Volume 5 Supplement 4
Dietary unsaturated fatty acids affect the mammary gland integrity and health in lactating dairy cows
© Mach et al; licensee BioMed Central Ltd. 2011
Published: 3 June 2011
Information about the effects of unsaturated fatty acids (UFA) supplementation on the health and integrity of the mammary gland in lactating dairy cows is lacking. Therefore, the aim of this study was to determine the effects of unprotected dietary UFA on the global expression pattern of genes in the mammary gland tissue of grazing dairy cows, and to translate this information into relevant biological knowledge.
Twenty-eight Holstein-Friesian dairy cows were randomly assigned to 4 different concentrated UFA-sources for 23 days after which all cows were switched to a non-UFA-supplemented concentrate 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 Bovine Genome Arrays.
Supplementation with UFA reduced the concentration of short chain fatty acids (FA), C16 FA and saturated FA in the milk, whereas that of trans-FA increased. One major finding was that canonical pathways associated with remodelling and immune functions of the mammary gland were predominantly down-regulated during UFA supplementation and negatively correlated with the concentration of milk trans-FA.
Supplementing grazing dairy cows with unprotected dietary UFA can affect the remodelling and immune functions of the mammary gland with potential consequences for its integrity and health, as well as milk quality.
Because of the potential health benefits of unsaturated fatty acids (UFA), there is considerable interest in increasing their concentration levels in milk. The effect of supplementing dietary UFA on the resulting milk fatty acid (FA) composition and expression of several genes involved in the mammary gland lipid metabolism has recently been studied in dairy cows [1, 2]. However, information about the effects of UFA supplementation on genome-wide expression of genes in the mammary gland tissue of dairy cows, as well as their relationship with the resultant milk FA composition, is lacking. Identifying these effects is expected to contribute to our understanding of milk fatty acid metabolism in the mammary gland tissue, and to enhance opportunities to improve milk fat composition through nutrition. Therefore, the aim of this study was to determine the effects of unprotected dietary UFA on the global expression pattern of genes in the mammary gland tissue of grazing dairy cows, to translate this into more biological knowledge, and to correlate gene expression patterns to the resulting milk fatty acid composition.
Twenty-eight Holstein-Friesian dairy cows were randomly assigned to 4 concentrated UFA-sources based on either unprotected rapeseed oil, soybean oil, linseed oil, or a proportional mix of these plants oils for 23 days (Period I), after which all cows were switched to a non-UFA-supplemented concentrate for an additional 28 days (Period II). On the last day of both periods, mammary gland biopsies were taken to study genome-wide differences in gene expression using Affymetrix GeneChip® Bovine Genome Arrays. In addition, milk samples were taken and stored at -20°C until analysis for FA composition by gas chromatography. Milk FA composition was analyzed using a mixed-effects ANOVA (SAS Inst. Inc. Cary, NC, release 9.1). The model included UFA-sources, experimental periods, and the interaction between UFA-sources and the experimental period, as fixed effects, and cow within pen as a random effect. The same model was performed to analyse gene expressions (MAANOVA package of R, release 1.16). The list of differentially expressed genes was generated using a False Discovery Rate (FDR) < 5% together with an absolute fold-change (FC) threshold of 1.3. Additionally, the Ingenuity Pathways Analysis (IPA; ver. 5.5., Ingenuity Systems, Redwood City, CA) was applied to identify the relevant genes associated with molecular and cellular functions, canonical pathways and biological functions, as well as the biological interaction networks among significant genes. As a means to potentially identify the association between differentially expressed genes in the mammary gland tissue affected by unprotected dietary UFA, and the resulting milk FA composition, the relationship between milk FA groups and mRNA expression of affected genes was calculated using the mixOmics package of R (release 2.7). The significance of the correlations described was tested by linear model using limma package of R.
Results and discussion
Milk fatty acid concentration (mg/L) when comparing dairy cows fed with unsaturated fatty acids (UFA) enriched-diet relative to the same cows fed control diet
Short Chain Fatty Acids, mg/L
Long-Chain Fatty Acids, mg/L
Unsaturated Fatty Acids, mg/L
Saturated Fatty Acids, mg/L
Polyunsaturated Fatty Acids, mg/L
4n-3 Fatty Acids, mg/L
5n-6 Fatty Acids, mg/L
Trans-octadecenoic Fatty Acids, mg/L
cis-9, trans-11-CLA, mg/L
The results of this study show that supplementing grazing dairy cows with different unprotected unsaturated fatty acids reduced the concentration of short chain fatty acids, C16 and saturated fatty acids in the milk, whereas that of trans-fatty acids increased. Dietary unsaturated fatty acid supplementation affected 78 remodelling and immune response-related genes, suggesting an effect on mammary gland tissue integrity and health. A novel finding was that the milk trans-FA presented a significant and negative correlation profile to these genes, therefore it is tempting to speculate on an active role of this FA-group in the regulation of mammary gland gene expression associated with immune system and remodelling components. Further functional knowledge by which fatty acids control these genes will be of great importance in understanding the resulting mammary gland health and integrity, as well as the milk composition and quality.
The authors gratefully acknowledge the financial support of WUR investment funds (BAS code KB-05-003-040-ASG-V-2) and the financial support of the “Comissionat per a Universitats i Recerca (CUR) del DIUE” of the Government of Catalonia.
This article has been published as part of BMC Proceedings Volume 5 Supplement 4, 2011: Proceedings of the International Symposium on Animal Genomics for Animal Health (AGAH 2010). The full contents of the supplement are available online at http://www.biomedcentral.com/1753-6561/5?issue=S4.
- Bauman D, Perfield J, Harvatine K, Baumgard L: Regulation of fat synthesis by conjugated linoleic acid: lactation and the ruminant model. J Nutr. 2008, 138: 403-409.PubMedGoogle Scholar
- Bionaz M, Loor J: Gene networks driving bovine milk fat synthesis during the lactation cycle. BMC Genomics. 2008, 9: 366-381. 10.1186/1471-2164-9-366.PubMed CentralView ArticlePubMedGoogle Scholar
- Albers R, van der Wielen R, Brink E, Hendriks H, Dorovska-Taran V, Mohede I: Effects of cis-9, trans-11 and trans-10, cis-12 conjugated linoleic acid (CLA) isomers on immune function in healthy men. Eur J Clin Nutr. 2003, 57: 595-603. 10.1038/sj.ejcn.1601585.View ArticlePubMedGoogle Scholar
- Carballo E, Lai W, Blackshear P: Feedback inhibition of macrophage tumor necrosis factor-alpha production by tristetraprolin. Science. 1998, 281: 1001-1005. 10.1126/science.281.5379.1001.View ArticlePubMedGoogle Scholar
- Jerri D, Dickinson E, Roberts A, Said T: Regulation of apoptosis during mammary involution by the p53 tumor suppressor gene. J Dairy Sci. 2002, 85: 1103-1110. 10.3168/jds.S0022-0302(02)74171-4.View ArticleGoogle Scholar
- Chatterjee S, Szustakowski JD, Nanguneri NR, Mickanin C, Labow MA, Nohturfft A, Dev K, Sivasankaran R: Identification of Novel Genes and Pathways Regulating SREBP Transcriptional Activity. PLoS ONE. 2009, 4: e5197-10.1371/journal.pone.0005197.PubMed CentralView ArticlePubMedGoogle Scholar
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