Short communicationEffects of supplemental dietary sodium bicarbonate on performance of lactating Holstein cows during the summer season in Brazil

Our objective was to evaluate the effect of dietary cation-anion difference (DCAD) on DMI, milk production, and DMI:milk production ratio (feed efficiency) in cows after peak lactation. Eight multiparous lactating Holstein cows were allotted to a 4×4 replicated Latin square, for 72 days during the summer season. Four diets with different sodium bicarbonate concentrations were formulated to have +150, +250, +400, and +500 meq/kg (DM-basis) DCAD levels. The measured DCAD values were +155, + 289, +410, and +491 meq/kg, respectively. Increasing DCAD resulted in greater (P<0.05) dry matter intake (DMI) and milk production. There was no difference in feed efficiency among treatments. Due to increased DMI and milk production, a beneficial effect of cationic diets was observed after peak lactation. Because increasing DCAD concentration resulted in a linear increase in DMI and milk production, studies with greater DCAD concentrations will be required to determine the optimal DCAD for maximum DMI and milk production, during the summer season.