Effectiveness of a mycotoxin binder to minimize transfer of aflatoxin from feed to milk in Nili-Ravi buffaloes
Mycotoxins resulting from fungal contamination of feeds provide a major limitation for dairy production in Pakistan. The objectives of this study were to observe the extent of transfer of aflatoxinB1 in feed to the aflatoxinM1 metabolite in milk in Nili-Ravi buffaloes and to evaluate the efficacy of a mycotoxin binder incorporated into feed to minimize this transfer. Multiparous animals (n=28) were randomly distributed to four groups corresponding to 2 treatments each with 2 levels in a factorial design. Animals were offered mycotoxin contaminated concentrate ration (2.5 or 5kg/day) and corn (200 or 400g/day) providing a total of 1475 µg (groups A and B) or 2950ug (groups C and D) of aflatoxinB1 together with either 80kg (groups A and B) or 70kg (groups C and D) of aflatoxin free fresh cut berseem clover(17.8 % DM). AflatoxinB1 concentrations in feed for the low and high groups were therefore 88.7 and 171.2 ug/kg DM. Groups B and D were given 50g of mycotoxin binder daily mixed with feed while groups A and C were kept as controls. Feed samples were analyzed by HPLC in Romer Labs Pte Ltd, Singapore for aflatoxinB1 and milk samples were evaluated by ELISA for the liver metabolite aflatoxinM1. There was a highly significant difference (P<0.001) in total daily aflatoxinM1 concentration in milk between animals fed the two concentrations of aflatoxinB1. The mean for those fed 2950 µg/day was 112.62 µg/kg of milk, almost double the concentration of 62.19 µg/kg in buffalo fed 1475 µg/day (SED=5.99). The mean daily concentration of aflatoxinM1 in milk of animals from both treatment groups fed with 50g of mycotoxin binder was 76.51 µg/kg, nearly 22 µg lower than those without mycotoxin binder 98.31±5 µg/kg (SED=5.99: p<0.01). The interaction between the 2 treatments was not statistically significant. The total carryover of aflatoxinB1 from feed to aflatoxinM1 in milk was 5.06 and 4.14 % for group A and C (without mycotoxin binder) and 3.37 and 3.50 %, for groups B and D respectively fed the mycotoxin binder. Thus buffaloes are highly efficient at transferring mycotoxins in feed to the aflatoxinM1 metabolite in milk, while mycotoxin binder is capable of alleviating without preventing this contamination risk. In spite of this, the concentrations in milk still exceeded the European Union minimum standard of 0.05 µg/kg by over 150 fold. Strategies to minimize fungal contamination of concentrate feeds remains of importance for food security in Pakistan.
Keywords: AflatoxinM1, AflatoxinB1, transfer, milk, mycotoxin binder, Nili-Ravi Buffaloes