Comparison of trace mineral concentrations between liver biopsies of different sizes and durations of storage by inductively coupled plasma mass spectrometry

Consequential adverse health effects in cattle may occur as a result of impaired physiological processes brought on by trace mineral (TM) deficiencies and toxicities. Small amounts of TM are necessary to facilitate these processes, but inadequate or excessive concentrations can result in reduced health and development. Ante mortem sampling of bovine hepatic tissue allows for the evaluation of TM status, specifically copper (Cu), manganese (Mn), selenium (Se), and zinc (Zn), permitting diagnosis of such deficiencies or toxicities. Variation in sample size as a result of differing biopsy instruments and techniques has led to conflict regarding the amount of liver considered adequate for reliable diagnostic interpretation. This study examined the difference of TM concentrations between liver samples of differing sizes and also between samples stored over differing durations of time. Variation among samples of differing storage durations post collection and prior to analytical processing was also evaluated. It was hypothesized that there would be no significant differences in TM concentrations between samples of different sizes stored for different durations. No differences regarding concentrations of copper, manganese, selenium, and zinc were observed between 0.02, 1.0 g, and homogenized samples stored for three and fourteen days. A difference in TM concentrations was observed between 0.02 g samples stored for seven days and all other samples. No difference in TM concentrations between 1.0 g and homogenized samples stored for seven days was observed. Concentrations of these samples did not differ from other samples of different sizes stored for different amounts of time Results at three and fourteen days of storage suggest that trace mineral concentrations did not significantly differ regarding sample size and that 0.02 g of fresh hepatic tissue, dried to approximately 0.005 g is reliable for diagnostic interpretation of toxicities and deficiencies in cattle pertaining to copper, manganese, selenium, and zinc. However, results of the day seven data were inconclusive as differences in TM concentrations were observed in 0.02 g samples while concentrations of different sample sizes and storage duration did not differ significantly