Upgrading the feeding value of oil palm fronds for ruminants through processing: Evidence from a meta-analysis of in vitro and in vivo studies

Oil palm fronds (OPF) have potential as a ruminant feed; however, their utilization is limited by low nutritional quality and digestibility. Various processing methods, including biological, chemical, physical, and their combinations, have been applied to improve the feeding value of OPF. This meta-analysis aimed to integrate findings from multiple studies to evaluate the effects of processing on OPF feeding value. A total of 25 relevant articles retrieved from Scopus were analysed to quantify the effects of OPF processing on nutrient composition, rumen fermentability (in vitro and in vivo), degradability (in vitro and in vivo), and animal performance. The results showed that processing improved OPF quality by increasing crude protein (CP) content and reducing lignin (P In vitro and in vivo evaluations further showed improvements (P < 0.05) in various parameters of rumen fermentability and nutrient degradability without adverse effects on animal performance. Furthermore, chemical, physical, and biological processing effectively enhanced OPF fermentability, with chemical processing being the most effective in reducing lignin content. In conclusion, appropriate processing strategies can substantially improve OPF utilization as a sustainable ruminant feed resource.