Effect of <i>Acanthopora muscoides</i> supplementation on methane emissions and protozoa population in <i>Pennisetum purpureum</i>

Abstract This study evaluates the effect of supplementing Acanthopora muscoides (L.) Bory on Pennisetum purpureum cv. Gama Umami as a basal diet on methane gas production and protozoa population. In June 2022, natural tropical seaweed A. muscoides (L.) Bory was harvested from Drini and Sepanjang Beach, Gunungkidul District, Yogyakarta Province, Indonesia. The setup of this research design used a randomized complete block with four treatments and replications. The methane production was measured with Gas Chromatography and the protozoa population was counted using a microscope with 10 or 40x magnification. The outcome demonstrated that taking supplements of A. muscoides (L.) Bory at 2.5-7.5% organic matter (OM) on P. purpureum cv. Gama Umami reduced (P&lt;0.01) methane production on 24 and 48 h of incubation. Higher supplementation levels of A. muscoides (L.) Bory significantly reduced (P&lt;0.01) methane production. Reducing (P&lt;0.01) methane up to 31.40% and 34.72% on 24 and 48 h of incubation with A. muscoides (L.) Bory supplementation at 7.5% OM. This level also declined (P&lt;0.01) in 28.14% of protozoa populations by 5.01 to 3.60 cells x 10 4 /mL. It is concluded that taking A. muscoides (L.) Bory supplements at 7.5% OM on P. purpureum cv. Gama Umami resulted in the lowest methane production and protozoa population. A. muscoides (L.) Bory, one of a tropical red seaweeds, potential to integrate as an feed additive into sustainable livestock feeding practices