The effect of the dried Gracilaria spp. undergoing different drying methods on in vitro rumen fermentation

Seaweed has an important role in the mitigation of enteric methane (CH4) production by ruminant animals. The utilisation and its effectiveness in enteric CH4 reduction require a preservation process. The aim of the study was to investigate the effect of different drying processes on the effectiveness of seaweed Gracilaria spp. in reducing CH4 production assessed through an in vitro method. Three drying techniques, sun-drying, oven-drying, and freeze-drying, were applied to produce a dried product of Glacilaria spp. Rice straw basal diets combined with concentrate at the 70 : 30% were used to test the inclusion of 4% of three differently dried products of Gracilaria spp. compared to the basal diet without seaweed (control group). Measurements were conducted on in vitro total and CH4 gas production, nutrient degradability, ammonia (NH3) and VFA concentration, and microbial population. Results showed that the three dried products of Gracilaria spp. significantly reduced in vitro CH4 production compared to the control group (P ≤ 0.05). All drying techniques gave a similar effect on in vitro CH4 reduction, but they did not affect dry matter (DM) and organic matter (OM) degradability (P ≤ 0.05) and significantly reduced neutral detergent fiber (NDF) degradability (P ≤ 0.05) compared to the control group, with oven-dried treatments having the lowest NDF degradability among the treatments. It is concluded that the three different drying techniques had similar effects on enteric CH4 reduction.