Effects of different sources of Saccharomyces cerevisiae biomass on milk production, composition, and aflatoxin M1 excretion in milk from dairy cows fed aflatoxin B1

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 1 (AFM 1 ) excretion in milk from dairy cows receiving 480 g aflatoxin B 1 (AFB 1 ) 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 1 or SC-based biomass), positive controls (AFB 1 alone), DY alone, DY + AFB 1 , BY alone, BY + AFB 1 , CW alone, CW + AFB 1 , AY alone, and AY + AFB 1 . The cows in the aflatoxin treatment group received AFB 1 from d 1 to 6, while the SC biomass was administered with the AFB 1 bolus from d 4 to 6. Aflatoxin B 1 or SC-based products did not affect milk production or milk composition during the experimental period. Aflatoxin M 1 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 g/L. At end of the treatment period, CW, AY, DY, and BY removed 78%, 89%, 45%, and 50% of AFM 1 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 1 in milk.