Decreasing dietary particle size of lupins increases apparent ileal amino acid digestibility and alters fermentation characteristics in the gastrointestinal tract of pigs

Two experiments were conducted to examine the effects of lupin particle size on amino acid (AA) and energy digestibility and fermentation characteristics in pigs. Expt 1 examined the effects of lupin variety (cv. Tanjil and Mandelup) and lupin particle size (746, 888, 1099 and 1136 μm) on the total-tract apparent digestibility of dietary components in 63·5 (sd 7·28) kg pigs. While variety had no effect on total-tract apparent digestibility, decreasing particle size of lupins linearly increased total-tract apparent digestibility of crude protein of diets containing 350 g lupins per kg (P sd 2·9) kg pigs. Pigs were fed the respective diets ad libitum for the first 2 weeks and fed at three times maintenance energy level in the third week. Pigs were euthanised under sedation at 46·7 (sd 4·21) kg to collect digesta samples along the intestinal tract. Decreasing particle size increased apparent ileal and total-tract digestible N (P P APB), while branched-chain fatty acids (sum of valeric, caproic, isobutyric and isovaleric acids) were linearly increased (P