Ruminal infusions of cobalt-EDTA reduce mammary delta9-desaturase index and alter milk fatty acid composition in lactating cows

Kevin J Shingfield, Anu Arölä, Seppo Ahvenjärvi, Aila Vanhatalo, Vesa Toivonen, J. Mikko Griinari, Pekka Huhtanen

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Ruminal administration of a triple indigestible marker system comprised of cobalt EDTA (CoEDTA), ytterbium acetate (YbAc), and chromium-mordanted straw (CrS) decreases product:substrate ratios for Delta9-desaturase in bovine milk fat. This experiment was designed to identify the marker(s) responsible and develop an alternative system for simultaneous determination of nutrient flow in the gastro-intestinal tract and milk fatty acid composition. Five lactating dairy cows were used in a 5 x 5 Latin square with 21-d periods to evaluate the effects of YbAc, CoEDTA, and CrS independently or as part of a triple marker system (TMS), and CrEDTA as an alternative to CoEDTA on milk fat composition. Markers were administered in the rumen over a 7-d interval and samples of milk were collected on d -1, 3, 7, and 11. Both TMS and CoEDTA alone reduced the concentrations of milk fatty acids containing a cis-9 double bond, whereas YbAc, CrS, and CrEDTA had no effect. Reductions in product:substrate ratios for Delta9-desaturase were time dependent and evident within 3 d of administration. Ruminal infusion of CoEDTA for 7 d induced mean decreases in milk cis-9 14:1/14:0, cis-9 16:1/16:0, cis-9 18:1/18:0, and cis-9, trans-11 conjugated linoleic acid/trans-11 18:1 concentration ratios of 47.7, 26.7, 40.3, and 42.6%, respectively. In conclusion, ruminal infusion of CoEDTA alters milk fatty acid composition and appears to inhibit Delta9-desaturase activity in the bovine mammary gland. Results indicate that a TMS based on CrEDTA, YbAc, and indigestible neutral detergent fiber can be used for estimating nutrient flow without altering milk fat composition in lactating cows.
Original languageEnglish
Pages (from-to)710-717
Number of pages8
JournalJournal of Nutrition
Issue number4
Publication statusPublished - 01 Apr 2008


  • Animal Feed
  • Animal Nutritional Physiological Phenomena
  • Animals
  • Biological Markers
  • Cattle
  • Chromium
  • Edetic Acid
  • Fatty Acids
  • Female
  • Lactation
  • Mammary Glands, Animal
  • Milk
  • Rumen
  • Stearoyl-CoA Desaturase
  • Time Factors
  • Ytterbium


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