Impact of grazing around industrial areas on milk heavy metals contamination and reproductive ovarian hormones of she-camel with assessment of some technological processes on reduction of toxic residue concentrations

Abstract

Abstract Heavy metals are one of the most toxic chemical pollutants of the environment. Their hazards not restricted to human but extend to animal productivity and reproductively. The present study aimed to assess the impact of grazing around industrial areas on the levels of copper (Cu) and aluminum (Al) residues in milk samples collected from dromedary she-camels and studying their effects on some ovarian hormones. In addition, the study aimed to investigate methods of removal of the toxic concentrations of these heavy metals in milk by applying different technological processes. Blood and milk samples were collected from 30 dromedary she-camels, 15 grazing in non-industrial areas (group A) and 15 grazing in industrial areas (group B). Detection of the levels of these heavy metals in milk was done. Ovarian hormones investigation on the blood was performed. Different technological processes such as boiling, skimming and fermentation were applied to all contaminated samples to reduce the toxic concentrations of these heavy metals. Results revealed that all examined milk samples in both groups contained Cu, while 40% of group A and 100 % of group B contained Al residues with different concentrations. The levels of Cu and Al residues in samples of group A not exceeded the maximum residual limit (MRL) set by World Health Organization (WHO) while 60% and 100% of milk samples in group B contained Cu and Al residues exceeded MRL, respectively. Technological processes induce variant changes in the levels of these metals in milk. Heat treatment of milk in Al vats leads to leaching of Al from containers to the milk causing significant increase in Al load, while Cu level was not significantly affected. Boiling in stainless-steel containers decreased the levels of Al and Cu but in non-significant levels. Regarding skimming process, small amount of Cu and Al escaped into the skimmed milk while greater amount were recovered in the cream. Fermentation by probiotic bacteria showed that milk fermentation has non-significant effect on Cu and Al levels. Investigation of ovarian hormones (estrogen and progesterone) revealed presence of a signification reduction in the levels of these hormones in group B compared to group A. In addition, a negative correlation was found between these heavy metals and ovarian hormones concentrations in the blood. It is concluded that grazing of dromedary camels around industrial areas induce heavy metals toxicity represented by excretion of these metals in milk and significant reduction on ovarian function showed by reduction of estrogen and progesterone levels. Technological processes such as skimming decreased the levels of Al and Cu residues in milk.

Keywords

• Heavy metals
• Milk
• Ovarian hormones
• She-camel
• Technological processes