Short term repeatability of body fat thickness measurement and body condition scoring in sheep as assessed by a relatively small number of assessors

• Repeatability and reproducibility of rump fat thickness measurement in sheep.
• Techniques: ultrasound and body condition scoring.
• 6 investigators determined rump fat at different sites, before and after shearing.
• Assessment of RFT or BCS should be performed in the lumbar region.
• Reproducibility was better in shorn sheep than in unshorn sheep.

This study evaluated the intra-observer repeatability of the rump fat thickness (RFT) measurements by ultrasound and body condition scoring (BCS) in sheep, and the reproducibility of RFT and BCS determined i) by six investigators, ii) at different sites (left and right, lumbar and sternal) and iii) in unshorn and shorn sheep. Six investigators with different experience in estimating body condition score in sheep determined BCS and RFT repeatedly at the different sites in 65 ewes before and after shearing. Intra-observer repeatability was greater for repeated measurement of RFT left (r = 0.83 and r = 0.84, in unshorn and shorn sheep) than RFT right (r = 0.64 and r = 0.77, resp.). A lower repeatability for measuring the sternal fat thickness (SFT) in unshorn sheep (r = 0.31) indicates that this method is not feasible to score ewes. The correlation between fat thicknesses determined at different sites (RFT left, RFT right, SFT) and in unshorn and shorn sheep revealed a generally higher reproducibility of RFT measurements left and right (r = 0.63–0.76) compared with the reproducibility of RFT and SFT (r = 0.37–0.79). Repeatability and reproducibility varied between investigators and in unshorn and shorn sheep. The repeatability for measuring BCS lumbar in unshorn and shorn sheep was greater (κ = 0.73 and κ = 0.67, resp.) than for determining BCS sternal (κ = 0.01 and κ = 0.44, resp.) and varied between investigators and in unshorn and shorn ewes. Reproducibility of lumbar and sternal BSC determined by the six investigators was poor to fair in unshorn and poor to moderate in shorn ewes. In summary, measuring RFT or BCS at a sternal site cannot be recommended. Furthermore, taking measurement on shorn seep improved reproducibility. Based on these results, the assessment of RFT or BCS in sheep has the greatest repeatability in the lumbar region. It has to be noted that this study analyzed the repeatability but not the accuracy of the described methods.