APPENDIX I MODEL FOR SIMULATION OF PLUTONIUM INGESTION BY GRAZING CATTLE Purpose of Program The purpose of this pocket calculator (Texas Instrument Model 59) program is to simulate the ingestion of plutonium by cattle grazing randomly in a fenced area where the vegetation and soils contain known concentrations of plutonium. The simulation model equation is Tou where = Te + Toc, “(1 (1) Lou. is the plutonium ingestion rate, pCi/day, 1, is the vegetation ingestion rate, g/day, Ty is the soil ingestion rate, g/day, Cy is the plutonium concentration in vegetation, pCi/g, Ce is the plutonium concentration in soil, pCi/g. and Input Data The required input data are the means and standard deviations (xg + sg) of In(I, y, In(C_), In(I_), and 1n(C_). To generate synthetic samples of I Equation Y is soled repeatedly by substituting random values, based’on the input data, for the factors on the right side of Input data for Cc, Is: and C_ may be estimated directly the equation. on the basis of samples collected from the specific reference site. For this model, the estimated mean and standard deviation of In(I, ) are obtained from synthetic samples based on In(I1,) = In(163.5 W°-73/4.5 D) where and (2) 163.5 W273 is the digestible energy (kcal/day) required for maintenance (no weight gain or loss) of adult cattle, W is the total live body weight (kg) of the animal, 4.5 kcal/g is the average calorie content of vegetation, D is the digestibility (dimensionless) of the vegetation ingested, To generate synthetic samples of I_, the site-specific estimates of the arithmetic means and standard devidtions of W and D are required. The values for W can be obtained from direct measurements of a reference herd. The values for D might be obtained from studies of the nutritional values of composite vegetation samples from the reference site. Vegetation and soil, of course, may be sampled directly at the reference site. The most difficult parameter to estimate may be I_, the soil ingestion rate. It seems probable, however, that some sort of estimate could be obtained by sampling the soil content of fecal materials. 507