Effects of polyphenol oxidase on lipolysis and proteolysis of red clover silage with and without a silage inoculant (Lactobacillus plantarum L54)

M. R. F. Lee, M. B. Scott, J. K. S. Tweed, F. R. Minchin, D. R. Davies

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67 Citations (SciVal)

Abstract

Polyphenol oxidase (PPO) has been shown to reduce proteolysis and lipolysis in red clover through deactivation of proteolytic and lipolytic enzymes and/or through formation of protein–phenol–lipid complexes. This experiment investigated the time course of both lipolysis and proteolysis in two red clover lines with different PPO activities with and without addition of a silage inoculant to help understand the action of PPO in the silo, and its potential effects on protein and glycerol-based lipid conservation, and to determine effects of a more rapid pH reduction with inoculation on PPO activity. Four silages were prepared from high or low PPO precision chopped red clover in 60 test-tube-silos, each containing 120 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 (d) low PPO red clover with inoculation (L+). Each treatment had three replicates for each time point of 1, 2, 4, 8 and 90 days. The inoculant used was Lactobacillus plantarum strain L54 applied at a rate of 106 CFU/g fresh weight. Silage pH was reduced (P <0.001) by inoculation with no effect of PPO. Inoculation had no effect on either lipolysis or free amino acid release, although more (P <0.01) soluble protein and less (P <0.01) ammonia-N was in inoculated silages. H silages had a lower level of both proteolysis (release of free amino acids, P <0.05) and lipolysis (loss of membrane lipid, P <0.01) than L red clover silages. Results indicate that PPO reduced proteolysis and lipolysis in the silo and that inoculation had no adverse effects on PPO activity.
Original languageEnglish
Pages (from-to)125-136
Number of pages12
JournalAnimal Feed Science and Technology
Volume144
Issue number1-2
DOIs
Publication statusPublished - 01 Jun 2008

Keywords

  • Proteolysis
  • Silage inoculant
  • Red clover silage
  • Polyphenol oxidase
  • Lipolysis

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