LAUSR

ABSTRACT Tropical plant phytonutrients have impacts on rumen fermentation and methane production. Dragon fruit peel powder (DFPP) including condensed tannins (CT) and saponins (SP). The objective was to conduct the effects of phytonutrients and non-protein nitrogen (NPN) source on in vitro rumen fermentation, nutrients degradability and methane production. The treatments were randomly assigned in a 2 × 3 × 3 factorial arrangement in a Completely randomized design. The three factors contains the R:C ratio (60:40 and 40:60), the doses of NPN addition (0, 1 and 2% of the total substrate) and the doses of DFPP addition (0, 2 and 4% of total substrate). The results indicated that the gas production rate constant for the insoluble fraction (c) was highly significant as the results of the R:C ratio, DFPP and NPN supplementation, whilst there was no difference obtained among treatments for cumulative gas production. Ammonia nitrogen concentration was influenced by the R:C ratio, NPN and DFPP addition both 4 and 8 h after incubation. In part of microbial population, protozoa was significantly reduced with DFPP addition. Importantly, the production of methane was remarkably affected by the R:C ratios and it was decreased due to increasing level of DFPP. Furthermore, in vitro dry matter degradability (IVDMD) was significantly improved by combination between R:C ratio and supplementation of DFPP at 12 h. In conclusion, addition of DFPP and NPN source could improve rumen fermentation, nutrients degradability and DFPP would be a potential dietary rumen enhancer.