High Dietary Cation and Anion Difference Enhanced Renal Response to an Acute Acid Load of Lactating Goat Fed Under Tropical Conditions.

High ambient temperature (HTa) in tropical conditions leads to evaporative heat dissipation by panting in lactating dairy goats. This panting causes respiratory hypocapnia, which increases the renal excretion of buffer molecules including sodium, potassium, and bicarbonate. In response, renal acid excretion decreases to preserve acidity. Besides hypocapnia, lactation and HTa could further deplete buffer molecules, enhancing acid preservation. This current study restored buffer molecules using high dietary cation and anion difference (DCAD) regimen and hypothesized that renal acid excretion during acute acid load would be increased in dairy goats fed high DCAD under HTa. To investigate this, 12 early-lactating dairy goats were randomly assigned to two groups: control and DCAD, which were fed control and high-DCAD diets, respectively, for 8 weeks. Acute acid loading during HTa was induced by high-dose ascorbic acid (AA) supplementation. During Weeks 4 and 8, the vehicle and AA were supplemented on the last two consecutive days of each week. The results showed that the renal acid excretion in DCAD group was higher than control group during high-dose AA supplementation. Together with high renal buffer excretion by DCAD, an increased renal acid excretion may be partially mediated by an increase in buffer reserve.