Reduction of proteolysis during ensilage of perennial ryegrass by protease inhibitors

Autor: David G Armstrong, John A Rooke, Heather J Finlayson, Jane A Wetherall
Rok vydání: 1995
Předmět:
Zdroj: Journal of the Science of Food and Agriculture. 68:497-505
ISSN: 1097-0010
0022-5142
DOI: 10.1002/jsfa.2740680414
Popis: 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 g DM kg - , 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 - ) 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 cystatin (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 additive. Cysteine endopeptidases therefore play an important role in protein breakdown during ensilage.
Databáze: OpenAIRE
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