The potential applications of brown seaweed as an alternative feed for ruminant livestock
This thesis builds on a growing areaof scientific research aimed at addressing the feasibility and potential benefits of feeding brown seaweed to ruminant livestock. The primary objectives of this research were to: identify gaps in current knowledge on the potential use of brown seaweed as a feed source for ruminant livestock; to establish a baseline knowledge of the nutritional composition of four commonly found brown seaweed species in Northern Ireland; to investigate the use of infrared spectroscopy as a tool to rapidly measure the nutritional composition of brown seaweed and to explore the use of ensilage as a preservation method for the application of brown seaweed as a ruminant livestock feed. Chapter 1 discusses a rationale forinvestigating alternative feeds for the ruminant livestock sector by discussingthe current challenges to modern agriculture (e.g. climate change, rising feedcosts and resource depletion) which accumulate in a series of unprecedentedthreats to the security of livestock feed supply chains. Following this,Chapter 2 presents a review of the current scientific literature on the use ofseaweed in ruminant diets. The first experimental chapter (Chapter 3) describesseason- and species-related trends in the nutritive value of a natural (i.e.uncultivated) population of seaweeds collected in Northern Ireland. Fourspecies (Ascophyllum nodosum (L.) Le Jolis, Fucusvesiculosus Linnaeus, Laminaria digitata (Hudson)J.V. Lamouroux and Saccharina latissimi (L.) C.E. Lane, C. Mayes,Druehl & G.W. Saunders) were chosen based on their availability in NorthernAtlantic regions. The chemical composition and in vitro drymatter digestibility of the species were screened over a 10-month period.Chapter 4 was designed to screen the effects of the four brown seaweed specieson in vitro gas and methane production compared to Medicagosativa, a terrestrial forage. Chapter 5 discusses the potential ofdeveloping rapid methods of measuring the nutritive value of seaweeds in theruminant diet using Near Infrared (NIR) and Mid Infrared (MIR) spectroscopy.Finally, Chapters 6 and 7 explored the effect of ensilage, a commonly usedpreservation method for ruminant livestock feeds, on the characteristics ofbrown seaweed as a livestock feed. In a preliminary study (Chapter 6), twospecies (Fucus vesiculosus and Saccharina latissimi) wereselected for ensilage; these species were chosen based on their contrastingchemical profiles and their high biomass availability at the time ofharvest. Saccharina latissimi progressed to the next study(Chapter 7) which was a more in-depth exploration of the characteristics ofseaweed silage. The studies presented in Chapters 6 and 7 highlightthe potential of ensilage as a method of preserving the nutritive valueof Saccharina latissimi, which might represent a feasible,post-harvest method of preserving seaweeds in temperate regions such asNorthern Ireland.The body of work presented in thisthesis contributes to the emerging knowledge on the potential applications ofbrown seaweed as a feed for ruminant livestock. It is expected that this workwill support the continued search for viable, alternative feeds for livestockto safeguard local feed security and to promote the sustainability of theruminant livestock sector in Northern Ireland. Thesis emabargoed until 31st July 2029
Brown seaweed, ruminant, rumen fermentation, methane, silage, spectroscopy, livestock feed, in vitro digestibility, Ascophyllum nodosum, Fucus vesiculosus, Laminaria digitata, Saccharina latissimi
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