This approach has been adopted for monitoring rabbit ages in Victoria. However, the method can be inaccurate because lens weights are sensitive to hydration changes that can occur during storage. Our previous research has indicated that total protein content could provide a more accurate measure of age. This would be unaffected by changes in tissue hydration or by the cell compression that occurs during lens growth. To explore this possibility, we are comparing the changes in parameters such as body weight, leg length, head size and molar wear, that have been used for determining kangaroo age with the variations in lens weight and protein content.
Total protein is the better of the two.
The approach is currently being explored with older animals and other species.