Short communication: Feed bunk utilization in dairy cows housed in pens with either two or three rows of free stalls.

The goal of this observational study was to determine whether there were significant differences in feed bunk utilization patterns of dairy cows in free-stall pens with either 2 or 3 rows of stalls. Previously recorded 24-h videos of the high-yielding, mature cow group in 5 herds with 2-row pen designs and 5 herds with 3-row pen designs that were provided fresh TMR once a day after the morning milking were scan-sampled at 10-min intervals to record feed bunk utilization score (proportion of feed bunk spaces in the pen that were filled). Data were aligned according to peak feed bunk utilization score following fresh feed delivery (primary peaks), return from the afternoon milking (secondary peaks), and return from the night milking (tertiary peaks). Bunk utilization score was highest for primary peaks; scores were not significantly different between 2- and 3-row pens (0.65 vs. 0.71 +/- 0.1, respectively), and rates of decline in bunk utilization score were similar over the ensuing 90-min period between pen designs. Differences in bunk utilization between peak type and pen row type were observed; tertiary bunk utilization with 2-row pens was significantly lower than bunk utilization with 3-row pens and significantly lower than either primary or secondary bunk utilization in 2-row pens. The feed space allowance provided by a 2-row pen design potentially allows cows to demonstrate other important feeding behaviors, such as avoidance of conflicts and maintenance of greater inter-cow distances between neighbors while feeding.