Published online by Cambridge University Press: 12 April 2010
In vitro gas production (GP) of substrate incubated with cow rumen liquor is commonly used to evaluate feed nutritional quality; GP is correlated with organic matter digestibility and metabolizable energy content. The hypothesis tested was that GP differs among liquors of ruminant species and is dependent on the natural dietary intake of the donors. Measurements were of 24 h GP of seven browse species using rumen liquor from a large (cow) and small (sheep) grazer and from a small intermediate feeder (goat). Mean GP for browse with goat liquor (7±2·4 ml per 200 mg substrate) was significantly (P=0·019) higher than that with cow liquor (5±1·9 ml), and GP with sheep liquor (6±1·1 ml) was intermediate, not significantly different from the cow liquor (P=0·197) and the goat liquor (P=0·061). There was a significant correlation in the ranking of the browses between goat and sheep (P=0·013) liquor using a Mantel test with 9999 permutations, which indicated a similar ranking of browses when using rumen liquor of either of these small ruminants. There were trends between both cow and sheep (P=0·096) and cow and goat (P=0·092) liquors. It was concluded that the dietary habits of ruminant species donors may affect in vitro nutritional studies when using rumen liquor.