Metabolic effects of nano-encapsulated extract of Moringa oleifera to reduce ruminal methane, carbon monoxide, and hydrogen sulfide outputs of high-concentrate diet studied in vitro

Abstract

The use of forage trees and their extracts at different levels, such as Moringa oleifera, has recently attracted the attention of many researchers as an alternative strategy to provide essential nutrients and reduce ruminant greenhouse gas emissions involved in global warming, using an in vitro gas production technique. Therefore, the present study aimed to evaluate increasing levels of M. oleifera extracts (methanolic or aqueous) chemically characterized using gas chromatography-mass spectrometry (GC-MS) processed as nanoencapsulation or not on biogas production such as methane, carbon monoxide, and hydrogen sulfide as well as ruminal fermentation kinetics in vitro. The nanoencapsulation process of M. oleifera was developed in two separate stages; 1 % acetic acid solution and 0.1 g of sodium tripolyphosphate were used for the first and second steps, respectively. Methane, carbon monoxide, hydrogen sulfide, and total gas production volumes were measured a long 48 h after inoculation. The main chemical compounds in the aqueous extract detected by GC-MS in M. oleifera leaves were oleic acid methyl ester (62.1 %), and cyclopentanetridecanoic acid methyl ester (11.9 %). In contrast, in the methanolic extract, they were oleic acid methyl ester (64.5 %), and methyl isostearate (10.1 %). Parameters related to gas production kinetics differed considerably within treatments, particularly with fractions b (P = 0.001, SEM = 11.12) and latency phase (P = 0.037, SEM = 0.15). The highest rates of fraction b (9.71 mL/g dry matter) and fermentation delay (1.92 h) were recorded for methanolic and nano-aqueous extracts, respectively. For both methanolic (10.56–10.68 mmol/g dry matter) and aqueous extracts (9.73–10.04 mmol/g dry matter), a linearly increasing trend was observed once the injection rate (0.25 and control groups, respectively) and metabolizable energy were elevated. During the incubation phase, 24 and 48 h, the types of extraction significantly impacted the amount of H2S synthesis (P = 0.021 (SEM = 0.005) and P = 0.045 (SEM = 0.017), respectively). The ratio of CH4: short-chain fatty acids had the highest efficiency (P = 0.277, SEM = 0.39), followed by CH4: organic matter (P = 0.118, SEM = 0.16) and CH4: metabolizable energy (P = 0.236, SEM = 0.068). Thus, it could be concluded that there is a possibility of selecting M. oleifera extracts to ameliorate greenhouse gas emissions, such as CH4 production, without compromising fermentation kinetics and feed degradability.