Effect of yeast cell wall and (1-3) b-D-glucan on transfer of aflatoxin from feed to milk in Sannen dairy goats

Abstract

Aflatoxin B1 (AFB1) is a carcinogenic compound of global concern due to its occurrence in milk as aflatoxin M1 (AFM1). The aim of this study was to investigate the potential reduction of carryover of feed AFB1 to dairy goat milk by yeast cell wall (CW) and its (1→3)-β-D-glucan (βG). To this end, the CW was physically extracted and its βG was also extracted by a modified method. Twenty one Saanen dairy goats (44.2 ± 4.10 kg BW) were assigned to 3 groups receiving 25 μg AFB1/kg DMI (AFB1 group), AFB1 group+5 g CW/d (AFB1+CW) and AFB1 group+3 g βG/d (AFB1+βG) in a completely randomized design. After one week of adaptation, all goats experienced a mild-15-day-AFB1 challenge during which their performance, DMI, AFM1 carryover and blood parameters were evaluated. Initial and final BW, milk yield and milk composition, DMI and efficiency of feed intake were similar among different groups, while energy corrected milk (ECM)/DMI were higher in βG and CW fed goats (1.28 and 1.24, respectively) compared to AFB1 group (0.92, p=0087). The AFB1+βG group had significantly lower milk AFM1 concentration, milk AFM1 excretion, and carryover than AFB1 group. The carryover of milk AFM1 (%) in AFB1, AFB1+CW and AFB1+βG groups were 0.29, 0.20 and 0.09 respectively in 3rd day (p=0.007) and 0.22, 0.11 and 0.6 respectively in 15th day (p=0.01). The milk AFM1 content of AFB1+CW group at 3rd day of experiment showed that CW failed to sequester AFB1 effectively, because milk AFM1 concentration, excretion, and carryover were similar to AFB1 group. The white blood cells (WBC), red blood cells (RBC), hemoglobin, hematocrit, total protein, aspartate transaminase (AST), alanine transaminase (ALT) and leukocyte count of different experimental groups were not significantly different. Overall, the results of this study indicated that βG had more AFB1 binding ability than CW and could reduce milk AFM1 concentration below the maximum permitted level of milk AFM1 set by European Commission without adverse effects on milk production and milk composition; therefore, it may be used as a potent AFB1 absorbent in livestock diet.