Seasonal Diversity and Occurrence of Filamentous Fungi in Smallholder Dairy Cattle Feeds and Feedstuffs in South Africa

Abstract

This study investigated 65 (35 in summer and 30 in winter) smallholder dairy cattle feeds from Free State and Limpopo provinces in South Africa from 2018 to 2019 for fungal contamination and assessed the impacts of seasonal variation on fungal contamination levels, isolation frequency, and diversity. Samples were examined for fungal contamination using macro- and microscopic approaches, and their identities were confirmed by molecular means. A total of 217 fungal isolates from 14 genera, including Aspergillus, Fusarium, and Penicillium, were recovered from feeds from both seasons. The most prevalent fungal species recovered were A. fumigatus and P. crustosum. Mycological analyses showed that 97% of samples were contaminated with one or more fungal isolates, with the summer fungal mean level (6.1 × 103 to 3.0 × 106 CFU/g) higher than that of feeds sampled during winter (mean level: 1.1 × 103 to 4.1 × 105 CFU/g). Independent sample t-test revealed that the isolation frequencies of the genera Aspergillus and Fusarium were significantly (p ≤ 0.05) higher in summer than winter, while Penicillium prevalence in both seasons was not statistically (p > 0.05) different. Furthermore, the Shannon–Weiner diversity index (H′) revealed a higher fungal diversity in summer (H′ = 2.8) than in winter (H′ = 2.1). This study on fungal contamination could be used for future fungal control and mycotoxin risk management in South Africa.

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

“…Mycotoxin contamination greatly contributes to agricultural product loss in SSA [ 41 ]. The prevalence of mycotoxin-producing fungi, particularly, Fusarium and Aspergillus , have previously been documented in feeds destined for smallholder dairy cows in both Free State and Limpopo provinces of SA [ 30 ], implying the presence of the mycotoxins recovered and reported herein.…”

“…Pure fungal strains ( n = 112) used in this study, including Aspergillus (83) and Fusarium (29), were recovered from smallholder dairy cow feeds collected from various dairy farms in Limpopo and Free State provinces in SA between summer 2018 and winter 2019. Information on fungal isolation and identification can be found in Adelusi et al [ 30 ]. The fungal isolates were tested for their potential to produce mycotoxins, including AFs (AFB 1 , AFG 1 , AFB 2, and AFG 2 ), DON, OTA, and ZEN by inoculating them on solid CYA agar ( Appendix A contains the procedures for agar preparation) treated with streptomycin and chloramphenicol to prevent bacterial growth.…”

“…The most prevalent toxigenic fungi in agricultural commodities are species belonging to the Aspergillus , Alternaria , Fusarium , and Penicillium genera [ 22 , 23 ]. Among them, Fusarium , Aspergillus , and Penicillium are considered the greatest producers of mycotoxins in cow diets worldwide [ 24 , 25 , 26 , 27 ], including SA [ 28 , 29 , 30 ]. Also, fungal toxins like aflatoxins (AFB 1 , AFB 2 , AFG 1 , and AFG 2 ) formed by fungal species in the genera Aspergillus ; ochratoxins (OTA and OTB) produced by Penicillium and Aspergillus spp.…”

Molecular characterization of gliotoxin-producing Aspergillus fumigatus in dairy cattle feed

“…The effects of fungus in maize grain, silage, and animal feed have been documented in other studies by Adelusi et al . [ 44 ], Nasaruddin et al . [ 45 ], Cavaglieri et al .…”

Mycotoxins evaluation of total mixed ration (TMR) in bovine dairy farms: An update

“…Since fungal development is very dependent on humidity and temperature conditions [ 63 ], current climate changes have a significant impact on the development of toxigenic fungi [ 64 ]. Climate change may alter the interactions between the host, its resistance, and the pathogen, thus influencing the production conditions of mycotoxins [ 65 , 66 ].…”