Can automated measures of lying time help assess lameness and leg lesions on tie-stall dairy farms?

The time that dairy cows spend lying down is an important measure of their comfort and lameness and injuries to hocks and knees are associated with alterations in lying time. We examined whether automated measures of lying time could identify cows and farms with problems of lameness or leg lesions. Data were collected from 40 lactating Holstein dairy cows from each of 100 tie-stall farms. The occurrence of lameness, hock and knee injuries was recorded and lying times were recorded automatically using accelerometers. There was large variation between individual cows, and between farms in all measures of lying time. At the cow level, there was no relationship ( P >0.10) between being lame and daily duration of lying time. A lower daily duration of lying time was found among cows with hock injuries (mean±SE: non-injured=12.79±0.06h, injured=12.21±0.06h; P P =0.04) than those without lesions. The median daily duration of lying time on a farm was negatively correlated with the prevalence of lameness ( r p =−0.27, P =0.006), of hock injuries ( r p =−0.35, P =0.003) and of knee injuries ( r p =−0.28, P =0.004). A canonical discriminant function with canonical coefficients of 0.63 for mean daily duration of lying down, and of 0.54 for mean bout frequency could correctly identify 72% of the farms that were above the median for percent of cows with hock or knee injuries or being lame (linear discriminant function: constant=−95.10, daily duration=11.39, bout frequency=4.83) and 68% of the farms below the median (linear discriminant function: constant=−106.95, daily duration=11.92, bout frequency=5.30) (Wilks Lambda test P =0.002). A criterion of a median lying time between 12h and 13h alone could identify over 60% of farms above or below the median for lameness, hock and knee lesion prevalence. Automated measures of lying time may be a useful animal-based measure to indicate farms with a high percentage of lame cows or cows with leg lesions.