The Accuracy and Repeatability of Sow Body Condition Scoring 1
- Citation data:
The Professional Animal Scientist, ISSN: 1080-7446, Vol: 25, Issue: 4, Page: 415-425
- Publication Year:
- Repository URL:
- https://works.bepress.com/anna_butters-johnson/302; https://lib.dr.iastate.edu/ans_pubs/395
- Agricultural and Biological Sciences; body condition score; interobserver agreement; intraobserver agreement; sows
The objective of this study was to estimate observer accuracy and repeatability of body condition scoring of sows when scorers had different levels of prior experience. Participants (n = 17) for this study were identified as having no (n = 7), some (n = 4), and extensive (n = 4) prior experience evaluating conformation or body condition in livestock species or having served as instructors (TR; n = 2) during the training sessions. Twenty-five of a total 150 sows were used in the participant training session, and the remaining sows (n = 125) were used during the independent scoring process. Sows used in the scoring process were objectively categorized into BCS on a 5- and 9-point scale (BCS 5 and BCS 9, respectively) using last-rib backfat estimates. Participant BCS 5 and BCS 9 deviation evaluations from last-rib backfat estimates revealed a tendency to overestimate BCS in some sows and underestimate BCS in others. Repeatability, a measure of variance attributed to individual participants between rounds of scoring, was the largest contributor (70.6%) to the total test variability. Reproducibility, a measure of variance attributed to BCS 9 assigned by multiple participants, accounted for only 29.4% of the total test variation. Much more opportunity exists to reduce repeatability variance as compared with variance associated with participant bias. Standard errors of the difference were lower on the BCS 9 scale, and participants were within scores of 0.50 between their first- and second-round values. Participants were consistently within 0.65 scores of BCS assigned by backfat measurements. Averaged across all participants, the ultrasonic trait of last-rib backfat yielded the greatest correlation (0.58) with BCS 9, followed by 10th-rib backfat (0.51), 10th-rib loin eye area (0.47), and last-rib loin eye area (0.43). Similar trends were observed for the BCS 5 scale. Therefore, practice assigning independent BCS should lower repeatability variance, but training to calibrate specific participants may influence total test variance only to a relatively small degree.