Occurrence and Levels of Aflatoxins in Fish Feeds and Their Potential Effects on Fish in Nyeri, Kenya

Abstract

Aflatoxins are fungal metabolites that contaminate foods and feeds, causing adverse health effects in humans and animals. This study determined the occurrence of aflatoxins in fish feeds and their potential effects on fish. Eighty-one fish feeds were sampled from 70 farms and 8 feed manufacturing plants in Nyeri, Kenya for aflatoxin analysis using competitive enzyme-linked immunosorbent assay. Fish were sampled from 12 farms for gross and microscopic pathological examination. Eighty-four percent of feeds sampled tested positive for aflatoxins, ranging from 1.8 to 39.7 µg/kg with a mean of 7.0 ± 8.3 µg/kg and the median of 3.6 µg/kg. Fifteen feeds (18.5%) had aflatoxins above the maximum allowable level in Kenya of 10 µg/kg. Homemade and tilapia feeds had significantly higher aflatoxin levels than commercial and trout feeds. Feeds containing maize bran and fish meal had significantly higher aflatoxin levels than those without these ingredients. Five trout farms (41.7%) had fish with swollen abdomens, and enlarged livers with white or yellow nodules, which microscopically had large dark basophilic hepatic cells with hyperchromatic nuclei in irregular cords. In conclusion, aflatoxin contamination of fish feeds is prevalent in Nyeri, and may be the cause of adverse health effects in fish in this region.

Occurrence of Mycotoxins in Fish Feed and Its Effects: A Review

“…In Bagdad, deoxynivalenol was detected at a concentration range from 2.0 to 5.0 mg/kg, while zearalenone was detected at concentrations of 0.5-5.0 mg/kg [49]. In Kenya, aflatoxins were detected in 84.0% of fish feed samples, in a mean concentration of 7.0 µg/kg (1.8 to 39.7 µg/kg) [50]. It is important to notice that mycotoxins are more commonly found and in higher concentrations in farm-made feed than in commercial feed [50].…”

“…In Kenya, aflatoxins were detected in 84.0% of fish feed samples, in a mean concentration of 7.0 µg/kg (1.8 to 39.7 µg/kg) [50]. It is important to notice that mycotoxins are more commonly found and in higher concentrations in farm-made feed than in commercial feed [50]. As farm-made feed is more commonly formulated in developing countries, this might contribute to why contamination by mycotoxins is more frequent developing countries.…”

“…Rainbow trout (Oncorhynchus mykiss) is the most sensitive fish species to aflatoxins. Chronic exposure to low levels of this toxin (as low as 0.0004 mg/kg) has been shown to increase the chances of rainbow trout developing cancer [50,67]. When these fish were fed a diet with 0.02 mg/kg of aflatoxin B 1 for 8 months and for 12 months, the occurrence of liver tumors was 58.0% and 83.0%, respectively [67].…”

“…The LD 50 calculated for channel catfish (Ictalurus punctatus) was 11.5 mg/kg of bodyweight (intraperitoneal administration) [76], around ten times higher than that of rainbow trout. Nile tilapia (Oreochromis niloticus) has also been shown to be less sensitive than rainbow trout to aflatoxin B 1 [50]. The LD 50 calculated for Nile tilapia was 1.0 and 1.3 mg/kg of bodyweight to aflatoxin B 1 [77].…”

Effects of the Use of Good Agricultural Practices on Aflatoxin Levels in Maize Grown in Nandi County, Kenya

“…Aflatoxins have received quite a bit of attention in Kenya over the last three decades [3][4][5][6][7][8][9], the most recent of which has been the case of aflatoxin contaminated peanut butter [10][11][12]. Associations between the nutritional status of children and dietary exposure to aflatoxins have been reported in studies conducted in Nairobi and Kisumu [13,14].…”