Does natural weathering change the stable isotope composition (2H, 13C, 15N, 18O and 34S) of cattle hair?

Stable isotope analysis of hair has found applications in many fields of science because it provides a temporally resolved, fairly stable isotopic archive of mammalian individuals. We investigated whether this hair archive is modified by natural weathering while attached to a living animal. We analyzed the tail switch hairs of one suckler cow, sampled seven times over a period of four annual summer pasture-winter stall feeding cycles. We compared relative isotope ratios (delta H-2, delta C-13, delta N-15, delta O-18 and delta S-34) of sections of hair that grew simultaneously but were exposed to natural weathering conditions over different periods of time. Natural wear caused a loss of mass of approx. 0.13% day(-1), with no apparent effect of environmental conditions. Changes in delta H-2, delta C-13, delta N-15 and delta O-18 were below the detection limit, indicating that hair is a reliable archive for the isotopes of these elements. In contrast, delta S-34 values increased during the grazing period by about 1 parts per thousand, with exposure to UV radiation appearing to have a major influence on this result. The delta S-34 values decreased during the subsequent stall period, probably due to abrasion. Seasonal variation in delta S-34 may indicate alternating environments that differ in their weathering conditions. Copyright (C) 2011 John Wiley & Sons, Ltd.