A Baseline Study of the Occurrence of Rare Earth Elements in Animal Feed

Abstract

The concentrations of rare earth elements (REEs) were determined by ICP-MS in feed for farm animals in three regions of Northwestern Italy. This is the first study aimed at defining the levels and patterns of REEs in feed for different animal species. REEs are in fact emerging as contaminants worldwide, following their applications in industry, technology, medicine, and agriculture. Moreover, in 2016, the first REE-based feed additive—a zootechnical additive for weaned piglets—was authorized in the EU. Therefore, information about the natural content of REEs in animal feed of vegetal origin is required to evaluate the potential use of REEs as a growth promoter. There was a high variability in the REEs content of the animal feed in three different Italian regions, and REEs content varied according to the different animal species for which the feed was intended. Concentrations of light REE (LREE) were higher than those of heavy REE (HREE) in each feed typology. Raw materials were shown to have higher ΣREE concentrations (mean concentration 2.4 mg kg−1) than complete or complementary feed. Considering the animal species, mean ΣREE concentrations were as follows: horse feed (2.7 mg kg−1) > poultry feed > bovine feed > swine feed (0.61 mg kg−1). REE levels in feed were in line with values available in the literature on vegetables; thus, REE concentrations in feed do not constitute a concern for animal health.