Vaccination of Heifers with Anaflatoxin Improves the Reduction of Aflatoxin B1 Carry Over in Milk of Lactating Dairy Cows

It was previously reported that injection of anaflatoxin B₁ (AnAFB₁) conjugated to keyhole limpet hemocyanin (KLH), together with Freund''s adjuvant, was effective in inducing in cows a long lasting titer of anti-aflatoxin B₁ (AFB₁) antibodies (Abs), cross-reacting with other aflatoxins, which were able to hinder, proportionally to their titer, the secretion of aflatoxin M₁ (AFM₁) into the milk of cows continuously fed with AFB₁. According to anti-AFB₁ Ab titer, 50% of the vaccinated cows were recognized as high responder animals. In an attempt to prepare a more effective formulation for vaccination of cows, it was compared the immunogenicity, in Holstein Friesian heifers, of AnAFB₁ covalently conjugated to KLH or to recombinant diphtheria toxin (CRM₁₉₇) molecules, and injected together with various adjuvants. This study demonstrated that injection of AnAFB₁ conjugated to KLH and mixed with complete (priming) and incomplete Freund''s adjuvant (boosters), as in the previous schedule of immunization, was the most effective regimen for inducing Ab responses against AFB₁, although pre-calving administration could increase the effectiveness of vaccination, resulting in 100% high responder animals. After one booster dose at the beginning of the milk production cycle, anti-AFB₁ Ab titers were comparable to those recorded at the end of the immunization schedule, and proved to be effective in reducing significantly AFB₁ carry over, as AFM₁, from feed to milk. Pre-calving vaccination of dairy heifers with conjugated AnAFB₁, adjuvated with complete and incomplete Freund''s adjuvant, may represent the most effective tool for preventing the public health hazard constituted by milk and cheese contaminated with aflatoxins.