Nonproteic Contents Interfere with the Analysis of Added Tryptophan in Feeds – Test of a Correction Model
Johannes Fontaine*, Elke Berlemann, Wolfgang Polzer
Identifiers and Pagination:Year: 2008
First Page: 38
Last Page: 42
Publisher Id: TOFSJ-2-38
Article History:Received Date: 19/12/2007
Revision Received Date: 27/3/2008
Acceptance Date: 11/4/2008
Electronic publication date: 6/5/2008
Collection year: 2008
open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: https://creativecommons.org/licenses/by/4.0/legalcode. This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
The nonproteic, free tryptophan contents in 23 important feed ingredients were analysed. Wheat, its bran and middlings, soybean meal, sunflower meal and other vegetable feed ingredients contain significant fractions of free tryptophan, up to 38% of total tryptophan. These natural contents considerably interfere with the accurate determination of supplemented L-tryptophan in mixed feeds. Two correction methods were successfully tested in four feeds, which were each supplemented at two levels. They allow a distinct improvement in the analysis of tryptophan addition.