Harrison Sabine M, Monahan Frank J, Zazzo Antoine, Bahar Bojlul, Moloney Aidan P, Scrimgeour Charlie M, Schmidt Olaf
UCD School of Agriculture, Food Science and Veterinary Medicine, Agriculture and Food Science Centre, University College Dublin, Belfield, Dublin 4, Ireland.
Rapid Commun Mass Spectrom. 2007;21(24):3971-6. doi: 10.1002/rcm.3309.
To investigate the usefulness of bovine hooves as incremental tissues, the objective of this research was to gain a better understanding of hoof growth in three dimensions. In a controlled experiment, cattle were switched from a barley-based diet to a maize-based diet (C isotopic spacing between diets was 13.6 per thousand) and maintained on this experimental diet for 168 days. To compare growth rates along the hoof wall, three slices were sampled post-mortem from one bovine claw. In addition, one claw from each of three different animals was sampled at different depths from the surface to determine any possible time lag ('offset') in the laying down of keratin tissue layers. From each hoof as many as 41 superficial samples were taken over the first 60 mm, starting at the periople, and up to 12 samples were taken sequentially at increasing depths to a depth of 6 mm at five particular points on the surface. The growth rate of the abaxial wall of the bovine claw increased from the anterior to the posterior region of the bovine hoof. Analysis of the deep samples revealed that the deeper layers were younger than the surface layers. This offset was inversely related to the hoof growth rate, i.e. hooves with a high hoof growth rate showed a smaller offset. Observed offsets ranged between 9.2 +/- 1.8 days per mm in depth for a high and 14.0 +/- 2.8 days per mm in depth for a low hoof growth rate and were significantly different (t > or = 3.92, p < 0.0005, n = 19 or 27). The results of this study demonstrate that when sampling hooves or hoof fragments for applications such as diet reconstruction, careful consideration needs to be given to sample location.
为了研究牛蹄作为增量组织的实用性，本研究的目的是更好地了解蹄在三维空间中的生长情况。在一项对照实验中，将牛从以大麦为基础的日粮改为以玉米为基础的日粮（日粮之间的碳同位素间距为千分之13.6），并在这种实验日粮上维持168天。为了比较沿蹄壁的生长速率，在一头牛的一个蹄爪死后采集了三个切片。此外，从三只不同动物的每个蹄爪在距表面不同深度处取样，以确定角蛋白组织层沉积中任何可能的时间滞后（“偏移”）。从每个蹄上，在距蹄冠开始的前60毫米内最多采集41个表面样本，并在表面的五个特定点上依次采集多达12个深度增加的样本，深度达6毫米。牛蹄爪背侧壁的生长速率从牛蹄的前部向后部区域增加。对深部样本的分析表明，较深层比较表层年轻。这种偏移与蹄生长速率呈负相关，即蹄生长速率高的蹄显示出较小的偏移。观察到的偏移范围在高蹄生长速率下为每毫米深度9.2±1.8天，低蹄生长速率下为每毫米深度14.0±2.8天，且差异显著（t≥3.92，p<0.0005，n=19或27）。本研究结果表明，在为饮食重建等应用采集蹄或蹄碎片样本时，需要仔细考虑样本位置。
