The relation betwwen heavy metals and trace element levels in blood of sheep reared on sewage-polluted plants

الملخص EN

In the past few years, increasing consideration has been given to 1 evaluate the relation between heavy metal toxicities and nutritional problems.

The aim of this study was to evaluate the heavy metal concentrations and their correlation with the other essential bio-elements in blood of sheep reared on sewage-irrigated pasture.

Blood was! sampled from two groups of ewes (n = 20 each), the first reared on Barseem (Trifolium alexandrinum) grown in a rural area east of Assiut city, where irrigation was carried out by the River Nile water (controls) and the second reared on sewage-irrigated Barseem in Arab El-Madabegh region, in the north of Assiut city (exposed).

Barseem allowed for these animals was also sampled.

Concentrations of lead (Pb), cadmium (Cd), iron (Fe), copper (Cu) and Zinc (Zn) were estimated in blood and food samples.

The results showed that polluted foods contained higher concentrations of Pb ( > 2 fold) and Cd ( > 11 fold) than the control values.

Concentrations of the biometals Fe, Cu and Zn in polluted and normal foods did not exceed the maximum tolerable level recommended for sheep nutrition.

Blood of the exposed ewes had higher concentrations of Pb ( > 4 fold, P > 0.001) and Cd ( >8 fold, P > 0.001) than the control values.

Exposed ewes had lower plasma concentrations of Fe (P = 0.Q02), Cu (p=0.016 and Zn (P = 0.009) compared with control values.

Pearson's correlation and linear, regression (R2) analysis coefficient revealed that Pb concentrations were negatively correlated with Fe concentrations (R2 = 0.46, PO.001).

On the other hand, there was negative significant correlation between Cd concentrations and the concentrations of Fe (R2 = 0.22, P = 0.014), Cu (R2 = 0.41, P-0.002) and Zn (R2 = 0.51, P = 0.0004).

In conclusion, animals reared on sewage-polluted pasture accumulate higher Pb and Cd than those reared on non-polluted areas.

Furthermore, Pb and Cd exposure have hazardous influence on the essential minerals profile in the blood.

Pb is more hazardous than Cd on fe status, but Cd is more than Pb on Cu and Zn metabolism.

This study Emphasizes a relation between the environmental exposure to heavy metals and the nutritional problems occur in the exposed animals.