Direct-fed microbials (DFM) are used in ruminant production to increase productivity and improve health, they can
be used as a possible option to decrease methane emission. The objectives of this study was i) to validate the
same test in two laboratories and ii) to asses the effect of
two DFM products in an in vitro rumen fermentation. Six
treatments (n=3/treatment) were fermentated twice for
48 hours using an automated gas pressure measurement
system, simultaneously at University of Copenhagen and
Chr. Hansen. Maize silage (MS) and grass silage (GS) was
fermented with and without two DFM products (P1: Lactobacillus animalis, Propionibacterium freudenreichii 1.5*107
total CFU/ml, P2: P1 + Bacillus subtilis, Bacillus licheniformis
5.9*107
total CFU/ml). Rumen fluid was added to a buffer
solution (2:1) and kept anaerobic at 39.5°C. The test units
were kept in a thermoshaker with 40 rotations per minute
for 48h. Total gas production (TGP: ml at Standard Temperature and Pressure/gram organic matter), pH, organic
matter degradability (dOM), methane concentration (MC)
and volatile fatty acids (VFA) were measured after fermentation. All the measured parameters were blank corrected
before statistical analysis. No significant effect of laboratory
was detected for any of the response variables. Therefore,
a mixed linear model with laboratory as a random variable
and feed and additive was used. Significance was determined if p<0.05. The dOM of MS (78.3%) was significantly
different from GS (81.4%) regardless of the additives (P1
and P2), however there were no significant differences of
the effect of either probiotic within the feed type. Degradation of MS produced significantly more gas than GS after 48
hours. Both probiotics increased TGP significantly in GS but
not in MS. There was no difference in total VFA production,
however GS with and without probiotics produced signifincantly more propionic acid and less butyric acid then MS
with and without probiotics. The addition P2 numerically
reduced the total methane production per gOM between
4-6% in both MS and GS. These results showed that i) there
is alignment between the two tested laboratories and ii)
the P2 DFM shows potential to reduce methane production
without affecting organic matter degradation.