Effects of Feeding${}^{90}{\rm Y}\text{-Labeled}$ Fallout Simulant to Sheep

A fallout simulant (88 to 176 μ) with a specific activity of 5 to 12 mCi/g was mixed with moistened alfalfa pellets and fed to sheep for 3 consecutive days. Each of 35 wethers was fed a total of 1.9 to 7.5 mCi/kg over the 3-day period. Most of the sheep developed signs of digestive disturbances including anorexia, diarrhea, and pyrexia. Sixteen treated and six control sheep were sacrificed at different intervals after feeding. Major lesions were found in the abomasum and ventral and lateral areas of the rumen of treated animals. The mucosal surface of the rumen had small blister-like lesions in the early stages. Later, 3 or 4 areas of polyp-like or cauliflower-like masses measuring up to 12 cm were observed. The abomasum was usually edematous and inflamed with large focal areas of hemorrhagic necrosis of the mucosal surface. In severe cases, the serosal surface of both organs was adhered to adjacent tissues. Contrary to earlier predictions, no major damage was observed in the large intestine. In vitro uptake of⁶⁵ Zn by erythrocytes of the treated sheep was 8% compared with 3% for the control animals.