Effect of ruminant species (bovine v sbuffalo) and source of inoculum (rumen liquor vs faeces) on in vitro fermentation

The role of inoculum (rumen liquor - RL vs faeces - FA) from cow or buffalo with respect to feed evaluation using in vitro gas systems was estimated in a trial using 8 substrates. The substrate influenced significantly all fermentation characteristics; with each inoculum the substrates were ranked according the same trends for organic matter digestibility (dOM) and cumulative gas volume per gram of OM incubated (OMCV). The animal species affected dOM and OMCV which were significantly higher in buffalo and cow, respectively. Buffalo showed significantly higher values of acetic, propionic, butyric acids and total VFA, while isobutyric, isovaleric and valeric acids were higher in cow. The inocula influenced the fermentation characteristics in both species: while in cow all parameters, except OMCV, were higher with FA than RL, in buffalo dOM, OMCV, acetic and total VFAs were higher with RL. The results confirmed the lower cellulolytic activity of FA micropopulation than RL one. All the data suggest that, while there may be scope for faeces to replace rumen fluid as inoculum for some end-point measures, is not possible to replace cow inocula to buffalo.