Flaxseed Supplementation in Chicken Feed Accelerates Salmonella enterica subsp. enterica Serovar Enteritidis Clearance, Modulates Cecum Microbiota, and Influences Ovarian Gene Expression in Laying Hens

Salmonella is a foodborne pathogen that poses a serious threat to both human and animal health and food safety. Flaxseed is rich in unsaturated fatty acids; has anti-metabolic syndrome, anti-inflammatory, and neuroprotective properties; and may be a potential source of feed additives. To investigate the impact of flaxseed on Salmonella-infected laying hens, we administered Salmonella enterica subsp. enterica serovar Enteritidis (S. Enteritidis) after adding flaxseed to the feed of laying hens (15% [750 mg/kg]). S. Enteritidis colonization was reduced and its clearance was accelerated from the laying hens. Furthermore, flaxseed supplementation mitigated the damage to the ileum caused by S. Enteritidis. We analyzed alterations in intestinal flora through 16S rRNA amplicon sequencing. S. Enteritidis infection increased the abundance of Akkermansia and triggered the host inflammatory response. Conversely, the addition of flaxseed to the feed increased the abundance of beneficial intestinal bacteria, such as Lactobacilli and Bacteroides. Ovarian health is important for egg production performance in laying hens and our findings indicate that S. Enteritidis can persist in the ovaries for an extended period. Therefore, we further performed transcriptome sequencing analysis of ovarian tissues on day seven after S. Enteritidis infection. S. Enteritidis infection leads to altered ovarian gene expression, including the downregulation of lipid metabolism and growth and development genes and the upregulation of host immune response genes in laying hens. The upregulation of genes associated with growth and development may have stimulated ovarian growth and development.