Effectiveness of modified yeast cell wall extracts to reduce aflatoxin B1 absorption in dairy ewes

Abstract

This study investigated the effect of a modified yeast cell wall extract preparation (YCW) on the excretion of aflatoxin B1 (AFB1) and aflatoxin M1 (AFM1) in feces, urine, and milk of dairy ewes fed an aflatoxin-contaminated diet. Sixteen ewes in mid-lactation were assigned to 4 treatment groups: control, AF (60μg of AFB1/kg of feed), YCW (2g/kg of feed), and AF+YCW. The trial consisted of a short-term (3-d) exposure period followed by a long-term (21-d) exposure period. At the end of each exposure period, milk, urine, and feces were collected over 72h. The treatments did not affect feed intake, milk production, milk composition, or body weight. The presence of AFM1 was detected in all matrices, whereas AFB1 was only present in feces. Daily excretion was higher following long-term exposure and reached 26.9μg of AFB1/d in feces, 37.2μg of AFM1/d in feces, and 10.7μg of AFM1/d in urine. Supplementation with YCW was effective in increasing aflatoxin excretion in feces in the long-term exposure (up to 156% increase). The effect was accompanied by a trend of decreasing urinary excretion of AFM1. In contrast, the addition of YCW to the contaminated diet did not affect the transfer of aflatoxins from feed to milk under the present experimental conditions with low-producing ewes. The transfer rates of AFM1 in milk ranged from 0.24 to 0.54%. In conclusion, feed supplementation with YCW reduced the absorption of AFB1 and increased the elimination of AFB1 and AFM1 in ewe feces. Yeast cell wall extract could be used to protect ruminants from chronic exposure to aflatoxins present in feeds.