The influence of pelleting and supplementing sodium metabisulfite (Na2S2O5) on nursery pigs fed diets contaminated with deoxynivalenol

• We proposed pelleting with sodium metabisulfite to reduce effects of deoxynivalenol.
• Pelleting or autoclaving with sodium metabisulfite reduced deoxynivalenol levels.
• Deoxynivalenol-contaminated grain negatively impacts nursery pig growth performance.
• Sodium metabisulfite added pre-pelleting recovered growth in DON-contaminated diets.

Four experiments were conducted to ascertain the effects of hydrothermal treatment and sodium metabisulfite (SMB) on deoxynivalenol (DON)-contaminated corn dried distillers grains with solubles (DDGS). Experiment 1 evaluated SMB and heat (autoclaving) on high-DON DDGS (20.6 mg/kg). Six levels of SMB were tested: 0.0% (control), 0.5%, 1%, 2.5%, 5%, and 5% with 100 mL/kg distilled water. Autoclaving after 1 h at 121 °C alone elicited a 9.8% reduction in DON, whereas an 82% reduction was achieved when 5% SMB was added before autoclaving. Experiment 2 tested pelleting high-DON DDGS with SMB. Four batches of DDGS (20.5 mg/kg DON) were tested: 0 (control), 1.0, 2.5, and 5.0% SMB. Pelleted samples were collected at conditioning temperatures of 66 and 82 °C and retention times of 30 and 60 s within temperature. Pelleting conditions had no effect on DON levels, but as SMB inclusion increased in pelleted DDGS, DON levels were reduced (quadratic; P < 0.001). Experiments 3 and 4 evaluated pelleting and SMB on nursery pig growth. Both trials were arranged in a 2 × 3 + 1 factorial with 5 replicate pens per treatment. In Exp. 3, 987 pigs (13.0 ± 0.2 kg) were used with main effects of (1) diet form: meal or pellet and (2) SMB level: Negative Control (NC), NC + 0.25% SMB, or NC + 0.50% SMB. Negative Control diets were formulated to contain 3 mg/kg DON. Treatment 7 was a Positive Control (PC; <0.5 mg/kg DON) fed in meal form. Pigs fed high-DON diets had reduced (P < 0.001) ADG and ADFI, but pelleting improved (P < 0.001) ADG and G:F. Adding SMB increased (linear; P < 0.03) ADG and tended to increase (P < 0.10) ADFI. In Exp. 4, 1180 pigs (11.1 ± 0.32 kg) were used with main effects of (1) diet form: meal or pellet and (2) DDGS source: PC (<0.5 mg/kg DON), NC (5 mg/kg DON), or NC + DDGS pelleted and crumbled before mixing into the final diet. In meal form, treatment 7 included 2.5% SMB prior to pelleting DDGS (final diet contained 0.77% SMB). Overall, a 2-way interaction (P < 0.04) was observed within NC diets where pelleting the final diet improved G:F by a greater margin in high-DON diets than when the DDGS was pelleted, crumbled, and re-pelleted. DON reduced (P < 0.002) ADG and ADFI, and pelleting the diet improved (P < 0.01) ADG and G:F. Including SMB prior to pelleting DON-contaminated DDGS increased (P < 0.01) ADG and ADFI. Using SMB combined with thermal processing can mitigate DON effects in diets for nursery pigs.