title: Ruminal infusions of cobalt-EDTA reduce mammary delta9-desaturase index and alter milk fatty acid composition in lactating cows.
abstract: 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.
authors: Animal Production Research, MTT Agrifood Research Finland, Jokioinen, FIN 31600, Finland. kevin.shingfield@mtt.fi
authors: Kevin J
authors: KJ
authors: Shingfield
authors: Anu
authors: A
authors: Arölä
authors: Seppo
authors: S
authors: Ahvenjärvi
authors: Aila
authors: A
authors: Vanhatalo
authors: Vesa
authors: V
authors: Toivonen
authors: J Mikko
authors: JM
authors: Griinari
authors: Pekka
authors: P
authors: Huhtanen
mesh_terms: D000821:Animal Feed; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D015415:Biomarkers; D002417:Cattle / Q000378:metabolism*; D002857:Chromium / Q000008:administration & dosage / Q000494:pharmacology / Q000652:urine; D004492:Edetic Acid / Q000008:administration & dosage / Q000494:pharmacology* / Q000652:urine; D005227:Fatty Acids / Q000032:analysis*; D005260:Female; D007774:Lactation; D008321:Mammary Glands, Animal / Q000201:enzymology*; D008892:Milk / Q000737:chemistry*; D012417:Rumen / Q000378:metabolism*; D013230:Stearoyl-CoA Desaturase / Q000378:metabolism*; D013997:Time Factors; D015018:Ytterbium / Q000008:administration & dosage / Q000494:pharmacology / Q000652:urine
chemical_list: D015415:Biomarkers; D005227:Fatty Acids; D002857:Chromium; C028222:cobalt-ethylenediamine tetraacetic acid chelate; D004492:Edetic Acid; D013230:Stearoyl-CoA Desaturase; D015018:Ytterbium