Other major factors which impacted the industry in the 20th century were the popularization of chemical fertilizers, the development of synthetic detergents, the widespread adoption of "boxed beef" in the USA, and the change in consumer eating habits to reject animal fats. In the early 20th century the low cost of synthesis of artificial nitrogen fertilizers undermined the economic use of animal waste to enrich soils. This resulted in the loss of a substantial market for meat by-product solids. But this lost market was replaced by the realisation that these products made good feed for animals. After World War II synthetic detergents came on the scene which eventually displaced soaps for both domestic and industrial washing uses.. Thus, in the early 1950's over 50% of the inedible fat market disappeared. Diversion in these materials into animal feeds soon replaced the lost soap market and eventually became the single largest use for inedible fats.

The widespread use of "boxed beef" in which the beef was cut up into consumer portions at the packing plant rather than at the retail level in local butcher shops and markets meant that the fat and meat scrap raw materials for renderers stayed at the packing plants and were rendered there by packer renderers, rather than by the "independent" renderering companies.

The rejection of animal fats by diet-conscious consumers led to a surplus of edible fats and their resultant diversion into soapmaking and oleochemicals, displacing inedible fats and contributing to the market volatility of this commodity.

The rendering industry is one of the oldest recycling industries, and made possible the development of a large food industry . The industry takes what would otherwise be waste materials and makes useful products such as fuels, soaps, rubber, plastics, etc. At the same time, rendering solves what would otherwise be a major disposal problem. As an example, the USA recycles more than 21 million metric tons annually of highly perishable and noxious organic matter. In 2004 the U.S. industry produced over 8 million metric tons of products, of which 1.6 million metric tons were exported