No abstract

| The objective of this study was to test oral insertion of sensors in calf, and to evaluate their accuracy to measure rumen pH for 28 days. Cannulated Holstein calf (5 mo; 200 kg BW) was used in this study. Four T9 data loggers sensors L1, L2, L3, and L4 were orally inserted into the rumen at d0, d7, d14, and d21 respectively to measure ruminal pH every 5 min. Calculated averages pH of 15 min were used to compare the 4 data loggers. Oral insertions of the data loggers were successfully performed. Data logger L1 was more accurate in the beginning of the experiment than at the end. However, the correlations between calculated pH mean at 15 min (L1 vs L2, L1 vs L3, and L1 vs L4) were consistent. Thus, the T9 data loggers can be used to monitor pH measurement for a long-term period of 28 days.