Transcriptome adaptation of the ovine mammary gland to dietary supplementation of extruded linseed

Several dietary strategies were adopted to reduce saturated fatty acids and increase beneficial fatty acids (FA) for human health. Few evidences are available about the pathways/genes involved in these processes. Illumina RNA-sequencing was used to investigate changes in the ovine mammary gland transcriptome following supplemental feeding with 5% linseed panel. Comisana ewes in mid-lactation were fed a control diet for 28 days (control period) followed by supplementation with 5% of linseed panel for 28 days (treatment period). Milk production was decreased by 30.46 % with linseed supplementation. Moreover, a significant reduction of fat, protein and lactose secretion was also observed. Several unsaturated FA were increased while short and medium chain saturated FA were decreased by linseed treatment. Around four thousand (1,795 up- and 2,133 down-regulated) genes were significantly differentially regulated by linseed supplementation. Main pathways affected by linseed supplementation were those involved in the energy balance of mammary gland. Principally, the mammary gland of fed linseed sheep showed a reduced abundance of transcripts related to the synthesis of lipids and carbohydrates and the oxidative phosphorylation. Our study suggests that the observed decrease in milk saturated FA was correlated to down-regulation of genes in the lipid synthesis and lipid metabolism pathways.