Effects of new sampling protocols on procaine penicillin G withdrawal intervals for cattle.

JAVMA, Vol 243, No. 10, November 15, 2013 A precision and accuracy in residue chemistry are constantly improving toward the goal of a safe food supply. On July 6, 2012, the USDA FSIS announced a restructuring of the US NRP with respect to sampling of compounds in meat, poultry, and egg products and the scheduling of animal production classes. The FSIS has also implemented several new MRMs for analyzing tissue samples from harvested animals for violative residues. These MRMs allow for several compounds to be tested simultaneously. As a result, compounds that have not been previously tested in certain animal production classes are now included in standard testing procedures. These modernized and sensitive MRMs allow for the simultaneous screening of more chemical compounds than was previously possible and are predicted to provide reliable results. As a result, animal production classes that do not have specific tolerances established for residues of new animal drugs are under increased scrutiny. The absence of an established tolerance for residues of a particular compound in Title 21 of the Code of Federal Regulations part 556 (21 CFR 556) equates to a tolerance of zero (or no detection with an analytic assay) for residues for that compound in tissue or milk samples. For example, dexamethasone is approved for use in both beef and dairy cattle but does not have a residue tolerance listed in 21 CFR 556. Therefore, any detection of dexamethasone found in tissue or milk samples is a violation. As another example, enrofloxacin is approved for use in beef cattle but not approved for use in lactating dairy cattle. The detection of any level of desethylene ciprofloxacin, Effects of new sampling protocols on procaine penicillin G withdrawal intervals for cattle