This is because residues accumulate quickly in animals. Even at 0.05ppm it would only take a growing 400kg steer about ten days to obtain a residue level of 0.1mg, or 50 per cent of the MRL for meat, if fed solely on contaminated feed. In drought conditions this would be less as the animals would not be getting enough feed for growth. In times of drought producers often look to unconventional feeds to maintain the dietary requirements of their animals. However, it is important to let the seller of the feed understand the purpose of the transaction and obtain a declaration that the feed is not affected by chemicals including OCs.
Contamination can occur at any stage between production, harvest storage, processing and transport.
This includes storage as OCs vaporise and can be absorbed into feed from silos and sheds previously treated. Potential soil contamination should be checked. In addition, MRLs may not be set for some of these crops so the potential for OC residues may not have been considered. Vegetables Vegetables are often used in addition to pasture based feed for cattle. It is likely during times of drought that more producers will look to vegetables as a feed source.