Alteration of gene expression in mammary gland tissue of dairy cows in response to dietary unsaturated fatty acids

Abstract

The aim of this study was to determine the effects of supplementing unprotected dietary unsaturated fatty acids (UFAs) from different plant oils on gene expression in the mammary gland of grazing dairy cows. A total of 28 Holstein-Friesian dairy cows in mid-lactation were blocked according to parity, days in milk, milk yield and fat percentage. The cows were then randomly assigned to four UFA sources based on rapeseed, soybean, linseed or a mixture of the three oils for 23 days, after which, all 28 cows were switched to a control diet for an additional 28 days. On the last day of both periods, mammary gland biopsies were taken to study genome-wide differences in gene expression on Affymetrix GeneChip R Bovine Genome Arrays (no. 900493) by ServiceXS (Leiden, The Netherlands). Supplementation with UFAs resulted in increased milk yield but decreased milk fat and protein percentages. Furthermore, the proportion of de novo fatty acids (FAs) in the milk was reduced, whereas that of long-chain FAs increased. Applying a statistical cut-off of false discovery rate of q-values ,0.05 together with an absolute fold change of 1.3, a total of 972 genes were found to be significantly affected through UFA supplementation, indicating that large transcriptional adaptations occurred in the mammary gland when grazing dairy cows were supplemented with unprotected dietary UFA. Gene sets related to cell development and remodeling, apoptosis, nutrient metabolic process, as well as immune system response were predominantly downregulated during UFA supplementation. Such molecular knowledge on the physiology of the mammary gland might provide the basis for further functional research on dairy cows.

mRNA abundance of genes involved in mammary lipogenesis during fish oil- or trans-10,cis-12 CLA-induced milk fat depression in dairy ewes

“…Downregulation of ACSS2 in FO may also have limited de novo FA synthesis through the potential inhibition of acetate activation, as previously suggested for this and another member of the same gene family (namely, ACSS1) in cows and sheep (Mach et al, 2011;Ibeagha-Awemu et al, 2016;Toral et al, 2016b). However, the apparent lack of relationship between transcript abundance of these genes and milk concentrations of 4:0-16:0 FA (at least at the particular time point when they were analyzed) seems difficult to reconcile, which merits further investigation.…”

“…Compared with the relatively well characterized MFD caused by high-concentrate diets and plant oils (e.g., Peterson et al, 2003;Mach et al, 2011), the effects of marine lipids on milk fat synthesis are still poorly understood (Ahnadi et al, 2002;Bichi et al, 2013;Vahmani et al, 2014). Feeding starch-rich diets and 18-carbon PUFA to dairy cows increases the ruminal outflow of the trans-10 cis-12 isomer of CLA, which is known to downregulate key genes and transcription factors involved in lipid metabolism in the mammary gland, such as ACACA, FASN or SREBF1 (Bernard et al, 2008;Bauman et al, 2011).…”

Mapping and fine-mapping of genetic factors affecting bovine milk composition

“…These processes are dependent on many factors that include: quantity and composition of microbiota (Haarfoot & Hazlewood, 1997;Lock & Bauman, 2004), the proportion of forages and concentrates in a cow's diet (Dewhurst et al, 2006) and the source of the PUFA supplied to dairy cows (Sterk et al, 2011). Therefore, part of the observed differences in milk fat composition between winter and summer milk can also be attributed to dietary effects on processes in the rumen, which are known to affect the amounts of C18:1trans-11 and CLA reaching the mammary gland of a cow (Mach et al, 2011).…”

“…Some studies indicate that nutrition affects mammary expression of lipogenic genes (Bernard et al, 2008;Mach et al, 2011). Therefore, effects of polymorphisms in DGAT1 and SCD1 on milk fat composition might differ between winter and summer.…”

“…It is well established that feeding dairy cows with polyunsaturated fatty acids (PUFA) that originate from forages results in a reduction of de novo synthesized FA and in an increase of long chain FA in milk fat (e.g., Chilliard et al, 2001;Bauman and Griinari, 2003). Furthermore, there are indications that nutrition affects mammary lipogenic gene expression (Bernard et al, 2008;Mach et al, 2011).…”