Background

Heavy metals such as arsenic (As), mercury (Hg), lead (Pb) and cadmium (Cd), are potential toxic substances that may incorporate in productive systems in multiple ways including contaminated feedstuff. In this regard, we hypothesize that the main input of heavy metal contamination include mineral feed ingredients which, in turn, are included in compound feed to meet animals’ nutritional requirements. Hence, we offer a comprehensive heavy metal determination on imported feed grade mineral supplement samples (n = 435), comprised of 27 different sources including calcium/phosphorus, iron, cobalt, copper, cobalt, manganese, iodide, sulfur, potassium, sodium, selenium and magnesium were collected from eight different local feedingstuff manufactures, mineral and heavy metal as cadmium (Cd), lead (Pb), arsenic (As) and mercury (Hg) analyses were performed using atomic absorption spectroscopy and microwave assisted digestion. Based on this premise, the main goals of the study were to determine mineral and trace mineral content and contrast these values with those advertised by the manufacturers and to determine heavy metal concentrations and compare these levels with the current regulation in commercially available mineral sources which are used in premixes and downstream formulation of compound feeds; a matter which remains undocumented.

Results

Our results show that occasionally mineral values for these supplements were lower than those declared. Additionally, several samples contravene, in at least one heavy metal, current regulations; samples in this condition correspond to 0.5 (n = 2), 13.8 (n = 60), 4.1 (n = 18) and 2.5 % (n = 11) for As, Hg, Pb and Cd, respectively with mercury as the most frequent mineral to surpass, in the majority of cases, current thresholds. Overall, 21.1 % (n = 92) of the samples exhibited concentrations of heavy metals above those stipulated by European guidelines. Meanwhile potassium chloride, (n = 17), exhibited the lower overall concentrations of heavy metals.

Conclusion

Samples of mineral origin may surpass, in some cases with elevated concentrations, permitted levels of undesirable substances, therefore, a monitoring programme for mineral ingredients in our country is recommended.

Graphical abstract

Approach for mineral and heavy metal analysis in feed grade minerals.