Within- and across-person uniformity of body condition scoring in Danish Holstein cattle

Body condition scores (BCS) are very useful for dairy herd management and breeding programs, but the consistency and quality of recordings made by consultants in the field are unknown. The objectives of this study were 1) to estimate the agreement in BCS within and among practicing dairy veterinarians and 2) to provide an indication of the effects of training and the value of calibration, and of what efforts need to be made to obtain a validity and precision in BCS adequate for management purposes. A total of 2,230 scores were recorded by 51 practicing dairy veterinarians and 6 highly trained instructors. The 6 instructors were cross-trained to validate calibration consistency in assigning BCS. Each individual scored approximately 20 cows twice, with the second scoring occurring approximately 2.5 h after the first. Between the 2 recordings, the respective instructors conducted a training session for the practicing veterinarians using other cows. A weighted kappa coefficient was used to assess agreement among and within classifiers. Excellent agreement (kappa > or = 0.86) was documented between repeated BCS recorded for the same cows by the highly trained instructors. In addition, the BCS provided by multiple classifiers from the instructor team appeared to be comparable across herds and classifiers. This legitimizes the use of BCS for benchmarking at both the cow and the herd level. The within-classifier and between-classifier kappa values were in the ranges of 0.22 to 0.75 and 0.17 to 0.78, respectively, in the group of practicing dairy veterinarians. Many of the veterinarians provided estimates of average BCS that differed considerably from the BCS recorded by the instructors. Between-classifier comparisons of herd BCS are not warranted unless a validation has been performed. If scores are collected by multiple classifiers with varying experience, a valid but imprecise estimate of the true population mean of BCS may be obtained if classifiers are inexperienced. The limited training effort used in this study seemed to have brought about substantial improvement in the validity and precision of the BCS determined by practicing veterinarians, compared with the BCS recorded on the same cows by highly trained classifiers.