Effects of nitrogen gas flushing in comparison with argon on rumen fermentation characteristics in in vitro studies

In rumen in vitro experiments, although nitrogen gas (N(2)) flushing has been widely used, its effects on rumen fermentation characteristics are not clearly determined. The present study is the first to evaluate the effects of N(2) flushing on rumen fermentation characteristics in in vitro batch culture system by comparing with new applicable non-metabolizable gas: argon (Ar). The rumen fluid was taken from two Korean native heifers followed by incubation for 3, 9, 12, and 24 h with N(2) or Ar flushing. As a result, in all incubation time, N(2) flushing resulted in higher total gas production than Ar flushing (p < 0.01). Additionally, in N(2) flushing group, ammonia nitrogen was increased (p < 0.01). However, volatile fatty acids profiles and pH were not affected by the flushing gases (p > 0.05). In conclusion, the present study demonstrated that N(2) flushing can influence the rumen nitrogen metabolism via increased ammonia nitrogen concentration and Ar flushing can be used as a new alternative flushing gas.