The aim of the present study was to evaluate the effect of different sources of Saccharomyces cerevisiae (SC) biomass (20.0 g/d) obtained from sugarcane (cell wall, CW; dried yeast, DY; autolyzed yeast, AY) and the beer industry (partially dehydrated brewery yeast, BY) on milk production, fat and protein percentages, and aflatoxin M (AFM) excretion in milk from dairy cows receiving 480 µg aflatoxin B (AFB) per day. A completely randomized design was used with 2 lactating cows assigned to each of 10 dietary treatments, as follows: negative controls (no AFB or SC-based biomass), positive controls (AFB alone), DY alone, DY + AFB, BY alone, BY + AFB, CW alone, CW + AFB, AY alone, and AY + AFB. The cows in the aflatoxin treatment group received AFB from d 1 to 6, while the SC biomass was administered with the AFB bolus from d 4 to 6. Aflatoxin B or SC-based products did not affect milk production or milk composition during the experimental period. Aflatoxin M was detected in the milk from all aflatoxin treatment group cows, reaching maximum levels at d 3 and varying from 0.52 ± 0.03 to 1.00 ± 0.04 µg/L. At end of the treatment period, CW, AY, DY, and BY removed 78%, 89%, 45%, and 50% of AFM from the milk, respectively, based on the highest level found on d 3. Results indicate a potential application of industrial fermentation by-products, especially CW and AY, as a feed additive in the diets of dairy cows to reduce the excretion of AFM in milk.