In vitro techniques have been developed to facilitate the measurement of nutritional variability amongst food. Many kinetic studies have utilized the modified Tilley and Terry technique, with long-term incubations carried out in Erlenmeyer flasks. These are inefficient in utilizing incubator space for large scale studies. However substitution of Erlenmeyer flasks with tubes as fermentation units leaves the system prone to ‘bridging’, the formation of dense mats of forage particles by entrapped gas, above the level of the media in a fermentation unit. The objective of experiment 1 was to establish an effective incubation technique to eliminate the random variation caused by bridging.