Poultry enterprise has been providing quality protein sources in the form of meat & eggs since its domestication. However, due to rapidly growing human population, every passing year multiplies the need of animal protein for human consumption. To increase protein production by this sector, adequate supply of quality feed is part and parcel. On tropical & subtropical belt of the globe, shortage & irregular supply of protein feed ingredients are considered the main attributes of decreased meat & egg production. Their adverse effects can be diluted by enrichment of low protein quality stuff by microbial growth or single cell protein (SCP) production. Comparative production potential of SCP is often quoted as, a 0.5t bullock synthesizes less than 0.5Kg of protein in 24-hr, however, 0.5t of soybeans produces the equivalent of 40Kg protein in 24-hr while 0.5t of yeast generates 50t in this time. Production of SCP requires less space and is independent of climate and produces less pollution, a burning issue in animal agriculture. This document reflects optimizing conditions for SCP & its response by birds when used as feed.