Animal feeds have an important role in enabling economic production of animal-source foods. Feeds may be produced in industrial feed mills or simple on-farm mixers or by hand mixing (Afsah-Hejri et al., 2013). Feed safety and supply are closely associated because the origin, processing, handling, and storage of feedstuffs, as well as other market related factors, can influence both quality and safety of feed at different levels (Pinotti, 2011).
Poor nutrition is a major barrier to market-oriented livestock production. It leads to a slow growth rate in growing animals and low production and reproduction performance. Poorly fed animals give a low output of meat and milk. Nutritional problems also lead to delayed age of onset of puberty, long parturition intervals, low conception rates, and low overall lifetime reproductive performance. Under poor feeding conditions, animals take too long to reach optimum slaughter weight and the meat produced by such animals may not satisfy the desired quality attributes to fulfill the demand of the consumers (Adugna, 2008).
Aflatoxin is one of the different types of mycotoxins fungal metabolites produced by some strains of Aspergillus flavus and Aspergillus parasiticus. Eighteen different aflatoxins have been identified, but the major aflatoxins found in animal feedstuffs are aflatoxin B1 (AFB1), B2, G1 and G2. Lactating mammals that ingest AFB1 deposit the 4-hydroxylated metabolite, aflatoxin M1 (AFM1), in their milk (Creppy, 2002). Aflatoxin is produced at a temperature ranging between 12°C and 40°C, and it also requires 3–18% moisture (Duncan and Hagler, 2008). Animals are exposed to aflatoxins through their feed (Gallo et al., 2015). Aflatoxins are produced in cereal grains as well as forages before, during and after harvest, in various environmental conditions (Yiannikouris and Jonany, 2002).
Several studies reported levels of aflatoxin levels in dairy cattle feeds, poultry layer feeds, broiler feeds, and feed ingredients which were above the recommended FDA limit (Gizachew et al.,2016; Rehrahie, 2018; Kotinagu, 2015; Greco, 2014). The presence of aflatoxins in feeds may decrease feed intake and affect animal performance. Besides, the possible presence of toxic residues in an edible animal product such as milk, meat, and eggs has detrimental effects on human health. Fungal contamination affects both the organoleptic characteristics and the alimentary value of feeds and entails a risk of toxicities (Akande et al., 2006; Gizachew et al., 2016).
Aflatoxins can cause acute or chronic toxic effects that can be characterized by mutagenic, teratogenic, carcinogenic, hepatotoxic, and immunotoxic nature (Chu, 2006). Several regulatory limits have been set for aflatoxins in feeds and feed ingredients. The levels vary depending on the feed type, ingredient type, or the age and type of animal that consumes the feed. Several countries use the guidelines established by the European Union (EU, 2002) or by the United States Food and Drug Administration (FDA, 2019) as a base for establishing regulatory limits. Although guidelines differ from each other, the maximum levels for aflatoxins are lower in the regulations given by the EU than those drafted by the FDA (Khanafari, 2007). The Ethiopian Standard Agency (ESA) has also set a regulatory limit of 20 µg/kg for both dairy and poultry feeds (ESA, 2019).
The presence of aflatoxin contaminated milk in the market is becoming an alarming problem. A recent study conducted on dairy and feed samples collected from the greater Addis Ababa milk shed indicated that all collected milk and feed samples had detectable levels of aflatoxin. Most of the milk was contaminated with aflatoxin M1 and it was presumed that aflatoxin M1 contamination in milk must have originated from aflatoxin B1 contaminated cattle feed of lactating cows (Gizachew et al., 2016; Rehrahie, 2018).
Considering the serious health related issues associated with aflatoxin, it is important to study the contamination level of animal feeds thoroughly. Possible factors for the contamination of animal source of food should be looked at to reduce the health risk of consumers and major economic setbacks. This study will investigate the occurrence and contamination level of aflatoxin in animal feeds and ingredients produced in Addis Ababa, Ethiopia.