Calcium Montmorillonite Clay for the Reduction of Aflatoxin Residues in Milk and Dairy Products

In this study, dairy cows were treated with calcium montmorillonite clay (NSP; BASF Corp., Ludwigshaven, Germany) in a replicated 5x5 Latin square design. The primary objectives were to determine if milk composition was altered following ingestion of NSP, and to investigate the ability of NSP to reduce aflatoxin (AF) transfer to milk with the inclusion of low doses in the diet (concentrations equal to 0.125 and 0.25% w/w). The experiment was conducted at the Bearden Dairy Research Center at Mississippi State University. Cows were housed in a free-stall barn with sand bedding and were fed and milked twice daily. The experiment consisted of 5 10-d periods, where cows were randomly assigned to 1 of 5 dietary treatments (n=3 for each treatment): A. absolute control (CON), basal total mix ration (TMR) with no AF or NSP; B. AF Control (AFC), basal TMR plus 50 ppb AF; C. NSP Control (NSPC), basal TMR plus 0.5% estimated dry matter intake (DMI) NSP; D. low-dose clay with AF (NSP-0.125%), basal TMR plus 0.125% estimated DMI NSP and 50 ppb AF; E. Or high-dose clay with AF (NSP-0.25%), basal TMR plus 0.25% estimated DMI NSP and 50 ppb AF. All additions to the basal TMR were top dressed and mixed into the top of feed offered. Dry matter intake and nutrient intake did not differ among dietary treatments (P>0.05). Milk yield and feed efficiency (FE) were similar throughout all treatments, and no treatment effects were observed for fat yield, lactose, protein yield, solids, or somatic cell count (SCC). Furthermore, vitamin A and riboflavin concentration in milk were similar across all treatments and averaged, 0.30±0.03 and 1.54±0.13μg/mL, respectively. A reduction (P < 0.01) in concentration of AFM1 in milk with the inclusion of NSP was shown.. Feeding the AFC diet resulted in 0.75±0.05μg AFM1/L; this value was reduced by 17.3% (0.62 ± 0.02 μg/L) with the inclusion of NSP at 0.125% of DMI and by 21.3% (0.59 ± 0.02 μg/L) when NSP was fed at 0.25% of DMI. Specifically, transfer rate was reduced from 1.78% with the AF diet to 1.50% and 1.46 ±0.16% with the inclusion of NSP at 0.125% and 0.25% of DMI. Due to reduced transfer rate, total excretion of AFM1 was also reduced (P<0.01). This study was part of a multistate dairy project. When compared to other studies in this project, NSP resulted in a linear decrease in AFM1 ranging from 17% (at the smallest dose of clay) to 71% (at the greatest dose of clay). At all doses, DMI, milk yield, milk composition, minerals, vitamin A, and riboflavin concentrations were unaffected by the dietary treatments. The inclusion of NSP in contaminated dairy feeds may help mitigate AF problems without affecting milk production or composition. The results of this study will aid in determining the appropriate dosage of NSP needed to decrease AFM1 below allowable concentrations.