Objective of the study

Residues in Livestock studies are conducted in order to quantify levels of residues in meat, milk, eggs and edible meat by-products, such as fat, liver, kidney of ruminants, following the use of a pesticide product.

The primary purposes of the residues in Livestock study are to provide:
• the basis for establishing maximum residue limits (MRLs), and
• for conducting dietary intake assessments for consumer safety

In livestock feeding studies, livestock are dosed daily with pesticide at levels that could occur
in their diet and higher for some weeks. Milk or eggs are collected throughout the dosing
period and in due course the dosed livestock are slaughtered for collection of meat and offal. The collected animal commodities are then analysed for pesticide residues to establish the
relationship between residues in the livestock diet and residues in the meat, milk or eggs.

Further information on residue trials for crops or plant products can be found in Chapter 3.9 of the JMPR Procedure Manual.

Worked examples on this topic are provided in Chapter 11 of the JMPR Training Manual.

Circumstances in which the study is required

Livestock feeding studies are generally required where significant residues occur in crops or commodities fed to animals and metabolism studies indicate that significant residues (> 0.01 mg/kg) may occur in edible tissues or that the potential for bioaccumulation exists.

For pesticides that are directly applied to livestock or are used in agricultural premises and label restrictions cannot preclude the possibility of residues in meat, milk or eggs, residue studies to determine residues levels in edible livestock commodities should be provided.

Test conditions

Animal feeding studies are typically conducted in ruminants (dairy cattle) and poultry (laying hen). In general, the results of cattle feeding studies may be extrapolated to other domestic animals (ruminants, horses, pigs, rabbits and others) and laying hen feeding studies to other types of poultry (turkey, goose, duck and others).

In cases where the metabolic pathways in rodents (typically rats) differ significantly from those in ruminants (typically goats), a pig metabolism study may be required.

In case of direct treatments of animals or premises, separate studies are required for each application type, e.g., ruminants (cattle), non-ruminants (swine) and poultry (chicken). Extrapolation based on direct animal treatment is generally not justified.

Test substance

Animal feeding studies are conducted with the (unlabelled) active ingredient and/or with its relevant metabolites.

Typical endpoints of the study

Residue levels of the pesticide (and relevant metabolites) in tissues and milk (and milk fat for fat soluble pesticides) or eggs, expressed as mg a.i./kg substrate.

Testing guidelines

The following testing guidelines may be used for livestock feeding studies:

• OECD Guidelines for the Testing of Chemicals. Test No. 505: Residues in livestock.
• OECD Series on Pesticides No 73. Guidance document on residues in livestock. Available at: http://www.oecd.org/env/ehs/pesticides-biocides/publicationsonpesticideresidues.htm 
• USEPA-OCSPP Harmonized Test Guidelines. Test No. OPPTS 860.1480. Residue Chemistry Test Guidelines – Meat, milk, poultry, eggs.
• European Commission. Guidelines for Residue Data – Livestock feeding studies. (Technical Guidelines - Appendix G)