ABSTRACT
The objective of this study was to systematically evaluate and compare the effect of selected spices on methanogenesis using in vitro cultures. Some of the spices selected are Allium cepa, piper nigrum. Aframonum melegueta, Dennttia tripetala,, syzygium aromaticum, Gongronema latifolium among others were dried and milled for chemical analysis and in vitro gas fermentation study. The results showed that the organic matter was highest in Allium crispum (97.98%) and lowest in Allium cepa (96.77%) ash content ranges from 4.2% to 2.34% for Allium cepa and Allium crispum respectively. The crude protein (CP) also was found to vary from 24.50% in Allium cepa to 11.19% for Gongroneme latifolium. NDF values ranges from 52.00% for Capsicum annuum to 14.43% for Allium ascalonium and ADF values was 40.50% for Capsicun annuum to 4.25% for Allium crispum, also hemicelluloses was noticed to be highest in Allium crispum (39.00%) and lowest in Allium cepa(white) (2.75%). The effect of spices was also observed on the dry matter digestibility (DMD), methane gas production and reduction and short chain fatty acid production. For digestibility shea butter gave the highest value of 96.15% while the lowest was noticed in Vernonia amygdalina (61.54%). Dennttia tripetala which had the least % methane production (25.02%) also had the highest percentage of methane reduction (47.69%) and short chain fatty acid (0.66mmol). This reduction in methane gas could be attributed to the bioactive substances such as tannin(0.09%) and saponin (0.20%) present in the spices. These results reveal that spices could be used to enhance digestibility, increases the energy value of feed and reduces methanogenesis which is of great concern worldwide. Spices such as Aframonum melegueta, Allium cepa, Vernonia amygdalina, Allium crispum, Cymbopogon citratus, Dennttia tripetala, Allium cepa(white), Syzygium aromaticum, Gongronema latifolium, Capiscum annuum that have the same degree of methane reduction potential like Dennttia tripetala are recommended for this purpose
CHAPTER ONE
INTRODUCTION
Livestock is one of the longest sources of methane emission with 80 – 115 million tons produced per year, equivalent to 15 – 20% of total anthropogenic methane (IPCC, 2001). Ruminants are major contributors to biogenic methane formation. It has been estimated that preventing methane formation from ruminants would stabilized atmospheric methane concentrations and improve animal performance (Johnson and Johnson, 1995). The global cattle population is responsible for 73% of methane emissions of all livestock and methane produced during ruminal fermentation represents a loss of 2-15% of gross energy intake and may also known as a great contributor to global warming which is a primary environmental concern world wide (moss et al., 2000). Recent studies have shown that plant secondary metabolites such as tannin, essential oils and Saponin at lower concentration could be used to manipulate rumen fermentation favorably. Plant bioactive (PB) or plant secondary compounds are chemicals synthesized in plants but are not involves in the primary biochemical processes of plant growth but acts as a protective agents against predators. Plant extracts from spices and medicinal plants with high concentrations of secondary compounds such as tannin and saponin are good candidates for reducing ruminal methanogenesis (Teferedegne, 2000). Therefore altering dietary formulation can have great impacts on environmental performance from dairy operations. Many studies have reported that feeding forages containing tannin decreases ruminal protein degradation (Min et al., 2003) and also have the potential to reduce enteric CH4 emissions (Carulla et al., 2005; Animut et al., 2008). It was also reported that saponins or saponin-like substances had the potential to suppress the methane emission, reduces protozoa counts and change fermentation patterns (Hristov et al., 1999). At appropriate dose tannin and saponin decreases methane production and increases the efficiency of microbial protein synthesis (Min et al., 2003). Therefore this experiment is planned to ascertain the effect of plants extracts such as tannin and saponin from different species and their effect on methane are other in vitro fermentation parameter.
1.2 Thesis Objectives
The study of tannin and saponin content of some species and its effect on in vitro rumen fermentation have been designed with the following objectives.
- To determine the tannin, crude protein, cell wall and saponin, contents of some spices in Edo State, Nigeria.
- To determine the effects of adding spices as additives on in vitro ruminal methane production and other fermentation parameters.
