Abstract/Summary

Willow is a tree fodder containing condensed tannins that has potential to improve protein efficiency, reduce ammonia and methane emissions and make farming more carbon-neutral. Ruminants contribute to UK agricultural methane emissions and their impact on climate change is a major concern. Willow contains condensed tannins (CT) able to bind proteins, inhibit their ruminal degradation and methanogenesis (Waghorn and McNabb, 2003). This study explored the effect of willow’s CT on in vitro rumen fermentation. Material and Methods: Samples were collected from AFBI Hillsborough, N. Ireland, freeze-dried and ground at 1-mm screen. ANKOMRF Gas production system was used and incubations were done anaerobically at 39 °C for 24 h in jars containing buffered rumen juice from 3 dairy cattle from the abattoir, Coleraine, N. Ireland. Gas production, pH, methane concentration (gas chromatography) in headspace gas samples, ammonia (Chaney and Marbach, 1962) in the fermentation medium, were measured at 0 h, 3.5 h and 24 h. To assess effects of CT, incubations were made with and without polyethylene glycol (PEG), which deactivates CT (Theodoridou et al., 2011). 4 g of willow and silage at different inclusion rates (0:100, 25:75, 50:50, 75:25, 100:0) were incubated. Two in vitro runs were carried out. Data were analysed by two-way ANOVA with willow inclusion rate and treatment being the variables. Results: Methane concentration was significantly lower for the willow incubation (100%) and was reduced by 23%, in comparison to silage (100%). No significant differences (P > 0.05) were observed between treatment (-PEG/+PEG) at each inclusion rate of willow. Ammonia production (mg/L NH3) significantly (P < 0.05) affected by willow inclusion and treatment at 3.5 hours. After 24 hours, a similar trend observed increasing willow inclusion reduced ammonia production (ml/LNH3) (P < 0.001), however the effect of treatment and willow inclusion on ammonia production was inconclusive (P = 0.1). Conclusions: Willow could be a potential approach to mitigate the adverse effects of climate change and improve animal performance. Further in vivo animal trials are needed and the most suitable variety and harvest strategy should be selected. Acknowledgements: Technical assistance of Richard Pilgrim is gratefully acknowledged. Financial support: DTP FoodBioSystems.