(Food and Drug Administration (FDA) Amendment to Animal Drug Regulations, effective Sept. 13, 2011; final rule based on veterinary medicine and science, FDA updates existing regulations governing allowable tolerances for progesterone residues above concentrations naturally occurring in untreated animals to specify the following acceptable levels in cattle and sheep: muscle - 5 parts per billion (ppb) [increase from 3ppb]; liver - 15 ppb [up from 6ppb in cattle and no increase in sheep; kidney - 30 ppb [up from 9 in cattle and 15 in sheep; fat - 30 ppb [up from 12 in cattle and 15 in sheep; updated regulation based on 1994 revised daily consumption values and is taken to improve the accuracy of the regulation; regulation to be codified at 21 C.F.R. Pt. 556).