TITLE:
Methodology Article: Can Ruminal Reducing Power Assessed in Batch Cultures be Comparable to in Vivo Measurements?
AUTHORS:
Christine Julien, Jean-Philippe Marden, Annabelle Troegeler-Meynadier, Corine Bayourthe
KEYWORDS:
Batch Cultures, Clark’s Exponent, Redox Potential
JOURNAL NAME:
Journal of Analytical Sciences, Methods and Instrumentation,
Vol.4 No.3,
September
2,
2014
ABSTRACT: In ruminant field
of digestive research, the appeal to methods of less invasive studies and reproducing
the in vivo conditions is essential. The
objective of the present study was to determine whether the conditions created
with the proposed in vitro batch
culture was an accurate reproduction of the physico-chemical and fermentative
ruminal conditions observed in vivo.
Two experiments were conducted to compare ruminal reducing power measured in
vitro, i.e. in batch
cultures or, in vivo i.e. in live animals: dairy cows at
maintenance (Experiment 1) and lactating dairy cows (Experiment 2). In
Experiment 1, at the beginning of incubation period, in vitro redox potential (Eh), pH
and Clark’s exponent (rH) values were significantly higher than in vivo (+42
mV, +0.25 and +1.9, respectively) whereas volatile fatty acids (VFA) contents
were 2.6 fold lower on average. At the end of incubation, Eh,
rH values and VFA contents were similar between both methods whereas pH still
remained different. In Experiment 2, at the beginning and at the end of incubation
period, in vitro Eh, pH and rH values differed
significantly than in vivo. As a result, the in vitro method did
not provide a tool to evaluate accurately the level of the reducing status of
ruminal milieu compared with in vivo measurement. Nonetheless, it
provided strong reducing conditions after 8 h of incubation with levels of rH
relatively closed to those observed in
vivo. In vitro batch culture
could be a good alternative to in vivo trials for a screening approach
from an ethic and economic point of view in ruminant field of research.