Effect of Supplementing TMR Diets with Artificial Saliva and Acid Buf on Optimizing Ruminal pH and Fermentation Activity in Cows

The objective of the study was to determine the effect of adding buffering agents to a total mixed ration (TMR) on the pH and on the VFA, lactic acid and NH₃-N content of rumen fluid. The experiment was carried out with three nonproductive cows fitted with permanent rumen fistulas in a 3×3 Latin square design with two stages differing in the amount of added buffer (50 g/day in stage I or 100 g/day in stage II). The control diet (C) contained no buffering agent. The AB experimental diet was supplemented with Acid Buf (Noack Polen Ltd.) containing calcium carbonate, major and trace elements, and the AS experimental diet was supplemented with our own produced artificial saliva powder containing a mixture of chemical compounds (NaHCO₃, KCl, CaCl₂, Na₂HO₄·12H₂O, NaCl, MgSO₄·7H2O) in the appropriate proportions (McDougall, 1948), combined with wheat bran at a 1:1 ratio. The preparations were added to the concentrate mixture in TMR which contained (% DM): maize silage, 29.9; wilted grass silage, 17.4; ensiled brewers’ grains, 2.4; barley straw, 10.3; and concentrate mixture, 40.0. Samples of rumen fluid collected before feeding (0 h) and after feeding (2, 4, 6 and 8 h) were analysed for pH, and the samples collected 4 h postprandial were analysed for VFA, lactic acid and NH₃-N. The artificial saliva added at 100 g/day to the mixture of chemical compounds (without a carrier) contributed to a significant (P≤0.01) increase in rumen fluid pH at 4 h compared to cows receiving diets C and AB. In both stages of the experiment, cows receiving the buffering agents tended to achieve higher pH values in the other hours of the test compared to group C. In the collected samples of rumen fluid, no significant (P>0.05) differences were observed among the cows in VFA and total VFA, in C2/C3 and C3/C4 acid ratios, and in NH₃-N content. Neither did the type and amount of buffers had a significant effect on the percentage ratios of selected fatty acids (acetic, propionic and butyric) in total VFA. No presence of lactic acid was detected in the analysed samples of rumen fluid. It can be stated that when the total mixed ration is properly balanced, the type and amount of buffers have no significant effect on changes in the rumen fermentation activity of cows.