title: Ruminal Infusions of Cobalt EDTA Modify Milk Fatty Acid Composition via Decreases in Fatty Acid Desaturation and Altered Gene Expression in the Mammary Gland of Lactating Cows.
abstract: Intravenous or ruminal infusion of lithium salt of cobalt EDTA (Co-EDTA) or cobalt-acetate alters milk fat composition in cattle, but the mechanisms involved are not known.
  
  
  
  The present study evaluated the effect of ruminal Co-EDTA infusion on milk FA composition, mammary lipid metabolism, and mammary lipogenic gene expression.
  
  
  
  For the experiment, 4 cows in midlactation and fitted with rumen cannulae were used in a 4 × 4 Latin square with 28-d periods. Co-EDTA was administered in the rumen to supply 0, 1.5, 3.0, or 4.5 g Co/d over an 18-d interval with a 10-d washout between experimental periods. Milk production was recorded daily, and milk FA composition was determined on alternate days. Mammary tissue was biopsied on day 16, and arteriovenous differences of circulating lipid fractions and FA uptake across the mammary gland were measured on day 18.
  
  
  
  Co-EDTA had no effect on intake, proportions of rumen volatile FA, or milk production but caused dose-dependent changes in milk FA composition. Alterations in milk fat composition were evident within 3 d of infusion and characterized by linear or quadratic decreases (P < 0.05) in FAs containing a cis-9 double bond, an increase in 4:0 and 16:0, and linear decreases in milk 8:0, 10:0, 12:0, and 14:0 concentrations. Co-EDTA progressively decreased (P < 0.05) the stearoyl-CoA desaturase (SCD)-catalyzed desaturation of FAs in the mammary gland by up to 72% but had no effect on mammary SCD1 mRNA or SCD protein abundance. Changes in milk FA composition were accompanied by altered expression of specific genes involved in de novo FA and triacylglycerol synthesis.
  
  
  
  Ruminal infusion of Co-EDTA alters milk FA composition in cattle via a mechanism that involves decreases in the desaturation of FAs synthesized de novo or extracted from blood and alterations in mammary lipogenic gene expression, without affecting milk fat yield.
authors.affiliation: Green Technology, Natural Resources Institute Finland (Luke), Jokioinen, Finland;
authors.forename: Heidi
authors.initials: H
authors.lastname: Leskinen
authors.affiliation: Green Technology, Natural Resources Institute Finland (Luke), Jokioinen, Finland;
authors.forename: Sirja
authors.initials: S
authors.lastname: Viitala
authors.affiliation: Green Technology, Natural Resources Institute Finland (Luke), Jokioinen, Finland;
authors.forename: Mervi
authors.initials: M
authors.lastname: Mutikainen
authors.affiliation: Green Technology, Natural Resources Institute Finland (Luke), Jokioinen, Finland;
authors.forename: Piia
authors.initials: P
authors.lastname: Kairenius
authors.affiliation: Green Technology, Natural Resources Institute Finland (Luke), Jokioinen, Finland;
authors.forename: Ilma
authors.initials: I
authors.lastname: Tapio
authors.affiliation: Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland;
authors.forename: Juhani
authors.initials: J
authors.lastname: Taponen
authors.affiliation: Adipose Tissue and Milk Lipid Laboratory, Herbivore Research Unit, INRA-Theix, Saint-Genès-Champanelle, France; and.
authors.forename: Laurence
authors.initials: L
authors.lastname: Bernard
authors.affiliation: Green Technology, Natural Resources Institute Finland (Luke), Jokioinen, Finland;
authors.forename: Johanna
authors.initials: J
authors.lastname: Vilkki
authors.affiliation: Green Technology, Natural Resources Institute Finland (Luke), Jokioinen, Finland; Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Aberystwyth, United Kingdom kes14@aber.ac.uk.
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Shingfield
mesh_terms: D000818:Animals; D002417:Cattle; D003035:Cobalt / Q000008:administration & dosage / Q000494:pharmacology*; D003612:Dairying / Q000379:methods; D004492:Edetic Acid / Q000008:administration & dosage / Q000494:pharmacology; D005227:Fatty Acids / Q000096:biosynthesis / Q000378:metabolism*; D005260:Female; D015870:Gene Expression / Q000187:drug effects*; D007774:Lactation / Q000378:metabolism; D050356:Lipid Metabolism / Q000187:drug effects* / Q000235:genetics; D008055:Lipids / Q000097:blood; D008321:Mammary Glands, Animal / Q000187:drug effects* / Q000378:metabolism; D008892:Milk / Q000378:metabolism*; D015394:Molecular Structure; D012333:RNA, Messenger / Q000378:metabolism; D012417:Rumen / Q000187:drug effects / Q000378:metabolism*; D013230:Stearoyl-CoA Desaturase / Q000235:genetics / Q000378:metabolism; D014280:Triglycerides / Q000378:metabolism
chemical_list: D005227:Fatty Acids; D008055:Lipids; D012333:RNA, Messenger; D014280:Triglycerides; D003035:Cobalt; D004492:Edetic Acid; D013230:Stearoyl-CoA Desaturase
keywords: cobalt; cow; mammary gene expression; milk fat; stearoyl Co A desaturase