Short communication: Intraoperator repeatability and interoperator reproducibility of devices measuring teat dimensions in dairy cows.

Various methods have been applied to measure teat dimensions. However, the accuracy and precision needed to obtain reliable results are often poor or have not yet been investigated. To determine the precision of the ruler, the caliper, and a recently developed 2-dimensional (2D) vision-based measuring device under field conditions, for respectively teat length, teat diameter, and both teat length and diameter, 2 experiments were conducted in which the consistency of measurements within operators (repeatability) and between operators (reproducibility) was tested. In addition, the agreement of the 2D device with the ruler and the caliper was studied. Although the ruler and the 2D device poorly agreed, both methods were precise in measuring teat length when the operators had experience in working with cows. The caliper was repeatable in measuring teat diameter, but was not reproducible. The 2D device was also repeatable in measuring teat diameter, and reproducible when the operators had experience with the device. The methods had poor agreement, most likely due to the operator-dependent pressure applied by the caliper. Because the 2D device has the advantage of measuring both teat length and teat diameters in a single measurement and is accurate and practical, this method allows efficient and fast collection of data on a large scale for various applications.