Effect of napier grass supplemented with Gliricidia sepium, Sapindus rarak or Hibiscus rosa-sinensis on in vitro rumen fermentation profiles and methanogenesis

Abstract

This study examined the supplementation effects of gliricidia leaves (GL, Gliricidia sepium), lerak fruit (LF, Sapindus rarak), or hibiscus leaves (HL, Hibiscus rosa-sinensis) on in vitro rumen fermentation and methanogenesis and made a comparison with the Napier grass (NG, Pennisetum purpureum) grass. In vitro rumen fermentation was designed according to a randomized complete block design with four replications and seven treatments: NG, GL, LF, HL, NG 70% + GL 30%, NG 70% + LF 30% and NG 70% + HL 30%. The generated data were subjected to analysis of variance (ANOVA) with Duncan’s multiple range test and compared among treatment means. Addition of a plant containing saponin such as LF or HL to NG did not alter gas production after 24 and 48 h of incubation period in comparison to NG alone. The HL alone or blended with NG produced the highest IVOMD during the fermentation process as compared to other treatments (P<0.05). Adding LF supplement either singly or in combination significantly (P<0.05) reduced methane production in terms of %TVFA as compared to NG. Supplementation of LF plants has shifted VFA proportion towards more propionate and less acetate. The microbial population of LF, whether single or in combination had a tendency to reduce the rumen protozoa population but had no effect on methanogen population. It can be concluded that utilization of saponin-rich materials is particularly beneficial for reducing ruminal methane emission.