1. Preservation of seaweeds as silage
Martin Riis Weisbjerg1, Mogens Larsen1, María Dolores Carro Travieso2, Eduarda Molina Alcaide3, Irene Sentana Gadea4, Margarita Novoa-Garrido5
1Department of Animal Science, AU Foulum, Aarhus University, Denmark
2Departamento de Producción Agraria, Universidad Politécnica de Madrid, Spain
3Estación Experimental del Zaidin (CSIC), Granada, Spain
4Instituto del Agua y de las Ciencias Ambientales, Universidad de Alicante, Spain
5Faculty of Biosciences and Aquaculture, Nord University, Norway
7th Nordic Seaweed Conference 11th – 12th October 2017, Grenaa, Denmark

2. Background Seaweed is a large biomass source
Use of seaweeds in animal feeding is not new
Knowledge on feed value is very limited, but now increasing
7th Nordic Seaweed Conference 11th – 12th October 2017, Grenaa, Denmark

3. Background Shelf life of harvested seaweed is short
Use of seaweeds in animal feeding therefore require preservation
Drying and/or ensiling most common preservation methods for feeds used for animal production
7th Nordic Seaweed Conference 11th – 12th October 2017, Grenaa, Denmark

4. Background Ensiling is anaerobic fermentation
Lactic acid bacteria ferment sugars into lactic acid
Homofermentative lactic acid bacteria mainly produce lactic acid
Heterofermentative lactic acid bacteria also produce other fermentation products like acetic acid
If lactic acid bacteria are few, or their growth conditions are impaired, other bacteria and microorganism might take over
Fermentation continue until fermentation products, pH and osmotic pressure arrest the fermentation
7th Nordic Seaweed Conference 11th – 12th October 2017, Grenaa, Denmark

5. Aim
The aim of this study was to get some basic info on whether it is possible to ensile seaweed for animal feed purposes
7th Nordic Seaweed Conference 11th – 12th October 2017, Grenaa, Denmark

6. Silage treatments 2 x 3 x 2 factorial design 2 seaweeds 3 silage types
Porphyra sp.
Saccharina latissima
3 silage types
unwashed (CON, control)
washed (WS)
washed added formic acid (4 g/kg) (WFA)
2 prewilting treatments
undried
predried
7th Nordic Seaweed Conference 11th – 12th October 2017, Grenaa, Denmark

7. Seaweeds used Collected from wild stocks in Bodø, Norway, in June 2016
Saccharina latissima
Porphyra sp.
Collected from wild stocks in Bodø, Norway, in June 2016
7th Nordic Seaweed Conference 11th – 12th October 2017, Grenaa, Denmark

8. Drying Drying (wilting) in forced air drying oven at max. 37 oC
Target 30% DM
Target weight based on fresh DM from earlier study!
7th Nordic Seaweed Conference 11th – 12th October 2017, Grenaa, Denmark

9. Ensiling Seaweeds were ensiled in vacuum bags
3 repetitions, in total 36 bags
7th Nordic Seaweed Conference 11th – 12th October 2017, Grenaa, Denmark

10. Silage extracts
Extraction: 100 g silage in 750 g water, blended 2x40 sec. in Waring blender, centrifuged. Analyses on supernatant
7th Nordic Seaweed Conference 11th – 12th October 2017, Grenaa, Denmark

11. Chemical composition of un-ensiled seaweeds
Washing remove ash especially for Porphyra
7th Nordic Seaweed Conference 11th – 12th October 2017, Grenaa, Denmark

12. Chemical composition of un-ensiled seaweeds
Crude protein lower than in earlier study on these species from Bodø
7th Nordic Seaweed Conference 11th – 12th October 2017, Grenaa, Denmark

13. Prewilting (drying) was overdone
Measures on silages
Prewilting (drying) was overdone
7th Nordic Seaweed Conference 11th – 12th October 2017, Grenaa, Denmark

14. Effluent high in silage without prewilting, especially Porphyra
Measures on silages
Effluent high in silage without prewilting, especially Porphyra
7th Nordic Seaweed Conference 11th – 12th October 2017, Grenaa, Denmark

15. Measures on freeze dried silage samples
Washing reduced ash especially for Porphyra
7th Nordic Seaweed Conference 11th – 12th October 2017, Grenaa, Denmark

16. Measures on freeze dried silage samples
Crude protein high in Porphyra, low in Saccharina
7th Nordic Seaweed Conference 11th – 12th October 2017, Grenaa, Denmark

17. Measures on silage extracts
pH high when no formic acid was added
7th Nordic Seaweed Conference 11th – 12th October 2017, Grenaa, Denmark

18. Measures on silage extracts
Ammonium high in Porphyra without prewilting
7th Nordic Seaweed Conference 11th – 12th October 2017, Grenaa, Denmark

19. Measures on silage extracts
Glucose high in Saccharina, absent in Porphyra
7th Nordic Seaweed Conference 11th – 12th October 2017, Grenaa, Denmark

20. Measures on silage extracts
Lactate from low to very low (not normal lactic acid ensiling)
7th Nordic Seaweed Conference 11th – 12th October 2017, Grenaa, Denmark

21. Measures on silage extracts
Acetate high - especially in Porphyra without prewilting
7th Nordic Seaweed Conference 11th – 12th October 2017, Grenaa, Denmark

22. Measures on silage extracts
Butyrate high to problematic high in Porphyra without prewilting
7th Nordic Seaweed Conference 11th – 12th October 2017, Grenaa, Denmark

23. Measures on silage extracts
Ethanol especially in Porphyra without prewilting
7th Nordic Seaweed Conference 11th – 12th October 2017, Grenaa, Denmark

24. Measures on silage extracts
Free alanine especially in Porphyra (with also higher CP)
7th Nordic Seaweed Conference 11th – 12th October 2017, Grenaa, Denmark

25. Conclusion The two seaweeds ensiled
But lactate was not the major fermentation acid as it is in terrestrial forage silages
7th Nordic Seaweed Conference 11th – 12th October 2017, Grenaa, Denmark

26. Literature Literature is scarce on info on ensiling seaweed
Study on U. lactuca, Ascophyllum nodosum, L. digitata, Saccorhiza polyschides and S. latissima:
Effluents serious
Lactic acid bacteria (LAB) number low
Substrate for LAB low
Mannitol high in some brown seaweeds and might increase during ensiling
7th Nordic Seaweed Conference 11th – 12th October 2017, Grenaa, Denmark

27. Further studies
This study was only a minor pilot study to get preliminary experience with ensiling seaweed
Priority questions for further research
Can addition of lactic acid bacteria give a more ‘normal’ lactic acid fermentation
How does ensiling affect rumen degradation of seaweed protein
Saccharides
Is a lot of mannitol produced when ensiling seaweed
What is the value of mannitol and seaweed polysaccharides as animal feed (monogastric/ruminants)
7th Nordic Seaweed Conference 11th – 12th October 2017, Grenaa, Denmark

28. Thank you for your attention
Project funded by the Norwegian research council
PREMAC - Preserving macroalgae for industrial purposes (Forprosjekt - RFFNORD)
7th Nordic Seaweed Conference 11th – 12th October 2017, Grenaa, Denmark