Intake and digestibility of range plants grown on plutonium contaminated soils as determined with grazing cattle

Area 13 is one of several areas of the Nevada Test Site contaminated with transuranics. Cattle were grazed on the area to study the botanical and chemical composition of the forage, the digestibility of range plants as selected by range cattle, and the intake of plutonium and americium by grazing cattle. The botanical and chemical composition of the diet of cattle grazing on plutonium-contaminated range was determined. The major portion of the diet was browse plants which were high in fiber and ash but low in energy. Daily feed intake of the grazing animals was also determined so that the amount of nuclides ingested daily could be ascertained. Cattle generally consumed over 2 kilograms per 100 kilograms body weight of dry matter daily which resulted in a daily intake of 3600 to 6600 picocuries of plutonium-238, 85,000 to 400,000 picocuries of plutonium-239, and 11,000 to 31,000 picocuries of americium-241. The soil ingested by range cattle constituted the principal source of ingested plutonium and americium. This is not unexpected as plutonium oxide is one of the least soluble substances known and the range studied is one of very limited rainfall. As expected, the forage from an inner compound was contaminated to a greater extent than the range plants from an outer compound