Comparison of Rumination Activities of Dairy Herds Fed Relatively High and Low Concentrate Diet

Rumination activities of 12 cows in Herd A fed on a relatively high concentrate diet were compared with those of 12 cows in Herd B fed on a high forage diet. The total eating time did not differ between the two herds. The total rumination time and rumination boli per day were significantly less in Herd A than in Herd B (P 0.05). There was no clear difference in the rumination time per rumination period, percentage for number of ruminating cows at each time of day or interval between end of meal and subsequent rumination between the two herds (P>0.05). Indexes from the results of short-term observation of rumination such as number of chews per bolus or duration of rumination period were not useful in detecting mild insufficiency of roughage. However, index from the observation throughout at least a 24 hour period such as total rumination time or total number of rumination boli per day was useful.