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United States Department of Agriculture

Agricultural Research Service

Research Project: METHODS FOR IMPROVING FEED EVALUATION FOR USE IN ENHANCING LACTATING DAIRY COW EFFICIENCY AND NUTRIENT MANAGEMENT Title: Evaluation of specificity of hydrolysis methods for separation of water-soluble carbohydrates

Author
item Hall, Mary Beth

Submitted to: Journal Dairy Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: February 25, 2011
Publication Date: July 10, 2011
Citation: Hall, M. 2011. Evaluation of specificity of hydrolysis methods for separation of water-soluble carbohydrates. Journal of Dairy Science. 94(E-Supplement 1):688.

Technical Abstract: Various hydrolysis methods have been recommended to convert oligo- or polymeric water-soluble carbohydrates to monomers for detection in reducing sugar assays, but responses and specificity for different carbohydrates have not been well characterized. The study objective was to evaluate reducing sugar responses of sucrose (SUC), maltose (MAL), lactose (LAC), raffinose (RAF), and inulin (INU) to hydrolysis (HYD) by invertase, 0.5 M HCl, or 0.037 M H2SO4 or a mixture of sucrase/maltase/pullulanase/ß-amylase (Sucrase Mix). The p-hydroxybenzoic acid hydrazide reducing sugar method was used for detection. Hydrolyzed and unhydrolyzed samples were analyzed in 2 runs for each method. The statistical model included carbohydrate (WSC), HYD method, and the interaction (INT). Values presented were least squares means for reducing sugars as a percentage of sample DM. Unhydrolyzed carbohydrates differed in reducing sugar values (P<0.01; SUC = 1.1%, MAL = 54%, LAC = 42%, RAF = 2.0%, and INU = 7.4%, SED = 1.5%). LAC and MAL values reflect reactivity of the reducing end hexose in both molecules, whereas RAF and SUC lack reactive reducing end hexoses. The value for INU may reflect presence of a small amount of damaged molecules. Hydrolyzed minus unhydrolyzed values describe the amount of reducing sugar released by hydrolysis. This difference differed by WSC (P<0.01), HYD (P<0.01), and INT (P<0.01)(SED = 3.5%). LAC was largely unaffected by HYD. Because of complete or partial hydrolysis of SUC, RAF, and INU by the same treatments, and responses of unhydrolyzed LAC and MAL, it is concluded that these hydrolyses do not allow separation of specific WSC.

Last Modified: 9/2/2014
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