Calcium montmorillonite clay in dairy feed reduces aflatoxin concentrations in milk without interfering with milk quality, composition or yield

•Calcium montmorillonite clay (NSP) was added to the diet of dairy cows.•NSP reduced the level of aflatoxin metabolite in milk.•Concentrations of vitamin A and riboflavin in milk were not affected by NSP.•Milk quality, fat, protein, and composition were not altered by addition of NSP.

This study was designed to determine if a calcium montmorillonite clay (Novasil Plus, NSP), can significantly reduce aflatoxin M1 (AFM1) concentrations in milk without affecting dry matter intake (DMI), milk yield, milk composition, vitamin A, or riboflavin concentrations. The study was designed using 15 lactating dairy cows randomly assigned to one of 5 treatment groups in a 5 × 5 Latin square experimental design. The cows were treated with diets containing AFB1 at 0 or 121 ppb and three different levels of NSP (0.0, 6.0 and 12.1 g/kg) of the diet. Milk samples were collected and analyzed for AFM1, milk composition, vitamin A, and riboflavin. In this study, AFM1 concentrations in milk were significantly reduced by both 6.0 g/kg and 12.1 g/kg NSP treatment levels. The low dose of NSP (6.0 g/kg) resulted in a decrease in the level of AFM1 in the milk equal to 55%; whereas, the high dose (12.1 g/kg) reduced the level of AFM1 by 68%; milk composition, vitamin A, and riboflavin concentrations were unaffected by any of the dietary treatments. Additionally, dry matter intake (DMI) and milk yield were not different among treatments.