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Introduction
It is well known that ruminants need bioavailable essential amino acids to perform as well as domesticated livestock (2,4). For this goal, if ruminants, like dairy cows, have not met their minimum requirements for essential amino acids such as lysine and methionine, they will not produce milk at optimum yield and generally, their health may be negatively impacted. Providing essential amino acids for ruminants is not simple. For example, bacteria in the rumen are known to routinely degrade amino acid, like lysine and methionine. This is done by bacteria in order to rumen metabolize the amino acids and thus “rob” the animal of the benefit of the amino acid. By the time the metabolized by-product passes from the rumen into the intestine, the amino acid is gone. Therefore, the challenge is to develop products which will allow amino acids to be stable in the rumen environment, but still capable of absorption when they pass from the rumen into the intestine. In other words, the essential amino acids, such as lysine and methionine, need to be bioavailable only in the intestine, and remain stable, and therefore, not metabolized in the rumen.
Previously, feed developers have used fats, minerals, carbohydrates, and binders to protect amino acids from rumen degradation. This technology involves a simple coating of the material in hopes that the coated amino acid is stable in the rumen. Recently, Rhone Poulenc (a French chemical and pharmaceutical company) has provided a pH-sensitive polymer coating. The theory of a pH-sensitive coating polymer for making the amino acid revolves around the pH difference between the rumen and the abomasum of ruminants. The rumen pH is usually 5.5 to 7.0, and the Abomasum pH is 2 to 3. Polymer-coated of essential amino acids (EAA) is a method of accomplishing this by profiting the AA in the rumen environment, but is soluble at lower pH’s of the post ruminal environment (pH 2 to 3), therefore it could be undegraded in the rumen, but be available in the intestine.
Technologies which have been used in the past, like coatings, and the more recently developed pH-sensitive polymers for coating, have had some limited success and some problems. The primary problem with these products is that they may become abraded during human...