A comparison of rumen fluid sampled by oro-ruminal probe versus rumen fistula

Ten adult (height 63-85 cm) rumen-fistulated sheep were used to test the usefulness of an oro-ruminal probe and a suction pump for the acquisition of ruminal fluid, Use of these instruments in 50 samplings rendered 200 mi of ruminal fluid each time. Introduction of the probe to a length of 91.3 +/- 3.5 cm took 18 +/- 6.5 s. Collection of 200 mi of ruminal fluid took 7.4 +/- 2.2 s, Sampling location was the ventral ruminal sack. Comparing fluid taken by the oro-ruminal probe with samples taken via ruminal fistula by a tube-like probe, no significant differences in pH, total acidity, reduction potential, ammonia, acetate, L-lactate, sodium and chloride concentrations were found. However, significant differences between oro-ruminal probe samples and fistula samples were observed with regard to the concentrations of total volatile fatty acids, propionate, n-butyrate, i-butyrate, n-valerate, i-valerate, calcium, phosphate, magnesium and potassium. The differences were independent of the sampling order (oro-ruminal probe prior to fistula and vice versa). These results indicate that samples taken by the oro-ruminal probe do not contain sampling-dependent saliva residues. Those samples collected via the fistula had consistently higher concentrations of total volatile fatty acids, propionate, n-butyrate, i-butyrate, n-valerate, and i-valerate, as well as higher concentrations of calcium, phosphate, magnesium and potassium than samples taken with the oro-ruminal probe. These results indicate that samples taken via fistula originated from more dorsal regions than the samples taken by oro-ruminal probe from the ventral ruminal sack. The oro-ruminal probe and the suction pump used proved to be useful for the collection of ruminal fluid from the ventral ruminal sack in adult sheep.