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Reduction of proteolysis during ensilage of perennial ryegrass by protease inhibitors
Author(s) -
Wetherall Jane A,
Armstrong David G,
Finlayson Heather J,
Rooke John A
Publication year - 1995
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.2740680414
Subject(s) - pepstatin , chemistry , lolium perenne , silage , proteolysis , lactic acid , zoology , dry matter , protease , food science , endopeptidase , formic acid , biochemistry , perennial plant , agronomy , biology , enzyme , genetics , bacteria
Two experiments were carried out to assess the effectiveness of protease inhibitors in reducing proteolysis during ensilage. Perennial ryegrass ( Lolium perenne ) (279 g dry matter (DM) kg −1 , experiment 1 and 170 gDM kg −1 experiment 2) was ensiled in laboratory silos for 82 and 50 days, respectively. With the exception of the application of formic acid (1.5 g kg −1 ) plus formalin (3 g kg −1 ) in experiment 1, all silages had pH values of less than 4.0 and lactic acid concentrations of greater than 100 g kg −1 DM. Application of the cysteine endopeptidase inhibitor E‐64 (1‐ trans ‐epoxysuccinyl‐leucylamido(4‐guanidino) butane, 22.5 mg kg −1 reduced proteolysis during ensilage as measured by a reduction in the quantities of soluble non‐protein N in silage to 0.76 and 0.91 of control values (528 and 643 g kg −1 total N) in experiments 1 and 2, respectively. In experiment 2 increasing the application rate of E‐64 from 22.5 to 45 mg kg −1 further reduced the extent of proteolysis from 0.91 to 0.75 of control soluble non‐protein N concentrations. Proteolysis was also reduced in experiment 2 by two other cysteine endopeptidase inhibitors, antipain (32 mg kg −1, 0.81 of control) and cystain (1.2 mg kg −1 ; 0.89 of control). Pepstatin A (300 mg kg −1 ), an inhibitor of aspartic acid endopeptidases, did not reduce soluble non‐protein N concentrations in experiment 1 but did do so in experiment 2 (0.81 of control). Treatment of grass at ensiling with Lactobacillus plantarum (10 6 g −1 ) reduced silage non‐protein N concentrations to 0.83 of the control. The effects of E‐64 and pepstatin A and of E‐64 and L plantarum in experiment 2 were addive. Cysteine endopeptidases therefore play an important role in protein breakdown during ensilage.