Effects of temporal restriction in availability of the total mixed ration on feeding and competitive behavior in lactating dairy cows

This study evaluated the effects of temporally restricting access to total mixed ration (TMR) on feeding and competitive behavior of Holstein dairy cows. Twenty multiparous cows were assigned to either housing in a free-stall barn with continuous access to TMR (CONTROL treatment) or to overnight (10 h/day) pasture and housing in the free-stall barn with access to TMR the remainder of the day (i.e. about 14 h/day minus milking times of access to TMR; PASTURE treatment). Treatments were applied from week 4 to week 8 relative to calving. Measures of feeding behavior and dry matter intake (DMI), time spent standing and competitive interactions in the feeding area were recorded individually from week 3 to 6 after calving. PASTURE cows consumed more TMR during the day time compared to CONTROL cows, particularly in the 3 h following the morning milking and fresh feed delivery (1.7 vs. 1.1 kg DM/h; SED=0.1; P<0.001). After the morning milking and fresh feed delivery. PASTURE cows also visited the feeding bin more often (4.6 vs. 2.7 visits/h; SED=0.4; P=0.01) and spent more time feeding (16.9 vs. 11.5 min/h; SED=1.2; P=0.01) relative to CONTROL cows. The frequency of competitive interactions in the feeding area in this period was higher for PASTURE cows compared to the CONTROL cows (6.8 vs. 3.5 interactions/h; SED=0.6; P=0.004). There were no differences between treatments in total standing time (on average 892 +/- 34 min/day) or non-feeding standing time while indoors (on average 393 +/- 22 min from 0700 to 2000 h). In conclusion, compared to cows with continuous access to TMR, PASTURE cows that did not have access to TMR overnight increased TMR intake during the day time and spent more time feeding and were involved in more competitive interactions at the feeder after the morning milking and fresh feed delivery. In this way. PASTURE cows were able to compensate for the lack of overnight access to TMR, such that there were no differences in the daily TMR intake or daily feeding times between the groups. (C) 2010 Elsevier B.V. All rights reserved.