Impact of tropical red seaweed (Palisada perforata) on in vitro methane mitigation and fermentation profiles: The role of forage-to-concentrate ratios

Abstract

ABSTRACT Palisada perforata is one of tropical seaweed that is promising as an additive to reduce rumen methane production, but in total mixed rations (TMR) as a basal feed not reported yet. A randomized factorial block design with two factors (3 x 2) and five replications was applied, time to collect rumen fluid from fistulated Bali cattle as a block. The first factor was the TMR type: TMR 1 (80% roughage, 20% concentrate), TMR 2 (70% roughage, 30% concentrate), and TMR 3 (60% roughage, 40% concentrate). The second factor was the P. perforata enrichment level (0.00 and 5.00% organic matter, OM). Interactions between the TMR type and P. perforata enrichment level were not significant for most variables, except microbial protein synthesis. TMR 3 enriched with 5.00% OM P. perforata resulted in the highest microbial protein synthesis. Methane production was lowest (31.99-36.32%; P < 0.01) in TMR 3, which also exhibited a reduced protozoa population, lower acetate and butyrate proportions, and a reduced acetate-to-propionate ratio, while yielding a higher (P < 0.01) total volatile fatty acid, propionate proportion, and NH3 concentration. Enrichment with P. perforata at 5.00% OM further decreased methane production, reducing the acetate proportion and acetate-to-propionate ratio while increasing the propionate proportion. In conclusion, a TMR consisting of 60% roughage and 40% concentrate combined with P. perforata at 5.00% OM was the most effective treatment, reducing methane emissions while enhancing rumen fermentation. Dietary P. perforata represents a promising strategy to optimize rumen fermentation efficiency and simultaneously mitigate ruminants’ methane emissions.