Occurrence and associated risk factors of aflatoxin contamination in animal feeds and raw milk from three agroecological zones of Tanzania

Abstract

Aflatoxins (AFs) are natural toxic compounds produced by a specific type of fungi, which subsequently contaminate foods and animal feeds, potentially carcinogenic to humans. This study assessed the AFs awareness, prevalence and associated risk factors through a survey of the smallholder dairy farmers (SDFs) and livestock feeds and raw cow milk samples from three agroecological zones in Tanzania. The aflatoxin awareness among SDFs (419) and agrovet dealers (26) was 23.2% and 50%, respectively. The prevalence of aflatoxin B1 (AFB1) in livestock feeds from agrovet dealers, and SDFs was 88.5 and 86.2%, with a concentration ranging from a limit of detection (LOD) to 22.99 and 32.9 μg/kg, respectively. However, 15.38 and 22.5% of AFB1 detected samples from agrovet dealers and SDFs exceeded the European Union (EU) and Tanzanian Bureau of Standards (TBS) limits of 5 μg/kg for dairy cow feeds. The prevalence of aflatoxin M1 (AFM1) in raw cow milk was 30.7%, of which 27.9% exceeded the EU and TBS limits of 0.05 μg/l for raw cow milk. The risk factors associated with AFB1 and AFM1 were cattle feeding systems: zero-grazing (odds ratio (OR) = 11.3 (1.5-22.9)) and mixed feeding (OR=16.0 (1.4-43.6)), use of concentrates feeds (OR=12.0 (0.6-55.6)), mixed feeding (OR=5.0 (0.5-11.1)); feed handling and storage practices: no moisture content measurement (OR=2.0 (0.3-15.0)) and storing feeds (OR=3.6 (1.7-8.5)); agroecological zones: central zone (OR=15.2 (5.4-50.6)) and northern zone (OR=2.1 (0.7-7.3)); aflatoxin (AF) awareness and level of education: primary (OR=16.0 (2.5-155.3)) and secondary education (OR=8.0 (2.14-43.9)) (P<0.05). This study revealed a high prevalence of aflatoxin contamination in animal feeds and raw cow milk, suggesting a potential health risk to consumers. Therefore, it is vital to increase awareness and knowledge on AFs, proper handling, storage and monitoring of feeds among the stakeholders in the dairy value chain.

Aflatoxins Contamination in Animal Feeds and Fresh Milk in Kondoa District, Tanzania

“…No sample exceeded the WHO, USFDA, and Codex Alimentarius limits (0.5 μg/kg). Contrary to the findings by Kang'ethe and Lang' [14] Negash, [20] in Kenya and Mwakosya et al [12], Kitigwa et al [13] in Tanzania, which revealed high occurrences of aflatoxin M1 (above 80%) with higher mean concentrations in milk samples collected from various stakeholders. These findings should be taken into account to justify the role of training programs on awareness of aflatoxins and their prevention among smallholder dairy farmers.…”

“…This study has assessed the association between storage practices and feeding practices to awareness of aflatoxin. It was found that feed storage and feeding practices have an insignificance association with awareness of aflatoxin, contrary to the study by Mohammedi-Ameur et al [11] and Kitigwa et al [13]. This may be attributed to the feeding system where most of the farmers adopted natural grazing without supplementation.…”

“…However, AFB1 in feeds intended for dairy cattle is limited to 20 µg/kg, while AFM1 levels in milk are limited to 0.05 µg/L according to TBS, Codex standard, and United States Food and Drugs Authority (USFDA). Studies conducted in some parts of Tanzania including Dar es Salaam, Morogoro, and Singida revealed higher levels of AFM1 in milk ranging from the limit of detection (LOD) to 2.007 ng/ml, as compared to the maximum daily intake of 1 ng/kg body weight/day for an adult [11][12][13]. The current study was conducted to assess the contamination of AFB1 in animal feeds and the occurrence of AFM1 in fresh milk, and to recommend the safety status of feeds and milk in the Kondoa district and what should be done to minimize aflatoxin contamination throughout Tanzania in general.…”