The use of certain medicinal plant extracts reduced in vitro methane production while improving in vitro organic matter digestibility

Abstract

Some medicinal plants have the tendency to manipulate the rumen microbial ecosystem, which in turn might reduce methane (CH4) emissions. The anti-methanogenic activities of leaf fraction of Piper betle, Aloe vera, Carica papaya, Azadirachta indica, Moringa oleifera, Tithonia diversifolia, Jatropha curcas and Moringa oleifera pods were studied at different doses. The plant materials were extracted with pure methanol and subsequently reconstituted at the rate of 25, 50, 75 and 100 mg in 1000 mL distilled water. Four mL of each plant extracts preparation was anaerobically incubated with 400 mg Eragrostis curvula hay in four replicates and the experiment was repeated five times. Plant extracts of P. betle and A. vera significantly increased total gas produced whereas other extracts recorded lesser or similar values to the control group. Leaf extracts of A. indica, C. papaya, J. curcas, M. oleifera, T. diversifolia and M. oleifera pods all significantly reduced CH4 volume at dosages of 25 and 50 mg/L due to the activities of their phytochemicals. Total volatile fatty acids and in vitro organic matter digestibility values recorded for all extracts were generally superior when compared with the control. Methane yield per unit of total gas were significantly lower in extracts of T. diversifolia, M. oleifera, A. indica, M. oleifera pods whereas it is higher in P. betle and A. vera. It can be concluded from the study that methanolic extracts of A. indica, C. papaya, J. curcas, M. oleifera, M. oleifera pods and T. diversifolia resulted in reduced CH4 production, and thus can be used potentially to manipulate rumen condition, improve feed digestibility and reduce enteric CH4 emission from ruminants. However, the in vitro results needs to be verified using in vivo studies by administering concentrated crude extracts at a rate of 25 mg or 50 mg per kg of roughage feed for small ruminants.

Haematology and Serum Biochemical Indices of Lambs Supplemented with Moringa oleifera, Jatropha curcas and Aloe vera Leaf Extract as Anti-Methanogenic Additives

“…This study was approved by the Animal Ethics Committee of the University of Pretoria with approval number ECO-030-14. Fresh foliage of MO, JC and AV was collected, freeze-dried and the extract obtained using 100% methanol as reported previously [2]. Extract solutions were prepared from an equal mass of each plant material by solubilising 100 mg of dried plant extracts in 100 mL of distilled water, stirring with an overhead stirrer and stored as a stock solution.…”

“…The plant secondary metabolites (PSMs) (also called phytonutrients) inherent in these medicinal plants have been found to exhibit strong antibacterial and antifungal properties, resulting in strong antimethanogenic properties in ruminant animals among other benefits reported in different studies [1,2]. Equally, some medicinal plants and their extracts tend to improve nutrient digestibility in ruminant livestock [3].…”

“…Equally, some medicinal plants and their extracts tend to improve nutrient digestibility in ruminant livestock [3]. Previous studies showed that extracts of Moringa oleifera (MO), Jatropha curcas (JC) and Aloe vera (AV) significantly reduced in vitro methane production when supplemented to a typical ruminant diet [2]. Moringa is reported to contain a moderate concentration of flavonoids, alkaloid and only negligible concentration of tannins [4], while Jatropha contains a high concentration of phorbol esters [5,6].…”

“…However, while some of these PSMs are capable of binding to specific receptors in neurons, intestines, and other cells and exhibit favourable physiological effects [7], others may be antinutritional and exert toxic effects on animals consuming them, depending on the type of plant or parts, or amount consumed [6,8]. Even though the use of methanolic extracts of Moringa, Jatropha and Aloe vera has been validated in vitro [2,9], nevertheless, a great deal of consideration should be given to the impact of these 'natural alternatives' on the health of animals before being recommended for wider application. For example, the phorbol esters in Jatropha curcas at a concentration above 1.45 mg/kg body weight (BW) in ruminants were found to exert reduced performance, physiological toxic effects and cause eventual death [5,10,11].…”

“…Moreover, some structure of plants like the barks of trees are difficult to feed to animals but also contain valuable phytochemicals. Previous in vitro and in vivo trials have validated the anti-methanogenic effects of MO, JC and AV when used as dietary additives at 50 mg/kg DM of substrate [2,9,14], however, potential harmful effects on the animals were not established [14]. To justify this previous in vitro trial as well as make wider recommendations on the beneficial effects of extracts of MO, JC and AV in methane reduction and improvement in feed digestibility, there is a need to evaluate the potential impact of these medicinal plant extracts on the physiology of the animals.…”