title: Short-term adaptation of the ruminal epithelium involves abrupt changes in sodium and short-chain fatty acid transport.
abstract: The objectives of this study were to determine the effect of an increase in diet fermentability on 1) the rate and extent to which short-chain fatty acid (SCFA) absorption pathways adapt relative to changes in Na(+) transport, 2) the epithelial surface area (SA), and 3) the barrier function of the bovine ruminal epithelium. Twenty-five Holstein steer calves were assigned to either the control diet (CON; 91.5% hay and 8.5% supplement) or a moderately fermentable diet (50% hay; 41.5% barley grain (G), and 8.5% supplement) fed for 3 (G3), 7 (G7), 14 (G14), or 21 days (G21). All calves were fed at 2.25% body weight at 0800. Calves were killed (at 1000), and ruminal tissue was collected to determine the rate and pathway of SCFA transport, Na(+) transport and barrier function in Ussing chambers. Tissue was also collected for SA measurement and gene expression. Mean reticular pH decreased from 6.90 for CON to 6.59 for G7 and then increased (quadratic P < 0.001). While effective SA of the ruminal epithelium was not affected (P > 0.10) by dietary treatment, the net Na(+) flux increased by 125% within 7 days (quadratic P = 0.016). Total acetate and butyrate flux increased from CON to G21, where passive diffusion was the primary SCFA absorption pathway affected. Increased mannitol flux, tissue conductance, and tendencies for increased expression of IL-1β and TLR2 indicated reduced rumen epithelium barrier function. This study indicates that an increase in diet fermentability acutely increases Na(+) and SCFA absorption in the absence of increased SA, but reduces barrier function.
authors: Department of Animal and Poultry Science, University of Saskatchewan, Saskatoon, Saskatchewan, Canada;
authors: Brittney L
authors: BL
authors: Schurmann
authors: Department of Animal and Poultry Science, University of Saskatchewan, Saskatoon, Saskatchewan, Canada;
authors: Matthew E
authors: ME
authors: Walpole
authors: Department of Animal and Poultry Science, University of Saskatchewan, Saskatoon, Saskatchewan, Canada; Department of Animal Nutrition and Feed Management, University of Agriculture in Krakow, Krakow, Poland; and.
authors: Pawel
authors: P
authors: Górka
authors: Department of Animal Nutrition and Feed Management, University of Agriculture in Krakow, Krakow, Poland; and.
authors: John C H
authors: JC
authors: Ching
authors: Department of Animal Nutrition and Feed Management, University of Agriculture in Krakow, Krakow, Poland; and.
authors: Matthew E
authors: ME
authors: Loewen
authors: Department of Animal and Poultry Science, University of Saskatchewan, Saskatoon, Saskatchewan, Canada; Department of Biomedical Sciences, Western College of Veterinary Medicine, Saskatoon, Saskatchewan, Canada greg.penner@usask.ca.
authors: Gregory B
authors: GB
authors: Penner
mesh_terms: D000222:Adaptation, Physiological; D000821:Animal Feed / Q000032:analysis; D000824:Animal Nutritional Physiological Phenomena / Q000502:physiology; D000818:Animals; D001692:Biological Transport / Q000502:physiology; D002417:Cattle; D004032:Diet / Q000662:veterinary; D019587:Dietary Supplements; D004848:Epithelium / Q000378:metabolism*; D005232:Fatty Acids, Volatile / Q000378:metabolism*; D012417:Rumen / Q000502:physiology; D012964:Sodium / Q000378:metabolism*; D013997:Time Factors
chemical_list: D005232:Fatty Acids, Volatile; D012964:Sodium
keywords: Ussing chamber; dietary adaptation; rumen epithelium; short chain fatty acid