Effects of different sources of Saccharomyces cerevisiae biomass on milk production, composition, and aflatoxin M-1 excretion in milk from dairy cows fed aflatoxin B-1

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 mu 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 mu 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. (AU)