Dear Dr. Anna Catharina Berge,
Thank you for sharing with us your very interesting article about Penicillium Moulds in Silage.
I would like to share with you some information regarding the adsorption of mycotoxins and specifically on the adsorption of aflatoxins and the use of yeast or yeast-derived glucomannan products.
On a very interesting and comprehensive s scientific report submitted to EFSA (European feed Safety Authority) an overview is given on this type of substances. http://www.efsa.europa.eu/en/scdocs/doc/22e.pdf
In page 107 of this report it can be read:
In vitro studied reported that yeast-derived glucomannan bound 96.2%, but the subsequent in vivo study reported that this product at 0.5% of a diet containing 170 µg of AFB1/kg of feed was not effective in reducing milk AFM1 concentrations (-8%), aflatoxin excretion (-7%), or aflatoxin transfer (-4%) from feed to milk. Similarly, Kutz et al., Waltman et al., Battacone et al. found that the addition of different kinds of non-digestible yeast oligosaccharides were not effective in reducing the AFM1 concentrations in milk (Battacone et al., 2009; Kutz et al., 2009; Waltman et al., 2008). In the study of Waltman et al., experimental sequestering agents (10g/cow/daily) consisting of yeast-derived glucomannan did not affect AFM1 concentrations when cows were fed diets containing 80 to 100 µg of AFB1/kg of diet. Kutz et al. found that yeast-derived glucomannan (0.56%) was not effective in reducing milk AFM1 concentrations (-4%), AFM1 excretion (-5%), or aflatoxin transfer from feed to milk (-2.52%) in cows consuming a total mixed ration containing 112 µg of AFB1/kg of diet. Battacone et al. showed that a dried yeast culture product (which is marketed as a probiotic feed supplement for high-producing dairy ruminants) fed at 12 g/day per ewe did not affect absorption of the aflatoxin in the gastro-intestinal tract of dairy ewes fed diets naturally contaminated with 1-5 µg of AFB1/kg of feed.
If a comparison is to be done with clay binders, then here is what the same report (page 100) says about the use of this type of materials for the sequestration of aflatoxins:
Over the past two decades the use of smectite clays to suppress aflatoxins has been demonstrated for many farm animals. In a series of experiments on growing swine, Lindemann et al. demonstrated that the addition of sodium bentonite (0.5%) to diets contaminated with 800 ppb AFB1 improved average daily feed intake and increased average daily gain. Bentonite supplementation significantly improved concentrations of blood urea, total protein, albumin and activities of AST, ALP and GGT, which were significantly altered by AFB1 (Lindemann et al., 1993).
Furthermore and regarding the use of these products to counteract aflatoxins in milk, Pietri et al., 2009 reported a reduction on the AfM1 content in milk of more than 40 % with an inclusion rate of 50 g per cow and day. http://scialert.net/qredirect.php?doi=ijds.2009.34.42&linkid=pdf
For the other mycotoxins and due to the non-adsorbability of other mycotoxins, such as trichothecenes, zearalenone, ochratoxins and fumonisins, adsorption is known not to be effective, and therefore other strategies must be used as biological detoxification. This is regarded as the biotransformation or degradation of the toxin by microorganisms/enzymes to produce metabolites that are either non-toxic when ingested by animals or less toxic than the parent toxin molecule.