Methane inhibition by Asparagopsis taxiformis with rumen fluid collected from ventral and central location - a pilot study

We assessed the effect of rumen fluid (RF) collection site (central vs. ventral), seaweed (with or without Asparagopsis taxiformis) and their interaction on in vitro total gas and methane yield, and fermentation parameters. Rumen fluid was collected via esophageal tubing from six cows, controlling sampling locations manually through the rumen cannula. Linear mixed-effect model analysis revealed no interactions between rumen fluid collection site and seaweed. Seaweed reduced (P < 0.01) total gas and methane yield (mL/g DM) by 10% and 93%, respectively. Collection site had no effect on total gas yield, but methane yield was slightly lower (P = 0.03) with central than ventral RF. Our pilot study is the first report on gas parameters for incubated rumen fluid from different collection sites, and the observed effect of collection site on CH4 yield provides further evidence for the importance of representative rumen sampling.