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    Effects of dietary fibre and protein on urea transport across the cecal mucosa of piglets (2013)

    Art
    Zeitschriftenartikel / wissenschaftlicher Beitrag
    Autoren
    Stumpff, Friederike (WE 2)
    Lodemann, Ulrike (WE 2)
    Van Kessel, A.G.
    Pieper, Robert (WE 4)
    Klingspor, S.
    Wolf, K. (WE 2)
    Martens, Holger (WE 2)
    Zentek, Jürgen (WE 4)
    Aschenbach, Jörg R. (WE 2)
    Quelle
    Journal of Comparative Physiology B, Biochemical, Systemic, and Environmental Physiology; 183(8) — S. 1053–1063
    ISSN: 0174-1578
    Sprache
    Englisch
    Verweise
    DOI: 10.1007/s00360-013-0771-2
    Pubmed: 23812549
    Kontakt
    Institut für Veterinär-Physiologie

    Oertzenweg 19 b
    14163 Berlin
    Tel.+49 30 838 62600 Fax.+49 30 838-62610
    email:physiologie@vetmed.fu-berlin.de

    Abstract / Zusammenfassung

    In ruminants, gastrointestinal recycling of urea is acutely enhanced by fibre-rich diets that lead to high ruminal concentration of short chain fatty acids (SCFA), while high ammonia has inhibitory effects. This study attempted to clarify if urea flux to the porcine cecum is similarly regulated. Thirty-two weaned piglets were fed diets containing protein (P) of poor prececal digestibility and fibre (F) at high (H) or low levels (L) in a 2 × 2 factorial design. After slaughter, cecal content was analyzed and the cecal mucosa incubated in Ussing chambers to measure the effect of pH, SCFA and NH4 + on the flux rates of urea, short-circuit current (I sc) and tissue conductance (G t). NH4 + significantly enhanced I sc (from 0.5 ± 0.2 to 1.2 ± 0.1 μEq cm-2 h-1). No acute effects of SCFA or ammonia on urea flux were observed. Tissue conductance was significantly lower in the high dietary fibre groups irrespective of the protein content. Only the HP-LF group emerged as different from all others in terms of urea flux (74 ± 6 versus 53 ± 3 nmol cm-2 h-1), associated with higher cecal ammonia concentration and reduced fecal consistency. The data suggest that as in the rumen, uptake of ammonia by the cecum may involve electrogenic transport of the ionic form (NH4 +). In contrast to findings in the rumen, neither a high fibre diet nor acute addition of SCFA enhanced urea transport across the pig cecum. Instead, a HP-LF diet had stimulatory effects. A potential role for urea recycling in stabilizing luminal pH is discussed.