Interaction of strains of non-toxigenic Aspergillus flavus with Aspergillus parasiticus on aflatoxin production
Aflatoxins production is affected by abiotic, biotic and genetic parameters. Eugenesic and dysgenetic condition for aflatoxinogenesis are relatively well studied, such as: the influence of temperature, pH, Aw, Oxigen tension, osmotic pression, organic and inorganic nutrients, substance with fungistatic effects: however there are relatively few knowledge about endogenous regulator mechanisms, the kinetic of the anabolism and the interaction between the productive moulds and remaining microflora holding in eutrophying substrates. The main objective of this study is to evaluate biotic interaction between five indigenous strains of A. flavus, confirmed non-toxigenic, and a productive strain (A. parasiticus ATCC 15 517), cultured simultaneously on two substrates: one natural (cracked corn) and a synthetic one, modified Czapeck-Dox broth. Aflatoxins quantifications were performed by HPLC at 8th and 12th days. Results of those interactive cultures showed that all strains were synergic, increasing aflatoxins production in a range between 5.6 and 106.5% over the control values, with an exception registered on one of the strains cultured in cracked corn at the 12th day, where the production decreased (-7.6%).
Reduction in Aflatoxin Content of Maize by Atoxigenic Strains of Aspergillus flavus.
In field plot experiments, an atoxigenic strain of Aspergillus flavus interfered with preharvest aflatoxin contamination of corn when applied either simultaneously with or one day prior to a toxigenic strain. The atoxigenic strain reduced preharvest aflatoxin contamination 80 to 95%. The atoxigenic strain was also effective in reducing postharvest aflatoxin contamination caused by both an introduced toxigenic strain and by strains resident on the kernels. The results suggest that atoxigenic strains of A. flavus may have potential use as biological control agents directed at reducing both preharvest and postharvest aflatoxin contamination of corn.
Drivers of Live Cattle Price in the Livestock Trading System of Central Cameroon
Livestock production and trade are critical for the food security and welfare of rural households in sub-Saharan Africa. In Cameroon, animal trade consists mainly of live cattle commercialized through livestock markets. Identifying the factors contributing to cattle price formation is critical for designing effective policies for sustainable production and for increasing food availability. In this study, we evaluated the influence of a range of individual- and market-level factors on the price of cattle that were sold in all transactions (n = 118,017) recorded over a 12-month period from 31 livestock markets in the main cattle production area of the country. An information-theoretic approach using a generalized additive mixed-effect model was implemented to select the best explanatory model as well as evaluate the robustness of the identified drivers and the predictive ability of the model. The age and gender of the cattle traded were consistently found to be important drivers of the price (p < 0.01). Also, strong, but complex, relationships were found between cattle prices and both local human and bovine population densities. Finally, the model highlighted a positive association between the number of incoming trading connections of a livestock market and the price of the traded live cattle (p < 0.01). Although our analysis did not account for factors informing on specific phenotypic traits nor breed characteristics of cattle traded, nearly 50% of the observed variation in live cattle prices was explained by the final model. Ultimately, our model gives a large scale overview of drivers of cattle price formation in Cameroon and to our knowledge is the first study of this scale in Central Africa. Our findings represent an important milestone in designing efficient and sustainable animal health management programme in Cameroon and ensure livelihood sustainability for rural households.