Cattle as competitors for biomass energy

Abstract

Crop residues represent a biomass source that have been extensively studied as a potential energy source. Fuel use would produce competitive demands for this resource to the cattle industry. A linear programming model of the United States beef production systems which maximized beef production was used to evaluate the potential contribution of crop residues to the support of beef cattle. Changes in the resource inputs of land, feed supplies and energy were determined along with beef output volume and quality. The scenarios studied included decreases of 25% from the current feeding systems in: (1) corn grain; or (2) silage; or (3) grazed forage; (4) corn grain and silage; (5) corn grain, silage and grazed forage; and (6) total elimination of corn grain and silage. Each scenario examined the system with and without crop residues. In addition to the maximize beef production objective function, the baseline scenario was run with another objective function which minimized energy use. Crop residues served to replace most of forage from grazing or silage. When corn grain was reduced beef production and beef quality declined. Land requirements were automatically reduced by feeding crop residues because land use was charged only to grain production. In all cases feeding residues reduced the energy requirement per kg of beef produced. Energy minimization resulted in a decline from an input of 95.0 to 47.7 × 10 9 Mcal while total beef production remained the same although quality grade was lower. When the feeding value of residues was compared to other energy production alternatives for biomass sources, such as gasification or direct combustion, with the manure produced from the cattle used for methane and the residue used as fertilizer, this alternative provided 3,020 Mcal of energy at a dollar substitution of $45.60 per ton.