Davies, D. R.

Lee, Michael R. F.

Minchin, F. R.

Scott, M. B.

English

University of Kentucky

University of Kentucky UKnowledge International Grassland Congress Proceedings XXI International Grassland Congress / VIII International Rangeland Congress The Effect of Polyphenol Oxidase on Lipolysis and Proteolysis of Red Clover Silage with and without a Silage Inoculant Michael R. F. Lee Institute of Grassland and Environmental Research, UK M. B. Scott Institute of Grassland and Environmental Research, UK D. R. Davies Institute of Grassland and Environmental Research, UK F. R. Minchin Institute of Grassland and Environmental Research, UK Follow this and additional works at: https://uknowledge.uky.edu/igc  Part of the Plant Sciences Commons, and the Soil Science Commons This document is available at https://uknowledge.uky.edu/igc/21/15-1/10 The XXI International Grassland Congress / VIII International Rangeland Congress took place in Hohhot, China from June 29 through July 5, 2008. Proceedings edited by Organizing Committee of 2008 IGC/IRC Conference Published by Guangdong People's Publishing House This Event is brought to you for free and open access by the Plant and Soil Sciences at UKnowledge. It has been accepted for inclusion in International Grassland Congress Proceedings by an authorized administrator of UKnowledge. For more information, please contact UKnowledge@lsv.uky.edu. 　 Multifunctional Grasslands in a Changing World 　 Volume Ⅱ 　 瞯 657　 瞯Grasslands/Rangelands Production Systems ——— Forage Quality ,Conservation and UtilizationThe effect of polyphenol oxidase on lipolysis and proteolysis of red clover silage with and withouta silage inoculantM .R .F . Lee , M .B . Scott , D .R . Davies and F .R . MinchinInstitute o f Grassland and Environmental Research , Plas Gogerddan , Aberystwyth , Ceredigion , UK , SY23 3EB michael .lee ＠ bbsrc .ac .ukKey words : red clover silage ,lactic acid bacteria inoculant ,polyphenol oxidase ,proteolysis ,lipolysisIntroduction Polyphenol oxidase ( PPO ) has been shown to reduce both proteolysis and lipolysis in red clover either throughdeactivation of proteolytic and lipolytic enzymes or / and through the formation of protein‐quinone‐lipid complexes ( Lee et al . ,２００４ ) . This experiment investigated the time course of both lipolysis and proteolysis in two red clovers with different PPOactivities with and without the addition of a silage inoculant ( Lactobacillus plantarum ) . This will help to understand the actionof PPO in the silo and hence its potential effects on protein and glycerol based lipid conservation . It will also determine theeffect of a more rapid pH reduction with inoculation on PPO activity and final silage quality .Materials and methods Four silages were prepared from high or low PPO macerated red clover in ６０ micro‐silos , each containing１２０ g fresh weight : a) High PPO red clover without inoculation ( H‐) , b ) Low PPO red clover without inoculation ( L‐) , c)High PPO red clover with inoculation ( H ＋ ) , and c) Low PPO red clover with inoculation ( L ＋ ) . Each treatment had ３ repsfor each time course of : １ , ２ , ４ , ８ and ９０ days . The inoculant used was Lactobacillus p lantarum strain L５４ applied at a rateof １０６ CFU/ g FM . Silage pH was determined at opening and a sample of the silage frozen for later assessment of proteolysis( free amino acid appearance ) and lipolysis ( loss of membrane lipid ) . Statistical analysis was carried out using a generalANOVA with Inoculation 倡 PPO as the treatment effect ( Payne et al . , ２００２ ) .Results and discussion Silage pH was ( P ＜ ０ .００１ ) reduced by inoculation ( ３ .９ vs ４ .３ at day ９０ ) with no effect of PPO .Inoculation had no effect on either lipolysis or free amino acid ( FAA ) release , although more soluble protein ( P ＜ ０ .０１ ) andless ammonia‐N ( P ＜ ０ .０１ ) were found in inoculated silages . H silages had a lower level of both proteolysis ( release of FAA ,P ＜ ０ .０５ ) and lipolysis ( loss of membrane lipid , P ＜ ０ .０１ ) than L red clover silages ( Figure １ ) . The release of FAA andlipolysis were affected by PPO whilst soluble protein and ammonia‐N was mainly affected by inoculation . The actions of the twoprocesses also show time differences i .e . prior to ensiling or in the early stages of ensiling for PPO versus during ensiling forinoculum .Figure 1 H igh and low PPO ( H and L) red clover silage with and without ( ＋ and‐) f resh culture inoculum : a) p roteolysis(release o f f ree amino acids) , b) li polysis ( loss o f membrane li p id) ( ＋ /‐standard error o f the mean) .Conclusion Both PPO and lactic acid bacteria inoculation offer solutions for increased protein and lipid quality in the conservedforage with potential to increase N use efficiency in the animal and the lipid profile of ruminant products .ReferencesLee , M .R .F . , Winters , A .L . , Scollan , N .D . , Dewhurst , R .J . , Theodorou , M .K . Minchin , F .R . ２００４ . Plant‐mediatedlipolysis and proteolysis in red clover with different polyphenol oxidase activities . Journal o f the Science o f Food andAgriculture ８４ : １６３９‐１６４５ .Payne , R .W . , Murray , D .A . , Harding , S .A . , Baird , D .B . , Soutar , D .M .２００２ . Genstat 眘 for WindowsTM (８th Edition)Introduction . Ox f ord : VSN International .

The Effect of Polyphenol Oxidase on Lipolysis and Proteolysis of Red Clover Silage with and without a Silage Inoculant

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The Effect of Polyphenol Oxidase on Lipolysis and Proteolysis of Red Clover Silage with and without a Silage Inoculant

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