Adel Vahedi
Abstract
The worldââ¬â¢s population and food consumption are increasing drastically while natural resources are decreasing. In particular, energy use is an important component of reaching sustainability in agricultural production processes because of its shortage as resource. Animal husbandry is one of the important subsectors of agriculture. Reducing energy inputs and enhancing energy use efficiency (EUE) are essential to ensure energy security and long-term sustainability of dairy cattle farms. The objectives of this study were to assess and compare energy flowin terms of energy input and output, yield, energy use efficiency(EUE), energy productivity (EP), net energy gain(NEG) and energy intensity(EI). The inputs in the calculation of energy use included human labour, machinery, electricity, diesel fuel, gasoline, natural gas, feed and building while milk, cow meat, calf meat, heifer meat and manure were included in the outputs. The results showed that the input and output energies for a one cycle of lactation were 193690.75 and 36886.48 MJ per head of cow, respectively. Livestock feed and diesel with 76.96% and 8.93% had the highest share in input energy, respectively, and the labor with 0.22% had the lowest share in input energy. Energy use efficiency (EUE), energy productivity (EP), specific energy (SE), net energy gain (NEG) and energy profitability (EPR) were calculated as 0.19, 0.086 kg.MJ-1, 11.64 MJ.kg-1, -156804.27 MJ.(a head of cow)-1 and -0.799, respectively.