Temporal feed restriction and overstocking increase competition for feed by dairy cattle.

Dairy cows are often overstocked. Some managers are now using "slick bunk" (i.e., feeding for 0% orts) management to save on feed costs, but this reduces the time that cows have access to feed. Both practices may increase competition and affect feeding behavior in dairy cows. The aim was to determine the effects of temporal and spatial restrictions on the feeding and competitive behavior of group-housed cows. Treatments were 2 levels of stocking (2:1 versus 1:1 cows:feed bin) and 2 levels of feed access time (14 versus 24h/d access). Eight groups (each of 6 cows) were tested on each of the 4 treatment combinations for 1 wk, with treatment order assigned using a replicated 4×4 Latin square design. Dry matter intake (DMI), feeding time, and feeding rate were measured for the last 4d of each week, and data were summarized daily and for the 2-h period immediately after the morning feeding. Displacements were recorded for 2h after the delivery of morning feed (peak feeding period) and 2h following the afternoon milking. The DMI did not decline when temporal access was restricted (27.0 vs. 25.7±0.5 kg/d), and was not affected by overstocking (26.4±1.9, mean ± SD). Cows with restricted temporal access spent less time feeding (190.9 vs. 207.9±6.1 min). Overstocked cows that were temporally restricted had greater feeding rates during the day (156 vs. 137±4 g/min) and especially during the peak feeding period (175 vs. 146±4 g/min) compared with cows that were not restricted. In the peak feeding period, overstocked cows had reduced DMI (3.0 vs. 3.4±0.1 kg/h) and feeding times (20.8 vs. 25.8±1.0 min/h) and increased feeding rates (161 vs. 138±4 g/min). Cows with restricted temporal access had greater DMI (3.9 vs. 2.6±0.2 kg/h) and time spent feeding (27.3 vs. 19.2±1.3 min/h) during the peak feeding period compared with cows that had continuous access to feed. Restricting temporal access in conjunction with overstocking resulted in the greatest increase in daily displacements (15.0 vs. 3.8±1.4 displacements/d); the majority of these occurred during the peak feeding period. Adequate space and time to access feed is essential to minimize feed bunk competition in indoor group housing systems.