Manipulation of Microbial Ecology for Sustainable Animal Production - Sustainable Animal Agriculture - page 260

dry matter intake, which also contributes to lower
methane production (Machmüller et al ., 2000).
Tallow and whole soybeans have been shown
to decrease methane by 11% and 25% per kg dry
mater intake, respectively (Jordan et al ., 2006a;
Beauchemin et al ., 2007a). However, palatabil-
ity issues resulted in 60% refusals. Sunflower
seed supplementation with heifers and dairy
cows resulted in 23% and 10.4% reduction in
methanogenesis, respectively (Beauchemin et al .,
2007a, 2009). Flaxseed and canola seed also
decreased methane by 17.8% and 16.0% per kg
dry matter intake, respectively (Beauchemin et al .,
2009). Supplementation with rapeseed, sun-
flower seed and linseed resulted in methane
abatements of 19%, 27% and 10%, respectively,
in growing lambs (Machmüller et al ., 2000). It is
important to note that the majority of in vivo
experiments undertaken to evaluate lipids
have been short-term in duration. Long-term
supplementation studies are needed compre-
hensively to assess the effectiveness of lipid
supplementation as an abatement strategy.
However, lipids can affect palatability, intake,
animal performance and milk components, all
of which can have implications for practical
on-farm use (Jordan et

Tiemann et al ., 2008). However, condensed tannin
from Schinopsis quebrachocolorado (Beauchemin
et al ., 2007b) and tannin-containing sorghum
silage (De Oliveira et al ., 2007) fed to cattle did
not suppress methanogenesis.
Essential oils have antimicrobial activities
that inhibit Gram-positive bacteria (Burt, 2004;
Calsamiglia et al ., 2007), which should reduce
the amount of available hydrogen for methano-
genesis. More in vivo research is needed with
essential oils, condensed tannins and saponins
to determine the optimal dosage where metha-
nogenesis is reduced without producing nega-
tive side effects on digestibility (Hook et al .,
2010), or detection of residues in meat or milk
(Calsamiglia et al ., 2007).

Immunization

A novel immunization approach was explored
and tested to increase the efficiency of nutrient
utilization in farmed ruminants and reduce
methane emissions (Wright et al ., 2004a;
Williams et al ., 2008, 2009). The idea was to
stimulate the host ruminant's immune system
to elicit an immune response and produce anti-
bodies against the rumen methanogens.
Wright et al . (2004a) vaccinated sheep with an
anti-methanogen vaccine that was based on
three strains (1Y, AK87 and ZA-10) belonging
to the genus Methanobrevibacter . Vaccination
induced a humoral immune response, as indi-
cated by the specific Immunoglobulin G (IgG)
titres in plasma and saliva, and specific anti-
methanogen IgG was also delivered to the
rumen as indicated by the titres in the rumen
fluid. As a result, vaccination produced a 7.7%
decrease in methane production per kg of dry
matter intake.
Curiously, Wright and his colleagues (2006)
later discovered that less than 20% of the metha-
nogen species identified in those sheep were
closely related to (i.e. targeted by) the methano-
gens in the vaccine. Based upon these findings, it
was suggested that greater methane abatement
might be possible if a greater proportion of the
methanogen species/strains were targeted by the
vaccine. Unfortunately, Williams et al . (2009)
failed to significantly impact methane emission
by these sheep, and the density of methanogens,

al ., 2006a; Odongo

et al ., 2007b).

Plant compounds

Saponins have been shown to inhibit protozoa
and decrease hydrogen availability in vitro
(Guo et al ., 2008). However, when Holtshausen
et al . (2009) supplemented cows with whole-
plant Yucca schidigera powder 10 g kg -1 dry
matter or whole-plant Quillaja saponaria powder
at 10 g kg -1 dry matter, no effect of the plant
supplementation was found due to reduced
feed digestion and fermentation in vivo , when
compared to the in vitro trials.
Condensed tannins are thought to directly
inhibit methanogens and limit methanogene-
sis by decreasing hydrogen availability (Carulla
et al ., 2005; Puchala et al ., 2005; Tavendale et al .,
2005). Lespedeza cuneata, Acacia mearnsii, Calli-
nada calothyrsus and Fleminga macrophylla all
contain condensed tannins, and were found
to make significant reductions (13-24%) in
methanogenesis in vivo (Carulla et al ., 2005;