Abstract:
The use of medicinal plants and their extracts has recently attracted the attention of
many researchers as a methane (CH4
) mitigation strategy. This study evaluated the relationship
of agronomic traits of Moringa accessions with in vitro gas production measurements and feed
digestibility from ruminants. Twelve Moringa accessions were grown at the Roodeplaat experimental
site of the Agricultural Research Council in Pretoria, South Africa. Agronomic traits, such as seedling
survival rate, leaf yield, canopy and stem diameter, plant height, number of primary branches, plant
vigor, greenness, chlorosis, disease and pest incidences were recorded. The leaves were harvested in
the fifth month after transplanting to the field. Freeze-dried leaves were extracted with methanol,
and their total phenolic and total flavonoid contents were determined. The extract was applied
at a dose of 50 mg/kg of dry matter (DM) feed for in vitro gas production studies. Most of the
growth and agronomic traits, i.e., seedling survival rate, leaf yield, canopy diameter, plant height,
number of primary branches, the score of plant vigor, and greenness, total phenolics and flavonoids
were significantly different among the accessions except for stem diameter and chlorosis score. All
accession leaf extracts significantly reduced the total gas and CH4 production compared with the
control with equal or higher in vitro organic matter digestibility. Higher CH4
inhibition was obtained
in Moringa oleifera (M. oleifera) A3 (28.4%) and A11 (29.1%), whereas a lower inhibition was recorded
in A1 (17.9%) and A2 (18.2%). The total phenolic (0.62) and total flavonoid (0.71) contents as well as
most agronomic traits of the accessions were positively correlated with the CH4
inhibition potential of
the accessions. Moringa oleifera accessions A3, A8 and A11 resulted in higher in vitro CH4
inhibition
potential and improved organic matter digestibility of the feed with equal or higher adaptability
performances in the field. Thus, there is a possibility of selecting Moringa accessions for higher
antimethanogenic activity without compromising the feed digestibility by selecting for higher total
phenolics, total flavonoids and agronomic performances traits. There is a need for further study
to determine the long-term adaptability of promising accessions in the study area with concurrent
antimethanogenesis efficacy when used in the diet of ruminant animals.
