What is your concern? Effects on the animals or residues in animal products or effects on people preparing and handling the feed?

For residues see attached file

Dear Professor,

First of all, I would like to thank you so much for your support.

In my country, the farmer produce sweet potato roots for diferent purposes and by-products from this such as sweet potato vines and roots (small size). I usually use them by making silage with sugarcane molasses or rice bran. However, toxic substances present in this by-products (A observation found carbendazim and ethoprophos over the limitation) need to be treated in order to use for ruminants. A question is how to eliminate or remove toxic substances to safe feed for animals.

Best regards,

Dear Tham

I am not sure on what basis the legal limits for these pesticides in these products are set in your country. This might make a difference.

If they are set on the basis of Good Agricultural Practice for these crops, than apparently there is inappropriate or illegal use of these compounds. This should then be addressed first in my opinion.

If they are set on the another basis (eg a general limit for all crops irrespective of application forms) than you might still not be in compliance, but there might be less worry for toxic effects on the animals.

You have to check the toxicological literature for (no) toxic effect levels of the compounds for your type of ruminants. Unfortunately there will probably be very little information on this subject. You might find some effects levels for acute toxicity but almost certainly not for long term exposure.

During the making of silage there is extensive microbial activity. This might also reduce the levels of these pesticides. Check the levels at start and at the moment of feeding the silage. There might be quite a difference and if not, try different additives in making silage; they also may have an effect.

Furthermore, ruminants are often quite effective in detoxifying noxious compounds due to their extensive microbial flora. 

All in all: yes you might have a problem but I see a number of items to study, before rejecting the feedstuffs for animal nutrition.

Good Luck

Kees Kan