Pressure Patterns in the Reticulum of the Cow

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Abstract
Two mature Holstein cows were used to ascertain reticular pressure patterns. A pressure-sensitive transmitter 2.54 cm in diameter and 20.32 cm long was passed down the esophagus to the retic- ulum. This transmitter sent a variable frequency signal which was decoded to indicate pressures from zero to 175 mm Hg. Continuous pressures were recorded. Rumination and nonrumination pressures were recorded and correlated to different activities such as standing, resting, drinking, and eating. The average length of contraction cycles was 42 sec in non- rumination whereas the average con- traction cycle in rnmination was 56 sec. Nonrumination patterns exhibited two pressure peaks per cycle whereas rumi- nation had three peaks per cycle. The time interval between the first and sec- ond pressure peak of a cycle was ap- proximately 3 sec in both rumination and nonrumination. In rumination the third pressure peak was approximately 3 sec after the second. Contraction pres- sure magnitudes varied with external ac- tivity of the cow. Peaks within each cy- cle were of different magnitude, usually the first peak was smaller than the sec- ond in nonrumination. During rumina- tion, peak averages were similar for the first two peaks but greater for the third.

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