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When calves are reared by cows, separation can be stressful, and it is often advised to use gradual weaning to minimize this stress. In foster cow systems, one gradual weaning method is to remove the foster cows, one by one, from the cow-calf group. The response to one-by-one removal of foster cows of 32 calves housed in 5 groups was studied. Calves were fostered to a designated foster cow individually, in pairs, or in trios, at the age of 1 to 2 wk and then housed in groups of 4 to 6 foster cows and 6 to 11 calves until gradual weaning started at 3 mo of age. Calf behavior and aggression received by calves from cows were recorded using video during 18 h before any foster cow was removed, as well as 18 h before and 18 h after the designated foster cow was removed from the group. Before any foster cow was removed, the calves spent a similar amount of time sucking the designated foster cow and other cows (in total 43 ± 5 min/18 h). The total duration of sucking was similar before and after the designated foster was removed, as the duration of sucking other cows increased. The number of aggressive events received from other cows also increased. The results indicate that milk availability for the group of calves decreases as foster cows are gradually removed and that the older and heavier calves increasingly compete with the younger and lighter calves for the available milk. This weaning method may also compromise the welfare of the foster cows that are left to wean off an increasing number of calves, and this warrants further research.

ABSTRACT: Under natural conditions, most parturient cows seek visual cover or seclude themselves from the herd when calving becomes imminent. Studies on calving site selection of dairy cows housed indoors show that predominantly older and dominant cows calve in secluded areas. This study aimed to investigate whether cows distance themselves further from herd members under spacious outdoor conditions and whether artificial hides on a pasture motivate cows to seek visual isolation from the herd. One hundred eighty-two Danish Holstein cows were allocated to 1 of 13 groups of 14 cows according to expected calving date. In 2 paddocks (each 75 × 150 m), 5 zones (75 m × 30 m) were defined; zone 0 contained the feeding and shade area, and zone 4 bordered an area with trees. Weekly and according to calving date, a group of 14 cows was moved either to a paddock that had 12 hides distributed evenly throughout zones 1 to 4 (7 groups) or to a paddock without hides (6 groups). The hides were wooden structures (3.3 m long × 1.0 m wide × 1.2 m high) that the cows could hide behind. One hundred seven cows calved within 14 d of having been moved to the paddock, and 82 of these (38 primiparous and 44 multiparous), and their calves, were included in the study. From 3 h before until 3 h after calving, the location, posture, and behavior of cows were recorded continuously from video recordings. In addition, location, posture, and behavior of the calves were recorded for the first 3 h after birth. Continuous variables were analyzed by linear mixed effects models, whereas binary data were analyzed using mixed effects logistic regression. The presence of hides did not affect selection of calving location in the paddock, but more primiparous than multiparous cows calved in zone 4; that is, furthest away from the feeding area. Before calving, primiparous cows were more likely to be positioned in zone 4 and less likely to approach and contact herd members. After calving, primiparous cows and their calves tended to be more likely to be positioned in zone 4. The more cows present in the paddock, the less likely the cows were to isolate (i.e., be further than 30 m away from any other cow) at the time of calving. In addition, the more cows in the paddock when a calf was born, the less time these calves spent in a lying posture. The results show that primiparous cows move further away from herd members at calving than multiparous cows and suggest that primiparous cows prefer to isolate themselves through distance rather than seeking artificial cover. Contrary to expectation, the hides did not make more cows select a calving site away from the feeding area.