Effect of fumaric acid and dietary buffering capacity on ileal and fecal amino acid digestibilities in early-weaned pigs

Experiments were conducted to determine the effect of fumaric acid suppleme ntation and buffering capacity of the diet on ileal and fecal digestibiliti es of CP, GE, and amino acids in early-weaned pigs. In two experiments, 12 pigs each were weaned at 14 d of age and fitted with a simple T-cannula at the distal ileum between 15 and 17 d of age. In both experiments, the pigs were fed four diets, based on wheat and soybean meal without (control) or w ith 1, 2, or 3% fumaric acid according to a balanced two-period changeover design. In Exp. 2, the buffering capacity of the diets was increased by sup plementation of 3% sodium bicarbonate. The pigs were fed three times daily: equal amounts at 8-h intervals. The diets were supplied at a rate of 5% (w t/wt) of body weight. The inclusion of fumaric acid to the diet with a low buffering capacity increased (P < .05) the ileal digestibilities of CP, GE, and the majority of amino acids. The highest responses were found at an in clusion level of 2% fumaric acid. The improvements in apparent ileal amino acid digestibilities ranged fi om 4.9 to 12.8 percentage units. Supplementa tion of fumaric acid to a diet with a high buffering capacity led only to n umerical increases in ileal digestibilities of CP, GE, and amino acids. In both studies, fumaric acid supplementation had no effect (P > .05) on the f ecal digestibilities of CP, GE, and amino acids, except histidine. A high b uffering capacity of the diet decreased the ileal amino acid digestibilitie s by 1 to 10 percentage units compared with diets with the low buffering ca pacities. In both experiments, ileal and fecal digestibilities were higher (P < .05) in Period 2 (on d 24 after weaning) than in Period 1 (on d II aft er weaning). A positive correlation (P < .05) between ileal digestibilities and fumaric acid supplementation to the diets with the low buffering capac ities was observed in Period 1 (on d II after weaning), but not in Period 2 (on d 24 after weaning). No relationship (P > .05) between ileal digestibi lities and fumaric acid supplementation to the diets with a high buffering capacity could be established. In conclusion, supplementation of fumaric ac id to starter diets during the first 3 to 4 wk after weaning increases the ileal digestibilities of GE, CP, and amino acids.