Seasonal and Geographical Impact on the Mycotoxigenicity of Aspergillus and Fusarium Species Isolated from Smallholder Dairy Cattle Feeds and Feedstuffs in Free State and Limpopo Provinces of South Africa.

This study evaluated the impact of seasonal and geographical variations on the toxigenicity of Aspergillus and Fusarium strains previously isolated from smallholder dairy cattle feeds and feedstuffs sampled during summer and winter in the Free State and Limpopo provinces of South Africa (SA). In total, 112 potential toxigenic fungal species were obtained and determined for their capability to produce mycotoxins on solid Czapek Yeast Extract Agar (CYA); followed by liquid chromatography-mass spectrometry (LC-MS/MS) analysis. Our result revealed that 41.96% of the fungal species produced their respective mycotoxins, including aflatoxin B1 (AFB1), aflatoxin B2 (AFB2), and zearalenone (ZEN), with higher levels of AFB1 (0.22 to 1045.80 µg/kg) and AFB2 (0.11 to 3.44 µg/kg) produced by fungal species isolated from summer samples than those in winter [(0.69 to 14.44 µg/kg) and (0.21 to 2.26 µg/kg), respectively]. The same pattern was also observed for AFB1 and AFB2 in Limpopo (0.43 to 1045.80 µg/kg and 0.13 to 3.44 µg/kg) and Free State (0.22 to 576.14 µg/kg and 0.11 to 2.82 µg/kg), respectively. More so, ZEN concentrations in summer (7.75 to 97.18 µg/kg) were higher than in winter (5.20 to 15.90 µg/kg). A similar observation was also noted for ZEN in Limpopo (7.80 to 97.18 µg/kg) and Free State (5.20 to 15.90 µg/kg). These findings were confirmed via Welch and Brown-Forsythe tests with significantly (p ≤ 0.05) higher mycotoxin levels produced by fungal strains obtained in samples during summer than those in winter. In contrast, the concentrations of mycotoxins produced by the fungal species from both provinces were not significantly (p > 0.05) different.

Feed-Based Multi-Mycotoxin Occurrence in Smallholder Dairy Farming Systems of South Africa: The Case of Limpopo and Free State.

Mycotoxin contamination of feed does not only cut across food and feed value chains but compromises animal productivity and health, affecting farmers, traders and consumers alike. To aid in the development of a sustainable strategy for mycotoxin control in animal-based food production systems, this study focused on smallholder farming systems where 77 dairy cattle feed samples were collected from 28 smallholder dairy establishments in the Limpopo and Free State provinces of South Africa between 2018 and 2019. Samples were analyzed using a confirmatory UHPLC-MS/MS (Ultra-high performance liquid chromatography-tandem mass spectrometry) method validated for simultaneous detection of 23 mycotoxins in feeds. Overall, mycotoxins assessed were detected across samples with 86% of samples containing at least one mycotoxin above respective decision limits; up to 66% of samples were found to be contaminated with at least three mycotoxins. Findings demonstrated that deoxynivalenol, sterigmatocystin, alternariol and enniatin B were the most common mycotoxins, while low to marginal detection rates were observed for all other mycotoxins with none of the samples containing fusarenon-X, HT-2-toxin and neosolaniol. Isolated cases of deoxynivalenol (maximum: 2385 µg/kg), aflatoxins (AFB1 (maximum: 30.2 µg/kg)/AFG1 (maximum: 23.1 µg/kg)), and zearalenone (maximum: 1793 µg/kg) in excess of local and European regulatory limits were found. Kruskal-Wallis testing for pairwise comparisons showed commercial feed had significantly higher contamination for deoxynivalenol and its acylated derivatives, ochratoxin A and fumonisins (FB1 and FB2), whereas forages had significantly higher alternariol; in addition to significantly higher fumonisin B1 contamination for Limpopo coupled with significantly higher enniatin B and sterigmatocystin for Free State. Statistically significant Spearman correlations (p < 0.01) were also apparent for ratios for deoxynivalenol/fumonisin B1 (rs = 0.587) and zearalenone/alternariol methylether (rs = 0.544).

Quantification of multi-mycotoxin in cereals (maize, maize porridge, sorghum and wheat) from Limpopo province of South Africa.

Mycotoxins are secondary metabolites that are produced by filamentous mycotoxigenic fungi belonging to the Alternaria, Aspergillus, Fusarium and Penicillium genera amongst others. Multi-class mycotoxins were extracted from 55 cereal samples and analysed using liquid chromatography-tandem mass spectrometry. The adopted extraction method for maize, maize porridge, sorghum and wheat was comprehensively validated. This method was further tested to determine the natural occurrence of mycotoxins in foodstuffs. Twelve (12) out of 22 mycotoxins were detected in maize, maize porridge, sorghum and wheat, including α-zearalenol (α-ZEL) (89%), fumonisin B3 (FB3) (84%), fumonisin B1 (FB1) (80%), tenuazonic acid (TeA) (78%), ochratoxin B (42%), deoxynivalenol (DON) (12%), ochratoxin A (11%), 3-acetyldeoxynivalenol (7%), sterigmatocystin (STG) (6%), 15-acetyldeoxynivalenol (2%), cyclopiazonic acid (CPA) (2%) and aflatoxin B2 (2%). The data revealed high incidence rate of α-ZEL (range: 6.5-70.5 µg kg-1) in all matrices. Maize samples had high mycotoxin co-occurrence compared to other matrices. All recovered mycotoxins in food commodities were within the maximum regulatory limits, with the exception of fumonisins (FB1 and FB3) exceeded the South African and European Commission regulation, and the highest concentration was 2153 µg kg-1 in maize. It is essential to monitor the level of emerging mycotoxins in food commodities from rural areas as trace amount of CPA (< limit of quantification), STG (range: 0.30-0.74 µg kg-1) were detected and high concentration of TeA (292.7 µg kg-1) was detected in sorghum. The occurrence of these mycotoxins further encourages frequent analyses, their co-occurrence in the samples poses a significant threat to public health and more emphasis should thus be placed on reducing the contamination levels of these toxins in staples.

Analysis of Mycotoxins Contamination in Poultry Feeds Manufactured in Selected Provinces of South Africa Using UHPLC-MS/MS.

A total of 105 different types of poultry feed samples from South Africa were simultaneously analysed for the presence of 16 mycotoxins using ultra-high-performance liquid chromatography coupled to a triple quadrupole mass spectrometer (UHPLC-MS/MS). The data revealed the presence of 16 mycotoxins in the various poultry feed samples. Fumonisin B1 (FB1) was the most dominant recovered from 100% of samples analysed at concentrations ranging between 38.7 and 7125.3 µg/kg. This was followed by zearalenone (ZEN) (range: 0.1-429 µg/kg) and deoxynivalenol (DON) (range: 2.5-154 µg/kg). Samples were also found to be contaminated with fumonisin B2 (FB2) (range: 0.7-125.1 µg/kg), fumonisin B3 (FB3) (range: 0.1-125.1 µg/kg), α-zearalenol (α-ZEL) (range: 0.6-20 µg/kg ), ß-zearalenol (ß-ZEL) (range: 0.2-22.1 µg/kg), 3-acetyldeoxynivalenol (3-ADON) (range: 0.1-12.9 µg/kg) and 15-acetyldeoxynivalenol (15-ADON) (range: 1.7-41.9 µg/kg). Alternaria mycotoxin, i.e., Alternariol monomethyl ether (AME) was recovered in 100% of samples at concentrations that ranged from 0.3-155.5 µg/kg. Aflatoxins (AFs) had an incidence rate of 92% with generally low concentration levels ranging from 0.1-3.7 µg/kg. Apart from these metabolites, 2 type A trichothecenes (THs), i.e., HT-2 toxin (HT-2) (range: 0.2-5.9 µg/kg) and T-2 toxin (T-2) (range: 0.1-15.3 µg/kg) were also detected. Mycotoxin contamination in South African poultry feed constitutes a concern as correspondingly high contamination levels, such as those observed herein are likely to affect birds, which can be accompanied by severe health implications, thus compromising animal productivity in the country. Such exposures, primarily to more than one mycotoxin concurrently, may elicit noticeable synergistic and or additive effects on poultry birds.

Multi-Mycotoxin Occurrence in Dairy Cattle Feeds from the Gauteng Province of South Africa: A Pilot Study Using UHPLC-QTOF-MS/MS.

The indispensable nature of toxigenic fungi and mycotoxins in agricultural systems is of worldwide concern, hence the need for surveillance studies to preserve public health. Thirteen dairy farms were surveyed and 40 dairy feeds of varying nature collected and analyzed for mycotoxins. Estimated levels of aflatoxins (AFs), fumonisin B1 (FB1), ochratoxin A (OTA), citrinin (CIT), zearalenone (ZEN), α-zearalenol (α-ZEL), ß-zearalenol (ß-ZEL), deoxynivalenol (DON), 3- and 15-acetyl-deoxynivalenol (ADONs), HT-2 toxin (HT-2), and beauvericin (BEA) were established using liquid chromatography-tandem mass spectrometry. Highest frequencies (40/40) were found for AFG2 (range: