Effect of dietary electrolyte balance on performance and blood parameters of growing-finishing swine fed in high ambient temperatures.

A growing-finishing trial using 96 crossbred pigs (21.8 kg initially) was conducted to determine the effect of dietary electrolyte balance (EB = Na + K - Cl, meq/kg of feed) on rate and efficiency of weight gain, blood gases and whole blood Na and K concentration during high ambient temperatures. Dietary EB (25, 100, 175, 250, 325 or 400 meq/kg) was altered by the substitution of CaCl2 for CaCO3 or NaHCO3 for corn and soybean meal. Increasing EB during the grower phase (21 to 50 kg) increased feed intake and average daily gain linearly (P less than .03). Efficiency of feed utilization was unaffected (P greater than .70). During the finisher phase (50 to 105 kg), live weight gain was 7% higher for pigs receiving the 250 meq EB diet compared with the average of all other EB levels. Feed intake during the finisher period increased linearly (P less than .03) as dietary EB increased from 25 to 400 meq/kg of diet. Live weight gain and daily feed intake measured over the entire growing-finishing period (21 to 105 kg) improved linearly (P less than .03) with increasing dietary EB. Blood pH, HCO3, total CO2, Na concentration, and base excess increased linearly (P less than .05) as dietary EB increased. We interpret the data to indicate that feed intake and weight gain of growing-finishing swine may be enhanced by dietary electrolyte modification during periods of high ambient temperature. This improvement probably is due to increased blood buffering capacity.