Table S2 genome information LS 2022.xlsx

The objective of the current study was to evaluate the effects of fumarate (34 g/d) and active dry yeast (ADY) (1.5 g/d) onrumen fermentation, methane emissions, microbial community and function, apparent total tract digestibility, lactation performance, and blood metabolitesof dairy goats. To achieve this, 28 primiparous Guanzhong dairy goats were assigned to 1 of 4 treatments in a randomized complete block design with a 2 × 2 factorial arrangement over a 38-day feeding period: 1) control; 2) fumarate supplied at 34 g/d; 3) ADY supplied at 1.5 g/d; 4) fumarate and ADY supplied in combination. Results showed that fumarate supplementation reduced methane production (L/d), yield (L/kg DMI), and intensity (L/kg Daily milk production, DMP) by 11.3%, 27.5%, and 21.8%, respectively, without affecting DMI or DMP. However, the methane-depressing effect of fumarate declined with hours after feeding, with lower hourly methane emissions for postprandial three hours, but thereafter recovered to control level. Fumarate supplementation increased rumen pH and reduced total VFA concentrations. ADY supplementation increased the molar proportion of ruminal butyrate, but had no effect on methane emissions or rumen pH. Both fumarate and ADY had no effect on apparent digestibility and lactation performance. To further explore the changeof rumen microbial community, deep metagenomic sequencing was employed to construct a rumen microbial genomic catalog comprising 4,674 metagenome-assembled genomes (MAGs) and a gene catalog comprising 7,758,615 nonredundant genes. Fumarate supplementation decreased the ACE index of the rumen microbial community. Neither fumarate nor ADY impacted the rumen microbial structure at the MAG or gene level, respectively. But fumarate stimulated the growth of specific bacterial populations, including fumarate- and lactate-utilizing bacteria, both of which could contribute torumen methane mitigationand pH rise. Most of the fumarate-influenced blood metabolites and enzyme were involved in the tricarboxylic acid (TCA)and urea cycles. Fumarate reduced the blood substrate concentrations of TCAcycle (glucose, malondialdehyde) and urea cycle (ammonia), while it increased the end products of the urea cycle (BUN, MUN) and enhanced the enzyme activity of malate dehydrogenase in the TCA cycle. Accordingly, fumarate, as an intermediate in both rumen microbe and animal metabolism pathways,could reduce rumen methane emissions, alleviate rumen acidosis, and enhance the animal's TCAcycle and urea cycle.