Mycotoxins and the Threat to Immunity
Mycotoxins are potentially toxic compounds produced by fungal mold spores. The molds are produced from fungi found in the field (pre-harvest contamination) or in storage (storage contamination) environments.
Along with weight loss, heat stress and acidosis, mycotoxins are one the most important factors affecting the immune function of a dairy cow.
Mycotoxins are immune suppressors. They work by damaging the intestinal lining and disrupting the protective barrier maintained by the animal to prevent the entry of disease-causing agents into the body. The cellular damage triggers an energy-costly inflammatory response, distracting the immune system from accurately managing insult by other pathogens. (Moreover, cell damage impairs nutrient absorption which also negatively affects animal performance.)
This Feed Season, Beware
And as you've undoubtedly heard, we are experiencing a major mycotoxin problem right now. Going off a OMAFRA report from the fall 25% of crops came in at over 5 parts per million for vomitoxin — a level well beyond what’s easily fed or managed through blending. And based off the survey of this year's corn silage crop, mycotoxins will continue to be an issue all through the winter feeding season.
Working in these conditions, we need to have some nutritional solutions at our disposal.
Feed Additives that Strengthen the Immune System
Specific ingredients have been shown to directly and/or indirectly contribute to immune enhancement and help us combat the damage brought on through high mycotoxin consumption.
These ingredients are mycotoxin adsorbents. They act like a “chemical sponge” when the surface of these materials are saturated with water by attracting polar functional groups of mycotoxins. The “bound” toxins are then eliminated in the faeces, thus preventing any deleterious effects on the animal. There are organic and inorganic adsorbent. Today we'll we'll focus on the organic adsorbents.
The primary organic adsorbents used in animal agriculture for toxin control are extracts of yeast cell wall, which contains both mannan (MOS) and ß-glucan, and has been shown to be an effective binder for a variety of mycotoxins.
Direct Immune Stimulation
Dietary ß-glucans have been shown to be directly immune-stimulatory. Specifically, ß-glucan is recognized by receptors of the immune system, in the same way a disease pathogen is recognized, stimulating an immune response, and essentially “turning on” the immune system. This stimulation is suggested to make the animal more prepared to handle infection, by reducing lag time for combating infections. However, the caveat is the energy requirement for stimulating the immune system; in the absence of disease threat, immune system activation could be costly for performance gains.
Prepared for Pathogen Invations
In contrast to ß-glucans, mannanoligosaccharides (MOS) are effective antimicrobials in both ruminants and monogastrics. Rather than a direct immune system stimulus, MOS interferes with pathogen colonization by binding receptors on the surface of intestinal pathogens, thereby blocking pathogen adhesion to the lining of the gastrointestinal tract. Although MOS products are often defi ned as “prebiotics”, this is an inaccurate description. MOS indirectly enhance microfl ora composition by binding to the pathogen, and limiting colonization. In contrast, a “true prebiotic” provides nutrients for beneficial microflora, in order to promote a robust population of bacteria that can compete with and exclude pathogenic bacteria from the gut.
Solid Dietary Solution
In the same way that we understand how nutritional modifications lead to improved production, it is essential to understand the mechanisms by which dietary ingredients affect immune status and animal health. By determining the mode of action of ingredients or products, we can begin to tailor the nutritional program to combat factors that influence the long term health of the animal. Further defining the relationship between health and nutrition will allow us to better design comprehensivenutritional programs that promote fast and accurate immune responses to disease causing agents.