Reducing methane production by rumen modulation through tropical seaweed supplementation in Napier grass

ABSTRACT Seaweed has been proven as reducing agent of ruminant methane emissions as well as increasing ruminant productivity. The present study evaluated the effect of supplementing three types of tropical seaweeds at different levels to Napier grass (Pennisetum purpureum cv. Gama Umami=GU) based on methane gas production and in vitro rumen fermentation parameters. When P. perforate was supplemented on GU at 5.00% organic matter (OM), the highest methane reduction was shown at 24 and 48 hour incubation (83.8% and 74.4%, respectively, P<0.01). Supplementation of 5.00% OM P. perforate on GU also resulted in the lowest (P<0.01) protozoa population (3.83×104/mL). However, adding P. perforate to GU lowers total gas production (a+b fraction) from 62.7 to 52.8 mL/200 mg DM, P<0.01). In terms of rumen fermentation parameters, P. perforate supplementation increased (P<0.01) total short-chain fatty acids (SCFA), as well as decreased acetate:propionate ratio (P<0.05) without negatively affecting rumen pH. Although ammonia (NH3) concentration was not affected, significant rumen synthesis microbial protein increases were noted. Supplementation with E. compressa 2.50% OM and C. linum (O.F.Mull) Kutz 7.50% OM increased methane in 24 hours incubation at 12.72% and 48 hours incubation at 6.08%. Supplementation of P. perforate at 5.00% OM on GU decreased methane production as well as increasing total SCFA and rumen microbial protein. P. perforate (Bory) K.W.Nam can be used as a potential agent of methane reduction in ruminants to enhance their production.