Effects of 3 sequestering agents on milk aflatoxin M1 concentration and the performance and immune status of dairy cows fed diets artificially contaminated with aflatoxin B1

Abstract This study examined whether adding 3 mycotoxin-sequestering agents to diets contaminated with aflatoxin B 1 (AFB 1 ) would reduce milk aflatoxin M 1 (AFM 1 ) concentration, and improve the performance and alter immune status of dairy cows. Fifteen lactating dairy cows were used in an experiment with an incomplete crossover design including four 28-d periods. Treatments included a control diet (C), a toxin diet (T; 1,725µg of AFB 1 /head per day; 75µg/kg), and diets containing the toxin and 20g/head per day of a proprietary mixture of Saccharomyces cerevisiae fermentation product containing a low (SEQ1) or high (SEQ2) dose of a chlorophyll-based additive, or a low dose of the chlorophyll-based additive and sodium bentonite clay (SEQ3). Sequestering agents were top-dressed on the total mixed ration (TMR) daily in each period, and AFB 1 was dosed orally in gelatin capsules before the TMR was fed on d 21 to 25. Milk was sampled twice daily on d 20 to 28 and plasma was sampled on d 20 and 25. Sequestering agents did not affect milk AFM 1 concentration during the toxin-dosing period. However, after AFB 1 was withdrawn, the sequestering agents reduced the time required (24 vs. 48h) to reduce the milk AFM 1 concentration below the Food and Drug Administration action level of 0.5µg/kg. Feeding T instead of C tended to reduce milk and fat-corrected milk yields, but feeding SEQ1 prevented these effects. Red blood cell count and hemoglobin concentration were reduced by feeding T instead of C, but not by feeding SEQ1, SEQ2, or SEQ3. The mean fluorescence intensity of antibody staining for 2 leukocyte adhesion molecules, L-selectin (CD62L) and β-integrin (CD18), tended to be greatest when SEQ1 and SEQ3 were fed. Plasma acid-soluble protein concentration was decreased by feeding SEQ1, SEQ2, and SEQ3 instead of T. Sequestering agents had no effect on milk AFM 1 concentration, but they reduced the time required to reduce milk AFM 1 concentration to a safe level after withdrawal of AFB 1 from the diet. Only SEQ1 prevented the adverse effects of AFB 1 on milk and fat-corrected milk yields.