Abstract

RANGEL-MUNOZ, Erika Janet et al. Characterization of Aspergillus flavus and quantification of aflatoxins in feed and raw milk of cows in Aguascalientes, Mexico. Rev. mex. de cienc. pecuarias [online]. 2020, vol.11, n.2, pp.435-454.  Epub Oct 23, 2020. ISSN 2448-6698.  https://doi.org/10.22319/rmcp.v11i2.5686.

Contamination of agricultural and livestock products with aflatoxins (AF) is distributed worldwide. AFs are toxic, carcinogenic, and immunosuppressive; however, in Mexico, there is little information about Aspergillus flavus, the main fungus that produces them. The objective was to characterize the molecular and morphological, aflatoxigenic isolates of A. flavus and quantify the AFs in the feed and in the milk of Holstein cows in Aguascalientes (Mexico). A dairy production unit (2,749 cows) was selected for reasons of convenience, and monthly samples of food ingredients and total mixed ration (n= 267), raw milk (n= 288), and agricultural soil (n =40) were collected during 24 months and were cultivated (in PDA) using the pour plate technique with serial dilutions. The fungi were characterized using SEM, TLC and vapors of ammonium in coconut agar; the genes of calmodulin and a regulator of the biosynthetic pathway of AF, as well as the region of the internal spacer of the transcript, were sequenced. AFs were quantified in feed with HPLC and in milk, using ELISA. A total of 283 fungal isolates were characterized molecularly; of which 88 proved to be Aspergillus spp. Five of these were A. flavus with an aflatoxigenic capacity, and one was non-aflatoxigenic. 99.3 % of the samples of feed and 39.9 % of the milk samples exhibited detectable levels of AF (14.8 and 0,021 µg/kg). The cows ate daily 621 µg of AF and eliminated 0.09 % as AFM1 in milk. This suggests that the occurrence of aflatoxigenic A. flavus in the feed of dairy cows leads to a widespread contamination of the diets and food chain with AF.

Keywords : Aflatoxins; A. flavus; Dairy foods; Calmodulin gene; Regulatory gene of aflatoxin.

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