Design and evaluation of an extruder to convert crop residues to animal feed

In the dry season in most of the livestock-growing regions in developing countries, the scarcity of good-quality forage makes it very difficult not just to maintain the bodyweight of animals but even to prevent their death. The paper describes the design and performance evaluation of an extruder able to convert crop residues and low-cost industrial by-products into briquettes of about 25 mm diameter to be used as animal feed. The extruder is a versatile machine that can be driven by the power take-off of category II agricultural tractors already available in most farming regions in Mexico. It is also shorter and has a lower specific energy than commercially available extruders. Performance tests showed that most of the requirements of small farmers could be fulfilled by this extruder. The extruder capacity was between 440 and 970 kg h−1 of air-dry material and typically had a power consumption of up to 36 kW. The bulk density of the briquettes found was in the range from 315 to 453 kg m−3 and the durability measurements showed average values of 92%.