Abstract

Rumen pH assessment by three techniques was compared using an in vitro, artificial rumen system. Rumen digesta from dairy cows fed kale, fodder beet or ryegrass and clover pasture was used in an in vitro artificial rumen system. The digesta pH was measured by obtaining rumen fluid by centesis, by direct probe insertion, and by removal and filtration of fluid through cloth. This was done at different time intervals and at different heights from the base of the artificial rumen. There were significant differences in mean diet group pH. There was a significant difference between mean pH of all three techniques at the first time interval, and similarly between centesis and both the other techniques at the second and third time intervals. There was no significant difference between collection site height at any time interval. For dairy cows fed these forage diets, the technique of pH assessment of in vitro rumen digesta significantly influenced the pH measured, with centesis associated with higher mean pH than direct probe assessment. Given the importance of accurate rumen pH assessment, and the implications of differences between rumen fluid and rumen digesta pH in forage based ruminants, further research using the methodology with in vivo models is warranted.

AM, Broomfield, and SJ Gibbs

Proceedings of the New Zealand Society of Animal Production, Volume 71, Invercargill, 9-12, 2011