Cassava pulp and rain tree pods fermented with loog pang kao mark improve feed utilization, modulate rumen microbial populations and reduce methane production in beef cattle

Importance of the work: Sustainable ruminant production requires feed strategies that improve nutrient utilization while lowering enteric methane emissions. Cassava pulp and rain tree pods fermented with loog pang khao mak (CPRFLK) represent a promising feed supplement because they may enhance intake and digestibility, improve rumen fermentation, and reduce methane production. Objectives: To evaluate the effects of cassava pulp and rain tree pods fermented with loog pang kao mark on feed intake, nutrient digestibility, rumen fermentation, methane production and microbial population in beef cattle. Materials and Methods: A 4 × 4 Latin square design was used to randomly allocate four beef cattle to four dietary treatments. The treatments consisted of cassava pulp and rain tree pods fermented with loog pang kao mark (CPRFLK) at cassava pulp:rain tree pod ratios of 100:0 (T1), 60:40 (T2), 50:50 (T3) and 40:60 (T4). Loog pang kao mark was used as the fermentation starter in all CPRFLK formulations. Feeding rates for the diet were 1.5% body weight (concentrate 50%, CPRFLK 50%). The experiment was conducted over four periods, each lasting 26 d (21 d for adaptation followed by 5 d for data collection), during which each animal received its respective diet. Results: Overall, rice straw consumption increased in the beef cattle fed CPRFLK at ratios of 60:40, 50:50, and 40:60, while DM intake increased at ratios of 50:50 and 40:60. In addition, these treatments enhanced DM and organic matter (OM) digestibility. The acetic acid concentration was reduced (p < 0.05), while the total VFA and propionic acid concentrations increased (p < 0.05), particularly in the cattle fed CPRFLK 40:60. Additionally, protozoal populations and CH4 production decreased (p < 0.05) with CPRFLK 40:60 supplementation. Main finding: Feeding concentrate along with CPRFLK 40:60 improved rumen fermentation by increasing total VFA, propionic acid, and total bacterial population, while reducing protozoal population and CH4 production.