2 research outputs found
Feeding barley grain-rich diets altered electrophysiological properties and permeability of the ruminal wall in a goat model
High-producing ruminants are commonly fed large amounts of concentrate to meet
their high energy demands for rapid growth or high milk production. However,
this feeding strategy can severely impair rumen functioning, leading to
subacute ruminal acidosis. Subacute ruminal acidosis might have consequences
for electrophysiological properties by changing the net ion transfer and
permeability of ruminal epithelia, which may increase the uptake of toxic
compounds generated in the rumen into the systemic circulation. The objective
of the present study was to investigate the effects of excessive barley
feeding on the electrophysiological and barrier functions of the ruminal
epithelium and serum inflammation and ketogenesis markers after a long-term
feeding challenge, using growing goats as a ruminant model. A feeding trial
was carried out with growing goats allocated to 1 of the 3 groups (n=5-6
animals/group), with diets consisting exclusively of hay (control diet) or hay
with 30 or 60% barley grain. Samples of the ventral ruminal epithelium were
taken after euthanasia and instantly subjected to Ussing chamber experiments,
where electrophysiological properties of the epithelium were measured in
parallel with the permeability of marker molecules of different sizes
[fluorescein 5(6)-isothiocyanate and horseradish peroxidase] from luminal to
apical side. Additionally, ruminal fluid and blood samples were taken at the
beginning of the experiment as well as shortly before euthanasia. Ruminal
fluid samples were analyzed for volatile fatty acids and pH, whereas blood
samples were analyzed for lipopolysaccharide, serum amyloid A, and
β-hydroxybutyrate. Electrophysiological data indicated that barley feeding
increased the epithelial short-circuit current compared with the control.
Tissue conductance also increased with dietary barley inclusion. As shown with
both marker molecules, permeability of ruminal epithelia increased with barley
inclusion in the diet. Despite a lowered ruminal pH associated with increased
volatile fatty acids (such as propionate and butyrate) concentrations as well
as altered epithelial properties in response to high-grain feeding, no signs
of inflammation became apparent, as blood serum amyloid A concentrations
remained unaffected by diet. However, greater amounts of grain in the diet
were associated with a quadratic increase in lipopolysaccharide concentration
in the serum. Also, increasing the amounts of barley grain in the diet
resulted in a tendency to quadratically augment serum concentrations of
β-hydroxybutyrate and, hence, the alimentary ketogenesis. Further studies are
needed to clarify the role of barley inclusion in the development of subacute
ruminal acidosis in relation to ruminal epithelial damage and the
translocation of toxic compounds in vivo. Copyright © 2013 American Dairy
Science Association. Published by Elsevier Inc. All rights reserved