Extruded linseed alone or in combination with fish oil modifies mammary gene expression profiles in lactating goats

Animal nutrition considerably affects milk composition that influences its nutritional quality. Milk component synthesis and secretion by the mammary gland involve the expression of a large number of genes whose nutritional regulation remains poorly defined. In this study, 14 lactating goats received 3 experimental diets: 1- the basal diet with hay prepared from regrowth of natural grassland pasture offered ad libitum and a concentrate mixture (CTRL, n = 5)), the basal diet with 530 g/d extruded linseed (EL, n = 4) or with a combination of 340 g/d extruded linseed and 39 g/d of fish oil (ELFO, n = 5). To investigate the pathways regulated by nutrition, we examined the effect of EL and ELFO diets compared with CRTL diet and the effect of EL diet compared to ELFO diet on the expression of approximately 8400 genes in caprine mammary gland using a bovine oligonucleotide microarray. The hybridization was performed with 40 pmol of incorporated Cy3 from the mammary mRNA from each goat fed one diet and 40 pmol of incorporated Cy5 from the mammary mRNA from goat fed another diet. Each hybridization was repeated in a dye-swap manner for a total of 26 slides (4 slides for the comparison of EL vs. CRTL diets, 5 slides for the comparison of ELFO vs. CRTL diets, 4 slides for the comparison of EL vs. ELFO diets). One sample of mammary gland from goat fed EL diet was suppressed because after mRNA extraction the RNA integrity number was lesser than 7.