Forestomach motility and behavior of bull calves according to changes in regimen.

Six 23-week-old bull calves were randomly assigned to a crossover design to study the effects of hay and concentrates given separately (A), silage and concentrates given in complete mixed ration (B), or given separately (C) on reticulo-ruminal motility and eating and resting behaviors after an adaptation period of 14 days (day 14). The effects of a change from one treatment to another on the same variables were also investigated (day 1). The differences observed between day 1 and day 14 indicate that a change in regimen, even not drastic, seems to affect reticulo-ruminal motility, rumination pattern, ruminal inactivity, and resting behavior. As expected, the number of triphasic and biphasic reticular spike bursts, as well as eating and resting behaviors, were affected by the type of forage ingested (A vs. C) on day 14 (p < or = 0.05). Moreover, the mode of distribution of concentrates affected also the variables measured (p < or = 0.05). Although the length of particles in complete mixed ration (B) was the same than in silage and concentrates given separately (C), the effect of regimen B on many variables was similar to that of regimen A or intermediate between A and C. The effect of regimens B and C was similar only for the rumination pattern, even though the number of boluses regurgitated for rumination differed (p < or = 0.05).