French to English Science Livestock / Animal Husbandry Nutritional value of animal feed

This term appears in the context of a pig feed research project. I came across it in a table of pig feed ingredients, each ingredient expressed as a percentage of the total dose given per pig and by pig group, as follows (two other ingredients presented for context):

Composition % : 1st : 2nd : 3rd : 4th
Gr, Soja extrudée : 3.5 : 3.6 : 3.7 : 3.8
Tt Soja 48 : 3.5 : 3.6 : 3.7 : 3.8
Udt lysine 400 : 3.5 : 3.6 : 3.7 : 3.8

Lysine 400 is simple enough, but I can't find what Udt refers to. It seems to be a unit of measure, or perhaps indicates the physical form of the Lysine that was added to the feed, as in "Tourteaux de Soja 48". Any ideas would be much appreciated.

This is a research project originating in France, for a US English agriculture audience. Here is a link to the document:

http://www.journees-recherche-porcine.com/texte/2003/03txtAl...