PLANT SECONDARY METABOLITES: EFFECTS ON REDUCTION OF METHANE AND CARBONDIOXIDE FROM LIVESTOCK PRODUCTION

Table of Contents

Certification. ii

DEDICATION.. iii

ACKNOWLEDGEMENT. iv

Abstract. vi

CHAPTER ONE. 1

1.0         INTRODUCTION.. 1

CHAPTER TWO.. 3

2.0         Greenhouse gases. 3

2.1         Contribution of ruminants to greenhouse gas.4

CHAPTER THREE. 5

2.0         PLANT SECONDARY METABOLITES. 5

3.1         Saponin. 6

3.2         TANNINS. 10

3.3         ESSENTIAL OILS. 13

3.4         ORGANOSULPHUR COMPOUNDS. 17

3.5         FLAVONOID.. 21

CHAPTER FOUR. 24

4.0         Conclusion. 24

4.1         References. 25

Abstract

During the recent decade, a paradigm shift has been initiated whether plant secondary metabolites (PSM) could be exploited as natural safe feed additives alternative to chemical additives to inhibit enteric methanogenesis. More than 200,000 defined structures of PSM have been known. Some plant or their extracts with high concentrations of bioactive plant secondary metabolites such as saponins, tannins, essential oils, organosulphur compounds, Flavonoids, and many other metabolites appear to have potential to inhibit methane on the rumen. Greenhouse gas emissions recently have been of great concern globally. Ruminant livestock system contribute significantly to emus so of methane, a potent greenhouse gas as they waste a portion of the ingested energy (2-15%) as methane and a large proportion (75-95%) of the ingested nitrogen and carbondioxide(CO2). Saponins may decrease methanogenesis through the inhibition of rumen protozoa and in turn may suppress the Rhett number and activity of methanogens. Tannins may inhibit the methanogenesis directly and also via inhibition of protozoal growth. Essential oils, organosulphur compounds and flavonoids appear to have direct effect against methanogens, and a reduction of protozoa associated methanogenesis probably plays a minor role for metabolites. Although PSM may negatively affect nutrient utilization, there is evidence that methanogenesis could be suppressed without adversely affect rumen fermentation, which could be exploited to mitigate methane and CO2emission in ruminant.