Solar Dryer Design for Reduced Levels of Aflatoxin Contamination in Forage Products; An Attempt to Mitigate the Consequences of Climate Change

In dairy production, feeds and feeding account for more than 70% of the production cost. In the tropics, forage harvesting and conservation coincide with the peaks of the rainy season. This implies that there limited chances of having timely forge drying leading to wastage and toxin contamination. In most parts of northern Uganda, the long dry seasons are characterized by forage feed shortages in quality and quantity. This study therefore aimed at developing a forage dryer design that could help dairy farmers curb the loss associated with pasture farming-based dairy production. To assess the two solar dryer prototypes including open drying as a control, similar forage quantities were loaded and moisture content determined at 2-hour intervals between 7: 00-19: 00. Using open drying, the drying rates decreased with the increasing density of Brachiaria forage loaded in the solar dryer. Generally, the rate of drying decreased at decreasing rates with a decrease in moisture content of the Brachiaria forages. As a consequence, using the second derivatives of the regression equations, minimum forage moisture contents of 30.1, 10.4, 10.4, and 5.8 were obtainable at 21.05, 17.17, 17.17, and 15.8 hours, respectively. Similarly, in non-ventilated solar dryers, the drying rates decreased with the increasing density of Brachiaria forage loaded in the solar dryer. Generally, the rate of drying decreased at decreasing rates with the decrease in moisture content of the Brachiaria forages. As a consequence, minimum forage moisture contents of 5.3, 7.5, 19.6, and 31.7 were obtainable at 15.5, 17.0, 17.1, and 19.4 hours, respectively. At the forage loading density of 2.5kg/m2, there was a significant difference (pless than0.05) in both the drying rates and minimum obtainable moisture contents of the forages. However, when the forage loading density was increased to 5, 7.5, and 10.0 kg/m2, higher drying rates were obtained due to the ventilation of the solar dryer. As a consequence of the increase in drying rates with drying hours, minimum obtainable moisture contents of 27, 37, and 34 were observed at; 17, 16, and 23 hours after loading the none ventilated solar dryer. For the case of the ventilated solar dryer, however, minimum obtainable moisture contents of 6.3, 1.6, and 15 were observed at; 17, 20.6, and 23 hours after loading the ventilated solar dryer. Whereas solar drying increased the rates of drying, a well-ventilated solar dryer offers the optimum solar dryer design for best results.