44 Amino acids in livestock: A historical perspective

Abstract

Abstract The advent of commercially viable synthetic amino acids (AA) and least cost formulation (LCF) have fundamentally changed swine and poultry diets over the past 40 years. Amino acids can be produced by chemical synthesis, hydrolysis of intact proteins and fermentation. Chemical synthesis of AA was first reported by Strecker (1850). Discovery of glutamate as the basis of Umami taste category (1907) spurred commercial AA production by hydrolysis. The discovery of commercially viable fermentative production of glutamate, by Kyowa Hakko Kogyo Co. (1957), revolutionized AA production. Their parallel discovery of lysine (Lys) production, using a natural C. glutmanicum mutant subsequently followed. This led to further screening for bacterial mutants for threonine (Thr, 1961), tryptophan (Trp, 1972), valine (Val, 1959) and isoleucine (Ile, 1972). The next milestone occurred with development of the first main-frame LCF programs (1960s). The first commercial application of dietary AA involved methionine (Met) for poultry, followed closely by Lys in swine. Use of other synthetic AA was cost-prohibitive, but they served as research tools. The next revolution involved recombinant DNA technology (1980s), which dramatically increased AA yield and reduced production cost. Simultaneously, development of PC based LCF enabled cost effective formulation. Subsequently, growth-derived AA ratio’s emerged from the labs of Fuller (1989) and Baker (1992). Patent expirations in the late 1980s led to new companies that produced rapid advances in fermentation methods, with new recombinant strains. Production cost declined further for Lys (1988), and production efficiencies allowed Thr (1995) and Trp (2000) to enter commercial diets. Advances in fermentation technology have enabled production of all ten essential AA. Extensive AA displacement of protein supplements has led to an ever-expanding global tonnage of AA for food and pet animals. With routine addition of 4–6 AA in swine diets, we question whether non-essential AA nitrogen may emerge as limiting (essential).