Concentrations of mercury and other elements in ewes' milk: Effect of lactation stage

Abstract

There is an increased production and demand for ewes' milk in the Republic of Croatia, as well as globally. There is also a growing concern about its quality, since milk from farm animals may become contaminated with mercury and other toxic elements. Thus, the aim of this paper is to determine the influence of lactation stage on the ewes' milk quality in western Croatia by considering concentrations of mercury and other elements in ewes' milk. The research was conducted on 36 Travnik pramenka sheep during different lactation stages. The digested milk samples were analysed with continuous flow hydride generation technique by using inductively coupled plasma mass spectrometry. Samples were taken during 40th, 80th and 120th d of lactation. Yield and quality of ewes' milk was within lactation curve. As lactation progressed, significantly lower concentrations of Hg (on 80th d compared to 40th d) and of Cd (120th d compared to 80th d) were noted, and Hg on 120th d was below the detection limit. Concentrations of Ca and Cu were lower on the 120th d compared to 40th d, while P, Mg, Fe, Zn, Mn, and Se were lower on the 80th and 120th d compared to the 40th d. Concentrations of K, Mo, and Cr differed among all stages of lactation. Regarding toxic elements, the observed low concentrations of Hg, Co, Cd and As suggest that ewes' milk in western Croatia is safe for human or animal consumption.

Keywords: Essential elements; Ewes’ milk quality; Mercury; Toxic elements; Western Croatia.