Aflatoxins in cattle concentrate feed and potential carry‑over of aflatoxin B1 into milk in Dar es Salaam, Tanzania

Abstract

Aflatoxin contamination of animal feed threatens livestock production and can harm human health when aflatoxin B1 (AFB1) is carried over as aflatoxin M1 (AFM1) into milk for human consumption; therefore, aflatoxins in cattle concentrate feeds sold in Dar es salaam, Tanzania were determined in this study. Aflatoxins in cattle concentrate feeds were determined using Enzyme-linked Immuno-Sorbent Assay (ELISA) and High-Performance Liquid Chromatography with a Fluorescent Detector (HPLC-FLD) and potential carry-over was determined using carry-over equations. Aflatoxins were found in 78% of the concentrate feed samples in the range LOD to 161.32 µg/kg. The mean total aflatoxins (TAFs) was 25.89 ± 3.3 µg/kg, higher than WHO/US-FDA limit of 20 µg/kg in feed although the difference was insignificant (P = 0.81). AFB1 mean was 18.87 ± 2.45 µg/kg and significantly exceeded the WHO/US-FDA limit of 5 µg/kg of AFB1 in dairy feed (P = 3.05 × 10–10). Aflatoxins B2, G1 and G2, were also detected ranging from ND – 75.06 µg/kg. The calculated AFM1 in milk was in the range 0.001 – 0.363 µg/L in low milkers, 0.002–0.666 µg/L in medium milkers and 0.002–0.806 µg/L in high milkers. Carry-over was estimated to range from 1.2 to 1.7%. This study revealed that concentrate feed sold in Dar es salaam was highly contaminated with aflatoxins; noteworthy aflatoxin B1 exceeded the WHO/US-FDA limit implying potential carry-over into milk which could expose milk consumers to aflatoxins, hence livestock feed chain participants need to be sensitized.