Paper Title
Quantification of Energy and Environmental Aspects of Iranian Dairy Farms Based on Optimal Nutrition

Abstract
Input and output energy are all important aspects for evaluating the performance of dairy farms which have been used in a multi-indicator modeling approach to optimize the performance of30 dairy farms in Khorasan Razavi Province (Iran). Total input and output energy, energy ratio, energy productivity, and net energy gain across all farms are 7.5×1008 MJ, 4×1008 MJ, 0.53, 0.13 kg/MJ and -3.5×1008 MJ, respectively. Therefore, in order to reduce the energy “consumption” for dairy farms in this region, we built an optimization model using multi-objective fractional mathematical programming and considered the renewable energy, energy intensity, GHG emissions, and animal feed costs as objective functions. Total optimization achieved all goals is 0.5467. The proposed nutrition was confirmed based on the results of the main model and means if the farmers use the proposed diet including 26.8 kg/day, 22.2 kg/day and 19 kg/day of total intake feed for high milk cow, middle milk cow and low milk cow, respectively, in addition to reducing feed costs, energy consumption and GHG emissions associated with dairy farms will also decrease. Our model can be used in various contexts to improve the environmental and energy performance of dairy farms based on an optimal nutrition. Keywords - Energy indicators, Dairy cattle nutrition, Multi-objective fractional mathematical programming, Dairy farms, Iran.