Jiří Hála claims in his textbook "Radioactivity, Ionizing Radiation and Nuclear Energy"  that cattle only pass a minority of the strontium, caesium, plutonium and americium they ingest to the humans who consume milk and meat.  Using milk as an example, if the cow has a daily intake of 1000 Bq of the preceding isotopes then the milk will have the following activities.
* Sr, 2 Bq/L
* Cs, 5 Bq/L
* Pu, 0.001 Bq/L
* Am, 0.001 Bq/L