History of the Corn-soy Diet

Abstract The soybean plant is native to Asia and seeds were first brought to the US in 1765, but it was not widely grown until the mid-20th century. It was the increased demand for cooking oil during WWII and introduction of new lipid processing methods in the late 1940’s that made soybean oil suitable for use in human food and led to the availability of increased quantities of the co-product, soybean oil meal (SBM), for use in animal diets. SBM was produced as early as 1915, and some research was initiated to understand the nutritional qualities of the product. For example, in 1917, it was shown that heat treatment improved growth in rats and that effect was later shown due to destruction of certain proteins in the soybean that inhibited function of digestive enzymes. With increasing production of SBM in the late 1940’s and recognition that it contained an excellent profile of essential amino acids, efforts to feed swine a corn-SBM diet supplemented with vitamins and minerals known to be necessary were undertaken but growth was less than optimal unless the formulation included one or more animal by-product ingredients. A significant amount of research was done to identify the so-called animal protein factor but without success. That changed with the discovery of vitamin B12 in 1948 and the subsequent commercial production by microbial fermentation. In 1949 it was demonstrated that vitamin B12 is an essential nutrient for swine. Subsequent swine feeding trials in the early 1950’s confirmed that a corn-soy diet supplemented with vitamins, including B12, and minerals resulted in growth equivalent to swine fed comparable diets that included some animal protein. In the mid-1950’s producers with access to SBM began to shift to on-the-farm manufacture of vitamin and mineral fortified corn-soybean meal diets. With that the pork industry market for both compound complete feeds and protein supplements began to decline and the demand for smaller vitamin and mineral packages for use in on-farm feed production increased with consequences for the feed industry. It is arguable that the decades of research leading to the corn-SBM diet was one of the most consequential developments in swine nutrition in the 20th century. Ongoing and future research will continue to identify and confirm the appropriate applications of dietary SBM in commercial pork production.