University of SaskatchewanHARVEST
  • Login
  • Submit Your Work
  • About
    • About HARVEST
    • Guidelines
    • Browse
      • All of HARVEST
      • Communities & Collections
      • By Issue Date
      • Authors
      • Titles
      • Subjects
      • This Collection
      • By Issue Date
      • Authors
      • Titles
      • Subjects
    • My Account
      • Login
      JavaScript is disabled for your browser. Some features of this site may not work without it.
      View Item 
      • HARVEST
      • Electronic Theses and Dissertations
      • Graduate Theses and Dissertations
      • View Item
      • HARVEST
      • Electronic Theses and Dissertations
      • Graduate Theses and Dissertations
      • View Item

      Barrier Function of the Gastrointestinal Tract of Holstein Steers When Exposed to Ruminal Acidosis and Low Feed Intake

      Thumbnail
      View/Open
      PEDERZOLLI-THESIS-2016.pdf (332.5Kb)
      Date
      2016-09-21
      Author
      Pederzolli, Rae-Leigh Amanda 1989-
      ORCID
      0000-0002-2715-5833
      Type
      Thesis
      Degree Level
      Masters
      Metadata
      Show full item record
      Abstract
      Ruminal acidosis and low feed intake are two nutritional challenges present on beef and dairy operations that result in reduced health and performance. The objective of this study was to determine the regional susceptibility of the gastrointestinal tract (GIT) to ruminal acidosis (RA) or low feed intake (LFI). Twenty-one Holstein steers, aged 6 to 8 mo, were blocked by body weight (BW) and within block randomly assigned to 1 of 3 treatments: 1) control (CON), 2) RA, and 3) LFI. All steers were fed a diet containing a 50:50 forage to concentrate ratio (F:C) and were exposed to a 5-d measurement period. The CON steers were provided the basal diet for ad libitum intake, the LFI steers were fed at 25% of ad libitum intake for 5 d before humane killing while the RA steers were restricted to 25% intake for 1 d and then were fed 30% of dry matter intake (DMI) in pelleted barley followed by their regular total mixed ration (TMR) allocation. The RA steers were killed 1 d after the RA challenge. After killing, tissues from the rumen, omasum, duodenum, jejunum, ileum, cecum, proximal, and distal colon were collected. Digesta from those regions were assessed and tissues were mounted in Ussing chambers in order to assess permeability using the mucosal-to-serosal flux of inulin (JMS-inulin) and mannitol (JMS-mannitol) and tissue conductance (Gt). Digesta pH were less for RA than CON in the rumen, cecum, and proximal colon while LFI had greater pH in the rumen and proximal colon compared to CON. Ruminal short-chain fatty acid (SCFA) concentrations in the rumen were less for the LFI (P = 0.010) and RA (P = 0.007) compared to CON steers. In the proximal colon, there was a greater proportion of butyrate (P = 0.025 and P = 0.022) and isobutyrate (P = 0.019 and P = 0.019), and a lower proportion of acetate (P = 0.028 and P = 0.028) for LFI and RA, respectively, when compared to CON steers. The JMS-mannitol differed between the CON and LFI steers in the proximal colon (P = 0.041) and in the distal colon (P = 0.015) with the LFI steers having a lower flux rate in both regions. Increases in gene expression for genes related to barrier function (in the rumen, jejunum, and distal colon), mucosal immunology (rumen and jejunum), and adaptive immunity (jejunum) were observed indicating compensatory mechanisms may have been stimulated. It was concluded from this study that an acute RA challenge had no effect on tissue permeability throughout the GIT within 1 d of the challenge, while steers that were on LFI for 5 d had reduced tissue permeability in the proximal and distal colon while other regions of the GIT were unaffected. Further research is needed to analyze different management strategies proposed to mitigate the negative impact of LFI shown in production animal agriculture.
      Degree
      Master of Science (M.Sc.)
      Department
      Animal and Poultry Science
      Program
      Animal Science
      Supervisor
      Penner, Greg
      Committee
      Van Kessel, Andrew; McKinnon, John; Alcorn, Jane; Mutsvangwa, Tim
      Copyright Date
      August 2016
      URI
      http://hdl.handle.net/10388/7441
      Subject
      Barrier function
      ruminal acidosis
      low feed intake
      cattle
      tissue permeability
      Collections
      • Graduate Theses and Dissertations
      University of Saskatchewan

      University Library

      The University of Saskatchewan's main campus is situated on Treaty 6 Territory and the Homeland of the Métis.

      © University of Saskatchewan
      Contact Us | Disclaimer | Privacy