum Hemicellulase Bifidobacterium longum Beta-glucanase Streptococcus faecium Bacillus subtilis Lactobacillus acidophilus L. acidophilus are short rod shaped, anaerobic, gram positive bacteria which obtain their energy from converting glucose to lactic acid during fermentation. Within the rumen, this increases the lactate available for further conversion to propionate and acetate, thereby increasing the metabolisable energy available to the cow. In the small intestine the production of lactic acid reduces the pH to levels that may inhibit the growth of pathogenic microbes. L. acidophilus also operates through ‘competitive exclusion’, whereby the beneficial bacteria colonise the lining of the intestinal wall, decreasing the area available for attachment by pathogenic microbes. Additionally, L. acidophilus produces a bateriocin (proteins which act against other bacteria) called lactacin B, as well as organic acids, hydrogen peroxide and diacetyl, which all inhibit the growth of competing microbes. Reports indicate that the bacteria inhibited by L. acidophilus include E. coli, Staphylococcus aureus, Listeria, Salmonella typhimurium and Pseudomonas. Bifidobacterium thermophilum and Bifidobacterium longum Both of these bifidobacteria are branched rod shaped, anaerobic, gram positive bacteria, which like L. acidophilus, obtain their energy from glucose. In addition to lactic acid, bifidobacteria also produce acetic acid from glucose metabolism. The benefits of lactate and acetate production are as discussed for L. acidophilus. Bifidobacteria are able to use a much larger variety of molecules as energy sources, and are reported to be able to use so-called nondigestible plant polymers. Bifidobacteria are also beneficial through competitive exclusion, and are reported to have a strong stimulatory effect on the immune system. In fact, it is reported that bifidobacteria are present in much greater numbers in faeces of infants fed human breast milk rather than baby formula, and this may contribute towards the lower incidence of diarrhoea and allergies in breast fed babies versus formula fed babies. WE BUILD HEALTHY COWS Page 2 HOW DFM’S WORK www.performanceprobiotics.com Streptococcus faecium (re-categorised in 1984 and called Enterococcus faecium) E. faecium is a spherical, gram positive bacteria that most often occurs in pairs or chains. It is a facultative anaerobe, meaning it will use oxygen for respiration if present, but in the absence of oxygen will obtain its energy through fermentation of sugars. E. faecium is considered a nasty, super bug, with the ability to survive the harshest of environments, develop resistance to drugs and antibiotics and reproduce prolifically. It’s inclusion as a probiotic comes about through its ability to out compete pathogenic bacteria through the production of bacteriocins, superoxide, and hydrogen peroxide. Bacillus subtilis B. subtilis are rod shaped, gram positive bacteria, which occur in singles or in chains. They were considered strictly aerobic (requiring oxygen and not fermentation), however this was disproved and they are known to be facultative anaerobes (discussed above). It receives its energy via fermentation of carbohydrates, as do the other bacteria, but also through nitrate ammonification. B. subtilis contains ‘nitrate reductase’ in two forms, which are enzymes responsible for the reduction of nitrate to nitrite and ammonia. This is an essential process when feeds are high in soluble protein as pastures are, and can help in the prevention of bloat. B. subtilis also produces a number of other enzymes which may make it beneficial throughout the digestive tract, including amylase, protease and lipase to name just a few. B. subtilis is also reported to stimulate broad spectrum immunity. Saccharomyces cerevisiae S. cerevisiae is a globular shaped, yellow-green yeast, which has a very fast growth rate and can live in aerobic and anaerobic environments. Within the rumen, in the absence of oxygen, S. cerevisiae obtains its energy through the conversion of sugars to ethanol. It is an excellent source of B vitamins, minerals and protein. In addition to its wide use in food science (beer and wine fermentation, bread baking etc) S. cerevisiae prevents the accumulation of excess lactic acid within the rumen through stimulating the lactic acid utilising bacteria, probably by supplying amino acids and vitamins. It also competes with Streptococcus bovis (major lactate producer responsible for acidosis) for nutrients such as glucose, thereby reducing their numbers. In addition to the role yeast plays in reducing the risk of ruminal acidosis, S. cerevisiae scavenges oxygen in the rumen, making a more optimal rumen environment for anaerobic bacteria. The major group to benefit are the cellulolytic bacteria, or fibre fermenters. WE BUILD HEALTHY COWS Page 3 HOW DFM’S WORK www.performanceprobiotics.com Alpha-amylase Starch is made up from glucose molecules linked together by alpha-1,4 and alpha-1,6 bonds. These bonds are strong hydrogen bonds, which necessitate the cracking of grain, or, in extreme cases, heat treatment such as steam flaking, when fed to ruminants. (e.g. sorghum requires steam flaking in order to make starch available for rumen fermentation.) Alpha-amylase is the enzyme required for the hydrolysis of starch, in that it breaks the alpha bonds of starch releasing glucose (breaks down starch into sugar). It is naturally produced in saliva and by the pancreas as one of the digestive juices in non-ruminants. In ruminants it is also produced by rumen microbes. Supplemental alpha-amylase has been shown to be beneficial, increasing yields of milk, fat and protein. Hemicellulase Hemicellulase is a mixture of enzymes which can break down the indigestible components of hemicelluloses within the cell wall of plants. These enzymes are classified with the Cellulase enzymes, with cellulose being another fibre fraction of the cell wall of plants. Cellulose is long chains of glucose molecules (7,000 – 15,000 glucose molecules) while hemicellulose is made up of fewer glucose molecules, branched (500 – 3,000 glucose molecules). The actions of hemicellulase are similar to those described below for betaglucanase (one of the cellulase enzymes). The following figure shows cellulose and hemicelluloses within the structure of a plant cell. Beta-glucanase Similar to alpha bonds in starch, the glucose molecules of fibre carbohydrates are joined by beta bonds. Beta-glucanase is responsible for the hydrolysis of beta bonds within the cell wall of plants. It is naturally produced by fungi, bacteria and protozoa within the rumen, and its absence in non-ruminants is one of the reasons they cannot digest plant fibre. In addition to improving fibre digestion, betaglucanase helps bind certain toxins for removal from the gut and reduces the slime production and viscosity of rumen contents, and can thus play an important role in reducing the risk of bloat from legume and high nitrate pastures. Summary The individual mode of action of each of the bacteria, the yeast and the enzymes has been well researched over the years. Each specific product has been selected and included due to the science supporting its action, and the benefits seen. Their true power, however, comes from their interactions. Improved starch and fibre digestion are proven benefits, as well as the reduction in pathogenic bacteria. Additionally, the immune system is improved and the incidence of metabolic disorders, including acidosis and bloat, are reduced. WE BUILD HEALTHY COWS Page 4 HOW DFM’S WORK www.performanceprobiotics.com Dr. Steve Blezinger (Cattle Today website) provides the following summary of the proposed mechamisms of how DFMs work. Competition with undesirables for space and/or nutrients Production and/or stimulation of enzymes Breakdown and/or detoxification of undesirable compounds Production of nutrients such as amino acids and vitamins, which stimulate growth and reproduction of other micro-organisms Stimulation of the immune system Beta-glucanase Hemicellulase Alpha-amylase E. faecium S. cerevisiae Bifidobacteris Production of antibacterial compounds MECHANISM B. subtilis L. acidophilis Added are the individual microbes presented in Performance DFM: DISCLAIMER Whilst all care has been taken in the preparation of this material, it may contain inaccuracies or typographical errors and may be changed or updated at any time without notice. Performance Probiotics makes no warranties or representations, express or implied, as to the accuracy, quality or fitness for purpose of the contents of this material. Performance Probiotics accepts no liability or responsibility for any losses or damage incurred by any party, including indirect or consequential losses or damage, as a result of the use of this information. Queensland & North Coast NSW Northern Victoria & Gippsland Head Office Kellie Cooke Libby Heard Brisbane 0448 845 343 [email protected] 0438 721 242 [email protected] 1800 118 872 [email protected] New South Wales & Tasmania Western Victoria & South Australia Jason Chesworth Tom Newton 0427 760 136 [email protected] 0439 773 145 [email protected] WE BUILD HEALTHY COWS Page 5