Comparative studies of ruminal fluid collected by oral tube or by puncture of the caudoventral ruminal sac

Abstract

Samples of ruminal fluid were collected in four groups of high-producing dairy cows simultaneously by an oral probe and by percutaneous puncture of the caudoventral ruminal sac. The samples were tested for basic indicators of the metabolic profile including pH, total acidity, ammonia, infusoria counts, and total and relative amounts of volatile fatty acids. Significant differences (P < 0.05) between the samples collected by oral probe (o) and by puncture (p) were observed for pH (o - 6.74 vs. p - 6.23), total acidity (o - 17.1 vs. p - 24.7), and total VFA (o - 101.18 vs. p - 131.70 mmol/l) in the group of cows with mean daily production of 18 1 of milk. Highly significant (P < 0.01) differences between the samples collected by oral probe and by puncture were observed in the groups yielding daily 24 and 381 of milk for pH (o -6.95 vs. p - 6.24 and o - 7.00 vs. 6.21, respectively), total acidity (o - 13.2 vs. p-22.2 and o - 12.6 vs. p - 25.2, respectively), and total VFA (o - 99.23 vs. p - 136.25 mmol/l and o - 89.66 vs. p - 140.14 mmol/l, respectively). Buffering of the ration for the cows yielding 38 1 of milk per day with 200 g of sodium hydrogen carbonate increased the above differences in pH, total acidity, and total VFA. Ruminal fluid samples collected by percutaneous puncture of the caudoventral ruminal sac better indicate the intensity of ruminal fermentation processes apparently because their composition is not influenced by the amount of saliva or buffer which is variable in the content of the cranial ruminal sacs where the oral samples are collected from. Although the sampling of ruminal fluid by percutaneous puncture is an easy method, it can be associated with some complications. Their risk can be minimised by strict adherence to the recommended procedure and observation of rules of aseptic work.