The productivity of livestock in the tropics has been grossly limited by the scarcity and consequent high prices of conventional protein and energy sources feed. The identification of new feed resources is crucial for sustainable animal production and future viability. Even though Spirulina occurs naturally in different rift valley lakes of Ethiopia there is no information available with regard to the utilization and nutritive value of Spirulina. Therefore, a study to assess availability and farmer's perception about the utilization of Spirulina (Arthrospira fusiformis) and comparative evaluation of the nutritive value of Spirulina and conventional referenced protein feeds in selected rift valley areas of Ethiopia was conducted. Overall, this book will help farmers, different stakeholders, students, researchers and governmental organizations in making information accessible.