Computer-controlled milk feeding of dairy calves: the effects of number of calves per feeder and number of milk portions on use of feeder and social behavior.

One hundred ninety-two calves (Holstein-Friesian, Danish Red, and Jersey) were allocated to either groups of 24 calves or groups of 12 calves with one computer-controlled milk feeder per group. Within group, one-half of the calves were offered the daily milk allowance in either 4 or 8 milk portions. In groups with 24 calves, there was a higher level of competition for access to the feeder than in groups with 12 calves. Calves waited longer for access, and while occupying the feeder, they were more often disturbed by other calves attempting to access the feeder. The increased level of competition resulted in a higher rate of milk ingestion among calves in groups of 24 and, as a result, a lower duration of time spent ingesting the milk and a lower occupation of the feeder per calf. The number of calves per feeder did not affect the amount of milk ingested, but the high level of disturbance and the increased feeding rate with 24 calves per feeder suggest that these calves were subject to social constraint. Offering the same milk allowance in 4 rather than 8 milk portions lowered the occupancy of the feeder. The number of portions did not affect the duration of ingesting milk, but the duration of occupying the feeder just after milk ingestion was lower with 4 than with 8 milk portions. Thus, fewer and larger portions may lower competition for access during the activity periods if all other factors remain equal.