Substrate-dependent detoxification of DON, ZEN, and AFB 1 by a commercial silage inoculant: From mycotoxin reduction to feed safety compliance

This study systematically evaluated the effects of a commercial microbial inoculant on nutritional quality, fermentation characteristics, and the detoxification of three major mycotoxins—deoxynivalenol (DON), zearalenone (ZEN), and aflatoxin B ₁ (AFB ₁ )—in the silage of four crop by-products: barley straw, corn straw, rice straw, and pressed sugarcane bagasse. The inoculant, containing Pediococcus pentosaceus, Lactobacillus plantarum, and cellulase, was applied to each substrate with an uninoculated control (CK, molasses only), ensiled for 60 days, and then analyzed for crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), ash, fermentation profile (pH, organic acids, ammonia nitrogen), and the three mycotoxins. Detoxification rates were calculated and safety was assessed against GB 13078 − 2017. The results demonstrated significant substrate- and toxin-dependent detoxification effects. Rice straw exhibited the best overall performance, with DON, ZEN, and AFB ₁ reduction rates of 66.67%, 99.02%, and 60.00%, respectively, with ZEN content decreasing from 600 ± 12.1 ppb to 5.9 ± 0.65 ppb (a 99% reduction). In barley straw, ZEN was reduced by 95.36% (from 172.5 ± 5.69 to 8 ± 1.27 ppb), while DON decreased from 7644.2 ± 42.86 to 4500 ± 18.69 ppb (a 41.13% reduction). Corn straw showed DON and ZEN reduction rates of 54.23% and 59.20%, respectively, but no reduction for AFB ₁ (0%). Sugarcane bagasse exhibited DON and AFB ₁ reduction rates of 45.43% and 29.72%, respectively, but only 11.51% for ZEN. The CK groups generally showed lower detoxification rates, and inoculation significantly reduced pH and increased lactic acid in barley straw and rice straw, while the differences were smaller in corn straw and sugarcane bagasse. Notably, despite the wide variation in detoxification rates (0–99.02%), all inoculated samples met the GB 13078 − 2017 safety limits, whereas CK of barley straw remained non-compliant for DON. In terms of nutritional quality, barley straw showed the greatest CP increase (+ 62.4%), followed by rice straw (+ 26.0%), while sugarcane bagasse had extremely low absolute CP content (2.39% after fermentation), and corn straw showed an abnormal decrease in CP (− 9.8%) and increase in NDF (+ 4.5%). These findings confirm that the inoculant has broad-spectrum detoxification potential, but its efficacy is strongly dependent on substrate and toxin type. Rice straw emerged as the optimal match for this inoculant, achieving simultaneous nutritional improvement and mycotoxin reduction. Although corn straw showed no AFB ₁ reduction, the final product remained safe due to its extremely low initial AFB ₁ concentration (1.00 ppb). This study provides a scientific basis for the precise selection of silage additives for different crop by-products.