IMPROVED MILBOND-TX® “REDUCTION OF AFLATOXIN TRANSFER FROM FEED TO MILK”
If cows consume feed contaminated with the mold toxins of Aspergillus flavus and Aspergillus parasiticus, there are four sub-types of aflatoxin that may be consumed and these are Aflatoxin B1, B2, G1 and G2. Of these, Aflatoxin B1 (AFB1) is the most toxic and the sub-type that is most commonly detected in the feed. Once AFB1 is consumed, absorbed from the digestive tract and enters the body it is then converted in the animal’s liver into a metabolite known as AFM1. In the case of a lactating cow, once produced, AFM1 will then be secreted into the milk. Since aflatoxins, especially AFB1, are some of the most carcinogenic substances that may possibly be consumed by animals, governments have set limits on the concentrations of aflatoxin in animal feed and milk. In the United States, for example, the Food and Drug Administration (FDA) has set aflatoxin limits in feeds consumed by dairy cows at 20 ppb. However, in milk intended for human consumption, the limit set by the FDA for AFM1 is 0.5 ppb.
No mycotoxin binder should ever be recommended or purchased unless it has been tested for its effectiveness in-vivo. The reason for this is because an additive that has claims of being able to bind a specific mycotoxin may indeed be very effective and bind up to 100% of a specific mycotoxin in-vitro, but once added to the diet and consumed by an animal the same mycotoxin binder may have very little or no ability to bind the same mycotoxin. An excellent example of why an additive should be tested in-vivo is presented in Table 1. These data were taken from a research study conducted by Dr. Lon Whitlow at North Carolina State University and eventually published by Stroud et al., 2006. The research was conducted to determine the efficacy of 8 feed additives to reduce the transfer of aflatoxin from feed to milk.
EXPERIMENTAL TREATMENTS AND STUDY DESIGN
In this study, sixty lactating Holstein cows were randomly assigned to 9 dietary treatments. Eight adsorbents were each added at 0.5% of the dry matter to a total mixed ration and fed to dairy cows. From ration intake data, each cow consumed approximately 100 grams of adsorbent daily. The naturally contaminated corn used in the ration contained 800 ppb aflatoxin. Treatment replicates consisted of six cows fed each dietary treatment with a control group if 12 cows fed a diet containing no adsorbent. Following consumption of the experimental diets the milk was collected from each cow and tested for AFM1. Further details and a complete description of the experimental methods used in this study can easily be found in the cited publication of Stroud et al. (2006).
It is clear from looking at the in-vitro AFB1 binding data in Table 1 that seven of the adsorbents were able to bind more than 96% AFB1 and one, MTB-100, was only able to bind 43.43%. IMPROVED MILBOND-TX (IMTX) was shown to have an ability to bind 98.21% of the AFB1 used in the in-vitro test. This was not surprising, since similar results for IMTX have been reported in previous in-vitro AFB1 binding tests conducted in numerous laboratories.
When looking at the in-vivo effectiveness of these 8 adsorbents to significantly reduce the total concentration of AFM1 in milk, only four adsorbent products were successful and these were IMTX, NOVASILPLUS, TOXYNIL+ and ASTRA BEN 20 A.
Even though ULTRASORB, MEXSIL and CONDITION ADE were successful in binding above 97% AFB1 in-vitro, these three adsorbents had minimal ability to decrease the total amount of AFM1 in milk. Also, MTB-100 was the only additive, among the eight tested, that was shown to have poor AFB1 binding properties both in-vitro and in-vivo. This additive was not a clay-based additive, but rather a product derived from yeast cell walls that contained non-digestible yeast oligosaccharides (i.e., glucomannans). On the other hand, it can also be seen in Table 2, when expressing their success in a different manner, the same 4 adsorbents that had the capability of significantly decreasing (P < 0.05) the total milk AFM1 concentration had the highest percent reduction in milk aflatoxin secretion as well as the highest percent reduction in AFM1 transfer from feed to milk.
The addition of mycotoxin binders to animal diets is now recognized as being one of the most effective approaches in preventing the absorption of mycotoxins across the animal’s digestive tract. Once a mycotoxin is bound to an additive in the digestive tract it is only a short time before it is eliminated. The data collected in this study re-emphasize the importance of having a proposed dietary feed additive that is going to be used as a mycotoxin binder tested in-vivo using the animal species to which it will be fed. In-vitro testing should only be used to screen-out those products that have poor mycotoxin binding potential and identify those that have promise. Also, research with mycotoxin binders during the past 30 years has never been able to demonstrate that in-vitro results correlate well with in-vivo results. In other words, there is no in-vitro test presently available that is 100% reliable in predicting how effectively an additive will bind one or more mycotoxins in an animal’s digestive tract. Therefore, continuous scrutiny of new products will assure that only the best additives will be available to the animal industry in order to minimize occurrences of mycotoxicosis in animals and prevent accumulation of mycotoxins in the products from these animals.
Note: This issue of Milwhite’s Journal was compiled by Dr. Orlando Osuna and Dr. Richard Miles, Professor Emeritus, University of Florida, Gainesville, FL, USA.
Stroud, J.S. 2006. The Effect of Feed Additives on Aflatoxin in Milk of Dairy Cows Fed Aflatoxin-Contaminated Diets. M.S. Thesis. North Carolina State University, Raleigh, NC. USA
For additional information contact Dr. Orlando Osuna at 956-547-1970 or firstname.lastname@example.org.