Abstract: [Objective] To investigate the effects of dietary supplementation with Enteromorpha polysaccharide-iron （EP-Fe） during late gestation on intestinal microbiota and iron metabolism in sows. [Methods] Sixty primiparous Landrace × Yorkshire crossbred sows at （90±2） d of gestation with similar body condition, expected farrowing date, and breeding sire were randomly allocated into two groups （30 sows per group, one sow per replicate）. The control group received a basal diet, while the EP-Fe group was fed the basal diet supplemented with 140 mg/kg EP-Fe from gestational day 95 until parturition. Fresh fecal samples from gestational day 112 and serum from farrowed sows were collected to analyze serum biochemical parameters, fecal microbial richness and diversity and fecal short-chain fatty acids （SCFAs） content. [Results] Dietary EP-Fe supplementation increased serum triglyceride （TG） and albumin （ALB） in sows. EP-Fe markedly altered the fecal microbial composition, elevated the relative abundance of Christensenellaceae_R-7_group, Oscillibacter, Prevotellaceae_NK3B31_group, UCG-002, Clostridium_sensu_stricto_1 and unclassified_f__Prevotell-aceae, while reducing UCG-008 and norank_f__norank_ o__Gastranaerophilales. A tendency toward an increase in fecal SCFA concentrations was also observed. EP-Fe supplementation enhanced the relative abundance of Lachnospiraceae_XPB1014_group, which was positively correlated with fecal iron, and decreased norank_f_ norank_ o_Clostridia_UCG-014, which was negatively correlated with placental iron transport genes. These changes reduced fecal iron, upregulated placental iron transporter gene expression, and enhanced iron absorption, utilization and transport in sows. [Conclusion] EP-Fe supplementation can modify the gut microbiota composition, increase SCFAs content, enhance intestinal iron absorption, and promote iron metabolic transfer between sows and piglets.

Key words: Enteromorpha polysaccharide-iron, sow, fecal short-chain fatty acids （SCFAs）, fecal microorganisms