title: Effect of safflower oil, flaxseed oil, monensin, and vitamin E on concentration of conjugated linoleic acid in bovine milk fat.
abstract: Conjugated linoleic acid (CLA) refers to a mixture of conjugated octadecadienoic acids of predominantly ruminant origin. The main isomer in bovine milk fat is the cis-9, trans-11 CLA. Interest in CLA increased after the discovery of its health-promoting properties, including potent anticarcinogenic activity. Two experiments were conducted to evaluate dietary strategies aimed at increasing the concentration of CLA in bovine milk fat. Both experiments were organized as a randomized complete block design with a repeated measures treatment structure. In Experiment 1, 28 Holstein cows received either a control diet or one of 3 treatments for a period of 2 wk. The control diet consisted of 60% forage (barley silage, alfalfa silage, and alfalfa hay) and 40% concentrate on a dry matter (DM) basis, fed as a total mixed ration (TMR). The concentrate was partially replaced in the treatment groups with 24 ppm of monensin (MON), 6% of DM safflower oil (SAFF), or 6% of DM safflower oil plus 24 ppm of monensin (SAFF/M). Average cis-9, trans-11 CLA levels in milk fat after 2 wk of feeding were 0.45, 0.52, 3.36, and 5.15% of total fatty acids for control, MON, SAFF, and SAFF/M, respectively. In Experiment 2, 62 Holstein cows received either a control diet or one of 5 treatment diets for a period of 9 wk. The control diet consisted of 60% forage (barley silage, alfalfa silage, and alfalfa hay) and 40% concentrate on a DM basis, fed as a TMR. The concentrate was partially replaced in the treatment groups with 6% of DM safflower oil (SAFF), 6% of DM safflower oil plus 150 IU of vitamin E/kg of DM (SAFF/E), 6% of DM safflower oil plus 24 ppm of monensin (SAFF/M), 6% of DM safflower oil plus 24 ppm of monensin plus 150 IU of vitamin E/kg of DM (SAFF/ME), or 6% of DM flaxseed oil plus 150 IU of vitamin E/kg of DM (FLAX/E). Average cis-9, trans-11 CLA levels during the treatment period were 0.68, 4.12, 3.48, 4.55, 4.75, and 2.80% of total fatty acids for control, SAFF, SAFF/E, SAFF/M, SAFF/ME, and FLAX/E, respectively. The combination of safflower oil with monensin was particularly effective at increasing milk fat CLA. The addition of vitamin E to the diet partially prevented the depression in milk fat associated with oilseed feeding, but had no significant effect on the concentration of CLA in milk.
authors.affiliation: Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, Canada T6G 2P5.
authors.forename: J A
authors.initials: JA
authors.lastname: Bell
authors.forename: J M
authors.initials: JM
authors.lastname: Griinari
authors.forename: J J
authors.initials: JJ
authors.lastname: Kennelly
mesh_terms: D000821:Animal Feed / Q000032:analysis; D000818:Animals; D002417:Cattle; D002452:Cell Count; D005223:Fats / Q000032:analysis; D005227:Fatty Acids / Q000032:analysis; D005260:Female; D006865:Hydrogenation; D007774:Lactation; D007785:Lactose / Q000032:analysis; D044243:Linoleic Acids, Conjugated / Q000032:analysis*; D008043:Linseed Oil / Q000008:administration & dosage*; D008892:Milk / Q000737:chemistry* / Q000166:cytology; D008894:Milk Proteins / Q000032:analysis; D008985:Monensin / Q000008:administration & dosage*; D012417:Rumen; D012450:Safflower Oil / Q000008:administration & dosage*; D014810:Vitamin E / Q000008:administration & dosage*
chemical_list: D005223:Fats; D005227:Fatty Acids; D044243:Linoleic Acids, Conjugated; D008894:Milk Proteins; D014810:Vitamin E; D012450:Safflower Oil; D008043:Linseed Oil; D008985:Monensin; D007785:Lactose