Quantitative Analysis of Total Aflatoxins in Dairy Cattle Feed Using a Competitive Lateral Flow Immunoassay: A Regional Study in Tigray, Ethiopia.

Abstract

Aflatoxins are toxic fungal metabolites produced mainly by Aspergillus flavus and A. parasiticus, posing serious health risks when they contaminate food and animal feed. In dairy systems, ingested aflatoxin B1 (AFB1) is metabolized in lactating cows and excreted in milk as aflatoxin M1 (AFM1), transferring the toxic burden to consumers. This study provides the first region-specific quantitative assessment of total aflatoxin contamination in dairy cattle feed across five major towns in Tigray, northern Ethiopia: Mekelle, Wukro, Adigrat, Korem and Alamata. Feed samples were analysed using the Competitive Lateral Flow Immunoassay system. A cross-sectional survey conducted from February to May 2025 involved 143 feed samples collected directly from farms. Substantial spatial variability in aflatoxin concentrations was observed across the study area. The mean total aflatoxin concentration was 8.84 µg/kg (SD = 15.21), with 22.4% of samples exceeding the Ethiopian regulatory limit (20 µg/kg), 29.1% surpassing the European Union threshold (5 µg/kg) and 74.1% falling below the EU limit. Roughage-based and traditional feeds showed significantly higher contamination than commercial concentrates. Major risk factors included high storage temperature, extended storage duration, soil-floor storage and the presence of toxigenic fungi, particularly A. flavus and A. parasiticus. Multivariate analysis confirmed fungal species type and total fungal colony count as the strongest predictors of aflatoxin levels. Alarmingly, 81.8% of farmers lacked awareness of aflatoxins, and 68.5% stored feed outdoors under unsafe conditions. Fungal isolation, species identification, toxigenicity testing and detection of aflatoxin metabolites in milk or meat were not included in this study. These findings reveal a systemic feed safety issue in the dairy sector of Tigray and indicate the need for integrated interventions, including farmer education, improved storage practices, routine monitoring and stricter regulatory enforcement. These baseline data are critical for informing local feed safety interventions and guiding aflatoxin risk management and policy development to support sustainable dairy production and public health in Ethiopia.