The effect of fumaric acid and sodium fumarate supplementation to diets for weanling pigs on amino acid digestibility and volatile fatty acid concentrations in ileal digesta

An experiment was carried out with 12 Camborough × Canabrid barrows to determine the effect of fumaric acid (FA) and sodium fumarate (NaFA) supplementation of the diet on the apparent ileal digestibility coefficients of amino acids and the concentrations of volatile fatty acids in ileal digesta. The pigs were weaned at 28 days of age (initial and final body weights 9.3 kg and 17.4 kg, respectively) and fitted with a simple T-cannula at the distal ileum. The pigs were fed four diets, based on wheat and soybean meal (200 g kg−1 crude protein), according to a two-period change-over design. Fumaric acid (15 and 30 g kg−1) and NaFA (15 g kg−1) were included in the diets at the expense of corn starch. The pigs were fed three times daily at a rate of 5% of body weight. Chromic oxide (3 g kg−1) was used as digestibility marker. The pH of the diets were 6.3, 4.4, 3.9, and 6.3 for the control, 15 g kg−1 FA, 30 g kg−1 FA, and 15 g kg−1 NaFA diets, respectively. Supplementation of diets with FA or NaFA did not increase the apparent ileal or total tract digestibility coefficients of amino acids and energy and did not affect (P>0.05) the pH or the concentrations of acetate and propionate in ileal digesta. Therefore, the growth-promoting effect of FA appears not to be due to improved protein and energy digestion or an effect on volatile fatty acid metabolism.