Variation in trace element content between liver lobes in cattle. How important is the sampling site?

The aim of the present study was to establish the pattern of lobular distribution of trace elements in the liver of cattle. The objective was to determine which part of the liver would provide accurate estimation of the trace element content of the whole organ. Liver samples were obtained from 10 Holstein-Friesian (HF), 10 Galician Blond (GB) and 10 GBxHF crosses (all aged 10 months) at slaughter. Samples were taken from 6 regions of the liver: the internal and external faces of the right lobe (IR and ER respetively); the left lobe (L), caudate lobe (CAU), quadrate lobe (QUA) and the processus papillaris (PP). The samples were acid digested and trace elements were determined by inductively coupled plasma mass spectrometry. The distribution of all trace elements, except cobalt and zinc, varied significant across the liver. In all cases, the concentrations were highest in L and lowest in CAU. Variations in the distribution between the other areas of the liver (ER, IR, QUA, PP) were not significant. The distribution of trace elements may be related to oxygen perfusion. Moreover, the trace element content of CAU was weakly correlated with those of the other lobes, and the capacity of L to accumulate high levels of trace elements would only be observed at high levels of exposure. Taking into account the main findings of the study, a single sample of liver taken from the same anatomical region (excluding CAU and L) would be adequate for determining the trace element status of cattle.