Coccidiostats in eggs

Changed on: 16.06.2020

What are coccidiostats?

The collective term coccidiostats refers to various veterinary drugs that are used to prevent and to treat coccidiosis, an intestinal disease caused by certain protozoa (single-cell organisms).
Eimeriosis, the most important coccidiosis, which occurs predominantly in poultry, manifests in bloody, watery diarrhoea and loss of performance and strength and in severe cases may lead to the death of the infected animals. In poultry production farms, where many animals live in extremely close proximity, the pathogens can spread through the entire flock via faeces (faecal-oral infection) in just a few days and can pose a grave risk to the livestock. The larger the number of animals and the lower the standard of hygiene, the greater is the risk of infection and the more likely it is to assume that coccidiostats will be used.

Statutory provisions concerning use and maximum levels

Within the EU, coccidiostats are authorised as feed additives for the prevention of coccidiosis in accordance with Directive 70/524EC and Regulation (EC) 1831/2003).
For the coccidiostats authorised as feed additives in poultry, authorisation is limited to poultry kept for meat and to young hens during the rearing phase (16 weeks). To avoid residues in eggs, the use of coccidiostats is not permitted for laying hens. The reason for this is that a generally significant degree of accumulation of active substances takes place in eggs.
In Regulation (EU) 37/2010 - which regulates maximum residue limits for veterinary drugs in foodstuffs of animal origin and which since the beginning of 2010 has repealed the Annexes to Regulation (EEC) 2377/90/EC - and in relation to the group of coccidiostats, only the polyether antibiotic lasalocid has a maximum level set for eggs. It is 150 µg/kg. 

Link between feedstuff and residues in eggs

Besides the prohibited treatment of laying hens, there is a second reason for the Incidence of illegal coccidiostat residues in eggs, which is linked to the production of feed. In the production process of feeds with authorised coccidiostat additives, it is possible that “carry over” occurs, where additives carry over into the subsequent production run for laying hen feed. The maximum levels for the presence of coccidiostats and histomonostats in feeds for non-target animals due to unavoidable carry over have been regulated by Directive 2009/8/EC since February 2009. This unavoidable, production technology-related carry over in feeds can also lead to the incidence of these substances in small concentrations as contaminants in foodstuffs of animal origin. In order to protect consumers, Regulation (EC) 124/2009 set maximum levels for coccidiostat residues caused by carry over in eggs (and in other foodstuffs of animal origin).

Monitoring eggs for coccidiostat residues

The monitoring of eggs produced in Austria for coccidiostat residues is an integral part of the National Residue Control Plan (NRKP) for foodstuffs of animal origin. Samples to be submitted for testing/examination are taken either directly from the producer or at the packaging company, so that traceability back to the producer farm is guaranteed for the sake of preventative consumer protection. In order to identify the cause of positive tests in eggs, the feed administered is also tested.

The Department of Veterinary Drugs, Hormones and Contaminants at the Institute for Food Safety in Vienna is entrusted with the analyses within the scope of the NRKP. The Department is also the National Reference Laboratory for these examinations/tests.
Further testing of eggs for coccidiostats is carried out within the scope of official foodstuff-monitoring activity or in cases of suspected contamination.

Range of testing

Testing for coccidiostats in eggs covers the following substances: lasalocid, monensin, narasin, salinomycin, nicarbazin, amprolium, diclazuril, maduramicin, semduramicin, halofuginone, decoquinate, robenidine.

Testing procedure

The multi-method used to determine coccidiostat residue levels in eggs involves purification by means of solid phase extraction (SPE) followed by chromatographic separation and mass spectrometric detection of substances (LC/MS-MS).
The procedure is environmentally friendly as it avoids using chlorinated solvents for clean-up - and substance-specific detection levels of between 0.9 and 2.2 µg/kg - mean it is characterised by extremely high sensitivity, such that trace levels of residues in eggs can be detected.

Legal basis

 Council Directive 70/524/EEC of 23 November 1970 concerning additives in animal feeding-stuffs (OJ No. L 270 of 14/12/1970).

  • Regulation (EC) No 1831/2003 of the European Parliament and of the Council of 22 September 2003 on additives for use in animal nutrition (OJ No L 268 of 18/10/2003 as amended).
  • Commission Regulation (EU) No. 37/2010 of 22 December 2009 on pharmacologically active substances and their classification regarding maximum residue limits in foodstuffs of animal origin (OJ EU No. L 15 of 20/1/2010).
  • Commission Directive 2009/8/EC of 10 February 2009 amending Annex I to Directive 2002/32/EC of the European Parliament and of the Council as regards maximum levels of unavoidable carry-over of coccidiostats or histomonostats in non-target feed (OJ No L 40 of 11/02/2009).
  • Commission Regulation (EC) No 124/2009 of 10 February 2009 setting maximum levels for the presence of coccidiostats or histomonostats in food resulting from the unavoidable carry-over of these substances in non-target feed (OJ No L 40 of 11/02/2009).