Uptake of coccidiostats in vegetables

General introduction

In Europe, chicken manure can be used to improve yield in vegetable cultivation. The key question of this research is whether residues of anticoccidial drugs present in the manure can be taken up by vegetables. If this is the case, can this contribute significantly to exposing the consumer to these compounds? What happens if the vegetables are cooked or baked? Can composting the manure cause a decrease in the concentration of anticoccidial drugs?

Research approach

We set up animal trials during which chickens are fed with feed supplemented with six different anticoccidial drugs (monensin, salinomycin, lasalocid, nicarbazin/narasin and diclazuril) at their maximum allowed concentration. We determine the concentration of the coccidiostats in manure using LC-MS/MS. We use this manure for the cultivation of five types of vegetables: lettuce, carrot, potato, courgette, and tomato. We also perform a worst case scenario experiment, in which the coccidiostats are added directly to the soil. By means of LC-MS/MS, we investigate whether the coccidiostats can be identified and quantified in the vegetables. We determine the influence of boiling or baking on possible residues present in the vegetables using the same analytical technique. In addition, we measure the effect of conserving the manure at room temperature and of composting the litter on the residue concentrations present in the manure and the litter.

Relevance/Valorisation

Some remarkable results were obtained: the concentrations of the residues detected in the chicken manure vary between 5 and 38% of the concentrations of these drugs in the chicken feed. Conservation of the manure during one month at room temperature leads to a decrease of the concentrations ranging from 4 to 83%, while composting the litter results in a decrease of the concentration with 79 to 98%. For the worst case scenario experiment, mainly cultivated potatoes seem to contain lasalocid and nicarbazin. During the experiment with chicken manure in vegetables grown in closed containers, only the uptake of nicarbazin in carrots and monensin in lettuce could be observed. However, the concentrations detected were very low. Hence, when accounting for the average consumption of vegetables, no real danger for the public health can be expected. Boiling and baking of potatoes result in a decrease of the concentrations found. Peeling the potatoes also effectively reduces the concentrations. For 100% certainty that uptake by vegetables cannot occur, composting the manure can offer a solution.