In the first, “op ti mis tic” sce nario, feed con ver- sion ra tios im prove pro gres sively. About 1 per cent more meat per year is pro duced per kilo gram of feed in de vel op ing coun tries, with a com pounded ef fect over time. This mir rors the rapid tech no logi- cal prog ress ob served in the de vel oped coun tries from the early 1980s to the early 1990s. Under the op ti mis tic sce nario, feed con ver sion ef fi ciency in de vel oped coun tries im proves by only .