Effect of fermentation of soybean meal with varying protein solubility on ileal digestibility of nutrients in growing pigs

Apparent ileal digestibility and standardised ileal digestibility of energy, dry matter, nitrogen and amino acids were evaluated in five cannulated [(Landrace x Yorkshire) x Duroc)] barrows with an initial bodyweight of 27.1 +/- 0.58 kg in a 5 x 5 Latin square design. Pigs were fed unfermented soybean meal (USM) as control and fermented soybean meal A, B and C (FSMA, FSMB and FSMC, respectively), with 52.4%, 62.0% and 71.8% protein solubility, respectively, and a nitrogen- free diet. The nitrogen-free diet was used to determine basal endogenous losses of crude protein and amino acids. The apparent ileal digestibility of dry matter and nitrogen was greater (P < 0.05) in FMSC and tended to improve in FSMA and FSMB compared with the control. The apparent ileal digestibility of isoleucine, phenylalanine and valine was greater in all fermented soybean meal whereas that of lysine was greater (P < 0.05) in FSMC compared with USM. Likewise, the apparent ileal digestibility of aspartic acid and proline was greater (P < 0.05) in FSMA and FSMC. The standardised ileal digestibility of crude protein and lysine was higher (P < 0.05) in FSMC and tended to improve in FSMAand FSMB whereas the standardised ileal digestibility of isoleucine was higher (P < 0.05) in FSMA, FSMB and FSMC compared with USM. In conclusion, fermentation of soybean meal showed better digestibility compared with USM regardless of its protein solubility values.