THE RELATION BETWEEN HEAVY METALS AND TRACE ELEMENTS LEVELS IN BLOOD OF SHEEP REARED ON SEWAGE-POLLUTED PLANTS

Document Type : Research article

Authors

1 Dept of Forensic Medicine and Toxicology, Fac. Vet. Med., Assiut Univ.

2 Shebeen El-Kome, Animal Health Research Institute

3 El-Wadi El-Gadid laboratories, Animal Health Research Institute

Abstract

In the past few years, increasing consideration has been given to 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 < br />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 sewageirrigated
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
651
(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=0.002), 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, P<0.001). 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.

Full Text

Lead, cadmium, trace elements sewage, sheep

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