Methane mitigation: nutritional highlights. John Rooke, Carol-Anne Duthie, Shane Troy, Rainer Roehe, Tony Waterhouse

Transcription

1 Methane mitigation: nutritional highlights John Rooke, Carol-Anne Duthie, Shane Troy, Rainer Roehe, Tony Waterhouse

2 Criteria for selection of nutritional mitigation strategies Proven effectiveness Economic and practical in use No adverse effects on animal performance / health Persistent over time 2

3 Scope is narrow Methane from rumen fermentation of feed χ methane emissions from excreta χ nitrous oxide emissions from N excretion χ No focus on farm production system / economics χ No life-cycle analysis Yet. 3

4 Extensive experimental records Feed and productive efficiency Chamber based measurements Carcass and meat quality based measurements Feed intake (Hoko) Live-weight gain Feed efficiency & RFI US fat and muscle depth CH 4 hood systems Methane measurements Feed intake Live-weight Rumen samples Faecal samples Feed characterisation EUROP grades VIA information Loin samples Sensory Fatty acid profiles Vitamin E Colour shelf life 4

5 METHANE METHANE 5

6 VFA 6

7 Methane mitigation - mechanisms Reduce hydrogen production Utilise hydrogen by pathways other than methanogenesis Inhibit archaea (numbers / activity) 7

8 Reduce hydrogen production Increase concentrate in diet Diet Concentrate 920 g/kg diet DM Forage 500 g/kg diet DM P Study Acetate:propionate ratio Methane (g/kg DMI) *** *** Less hydrogen produced fermentation with propionate as end-product So reduction in methane produced by over 30% 8

9 Utilise hydrogen by alternative pathway Use nitrate (18 g/kg) as feed additive Methane (g/kg DMI) P<0.001 Control Nitrate Energetically reduction of nitrate to ammonia NO 3 + 4H 2 = NH 4+ 2H 2 O superior to CO 2 + 4H 2 = CH 4 + 2H 2 O 20% reduction in methane in forage diet but No reduction in concentrate diet 0 Forage Concentrate Why? 9

10 Inhibit archaea (numbers / activity) Increase dietary lipid (but not only mechanism) Lipid increased by feeding rape cake (26 g/kg) or brewers grains (17 g/kg) Variable reductions in methane output (g/kg DMI; in red below) may be diet-type dependant % Control Rape cake Silage Brewers grains 17% Methane reduction 20 None Forage Concentrate 0 Barley straw 10

11 Methane emissions are consistent across time 12 Hoods (July) vs Chambers (September-December) Hood CH4 (L/hr) y = x R² = Chamber CH4 (g/day) Good agreement between animals on different treatments with measurements made 2 to 4 months apart demonstrates effects of mitigation strategies (concentrate, nitrate, lipid) consistent across time 11

12 Criteria for selection of nutritional mitigation strategies Strategy Concentrate Nitrate Lipid Effectiveness Practical No adverse performance effects No adverse health effects Persistent

13 Scope is narrow Methane from rumen fermentation of feed χ methane emissions from excreta χ nitrous oxide emissions from N excretion χ No focus on farm production system / economics χ No life-cycle analysis Yet. 13

14 Methane emissions per kg gain Diet Forage Methane / kg gain Control 162 Lipid 156 Nitrate 139 (-14%) Concentrate Control 108 Lipid 113 Nitrate 92 (-15%) Because concentratenitrate fed animals were more efficient, nitrate reduces methane per unit gain on both basal diets. 14

15 Gaps in basic data on methane output for UK GAPS ACTUAL PLANS Growing/ Growing/ Diet/System finishing finishing beef Beef beef Beef cows cattle cows cattle Housed Grass silage AFBINI SAC SAC Maize silage Straw and by-product based?? SAC High concentrate inputs + + SAC Grazing Improved grass grazing 0 0 Permanent pasture grazing 0 0 Rough grazing 0 0 Moorland 0/NA 0 AFBINI SAC AFBINI SAC IBERS AFBINI IBERS AFBINI 15

16 Gaps in basic data on methane output for UK GAPS ACTUAL PLANS Growing/ Growing/ Diet/System finishing finishing beef Beef beef Beef cows cattle cows cattle Housed Grass silage AFBINI SAC SAC Maize silage Straw and by-product based?? SAC High concentrate inputs + + SAC Grazing Improved grass grazing 0 0 Project finished March 2014 AFBINI generated IBERS 2100 SAC AFBINI new observations AFBINI IBERS Modelling in progress SAC AFBINI Permanent pasture grazing 0 0 Rough grazing 0 0 Moorland 0/NA 0 16

17 Methane outputs from suckler cows grazing low-ground and hill pasture Daily CH 4 output g/d adjusted for digestibility Low Hill Low Hill Cows grazing on hill pasture produced less methane than on perennial ryegrass pasture (P<0.001; left hand chart) Hill pasture of lower digestibility which accounts for some of difference (right hand chart) Cows grazing hill pasture probably ate less 17

18 Conclusions For housed cattle, there are proven nutritional methods for mitigating methane emissions For grazing cattle, particularly beef cattle, opportunities for nutritional mitigation less advanced 18

19 Acknowledgments 19