The radionuclides’ presence in animal feed is due both to natural radioactivity and radioactive
pollution from different sources. Controls of radionuclides in animal feed will reduce the risk
of radioactive hazards to animal and human health. The study was carried out in order to
detect the natural radioactivity in animal feed and feed additive. Gamma spectrometer
Canberra Packard with a high-purity germanium detector and Marinelli beakers (1 l capacity)
were used for the samples measurement. The most prominent gamma energies observed in
the spectra belonged to the naturally occurring radionuclides 40K, 226Ra and 232Th. Other
radionuclides if present occurred infrequently at low activity concentration under the
measurable level. The results show that 40K had the largest contribution to the specific
radioactivity in all the samples. The mean activity concentration of the 40K was highest in
feed additive mono calcium phosphate (245.03±17.778 Bq/kg) and lowest activity
concentration of the 40K was measured in concentrate feed for dairy cows (23.20±2.626
Bq/kg). The average activity of the other two detected natural radionuclides in feed samples
was lowest and ranged from 0.42 to 5.81 Bq/kg for 226Ra and from 0.61 to 2.55 Bq/kg for
232Th. The data analysis using ANOVA showed statistical significant differences in the
radioactivity concentration of 40K, 226Ra and 232Th between feed samples (p<0.001).
Key words: gamma spectrometry, feeds, natural radioactivity
