Four buffaloes and four cattle rumen fistulated were used to study the effects of different levels of neutral detergent fiber in the diet on the rumen fermentation characteristics. Ammonia concentration, volatile fatty acids (VFA) production (acetic acid, propionic acid and butyric acid) and pH in the ruminal fluid were evaluated. The animals were allotted to two latin square experimental design (4x4) in a 4x2 factorial arrangement with four increasing levels of NDF in the DM (54, 60, 66 and 72%) and two animal species (buffaloes and cattle). Four twenty-nine days subperiods were used, with 13 days for diet adaptation. It was observed the effect of species on the ruminal pH, with average of 6.78 for buffaloes and of 6.58 for cattle. There was an interaction time x species effect for rumen ammonia concentration only at 2 hours after feeding, and buffaloes showed mean of 31.76 mg% and cattle 27.74 mg%. Buffaloes showed lower VFA average concentration of acetic acid, propionic acid and butyric acid, (69.94, 51.31 and 6.12 mM), than the cattle (77.96, 56.72 and 8.01 mM), respectively. There was no difference in the propionic acid concentration and acetic: propionic ratio, which was not influenced by anyone of the mainly determined characteristics.
cattle; buffalo; ruminal fermentation; neutral detergent fiber
