Abstract:
Crop residues, such as straw, chaff, stalk, stover, bran, etc., are roughages that can be processed
as livestock feeds after crops have been harvested, and grains/seeds detached. The residues are
piled in stacks near homesteads, and animals are either allowed to eat directly or given a small
quantity as deemed necessary without processing. Nonetheless, unprocessed maize and sorghum
stover are not palatable and prone to wastage due to their natural sizes. To overcome this
problem, the physical and mechanical properties of stover, such as moisture content, diameter,
length, weight, and cutting resistance, were studied, and a size-reduction stover crusher, was
designed, manufactured, and evaluated. The functional parts of the crusher were the stover inlet,
crushing chamber, rotating blades, counter shear, half-bore shaft, outlet chute, supporting
frame, motor seat, and high-speed electric motor. An operator was used to feed the stover
through the feed inlet into the crushing chamber where rotating blades and counter shear
effected the crushing of the stover. The crushed stover was forced out through an outlet chute
due to the centrifugal force imparted on the chopped pieces. The treatments were arranged in a
factorial arrangement in a CRD with three replications. The crusher was evaluated at three
levels of feed rate, 250.00, 500.00, and 750.00 kg/hr, and three levels of rotating blades, 2, 3,
and 4. The collected data were analyzed using GenStat 18th edition statistical software. From
the analysis, it was noted that better performance was obtained at a feeding rate of 750.00 kg/hr
where 4 rotating blades were used. Crushing capacity of 710.40 and 727.90 kg/hr, crushing
efficiency of 94.74 and 97.06 %, coarsened stover, of 3.94 and 2.27 %, and crushing losses of
1.30 and 0.67 % were recorded, for sorghum and maize stover, respectively. ANOVA indicated
that feed rate and blade number had a significant effect on the crushing efficiency, crushing
capacity, fineness, and coarsened stover at a 95.00 % level of confidence, but had not significant
effect on crushing loss. Hence, as the blade number increased, the crushing capacity and
efficiency increased keeping the feed rate constant. However, as the feed rate increased,
crushing efficiency decreased, but crushing capacity increased due to an increment in feed rate,
keeping the crushing blades constant. To improve the chopper, it is recommended that further
study be made on blade bevel angle and thickness, feeding mechanism, and crushing chamber
material. Further evaluation of the chopper with other crop residues to make it versatile is
essential
