Alpaca nutrition news                                                                              August 2009

Probiotics and direct-fed microbials (DFM)

Probiotics, or direct-fed microbials (DFM), are live microbial feed supplements which beneficially affect the host animal by improving its microbial balance (Fuller, 1989). Although the first use of the term probiotic was by Parker in 1974, Metchnikoff initially proposed the concept in 1907 (Cole and Fuller, 1984). Since then, a multitude of microbial cocktails have been sold to livestock producers.

 Many of these early versions often did not improve livestock performance. This was mainly due to either ignorance of the fragile nature of bacterial viability outside of the host, or desire to make a quick buck. This earned probiotics a poor reputation that they are still struggling to overcome today. Probiotic effectiveness depends on several factors:

 1. Viability Many of the modes of action listed below depend on live microorganisms. Viability is reduced by exposure to sunlight and/or heat. Proper storage is required to insure microbial viability up to or beyond the stated expiration date. Refrigeration or storage in a cool place away from sunlight is recommended.

2. Selection of proven effective strains Bacteria can be good, bad, and indifferent. Careful research is required to identify which is which. Several species have already been demonstrated to be effective, including Lactobacillus sp., Streptococcus faecium, yeast (Saccharomyces cerevisiae), and certain species of fungus (Aspergillus sp.).

3. Concentration Most probiotics on the market contain from 107 to 108 viable microorganisms/gram. Generally speaking, the higher the concentration, the more effective the product.

Probiotic microorganisms must survive several hazards, including low pH in the stomach and digestive enzymes in the small intestine. A large number of initial microorganisms must be fed to insure enough remain viable by the time they reach their target. The effectiveness of probiotic microorganisms is often attributed to the enzymes they secrete. However, this is just one mode of action. Others include:

 1. Decreasing pH by production of volatile fatty acids (VFA)

2. Competition for nutrients

3. Production of substances toxic to pathogens

4. Production of antibiotic-like substances

5. Competition for adhesion sites

 Some of the modes of action described above involve competition. For this reason, the probiotic mechanism is often called competitive exclusion . Pathogens would be able to dominate the digestive microflora under normal, healthy conditions if they were better competitors. In many cases, opportunistic pathogens, as they are called, wait in small numbers for disaster to strike. Usually, the only time they can gain the upper hand is when the animal is stressed (Tannock, 1983).

 Probiotics are usually available in two concentrations. The lower concentration is meant to be fed to healthy animals on a daily basis (MSE Microbial Concentrate or granulated ), and is often mixed with feed. Probiotics with greater numbers of viable microorganisms are designed to be fed preventatively before major stresses or to treat animals that are already sick (MSE Micronial Paste or Drench). This latter concentration is usually available either as a paste or liquid.

 The best way to protect livestock is to use prevention. This means the daily and preventive use of probiotics and quarantining sick animals. There are other, more severe prevention methods such as foot baths, showers and clothing change, but they may be a little extreme for exotic livestock production.

 Be aware of what causes stress, this includes biological events such as birth and weaning; production activities such as shearing, transport, and showing; and weather, especially extremes and alternations in temperature. Probiotics can protect against stress if the right strains and numbers of viable microorganisms are used.

 Litertured cited

Cole, C. B. and R. Fuller.  1984.  A note on the effect of host specific feremented milk on the coliform population of the neonatal rat gut.  J. Appl. Bact.  56:495-498.

 Fuller, R.  1989:  Probiotics in man and animals. J Appl. Bacteriol. 66,             365- 378.

 Parker, R. B.  1974.  Probiotics, the other half of the antibiotics story. Anim. Nutr. Health  29:4-8.

 Tannock, G. W.  1983.  Effect of dietary and environmental stress on the gastrointestinal microbiota.   Pages 517-539 in Human intestinal microflora in health and disease.  D. J. Hertges, ed.  Academic Press, New York, NY.

MSE probiotics are available online at

Please contact ruminant nutritionist Lark Burnham if you have any questions (


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