• Login
    View Item 
    •   Home
    • Massey Documents by Type
    • Theses and Dissertations
    • View Item
    •   Home
    • Massey Documents by Type
    • Theses and Dissertations
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    The role of plant lipases in the bovine rumen : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Biochemistry

    Icon
    View/Open Full Text
    02_whole.pdf (5.031Mb)
    01_front.pdf (1.465Mb)
    Export to EndNote
    Abstract
    The role of plant lipases in the hydrolysis of dietary lipids in the rumen of pasture-fed ruminants has been investigated by means of in vitro and in vivo experiments with rumen contents. Lipases present in the leaves of numerous pasture plants remained highly active for at least 5h in the presence of actively metabolising rumen microorganisms, leading to the hydrolysis of triglyceride. Parallel experiments showed that the lipase activity of actively metabolising rumen microorganisms in rumen fluid was very low. A slight increase in lipase activity attributable to microorganisms occurred after about a 4h incubation with autoclaved plant extract at which stage the metabolic activity of the microbial population had passed its peak. In vivo experiments showed that the lipolytic activity of rumen fluid obtained 0.5h to 5.0h after feeding fresh grass was about twice that of rumen fluid obtained after overnight fasting. Lipase activity was present in clarified rumen fluid. Pairedfeeding experiments with monozygotic twin cows demonstrated that the lipase activity of clarified rumen fluid prepared from the twin 0.5h after feeding fresh pasture was much higher than that of clarified rumen fluid from the 20h-fasted twin. Further paired-feeding experiments showed that lipase activity was higher in protozoa-free rumen fluid from the pasture-fed than from the hay-fed cow. In both treatments the highest levels of lipolytic activity were observed in the rumen samples removed 0.5h after feeding and there was a steady decline in activity over the sampling periods. Nevertheless, there was appreciable activity in the rumen samples obtained from the hay-fed animal which is consistent with the presence of lipase activity in the extracts of dried grass. Multiple forms of plant esterases and phosphatases were present in the soluble fraction of rumen fluid several hours after feeding. It is concluded that the rapid release of fatty acids which follows the ingestion of pasture is due mainly to the activity of plant lipases and that rumen microorganisms have a subsidiary role in hydrolysing ingested lipid in a pasture-fed ruminant.
    Date
    1974
    Author
    Faruque, Abu J M Omar
    Rights
    The Author
    Publisher
    Massey University
    URI
    http://hdl.handle.net/10179/4598
    Collections
    • Theses and Dissertations
    Metadata
    Show full item record

    Copyright © Massey University
    Contact Us | Send Feedback | Copyright Take Down Request | Massey University Privacy Statement
    DSpace software copyright © Duraspace
    v5.7-2020.1
     

     

    Tweets by @Massey_Research
    Information PagesContent PolicyDepositing content to MROCopyright and Access InformationDeposit LicenseDeposit License SummaryTheses FAQFile FormatsDoctoral Thesis Deposit

    Browse

    All of MROCommunities & CollectionsBy Issue DateAuthorsTitlesSubjectsThis CollectionBy Issue DateAuthorsTitlesSubjects

    My Account

    LoginRegister

    Statistics

    View Usage Statistics

    Copyright © Massey University
    Contact Us | Send Feedback | Copyright Take Down Request | Massey University Privacy Statement
    DSpace software copyright © Duraspace
    v5.7-2020.1