Abstract
The potent hepatotoxin and carcinogen aflatoxin B1 (AFB1) is a common mycotoxin contaminant of grains used in animal feeds. Aflatoxin M1 (AFM1) is the major metabolite of AFB1 in mammals, being partially excreted into milk, and is a possible human carcinogen. The maximum permitted concentration of AFM1 in cows’ milk is 0.05 μg/kg in Israel and the European Union. Since milk yield and the carry-over of AFB1 in the feed to AFM1 in the milk are highly correlated, it was considered important to determine the AFM1 carry-over in Israeli-Holstein dairy cows, distinguished by world record high milk production. Twelve such cows were used to determine AFM1 carry-over following daily oral administration of feed containing ~86 μg AFB1 for 7 days. The mean carry-over rate at steady-state (Days 3–7) was 5.8% and 2.5% in mid-lactation and late-lactation groups, respectively. The carry-over appears to increase exponentially with milk yield and could be described by the equation: carry-over% = 0.5154 e0.0521 × milk yield, with r2 = 0.6224. If these data truly reflect the carry-over in the national Israeli dairy herd, the maximum level of AFB1 in feed should not exceed 1.4 μg/kg, a value 3.6 times lower than the maximum residue level currently applied in Israel.
Highlights
Aflatoxins (AF) are hepatotoxic and carcinogenic secondary metabolic products from fungi belonging in particular to the Aspergillus flavus and A. parasiticus species [1,2,3,4].More than 20 AF-like secondary metabolites have been identified and aflatoxin B1 (AFB1) was shown to possess the most toxic and carcinogenic properties to humans and animals [2,3]
High milk yield and an early stage of lactation have been identified as the main factors contributing to increased carry-over [19,22]
AFB1 exposure of the Israeli cow characterized by an average daily intake of 25 kg dry matter (DM) feed and an average daily milk yield of 45 kg during early lactation [26,27] has to be below 1.4 μg/kg in the feed in order to ensure milk production compliant with the regulatory maximum residue level (MRL) of 0.05 μg/kg Aflatoxin M1 (AFM1) applied in Israel
Summary
Aflatoxins (AF) are hepatotoxic and carcinogenic secondary metabolic products from fungi belonging in particular to the Aspergillus flavus and A. parasiticus species [1,2,3,4]. More than 20 AF-like secondary metabolites have been identified and aflatoxin B1 (AFB1) was shown to possess the most toxic and carcinogenic properties to humans and animals [2,3]. AF are found as natural contaminants in many feedstuffs of plant origin, especially in cereals and in fruits, hazelnuts, almonds and foods consisting of, or manufactured from, these products and intended for human or animal consumption [1]. It is well known that AFB1 can cause chronic diseases in humans and animals and can have different effects such as hepatotoxicity, genotoxicity and immunotoxicity [2,3]. The primary disease associated with AFB1 intake is hepatocellular carcinoma, being the third-leading cause of death from cancer globally [8], with about 550,000–600,000 new cases each year [5,9] and aflatoxin may play a causative role in up to 28% of all global cases of hepatocellular carcinoma [5]
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