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• In tie-stalls, cows laid down regardless of stall surface.
• Significant differences in hock appearance and size for 46 cows were not related to stall surfaces.

Dairy cows in the north Lincoln Avenue dairy barn at the University of Illinois were monitored for any influence of bedding type on the cow's comfort. Specifically, the objective of the project was to evaluate potential differences in how the cows used the stalls or any changes in size or appearance of the cow's hocks. Data on stall usage and hock measurements were collected on 46 cows approximately every two weeks between July 2, 1997 and December 14, 1997. Hourly stall usage was monitored between 7:00pm and 3:00am. At each hour throughout the night, cows were observed to be either lying or standing in their stall. Each evening, approximately every two weeks, hock appearance and circumference were measured. Half of the stalls had kildried sawdust on mattresses over rubber mats embedded in a concrete base and the other half of the stalls had only kildried sawdust over rubber mats embedded in a concrete base. The majority of cows were lying down between 10:00pm and 2:00am in constrast to the majority of cows being up at 3:00am in anticipation of soon being milked. Winter nights had cows lying down sooner in the evening than on summer nights with extended daylight. Differences due to time of night or season were similar on both stall surfaces. In the tie-stall barn where cows had either a mattress or no mattress, no difference in time spent lying down was detected. Interpretation of this result is that cows will lie on either surface when they are ready without regard to the surface. This result in the tie-stall barn differs from what we had observed in the free stall barn where cows laid down more in mattress than sand stalls. In the tie-stall barn, the cow did not have the opportunity to choose a different stall, only the opportunity to stand or lie in the assigned stall. A greater percentage of right hocks were slightly worn in July and left hocks were more worn in October. The appearance of the hocks were not different by stall surface. Right and left hock circumferences were approximately 1 cm larger, although not significant, on mattresses than those not on mattresses. The mean hock circumference of 42 cm helps to put the small, 1 cm, change in perspective as being less than 3% of the mean. Anticipated differences in size and appearance of the hocks were not supported from this study.