The rumen fluid was collected once during each collection period at 4 hr post‐feeding. Rumen fluid was aspirated using an oral probe. After filtering the ruminal fluid with four layers of gauze, it was frozen and preserved at −30°C until the concentration of volatile fatty acid (VFA), ammonium nitrogen (NH
3‐N), and lipopolysaccharide (LPS) level could be measured.
The VFA composition in the ruminal fluid was analyzed by high‐performance liquid chromatography (CTO‐10AV; Shimazu Corporation, Kyoto, Japan) using the bromothymol blue post‐label method. The concentration of ruminal NH
3‐N was quantified using an
ammonia test (Wako Pure Chemical Industries, Ltd, Tokyo, Japan). The LPS level was measured in accordance with the method described by Hirabayashi et al. (
2017).
Nishimura K., Kurosu K., Terada F., Mizuguchi H., Sato S, & Kushibiki S. (2018). Effect of wood kraft pulp feed on digestibility, ruminal characteristics, and milk production performance in lactating dairy cows. Animal Science Journal = Nihon Chikusan Gakkaiho, 90(2), 189-195.