Publikationsdatenbank

Short-term and long term adaptation of SCFA absorption from the rumen (2019)

Art

Vortrag

Autoren

Penner, Gregory B.

Aschenbach, Jörg R. (WE 2)

Gäbel, Gotthold

Kongress

International Symposium on Ruminant Physiology (ISRP 2019)

Leipzig, 03. – 06.09.2019

Quelle

Advances in Animal Biosciences

Bandzählung: 10

Heftzählung: 3

Seiten: 372

ISSN: 2040-4719

Sprache

Englisch

Verweise

URL (Volltext): https://www.cambridge.org/core/services/aop-cambridge-core/content/view/7D464B8882B4D5304683797665CD9E5E/S2040470019000037a.pdf/proceedings_of_the_xiiith_international_symposium_on_ruminant_physiology_isrp_2019.pdf

Kontakt

Institut für Veterinär-Physiologie

Oertzenweg 19 b
14163 Berlin
+49 30 838 62600
physiologie@vetmed.fu-berlin.de

Abstract / Zusammenfassung

Short-chain fatty acid (SCFA) absorption across the ruminal epithelium is critical for energy balance of the animal and for maintaining intraruminal pH. Adaptation for SCFA absorption occurs acutely for proliferative and retrogressive responses. For example, marked reductions for the rates of SCFA absorption occur within 48 h of feed deprivation and when exposed to 5 d of low-feed intake. On the other hand, exposure of lambs and calves to an abrupt increase in dietary fermentability increases SCFA uptake into the epithelium and net flux of SCFA across the epithelium. The increases in uptake and flux occur within 1 week of the dietary change and prior to the detection of changes in absorptive surface area. As increases in uptake and flux can be measured ex vivo, they must occur independently or additionally to changes in blood flow and represent direct adaptation of the epithelia. Interestingly, of the pathways for SCFA absorption, passive diffusion appears to be acutely responsive promoting SCFA flux during proliferative adaptation and the increases in passive diffusion support previously reported increases in Na uptake and greater sodium-hydrogen exchanger expression. Adaptation to allow for greater passive diffusion must be mediated via changes in the permeability of the apical membrane. Supporting the concept that permeability of the epithelium may limit apical uptake of SCFA, altering dietary fatty acid supply and composition to favor greater dietary fat concentration and greater proportions of long-chain saturated fatty acids relative to long-chain polyunsaturated fatty acids increases passive apical uptake of propionate and tends to increase passive apical uptake of butyrate. Dietary composition such as greater dietary fermentability may promote longer-term adaptation through increases in absorptive surface area, greater blood flow, and by altering pathways for SCFA absorption. For example, increasing the dietary sugar concentration does not appear to have a major effect on rates of SCFA absorption, but increases bicarbonate-dependent SCFA flux. Transition from a hay diet to a highly fermentable diet stimulates both SCFA absorption and bicarbonate secretion. However, if highly fermentable diets induce ruminal acidosis, SCFA absorption is rapidly reduced with recovery occurring within ~1 week depending on severity. Thus, the ruminal epithelium adapts to modulate SCFA absorption using both short-term and long-term mechanisms.