Design and fabrication of an improved forage chopper.

Abstract

Uganda is an agricultural country and its livestock sector contributes about 30% of the national Agriculture Gross Domestic Product (GDP) in the form of milk and meat and is a source of livelihood to about 4.5 million people living in the country (UIA, 2009). Animal feeding is a very important factor regarding animal husbandry and natural forage or pasture provides over 90% of the feed requirements for ruminant livestock (Sarwatt and Mollel, 2013). Forage is plant material (mainly plant leaves and stems) eaten by livestock. In most areas forage is fed to animals by providing it in form of whole crop. By doing this, a lot of forage is wasted and it also affects the digestion system of animals therefore for the complete utilization of forage, we need to cut the forage into small pieces with the help of a forage cutter.(Mustafa, 2016). Also through chopping, different grass varieties can be mixed together which increases on the palatability of the feeds. But most importantly, excess pasture grown during the rainy season has to be chopped and preserved in form of hay or silage which is the conserved green fodder having moisture content in the range of 65 to 70% (Anand, 2017) to await scarcity like during the dry seasons and this can be achieved using a mechanical device known as a forage chopper. Conceptualization of the machine involved two inter-related units; the feeding unit and the cutting unit. Different components of the machine were designed basing on the physical, mechanical and chemical properties of the forage, the components include; the feed hopper, feed rollers, blade shaft and roller shafts, main frame, driving mechanism and analyzing forces acting on the components to prevent failure. From the designs, cutting unit operates at a speed of 1050rpm and the feeding unit at a speed of 350rpm with a total maximum transmitted power requirement of 4HP after fabrication, the performance and economic analysis of the machine were performed in terms of chopping efficiency of 78.4%. Machine’s total cost; Ugx.1.125M, and its Net present value is 4,232282, and since its greater than 0, the project is viable, owing to the performance and economic analysis of the machine, it achieves all its design purposes hence it is recommended for commercialization and adoption by the target groups.