Livestock diet optimization with emphasis on reducing greenhouse gases emissions: A case study of an industrial nurture unit of Holstein dairy cows in Sari

In this study, two mathematical programming patterns were solved in order to determine the diet consistent with the environment for dairy cows. In first, the optimal diet was determined with the aim of minimizing ration cost, and in the next model, the optimal ration was determined with minimizing greenhouse gas emissions with non-increasing costs. According to the results in the conditions of determining the optimal ration based on the minimizing the ration cost, sugar beet pulp, wheat bran, wheat straw and barley make the most of it. Also, materials such as corn, fish, and soybeans are removed from the diet. In order to reduce greenhouse gas emissions in different scenarios, materials such as corn silage, beet pulp and wheat bran have a higher share than other materials. Barley and Wheat straw are also products that reduce the amount of greenhouse gases in the diet. Based on the results, in order to reduce the greenhouse gas emissions by 26.6%, it is necessary to spend about 20% more than the cost of conventional models.