Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)


Animal Science

First Advisor

George W. Libal


The objective of adding supplemental protein to swine diets is to provide the levels of available essential amino acids and nitrogen necessary for maximum protein synthesis in the pig. Lysine has been determined to be the limiting amino acid in many swine diets. Thus, the real objective of protein supplementation is to provide the amount of lysine necessary for maximum protein synthesis, and if this objective is met the requirements for the other essential amino acids and nitrogen will generally be met. Since swine diets are formulated to meet the lysine requirement of the pig, it is necessary to derive maximum utilization of the dietary lysine in order to minimize the cost of lean tissue production. Several factors may influence lysine utilization, including the nature of the protein source, amount of heat processing, level of feed intake and relative amount of other amino acids. Swine diets formulated to meet the lysine requirement of the pig will usually contain an excess of several amino acids including arginine, leucine and phenylalanine plus tyrosine. Currently, there is much debate on the effects of these excess amino acids on pig performance. Lysine and arginine are both basic amino acids, meaning that they have a positively charged R group when in the physiological pH range. Poultry researchers have demonstrated a very marked effect of excess lysine on arginine transport and metabolism in the chick. It is possible that the excess arginine found in common swine diets may affect lysine utilization and thereby directly affect pig performance. There are two basic approaches used in the study of the arginine-lysine relationship. The first approach is to alter the arginine content of the diet by reformulation with different sources and levels of protein. This type of research provides little basic knowledge on the arginine-lysine relationship since the arginine levels are confounded by changing protein sources. However, it does provide information on the prospects for improving pig performance by reducing the amount of arginine in common swine diets. The second approach is to use crystalline arginine to alter the arginine content of the test diets. This is the method used in the present series of experiments. This method allows evaluation of the arginine-lysine relationship with a minimum of confounding but does not provide a method for incorporating the knowledge into practical swine production methods. The objectives of this study were as follows: 1. To determine the relationship between arginine and lysine in the growing rat. 2. To determine if excess arginine affects the absorption of lysine from the small intestine of the rat. 3. To examine the effects of excess arginine on swine growth, feed intake and feed efficiency.

Library of Congress Subject Headings

Swine -- Physiology
Rats -- Physiology
Lysine -- Synthesis
Lysine in animal nutrition



Number of Pages



South Dakota State University