India receives its major supply of maize from Bihar in April- May and from Karnataka and Andhra Pradesh in last quarter of the year[1]. This maize is mostly used in feed production around the year. At the time of harvest, the crop contains high moisture content, which makes it conducive for growth of toxigenic fungus and subsequent mycotoxin production. It is generally observed that mycotoxin related problems are encountered more in 3rd and 4th quarter of the year[2]. This is also because of the high precipitation during these parts of the year, resulting in improper moisture loss from the harvested maize, which further increases the chances of mold growth. Generally, the strategy to reduce the mould growth and production of toxins in these times is to dilute the high moisture maize with older stored maize and using a more potent toxin binder. While some recommend increasing the dosage of regular toxin binder in case of high toxin challenge, increasing dosage of normal bentonite-basedtoxin binder or activated charcoal also enables more vitamin interaction in feed, which ends up doing more harm than good[3].
Now the question is as how to arrive at the correct dosage of toxin binder when the challenge is high to get the best protection while keeping the production cost economically viable. Kemin team has devised a method to find the required dosage to control very high levels of fungal contamination. The method is called in-vitrodose dependent study at high mycotoxin contamination. To correctly simulate the challenge in the newly harvested maize, a very high contamination level of mycotoxins was taken to test toxin binder at various dosages.
Understanding in-vitrodose dependent study at high mycotoxin contamination
Usually, in vitro binding efficacy of toxin binders is tested at lower dosages. In this study, very high dosage of common mycotoxins is studied for binding efficacy at different dosage of toxin binder. These studies are done at 2 different pH (3.2 and 6.8) to simulate foregut and hindgut conditions of birds. This will give the net binding subtracting desorption at high pH
- All the results were calculated as biphasic net binding% i.e.Mycotoxin % net binding= Adsorption (%) at pH 3.2- Desorption (%) at pH 6.8 (See Fig.1)
- Contamination Level- Working concentration of 5ppm
- Aflatoxin B1- 5ppm- 250 times above the EFSA recommendations
- Zearalenone- 5ppm- 12.5 times above the EFSA recommendations
- Ochratoxin A- 5ppm- 125 times above the EFSA recommendations[4]
- Kemin’s Hybrid Nanosilicates (HNS) technology was tested at 0.5kg/MT, 1kg/MT, 1.5kg/MT, 2kg/MT, 2.5kg/MT and 3kg.MT
How is this study different?
While in vitro studies cannot give the exact measure of binding ability of toxin binders inside birds’ body, it can certainly help to categorize the different toxin binders. Also, this study goes beyond the conventional net binding study at lower dosage and demonstrates the ability of more potent toxin binder technology like Hybrid Nanosilicates (HNS) to tackle very high mycotoxin contamination.
Although contamination levels of 5000ppb is rarely seen in practical world, this study gives an insight into the ability of the test toxin binder to bind the mycotoxins even at unrealistic levels. This will ensure that in the high challenge period like monsoon and with newly harvested maize, an efficient technology can ensure adequate prevention.
Results[5]
- HNS showed high level of binding with all three mycotoxins.
- While 0.5kg/MT of HNS was not enough to control high level of contamination, 1.0kg/MT and above dosage of HNS was found to be enough[5].(Fig.2).
- Also, dosage more than 1kg/MT did not prove to be showing a major increase in binding%
Conclusions
in-vitro dose dependent study at high mycotoxin contamination can be an ideal measure to test the right dosage of the toxin binder. Also, ideally a toxin binder should have efficacy to bind multiple mycotoxins and when the toxin contamination is high. HNS proves to have efficacy for the most common mycotoxins and 1kg/MT dosage can be safely used to prevent mycotoxicoses in high challenge periods
References are available on request
by Dr. Rahul Mittal & Nabila Fathima, Kemin
