Short communication Direction of jaw movement in dairy cattle during the rumination period

Jaw movements in dairy cattle were observed during rumination. The direction of jaw movement was recorded to determine the frequency in three phases: the first jaw-opening !. movement FJM which serves to keep the major part of the bolus on one side of the oral cavity, !. the main jaw-opening and -closing movements MJM , from the second movement to the penultimate one, which serve to repeatedly jumble and grind the bolus, and the last jaw-opening !. movement LJM which serves to prepare the bolus for swallowing. Five dairy cattle were monitored in trial 1 to record FJM, MJM and LJM, and 16 cows were monitored in trial 2 to record MJM. It was found that the direction of FJM and MJM during a single rumination period ! . time spent chewing one bolus was a one-way movement, either left or right depending on the