FUNCTIONAL ADAPTATION OF THE RUMINAL EPITHELIUM
type: CreativeWork
description: Short chain fatty acids (SCFA) synthesized in the rumen from carbohydrate fermentation are an essential energy source for ruminants. Current literature supports that SCFA are absorbed across the rumen epithelium via passive diffusion or protein-mediated transport, however, the rate and degree to which these pathways adapt to a change in diet fermentability is unknown. Furthermore, Na+ flux is partially determined by SCFA absorption, and thus is a key indicator of functional changes in the rumen epithelium. The objectives of this study were to determine the time required for a change in SCFA and Na+ absorption across the bovine rumen epithelium and to evaluate the rate and degree to which absorption pathways adapt to an increase in diet fermentability relative to changes in surface area. Twenty-five weaned Holstein steer calves were blocked by body weight and randomly assigned to either the control diet (CON; 91.5% hay and 8.5% vitamin/mineral supplement) or a moderately fermentable diet (50% hay; 41.5% barley grain, and 8.5% vitamin/mineral supplement) fed for 3 (G3), 7 (G7), 14 (G14), or 21 d (G21). All calves were fed at 2.25% BW at 0800 h. Reticular pH was recorded every 5 min for 48 h prior to killing (1000 h). Ruminal tissue was collected for Ussing chamber, barrier function, surface area measurements, and gene expression. Net 22Na+ flux (JNET-Na; 80 kBq/15 mL), the rate and pathway of mucosal to serosal 3H-acetate (JMS-acetate; 37 kBq/15 mL) and 14C-butyrate (JMS-butyrate; 74 kBq/15 mL) flux, and serosal to mucosal flux of 3H-mannitol (JSM-mannitol; 74 KBq/15 mL) and tissue conductance were measured. Half of the chambers assigned to measure JMS-acetate and JMS-butyrate were further assigned to 1 of 2 acetate and butyrate concentration treatments: 10 mM (Low) and 50 mM (High). Furthermore, JSM-mannitol flux was also measured during an acidotic and hyperosmotic challenge (CHAL) and recovery (REC) to measure barrier function of ruminal tissue. Mean reticular pH, …
abstract: Short chain fatty acids (SCFA) synthesized in the rumen from carbohydrate fermentation are an essential energy source for ruminants. Current literature supports that SCFA are absorbed across the rumen epithelium via passive diffusion or protein-mediated transport, however, the rate and degree to which these pathways adapt to a change in diet fermentability is unknown. Furthermore, Na+ flux is partially determined by SCFA absorption, and thus is a key indicator of functional changes in the rumen epithelium. The objectives of this study were to determine the time required for a change in SCFA and Na+ absorption across the bovine rumen epithelium and to evaluate the rate and degree to which absorption pathways adapt to an increase in diet fermentability relative to changes in surface area. Twenty-five weaned Holstein steer calves were blocked by body weight and randomly assigned to either the control diet (CON; 91.5% hay and 8.5% vitamin/mineral supplement) or a moderately fermentable diet (50% hay; 41.5% barley grain, and 8.5% vitamin/mineral supplement) fed for 3 (G3), 7 (G7), 14 (G14), or 21 d (G21). All calves were fed at 2.25% BW at 0800 h. Reticular pH was recorded every 5 min for 48 h prior to killing (1000 h). Ruminal tissue was collected for Ussing chamber, barrier function, surface area measurements, and gene expression. Net 22Na+ flux (JNET-Na; 80 kBq/15 mL), the rate and pathway of mucosal to serosal 3H-acetate (JMS-acetate; 37 kBq/15 mL) and 14C-butyrate (JMS-butyrate; 74 kBq/15 mL) flux, and serosal to mucosal flux of 3H-mannitol (JSM-mannitol; 74 KBq/15 mL) and tissue conductance were measured. Half of the chambers assigned to measure JMS-acetate and JMS-butyrate were further assigned to 1 of 2 acetate and butyrate concentration treatments: 10 mM (Low) and 50 mM (High). Furthermore, JSM-mannitol flux was also measured during an acidotic and hyperosmotic challenge (CHAL) and recovery (REC) to measure barrier function of ruminal tissue. Mean reticular pH, …
author: Schurmann, Brittney
language: eng
keywords: rumen epithelium, dietary adaptation, short chain fatty acid, ion transport, Ussing chamber
date published: 2014-01-20
date modified: 2026-07-24T04:26:45Z
provider: University of Saskatchewan
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Saskatchewan

PropertyValue
property ID: Handle
value: https://hdl.handle.net/10388/ETD-2013-12-1381