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Publication type: Journal Article
Document type: Full Paper

Year: 2013

Author(s): Metzler-Zebeli, BU; Hollmann, M; Sabitzer, S; Podstatzky-Lichtenstein, L; Klein, D; Zebeli, Q

Title: Epithelial response to high-grain diets involves alteration in nutrient transporters and Na+/K+-ATPase mRNA expression in rumen and colon of goats.

Source: J Anim Sci. 2013; 91(9):4256-4266



Authors Vetmeduni Vienna:

Hollmann Manfred
Klein Dieter
Metzler-Zebeli Barbara
Weigelsperger Sonja
Zebeli Qendrim

Vetmed Research Units
Institute of Animal Nutrition and Functional Plant Compounds
University Clinic for Swine
VetCore


Abstract:
Emerging evidence at the mRNA level indicates that feeding high-grain diets to ruminants leads to coordinated changes in the molecular response of the rumen epithelium. Yet, epithelial adaptation of the hindgut to increasing dietary grain levels has not been established in ruminants. Therefore, the objective of this study was to characterize alterations in mRNA expression associated with nutrient transport and electrochemical gradients in rumen and colon epithelium, and rumen morphology in growing goats fed different grain levels. Goats (n = 6) were fed diets with increasing levels of 0, 30, or 60% barley grain for 6 wk. Goats were euthanized 2 h after their last feeding, and digesta and tissue samples of the cranial part of the ventral rumen and proximal colon were collected. Goats fed the 60% grain diet exhibited a lower ruminal and colonic pH (P < 0.01) and a greater colonic total VFA concentration (P < 0.05) compared with those fed the 0 and 30% grain diets. As response to the decreased ruminal pH, goats fed the 60% grain diet had a greater (P < 0.05) keratinization and thicker stratum corneum of the rumen epithelium than goats fed the 0 and 30% grain diets. The 60% grain diet upregulated (P < 0.05) MCT1 expression by 45% and downregulated (P < 0.05) the expression of MCT4 and SGLT1 by 28 and 50%, respectively, in rumen epithelium compared with the 0 and 30% grain diets. Accordingly, goats fed the 60% grain diet had a greater (P < 0.05) expression of MCT1 and ATP1A1 in colon epithelium than goats fed the 0 and 30% grain diets. Regression analyses showed negative relationships (R(2) = 0.35 to 0.87, P < 0.05) of MCT1 and ATP1A1 expression in rumen and colon epithelium and thickening of ruminal stratum corneum to decreasing luminal pH values, suggesting greater mRNA expression at lower pH. In contrast, MCT4 expression in rumen epithelium positively correlated to luminal pH (R(2) = 0.95, P < 0.01). In conclusion, results of this model study indicated that with the greatest grain level rumen and colon molecular epithelial responses may have been related to counteract the consequences of luminal acidification on intracellular homeostasis in epithelial cells and concomitantly to increase systemic absorption of VFA.

Keywords Pubmed: Animal Feed/analysis
Animals
Colon/physiology*
Diet/veterinary
Epithelium
Fatty Acids, Volatile/metabolism
Fermentation
Gene Expression Regulation/drug effects*
Glucose/metabolism
Goats/growth & development
Goats/physiology*
Homeostasis
Male
Membrane Transport Proteins/genetics*
Membrane Transport Proteins/metabolism
Polymerase Chain Reaction/veterinary
RNA, Messenger/genetics
RNA, Messenger/metabolism
Random Allocation
Rumen/anatomy & histology
Rumen/physiology*
Sodium-Potassium-Exchanging ATPase/metabolism


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