Too little Lysine
If the ration contains enough protein, but too little lysine, the quality of the protein may be poor. A good protein quality is of particular importance for young growing horses and for lactating mares.
Deficiency of lysine in the diet impairs growth and development.
Recommendation: Good sources of lysine are commercial feeds where lysine has been supplemented. Soyabean meal is also high in lysine and can be fed as a supplement to the diet. Pasture is a good source of lysine but varies over the year with a high content in the spring and low content in the winter.
Too much Lysine
The diet contains too much lysine. This is not directly harmful to the horse but is unnecessary and places stress on the liver. Reduce the lysine content by considering lower protein feeds. Lysine is only effective when fed in combination with all other 20 amino acids therefore supplementing on its own is not beneficial
Recommendation Select feeds with lower protein content. Save money and reduce the stress on the liver of your horse.