The impact of adding hops to alfalfa at different rates on silage quality and methane emissions in vitro

Abstract

Legumes are typically challenging to ensile due to their low concentration of water-soluble carbohydrates and high capacity for buffering. If legumes and medicinal plants are ensiled together, the silage quality increases, which benefits the digestive system of ruminates. The aim of this study was to research the effects of different alfalfa (Medicago sativa L.) and hops (Humulus lupulus L.) ratios on silage quality and in vitro rumen fermentation traits. The plant materials were chopped to a particle size of <2 cm; then alfalfa (A) and hops (H) were ensiled in ratios of 100A + 0H, 75A + 25H, 50A + 50H, 25A + 75H and 0A + 100H by weight with 4 replicates. Fresh silage samples were left to ferment for 45 days at 25 ± 2 °C. Subsequently, it was observed that hops added to alfalfa improved the silage’s fermentation qualities. At a 75A + 25H ratio, the silage quality increased due to having a lower pH and dry matter ratio as well as increased values for Flieg score, crude protein, relative feed, and condensed tannin concentration. A higher proportion of alfalfa in the silage mixture increased methane (CH4 ) and carbon dioxide (CO2 ) and decreased lactic acid (LA). Comparing 50A + 50H and 25A + 75H silages to 100A + 0H, the CH4 production was 26.19% and 27.80% lower, respectively, and the CO2 production decreased by 25.61% and 28.15%, respectively. Consequently, the 50A + 50H and 25A + 75H silage ratios are advised for feeding ruminants. Furthermore, more research with different forage combinations is required to understand how hops influence rumen fermentation. © TÜBİTAK.