Effects of Seaweeds on in vitro rumen fermentation, methane and total gas production

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1 Effects of Seaweeds on in vitro rumen fermentation, methane and total gas production Gizaw Dabessa Satessa, Mette Olaf Nielsen, Jens Legarth, Rajan Dhakal and Hanne Helene Hansen 15 October 2017

2 Introduction Methane (CH4) is a greenhouse gas (GHG) synthesized by methanogenic archea from hydrogen (H2) and carbon dioxide (CO2) released during ruminal fermentation Ruminal fermentation 2CO2 + 4H2 CH4 + 2H2O Methanogenic Archea Figure 1. Synthesis of methane from H2 in the rumen Methane released from livestock: one of the GHG; accounting for ~28% of global anthropogenic CH4

3 15/11/ Impacts of enteric methane emission 1) Global warming and climate change CH 4 has 25 times global warming potential compared to CO 2 2) Represents loss of energy: Lowers feed efficiency and animal productivity Results in loss of 2 to 12% gross energy intake Reduction of CH4 is a win/win situation: - Environment - Farmer economy and cow energy metabolism

4 15/11/ EU Policy EU countries must reduce GHG emissions by 40% in 2030 in the non-quota sector (includes agriculture) compared to 1990 (5,716 mega tons CO2 equivalents) Reducing CH4 emission from (ruminant) livestock sector will be a positive contribution to global efforts in GHG emission reduction

5 15/11/ Enteric Methane emission mitigation strategies No safe and efficient methods exist as yet: Which reduce enteric methanogenesis Without significantly reducing feed degradability and hence animal performance Recently, seaweeds (macroalgae) have attracted interest: Contain bioactive compounds Some of these are capable of reducing methane formation

6 15/11/ Macroalgae (Seaweeds) Classified based on pigmentation as: red macroalgae brown macroalgae and green macroalgae Contains compounds not found in terrestrial plants: eg. complex carbohydrates: alginates, laminarin, fucoidan, mannitol, etc.

7 15/11/ Macroalgae Cont d Wide range of potential uses: antibiotic, anti-oxidant, anti-inflammatory, immunostimulants, prebiotics, etc. Some compounds: anti-methanogenic properties Different species of macroalgae differ in their antimethanogenic efficiency

8 Macroalgae Cont d In vitro study on Asparagopsis taxiformis in Australia showed about 99% inhibition of methane production - bromoform, dibromochloromethane, chloroform, etc Dictyota bartayresii Asparagopsis taxiformis Figure 2. CH4 production from in vitro fermentation of different seaweed species Machado et al (1):e85289

9 15/11/ Macroalgae Cont d Asparagopsis is not likely to be used to mitigate CH4 emission: - halogenated hydrocarbons: - deplete ozone (environement) and carcinogenic (consumer health issues)

10 15/11/ Objectives Do seaweeds, which can be produced in the Northern Hemisphere, contain compounds with anti-methanogenic properties in the rumen? Do they interfere with feed efficiency in ruminants? Do they reduce enteric methane emission?

11 15/11/ Experimental approach We do not want to test this in the first instance in live animals because 1) very expensive 2) we need to know if we have safe compounds So, we addressed this question using an in vitro system that mimicks rumen fermentation and allows rapid screening for effective products

12 Cumulative pressure 15/11/ In vitro system: mimicking rumen fermentation Output - Total gas - Methane Rumen fluid Basal diets (One at a time) 2 systems: - Ankom - BPC Additives (One at a time) Time Degraded feed (Microbiota profile) Beet pulp (BP) Maize silage (MS) Various seaweed products (SWP): Brown Algae (alone or prefermented with rapeseed), Ocean Feed

13 Total gas production in ml/g DM Rumen fermentation of seaweed products 15/11/ TG produced from pure maize silage (MS), sugar beet pulp (BP), brown algae species (BA) and Ocean Feed (OF) Duration of incubation (hours) Sea weed products: virtually no gas production in rumen (Low fermentability)

14 Total gas produced in ml/g DM Total gas production in ml/g DM 15/11/ Effect of seaweeds on in vitro rumen gas production % Basal feeds Additives % reduction MS BA 18.2 OF Maize silage Duration of incubation (hours Pure % 150 Beet pulp Basal feeds Additives % reduction 100 BP BA 21.3 OF Duration of incubation (hours) Pure

15 Methane released (ml/g DM) 15/11/ Effect of seaweeds on in vitro rumen methane release % Basal feed Additves % reduction MS BA 32 OF Duration of incubation (hours)

16 Percentage DM degraded Percentage DM degraded Effect of seaweeds on in vitro rumen feed degradation c c b b a BA OF RBA MS BP Pure MS, BP and SWP % digestibility of pure (0.5g): BA=21.9 OF=51.5 RBA=50.7 MS =78.5 BP = a a b b c c d d e e f f % degradability of feed mix: (0.5g MS + 0.1g SWP) - Observed 40 Observed Predicted - Theoretical 20 0 MBA MOF MRBA BBA BOF BRBA SWP mixed with MS or BP

17 15/11/ Take home messages: The two seaweed products: very low fermentability in the rumen very little gas produced during fermentation Brown Algae and to less extent Ocean Feed: reduced total gas production from feeds by up to 21% depending on seaweed product and basal feed. Specifically inhibited methane production by up to 32% AND, importantly, rumen in vitro degradability of feeds was not affected Next step: Identify and test bioactive components Test in live animals

18 15/11/ Acknowledgement I would like to thank MAB4 and FEX for funding my PhD and University of Copenhagen for hosting my study. I would also like to thank Mette Olaf Nielsen (Professor) and Hanne Helene Hansen (Associate Professor) for supervision

19 Thank You 15/11/