Fission products and the dairy cow 1. The fate of orally administered cerium-144

Abstract

1. The excretion of 144Ce in the faeces, urine and milk has been followed in two dairy cows receiving twice daily doses of 120 μc. with the feed over a 10-day experimental period. During the terminal 3 days, recoveries from the faeces amounted to 93–119% of the daily dose. From the urine and milk, respectively, 0·23 and 0·17% and 0010 and 0·016% of the total amount fed was recovered from the two animals.2. The concentration of 144Ce in various parts of the gut was estimated after equilibrium conditions had been attained. The highest concentrations were found in the contents of the omasum and hind-gut.3. The possible use of 144Ce as a marker in digestibility and similar trials is discussed.