The present research was conducted aimed at using the approach involving the in vitro tests to evaluate effect by various inorganic buffers used in the diets of Holstein dairy cow on the dietary buffering capacity, ruminal acidogenicity value (AV), methane emission and assess the relationship between them. The buffers were sodium bicarbonate (SB), sodium sesquicarbonate (SSc), a commercial buffer [BEHINA, (BH)], and potassium carbonate (PC). Basal diets were low forage [30% forage and 70% concentrate, (LF)], mid forage [35% forage and 65% concentrate, (MF)], and high forage [40% forage and 60% concentrate, (HF)]. The buffers were added to the diets in the concentrations of 0.0, 8.0 and 12.0 g/kg DM. In vitro pH, AV, and methane emission of the experimental diets were determined using the gas production technique. Results showed that buffering capacity was significantly the highest for the PC, followed by BH, SB, and SSc (143.3, 138.3, 136.6, and 135, respectively). Analysis of the acid load revealed that adding 8 g/kg of DM of SB in the HF diet led to the lowest AV (9.6 mg Ca g–1 DM). In addition, adding 12 g/kg of DM of BH in the LF and 8 g/kg of DM of SB in the MF diet caused the lowest (5.27) and highest (5.43) pH compared to the other treatments, respectively. The HF diet containing 8 g/kg DM of PC had the lowest level of methane emission (1.01 mL/0.20 g DM). Our findings demonstrated that the rumen acid load and methane emission may alter when the dietary buffering capacities are changed using the inorganic buffers.

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