Soybean meal is the most important protein source used to feed farm animals. It represents two-thirds of the total world output of protein feedstuffs, including all other major oil meals and fish meal. Its feeding value is unsurpassed by any other plant protein source and it is the standard to which other protein sources are compared. While it has been an accepted part of livestock and poultry diets in the USA since the mid-1930s, soybean feed production took off in the mid-1970s and then accelerated in the early 1990s due to a growing demand from developing countries. The expansion of aquaculture and prohibitions on the feed use of slaughterhouse by-products have also fueled the demand for this high-quality source of protein.