Dose-dependent effects of pomegranate peel extract on modulating ruminal fermentation, methane emission, nutrient digestibility and productive values in camels: an in vitro and in silico integrations

Introduction Sustainable management of bioactive-rich byproducts, including pomegranate peels, is crucial to support the rise of environmentally resilient intensive camel farming. The objective of this study was to investigate the impact of pomegranate peel extract (PPE) (0, 0.5, 1, and 2 g/kg) on methane production gas production, nutrient digestibility, and predictive values in camels through in vitro model and molecular docking simulations. Materials and methods Rumen samples were fortified with PPE at levels of 0 (PPE0), 0.5 (PPE0.5), 1 (PPE1), and 2 (PPE2) g/kg diet to assess methane emissions, gas production, nutrient digestibility, and predictive values. Molecular docking was used to assess the inhibition of the methanogenic pathway enzymes formylmethanofuran dehydrogenase (Fmd), F420H2 oxidase, and shikimate dehydrogenase (SDH) by ellagic acid (EA) and punicalagin (PG). Results The PPE1 and PPE0.5 groups showed significantly higher gas production across all incubation intervals (3, 6, 12, 24 and 48 h; p 0.001). Supplementation at 0.5, 1, and 2 g/kg significantly ( p 0.05) lowered methane emissions (by 11.62, 13.17, and 19.39%) and total digestible dry matter (by 20.30, 22.19, 33.34%) relative to the control, respectively. PPE1 group significantly improved dry matter digestibility ( p 0.01, linear effect) and TVFA production ( p 0.05, quadratic effect) compared to the control. Rumen pH was significantly affected by treatment, with the lowest values observed in the PPE0.5 and PPE1 groups ( p 0.01, quadratic effect). All PPE groups had greater SCFA levels relative to the control group ( p 0.001, quadratic effect). The PPE1 and PPE0.5 treatments showed higher ME, NEL, and OMD, and lower partitioning factor (PF) compared to the other groups ( p 0.001, quadratic effect). The PPE1 group had the greatest MCP compared to other groups ( p 0.05). Docking analysis revealed that punicalagin (PG) exhibited superior binding affinities (−10.04 kcal/mol) against SDH compared to ellagic acid (EA), which reached a peak of −7.22 kcal/mol against F420H2 oxidase. PG also demonstrated better binding stability against F420H2 oxidase oxidase (−8.05 kcal/mol) compared to EA (−7.22 kcal/mol). Conclusion These results suggest that dietary inclusion of 0.5 or 1 g/kg PPE significantly improves nutrient digestibility, productive performance, and rumen fermentation efficiency, while concurrently reducing methane emissions using an in vitro model in camels.