Effect of dietary electrolyte balance on growth and acid-base status in swine

The effect of dietary electrolyte balance on pigs fed lysine- or tryptophan-adequate or tryptophan-deficient diets was investigated in four experiments using 8- to 12-wk-old pigs. Electrolyte balance, expressed as Na+K-Cl in meq/kg of diet, was varied by altering dietary levels of Na and Cl while holding all other minerals constant. In two experiments in which the basal diet contained a balance of 135 meq/kg, simple lysine or tryptophan deficiences caused depressed growth, feed intake and efficiency of feed utilization, but none of these responses was altered by dietary supplementation with NaHCO3. In one experiment in which the electrolyte balance of the basal diet was 61 meq/kg and in which both lysine and tryptophan were limiting. NaHCO3 supplementation significantly increased growth and feed intake. This did not occur if the diet was also supplemented with tryptophan. A final experiment was conducted to determine the response of pigs to a range of electrolyte balance (-85 to 341 meq/kg) in a practical corn-soy diet containing adequate levels of all amino acids. Growth and feed intake appeared to be maximal for balances of 0 to 341 meq/kg Na+K-Cl, but were decreased at -85 meq/kg (P less than .05). Acid-base balance was adversely affected at 0 meq/kg. The results suggest that the response of lysine-deficient pigs to sodium bicarbonate is dependent upon the electrolyte balance of the diet, and also is influenced by other dietary amino acids.