Comparison Between Cattle Rruminal pH Determination Using Mobile Continuous Recording System and Regular Ruminal Spot Sampling

The objective of this study was to develop a continuous rumen pH data acquisition system that permitted animal mobility during data acquisition. A further objective was to compare pH readings obtained using the continuous recording system to readings obtained at the same time using spot sampling. The continuous recording system was composed of a heavy-duty electrode and a data logger. The electrode was attached to a 0. 5-kg weight to help maintain the electrode in the ventral sac of rumen. The electrode was connected via a cable to a lightweight data logger that was mounted on the animal’s back using a belt wrapped around the girth. The data logger was battery powered and could hold over 13،000 pH data values. Ruminal pH was continuously recorded (every 10 s) using a lactating Holstein cow to compare the performance of the continuous system to spot samples taken from the ventral sac of the rumen، the same location as the continuous electrode. The spot samples were collected 3 times per d for 3 d. At every sampling time، 3 replicate samples were collected، pH was determined immediately using a handheld pH meter، and readings were averaged (n = 3) and compared with the average of the 3 pH readings recorded using the continuous system at the same time. The pH recorded by spot sampling (6. 06 ± 0. 05) was greater (P0. 05) than that of the continuous system (5. 87 ± 0. 04)، with a correlation of r = 0. 82 (P0. 05). The continuous recording system may has the potential to facilitate measurement of ruminal pH in free-roaming cattle.