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Animal nutrition 2 -TB > Cause and control of enteric methane emissions from ruminants > Flashcards

Cause and control of enteric methane emissions from ruminants Flashcards

1
Q

What is methane production caused by

A

Methane produced -> caused by anaerobic fermentation -> produced as a by-product

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2
Q

what is the predominant source of methane gas production in ireland 2022

A

agriculture
- accounting for 38.4%

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3
Q

what % does enteric fermentation of all GHG’s account for

A

63%

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4
Q

based on 2020-2022 what was the decrease in methane production

A

1.2%

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5
Q

By 2030, what is the target to reduce GHG emissions by?

A

25%

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6
Q

By 2050, methane emissions need to get a net of ___?

A

0

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7
Q

from 2010 onwards, why is there more methane produced

A

more dairy cows
- dairy cows have a higher feed intake so produce more methane as they eating more.

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8
Q

where is enteric methane produced

A

enteric methane is produced in the digestive tract.

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9
Q

what are the 3 mains form of enteric methane

A
  • methane
  • carbon dioxide
  • nitrous oxide
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10
Q

what compares warming impact on the 3 main gases across a 100-year timeframe

A

GWP100

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11
Q

what metric is used for methane

A

GWP*

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12
Q

Over 12 years, how much more of an effect has methane than carbon dioxide

A

80 times

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13
Q

What are the 3 main Volatile Fatty Acids

A
  • Acetate
  • Butyrate
  • Propionate
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14
Q

why does the rumen produce methane?

A
  • 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
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15
Q

what happens when acetate is produced

A

hydrogen is released

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16
Q

what happens when propionate is produced?

A

hydrogen is utilised

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17
Q

over 100 years, how much more warming impact has methane than carbon dioxide

A

28 times

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18
Q

Archaebacteria (rumen methane production)

A
  • 0.5% to 0.3% of total microbes
  • associated with protozoa
  • obligate anaerobes
  • methane formation sole energy generating mechanism
  • really good at capturing energy.
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19
Q

in rumen methane production, how is C02 reduced to CH4

A

using H2 as an energy source

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20
Q

what sort of carbs drive methane

A

structural carbs

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21
Q

what influences the level of methane produced

A

VFA’s

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22
Q

in hind gut fermentation what is produced

A
  • less methane is produced than expected.
  • acetogens rather than methanogen predominate
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23
Q

Acetogens

A

acetogens need to be fed daily to utilize hydrogen in the rumen but can establish a stable population in the rumen.

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24
Q

during hind gut fermentation, what happens most of the methane that is produced?

A

most of the methane produced is absorbed into blood and excreted in the breath by the lungs

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25
Q

how can we reduce methane emissions?

A
  • select animals for reduced methane emissions(Greenbreed in ireland)

-different feeds result in different levels of methane production
(improve forage quality, feed concentrates/ additives)

26
Q

what % difference in methane is between the high and low performing animals

A

10% different

27
Q

what is methane production a function of?

A

the animal, the diet and the microbial population in the rumen

28
Q

Bromochloromethane

A

-red seaweed from australia
- targets methanogens in rumen

29
Q

out of all the feed additives that have been tested, how many consistent of potential to reduce methane

A

3

30
Q

Screening candidates for methane mitigation

A

o Oxidising methane inhibitors (2/3)
o Asparagopsis (2/3)
o Ascophyllum nodosum (1/3)

31
Q

Bovaer ( 3-nitrooxypropanol, 3NOP)

A

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.

32
Q

who approved for feeding 3-nitrooxypropanol to dairy cattle

A

EFSA approved in EU

33
Q

have Bovaer 3-nitrooxypropanol an effect on DMI,ADG, feed efficiency

A

no effect on DMI, ADG, feed efficeny

34
Q

what is the % reduction in methane after 2.5 hours of feeding bovaer supplementation

A

30% reduction in methane after 2.5 hours after feeding

35
Q

what is the overall reduction in methane emissions when using bovaer supplementation in grazing dairy cows

A

7% reduction

36
Q

how is bovaer supplementation fed to dairy cows during the dry period

A

mixed throughout feed using a diet feeder
-22% reduction in methane

37
Q

what are oxidising methane inhibitors

A

peroxide based compounds used in human food
- E.G calcium peroxide- RumenGlas
- based on the control of rumen oxidation reduction potential

38
Q

what is the mechanism of action in oxidising methane inhibitors

A
  1. inhibit methanogens
  2. divert electrons from H2 -> trap energy in biomass
39
Q

what does ORP stand for

A

oxidation reduction potential

40
Q

by how much can RumenGlasa reduce methane emissions from from stored storage

A

by 80%

41
Q

how much does oxidising methane in hibitoes cost

A

0.09-0.13 euro per head per day

42
Q

what is GREENBREED?

A

Identification of low methane emitting cattle

43
Q

what is a function of DMI

A

enteric methane emissions

44
Q

what is the biggest drive of methane output

A

feed intake
- 20g of methane per 1kg of feed

45
Q

which produces less amount of methane?
- cows at pasture at spring time
OR
- cows housed indoor at autumn

A

cows at pasture at spring time

46
Q

by how much is methane reduced
- per day?
- per kg ADG
in grass quality beef cattle

A

Methane per day: 7%
methane per kg ADG : 22%

47
Q

by how much is methane reduced
- per day?
- per kg milk solids:
grass quality, dairy cattle

A

methane per day: 13%
methane per kg milk solids: 18%

48
Q

did chickery have an impact on methane emissions

A

no

49
Q

By how much was methane emissions reduced by when clover was added

A

12%

50
Q

what crop had highest methane output

A

grass silage
- more fibrous feeds= more emissions produced

51
Q

by how much is methane reduced
- per day?
- per kg carcass gain
finishing system of beef cattle

A

per day: 42%
- per kg carcass gain: 60:

52
Q

what is defaunation

A

removal of protozoa
- responsible for significant proportion of methane production

52
Q

what does protozoa release from carbs

A

hydrogen

52
Q

where does methanogens live

A

on the surface

52
Q

what does dietary oil supplementation have the potential to do?

A

reduce methane emissions

53
Q

what are the challenges of defaunation

A
  • find a substance that is non-toxic to another bacteria/animal.
  • Achieve defaunation without compromising fibre digestion.
53
Q

what gives the greatest response of defaunation

A

high concentrate diets
- protozoa population increases

53
Q

Literature summary of added fat vs Ch4 production

A

-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.

54
Q

what length carbons is soya oil

A

18 carbon chain
- 2 double bonds in linoleic
-3 double bonds in linolenic

55
Q

fish oils

A
  • high polyunsaturated fats
  • 20 carbons
    -5 double bonds
56
Q

oils vs Grass

A

oils are:
-expensive
-high carbon footprint

  • some fatty acids present in soya and linseed oil are found in grass
57
Q

Name the most common feed additives

A
  1. agolin
  2. asparagopis armata
  3. asparagopis taxiforms (seaweed)
    - carsogenic
  4. Bovaer - best established

Animal nutrition 2 -TB (2 decks)

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