Measuring Sheep Tails: A Preliminary Study Using Length (Mm), Vulva Cover Assessment, and Number of Tail Joints.

Docking sheep tails is a long-standing practice that, when done at the recommended length, reduces the risk of flystrike. The recommended length is to cover the vulva of ewes and to a similar length in males. This length is often equated to three coccygeal joints left intact, and there are many other ways the recommended length is described by researchers, industry, and government. This study compared the observer consistency and retest consistency using three different tail length measurement methods: vulva cover assessment, length (mm), and joint palpation. The tails of 51 yearling and 48 weaner Merino ewes were assessed by two observers. Length and vulva cover assessment methods provided the most reliable results, and joint palpation was the least reliable method of tail measurement. In the sample, tails that covered the vulva of yearlings and weaners measured 57.6 mm (n = 14) and 63.7 mm (n = 30) on average, respectively, and contained two coccygeal joints (more than two coccygeal vertebrae). Tails that did not cover the vulva of yearlings and weaners measured 41.3 mm (n = 36) and 52.8 mm (n = 17) on average, respectively, and had less than two coccygeal joints. The two most reliable methods enable valid comparison to the best practice recommendations.