HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Interpretive Summary Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Google Scholar Articles by Boucher, S. E. Articles by Schwab, C. G. PubMed PubMed Citation Articles by Boucher, S. E. Articles by Schwab, C. G.

Evaluation of the furosine and homoarginine methods for determining reactive lysine in rumen-undegraded protein¹

S. E. Boucher^*,2, C. Pedersen^,3, H. H. Stein^,4 and C. G. Schwab^*,5

^* Department of Biological Sciences, University of New Hampshire, Durham 03824
Department of Animal and Range Sciences, South Dakota State University, Brookings 57007

⁵ Corresponding author: charles.schwab{at}unh.edu

Three samples of soybean meal (SBM), 3 samples of expeller SBM (SoyPlus, West Central Cooperative, Ralston, IA), 5 samples of distillers dried grains with solubles (DDGS), and 5 samples of fish meal were used to evaluate the furosine and homoarginine procedures to estimate reactive Lys in the rumen-undegraded protein fraction (RUP-Lys). One sample each of SBM, expeller SBM, and DDGS were subjected to additional heat treatment in the lab to ensure there was a wide range in reactive RUP-Lys content among the samples. Furosine is a secondary product of the initial stages of the Maillard reaction and can be used to calculate blocked Lys. Homoarginine is formed via the reaction of reactive Lys with O-methylisourea and can be used to calculate the concentration of reactive Lys. In previous experiments, each sample was ruminally incubated in situ for 16 h, and standardized RUP-Lys digestibility of the samples was determined in cecectomized roosters. All rumen-undegraded residue (RUR) samples were analyzed for furosine and Lys; however, only 9 of the 16 samples contained furosine, and only the 4 unheated DDGS samples contained appreciable amounts of furosine. Blocked RUP-Lys was calculated from the furosine and Lys concentrations of the RUR. Both the intact feed and RUR samples were evaluated using the homoarginine method. All samples were incubated with an O-methylisourea/BaOH solution for 72 h and analyzed for Lys and homoarginine concentrations. Reactive Lys concentrations of the intact feeds and RUR were calculated. Results of the experiment indicate that blocked RUP-Lys determined via the furosine method was negatively correlated with standardized RUP-Lys digestibility, and reactive RUP-Lys determined via the guanidination method was positively correlated with standardized RUP-Lys digestibility. Reactive Lys concentrations of the intact samples were also highly correlated with RUP-Lys digestibility. In conclusion, the furosine assay is useful in predicting RUP-Lys digestibility of DDGS samples, and the guanidination procedure can be used to predict RUP-Lys digestibility of SBM, expeller SBM, DDGS, and fish meal samples.

Key Words: reactive lysine • furosine method • homoarginine method

This article has been cited by other articles:

				S. E. Boucher, S. Calsamiglia, C. M. Parsons, H. H. Stein, M. D. Stern, P. S. Erickson, P. L. Utterback, and C. G. Schwab Intestinal digestibility of amino acids in rumen-undegraded protein estimated using a precision-fed cecectomized rooster bioassay: II. Distillers dried grains with solubles and fish meal J Dairy Sci, December 1, 2009; 92(12): 6056 - 6067. [Abstract] [Full Text] [PDF]

				S. E. Boucher, S. Calsamiglia, C. M. Parsons, H. H. Stein, M. D. Stern, P. S. Erickson, P. L. Utterback, and C. G. Schwab Intestinal digestibility of amino acids in rumen undegradable protein estimated using a precision-fed cecectomized rooster bioassay: I. Soybean meal and SoyPlus J Dairy Sci, September 1, 2009; 92(9): 4489 - 4498. [Abstract] [Full Text] [PDF]