Influence of daily feeding ration of cattle on the transfer of 137Cs and 90Sr to animal organisms and manure in the agroecosystems of Central Forest-Steppe

The ration of feeding for large cattle was investigated and analyzed in terms of the transfer of 137Cs and 90Sr to muscle tissue, bones, milk, and manure biomass. The specific activity of radionuclides 137Cs and 90Sr was determined in the daily feeding ration of animals. It was found that the soil contamination density of 137Cs at the «Nadiya» farm ranged from 104.2 to 396.5 Bq/m2, while for 90Sr, it ranged from 9.4 to 36.2 Bq/m2. The fields at the «Ivanivske» farm had soil contamination densities of 137Cs ranging from 37.5 to 283.6 Bq/m2 and 90Sr ranging from 7.4 to 32.1 Bq/m2. The soil contamination density of 137Cs at the NNDC BNAU ranged from 4.18 to 8.66 Bq/m2, while for 90Sr, it ranged from 0.44 to 0.88 Bq/m2. The results of the ration assessment indicate that the average daily intake of 137Cs from feed into the animal’s body at the «Nadiya» farm was 375.3±84.2 Bq/kg, and for 90Sr, it was 345.1±98.2 Bq/kg. Significantly lower amounts of radionuclides from the ration entered the animals’ bodies at the «Ivanivske» farm, with an average daily intake of 137Cs at 174.9 Bq/kg and 90Sr at 236.0 Bq/kg. The lowest transfer coefficients of 137Cs and 90Sr from the daily ration to the body were observed at the NNDC BNAU, with 8.56 Bq for 137Cs and 9.69 Bq for 90Sr. It was determined that, overall, the muscle tissue of animals received 6.37% of 137Cs and 0.06% of 90Sr from the ration at the «Nadiya» farm; 2.0% of 137Cs and 0.02% of 90Sr at the «Ivanivske» farm, and 2.22% of 137Cs at the NNDC BNAU. In the case of bones, it was 6.47% of 90Sr at the «Nadiya» farm; 5.47% of 90Sr at the «Ivanivske» farm, and 0.41% of 90Sr at the NNDC BNAU. The obtained results confirmed that 137Cs is capable of evenly accumulating in all organs of the animal, while 90Sr selectively or predominantly accumulates in specific organs. It was established that under conditions of prolonged intake of radionuclides through the ration into the body of large cattle, 85–90% is excreted with the manure biomass.