Rapidly rising feed costs has everyone looking for ways to relieve the pain.

Implementing technologies designed to improve feed efficiency or reduce input costs often becomes critical. When implemented correctly, the aggressive use of synthetic amino acids is one such research-proven technology.

As an independent swine nutrition consultant, it surprises me how often this technology is not fully utilized in formulating swine diets. For a number of years, our clients have benefited from the feeding of high levels of synthetic amino acids with no adverse effects.

A closer look at the research, implementation, and cost savings realized from the use of high levels of synthetic amino acids during various phases of swine production is warranted.

Amino Acid Balancing Act

Understanding the relationships of supplemented amino acids to other nutrients and animal requirements is central to developing feeding strategies for all stages of production.

Amino acids are nitrogen-containing organic building blocks needed by all living organisms to synthesize proteins. The quantities and ratios of amino acids consumed daily are of major concern for the growth of lean tissue.

From birth on, all “essential” amino acids are supplied by the diet, while non-essential amino acids are synthesized in the body. Several of the essential amino acids available in a synthetic form include lysine, threonine, valine, tryptophan and DL-methionine, or the substitutes, Methionine Hydroxy Analog (MHA) and Alimet (Novus International). All other essential amino acids must be obtained from dietary protein.

As a nutrient, lysine is the first limiting amino acid in a corn and soybean meal-based swine diet. Therefore, you can add synthetic lysine as an ingredient to the diet and take out a defined amount of soybean meal and lower the overall level of protein.

Synthetic lysine is available in multiple feed-grade sources: L-Lysine HCl (78.8%), Lysine Sulfate (50.7%) and Liquid Lysine (50% and 60%). All sources have been proven efficacious and should be compared on a percent lysine basis.

To better understand the maximum level of synthetic L-Lysine HCl that can be added to swine diets, Kansas State University researchers conducted a study comparing a corn and soybean meal control diet to diets containing incremental levels of L-Lysine HCl. The results indicated no suppression in growth performance in pigs weighing from 65 to 265 lb. when diets contained up to 3 lb. of L-Lysine HCL (Figure 1).

This and other trials effectively illustrate how reducing soybean meal use by approximately 100 lb./ton of complete feed can lower the cost of a diet. One should note that only L-Lysine HCl and corn replaced the soybean meal.

Old Rules May Not Apply

The 3 lb./ton “rule of thumb” has been in place for many years, but with increased availability and relative lower cost for L-Threonine and methionine, strictly adhering to the old rule of thumb may no longer be the most cost-effective way to formulate swine diets.

Three commercial studies were conducted at the University of Missouri looking at the maximum inclusion level of L-Lysine HCl when a source of both synthetic methionine (DL-Methionine or Alimet) and threonine were also added to the diet. Results indicated that up to 7 lb. of L-Lysine HCl could be fed to pigs weighing 60 to 180 lb. (Figure 2, Ratliff 2005). In 2004, Kendall demonstrated that up to 4.5 lb. of L-Lysine could be added to diets for pigs weighing from 200 to 250 lb. Also in 2004, Ratliff showed that up to 8 lb. of L-Lysine HCl could be fed in diets containing ractopamine (Paylean from Elanco Animal Health).

The three trials demonstrate the effectiveness of feeding diets high in the synthetic amino acids lysine, threonine, methionine or Alimet.

Cutting Diet Costs

Figure 3 shows that by using 7 lb. of L-Lysine HCl (plus threonine and methionine) in early grower diets, and transitioning down to 4.5 lb. during late finishing, we can substantially reduce soybean meal levels by approximately 200 lb. and 125 lb., respectively. Furthermore, there is the potential for a similar reduction in soybean meal by utilizing up to 8 lb. of L-Lysine HCl when ractopamine is fed.

Given the current protein prices, substantial cost savings can be realized if high levels of synthetic amino acids are used. Figure 3 also demonstrates the cost of the diet can be reduced $4.41/ton of complete feed by utilizing 3 lb. of L-Lysine HCl compared to a corn and soybean meal diet without synthetic amino acids. Increasing L-Lysine HCl from 3 lb. to 7 lb. and utilizing a methionine and threonine source can realize an additional savings of $2.24/ton. Therefore, in this example, a savings of $6.65 can be realized by feeding these levels of synthetic amino acids.

While these savings are significant, I have witnessed savings nearly twice that amount. How much you save will depend on the relative cost of soybean meal to corn and the price paid for the synthetic amino acids.

Table 1 shows the relationship of the spread between corn and soybean meal and how the cost of synthetic amino acids affects the potential savings on a ton of grower feed. Feeding high levels of synthetic amino acids reduces diet costs, maintains performance and results in a significant reduction in cost per pound of gain.

It's Not Just About Lysine

In order to capture the potential savings with diets containing high levels of synthetic lysine, you must also include a methionine source and an added L-Threonine source. The amount of amino acids to use is determined by the ingredients in the diets and the stage of production. The appropriate ratio of these three amino acids to each other and to other amino acids must also be maintained.

For late-nursery and grower diets, it is generally necessary to supplement higher levels of methionine, whereas in mid- to late-finishing diets, a methionine source may not be necessary.

For example, when distiller's dried grains with solubles (DDGS) are fed, the amount of synthetic methionine and threonine required, relative to the amount of synthetic lysine, are reduced and the methionine is often not included in the mid- to late-finishing diets.

A potential problem for using high levels of synthetic amino acids may be the method by which producers buy their micro ingredients (i.e., base mixes and premixes). Some mixes contain synthetic lysine and some do not. The more traditional base mixes contain synthetic lysine at levels designed to supply approximately 3 lb./ton in the grower, with less L-Lysine supplied to the finisher diets.

No matter the type of base mix used, the producer should consult with his nutritional supplier to determine ways to feed the higher levels of amino acids. In order to capture the greatest savings, all three amino acids may need to be added at the mixer instead of in the base mix. This also allows flexibility in the sourcing of alternative ingredients to a corn-soybean meal diet.

For some producers, a two base mix program containing high levels of synthetics may be the only alternative to capturing some of the potential savings during the grow-finisher phase. Buying base mixes high in threonine and lysine, then adding methionine by hand, as needed, is another alternative. All options require a little more work than the base mix containing only 3 lb./ton L-Lysine. Whichever the method used, the economic savings are worth the minor trouble.

Two other synthetic amino acids are also commercially available — valine and tryptophan. We do not currently use these two amino acids in grow-finishing diets, but we do use them in nursery diets.

The use of synthetic amino acids at higher than traditional levels in swine diets is a proven technology, which can result in a substantial savings. Producers and buying groups that purchase sufficient quantities of these synthetic amino acids generally are able to capture a greater portion of the potential savings.