Cause and control of enteric methane emissions from ruminants Flashcards
What is methane production caused by
Methane produced -> caused by anaerobic fermentation -> produced as a by-product
what is the predominant source of methane gas production in ireland 2022
agriculture
- accounting for 38.4%
what % does enteric fermentation of all GHG’s account for
63%
based on 2020-2022 what was the decrease in methane production
1.2%
By 2030, what is the target to reduce GHG emissions by?
25%
By 2050, methane emissions need to get a net of ___?
0
from 2010 onwards, why is there more methane produced
more dairy cows
- dairy cows have a higher feed intake so produce more methane as they eating more.
where is enteric methane produced
enteric methane is produced in the digestive tract.
what are the 3 mains form of enteric methane
- methane
- carbon dioxide
- nitrous oxide
what compares warming impact on the 3 main gases across a 100-year timeframe
GWP100
what metric is used for methane
GWP*
Over 12 years, how much more of an effect has methane than carbon dioxide
80 times
What are the 3 main Volatile Fatty Acids
- Acetate
- Butyrate
- Propionate
why does the rumen produce methane?
- One of the end products of feed (mainly fibre) digestion
-Produced by archaea in association with protozoa. - An inevitable consequence
- Must be careful not to disrupt ruminal fibre digestion through mitigation.
- Is influenced by diet (and genetics)- therefore some opportunities to manipulate.
- Methane production in an inevitable consequence of anaerobic fermentation
- Can modify/reduce
what happens when acetate is produced
hydrogen is released
what happens when propionate is produced?
hydrogen is utilised
over 100 years, how much more warming impact has methane than carbon dioxide
28 times
Archaebacteria (rumen methane production)
- 0.5% to 0.3% of total microbes
- associated with protozoa
- obligate anaerobes
- methane formation sole energy generating mechanism
- really good at capturing energy.
in rumen methane production, how is C02 reduced to CH4
using H2 as an energy source
what sort of carbs drive methane
structural carbs
what influences the level of methane produced
VFA’s
in hind gut fermentation what is produced
- less methane is produced than expected.
- acetogens rather than methanogen predominate
Acetogens
acetogens need to be fed daily to utilize hydrogen in the rumen but can establish a stable population in the rumen.
during hind gut fermentation, what happens most of the methane that is produced?
most of the methane produced is absorbed into blood and excreted in the breath by the lungs
how can we reduce methane emissions?
- select animals for reduced methane emissions(Greenbreed in ireland)
-different feeds result in different levels of methane production
(improve forage quality, feed concentrates/ additives)
what % difference in methane is between the high and low performing animals
10% different
what is methane production a function of?
the animal, the diet and the microbial population in the rumen
Bromochloromethane
-red seaweed from australia
- targets methanogens in rumen
out of all the feed additives that have been tested, how many consistent of potential to reduce methane
3
Screening candidates for methane mitigation
o Oxidising methane inhibitors (2/3)
o Asparagopsis (2/3)
o Ascophyllum nodosum (1/3)
Bovaer ( 3-nitrooxypropanol, 3NOP)
synthetic non - toxic compound
- mean reduction of 30% in methane
- Mode of action: limits the last step of the methanogenesis cycle
-immediate reduction to CH4 once fed.
who approved for feeding 3-nitrooxypropanol to dairy cattle
EFSA approved in EU
have Bovaer 3-nitrooxypropanol an effect on DMI,ADG, feed efficiency
no effect on DMI, ADG, feed efficeny
what is the % reduction in methane after 2.5 hours of feeding bovaer supplementation
30% reduction in methane after 2.5 hours after feeding
what is the overall reduction in methane emissions when using bovaer supplementation in grazing dairy cows
7% reduction
how is bovaer supplementation fed to dairy cows during the dry period
mixed throughout feed using a diet feeder
-22% reduction in methane
what are oxidising methane inhibitors
peroxide based compounds used in human food
- E.G calcium peroxide- RumenGlas
- based on the control of rumen oxidation reduction potential
what is the mechanism of action in oxidising methane inhibitors
- inhibit methanogens
- divert electrons from H2 -> trap energy in biomass
what does ORP stand for
oxidation reduction potential
by how much can RumenGlasa reduce methane emissions from from stored storage
by 80%
how much does oxidising methane in hibitoes cost
0.09-0.13 euro per head per day
what is GREENBREED?
Identification of low methane emitting cattle
what is a function of DMI
enteric methane emissions
what is the biggest drive of methane output
feed intake
- 20g of methane per 1kg of feed
which produces less amount of methane?
- cows at pasture at spring time
OR
- cows housed indoor at autumn
cows at pasture at spring time
by how much is methane reduced
- per day?
- per kg ADG
in grass quality beef cattle
Methane per day: 7%
methane per kg ADG : 22%
by how much is methane reduced
- per day?
- per kg milk solids:
grass quality, dairy cattle
methane per day: 13%
methane per kg milk solids: 18%
did chickery have an impact on methane emissions
no
By how much was methane emissions reduced by when clover was added
12%
what crop had highest methane output
grass silage
- more fibrous feeds= more emissions produced
by how much is methane reduced
- per day?
- per kg carcass gain
finishing system of beef cattle
per day: 42%
- per kg carcass gain: 60:
what is defaunation
removal of protozoa
- responsible for significant proportion of methane production
what does protozoa release from carbs
hydrogen
where does methanogens live
on the surface
what does dietary oil supplementation have the potential to do?
reduce methane emissions
what are the challenges of defaunation
- find a substance that is non-toxic to another bacteria/animal.
- Achieve defaunation without compromising fibre digestion.
what gives the greatest response of defaunation
high concentrate diets
- protozoa population increases
Literature summary of added fat vs Ch4 production
-For every 1% additional fat added to the diet, methane is reduced by 5.5%.
-More oil we feed greater linear reduction.
-Cut off at 6% because too much fat can significantly reduce fibre digestion in rumen.
what length carbons is soya oil
18 carbon chain
- 2 double bonds in linoleic
-3 double bonds in linolenic
fish oils
- high polyunsaturated fats
- 20 carbons
-5 double bonds
oils vs Grass
oils are:
-expensive
-high carbon footprint
- some fatty acids present in soya and linseed oil are found in grass
Name the most common feed additives
- agolin
- asparagopis armata
- asparagopis taxiforms (seaweed)
- carsogenic - Bovaer - best established
