TRANSFERABILITY OF CERTAIN HEAVY METALS FROM HENS FEED TO TABLE EGGS LAID WITHIN DIFFERENT REARING SYSTEMS
Cristina Gabriela Radu-Rusu, I.M. Pop, Aida Albu, Maria Bologa, R.M. Radu-Rusu
Conversion from conventional to alternative farming systems in aviculture, especially in the table eggs producing sector, imposed various studies to be carried out, related to the effect given by technological changes on the nutritional and sanogenic quality of these animal originated products. Within a wider study, there were monitored the alterations related to mixed feed content in certain pollutants, such as heavy metals and the proportion of their transfer in eggs. As biological materials, we used feed and samples and eggs laid by 500 Lohmann Brown hens, randomly allocated in two groups, on the housing system criteria: IC group-improved cages (250 hens), FR group-free range farm (250 hens). 100 eggs produced during the 42nd week of fowl life (laying peak) were sampled from each group. Yolks and albumens were submitted to atomic absorption spectrometry to assess heavy metals. Pb was below detection limit (0.012 ppm). For other metals, there were found slightly higher levels in the yolks produced in the free range system: Cd from 0.018 ppm (IC group) to 0.023 ppm (FR group); Cu from 2.591 ppm in improved cages vs. 2.734 ppm in free range farm (P<0.01, statistically distinct significant differences). Zn levels also exceeded in free range system, varying thus between 5.386ppm (IC) to 5.522 ppm (FR). Lower levels of heavy metals were found in albumens, compared to yolks. All levels did not exceed the toxicity limits for humans.
Key words: laying hens, improved cages, free range, eggs, heavy metals