title: Short communication: Effect of conjugated linoleic acid on concentrations of fat-soluble vitamins in milk of lactating ewes.
abstract: Conjugated linoleic acids (CLA) are well known as milk fat-reducing feed supplements in diets for lactating ruminants. However, their effects on milk concentrations of fat-soluble vitamins are unknown. This study was performed to investigate the hypothesis that CLA affect the concentrations of retinol and tocopherol in ewe milk. For that purpose, group-housed Merino ewes (101 ± 13.7 kg) nursing twin lambs and fed with a hay:concentrate diet were supplemented with either 45 g of a rumen-protected CLA supplement containing 3.4 g of cis-9,trans-11-CLA and 3.4 g of trans-10,cis-12-CLA (CLA group, n=11) or with 45 g of a hydrogenated vegetable fat (control group, n=12) per ewe per day during the first 6 wk of lactation. Feed intake was recorded daily (concentrate) or weekly (hay) per group. Milk spot samples were collected at the beginning of the experiment (5 ± 2.4 d postpartum) and then weekly after lambs had been separated for 2 h from their mothers. The milk fat content was determined and feed and milk were analyzed for concentrations of α-, γ-, and δ-tocopherol and for retinol by HPLC. Dietary intake of tocopherol and retinol was similar in both groups. Feeding CLA decreased milk fat concentration by 23% on average, and during the first 3 wk of the study milk tocopherol concentration tended to be increased by feeding CLA (+17%), but retinol concentrations were not influenced. When related to milk fat, CLA feeding significantly increased both milk tocopherol (+40%) and retinol (+32%) and these effects were evident during the whole experimental period corresponding to the first half of lactation.
authors.affiliation: University of Giessen, Institute of Animal Nutrition and Nutritional Physiology, Heinrich-Buff-Ring 26-32 (IFZ), D-35392 Giessen, Germany. Electronic address: Johanna.O.Zeitz@ernaehrung.uni-giessen.de.
authors.forename: J O
authors.initials: JO
authors.lastname: Zeitz
authors.affiliation: University of Giessen, Institute of Animal Nutrition and Nutritional Physiology, Heinrich-Buff-Ring 26-32 (IFZ), D-35392 Giessen, Germany.
authors.forename: E
authors.initials: E
authors.lastname: Most
authors.affiliation: University of Giessen, Institute of Animal Nutrition and Nutritional Physiology, Heinrich-Buff-Ring 26-32 (IFZ), D-35392 Giessen, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Eder
mesh_terms: D000821:Animal Feed / Q000032:analysis; D000818:Animals; D004032:Diet / Q000662:veterinary; D019587:Dietary Supplements / Q000032:analysis; D005260:Female; D044243:Linoleic Acids, Conjugated / Q000008:administration & dosage / Q000378:metabolism*; D008892:Milk / Q000737:chemistry*; D011897:Random Allocation; D034561:Sheep, Domestic / Q000378:metabolism*; D024505:Tocopherols / Q000378:metabolism*; D014801:Vitamin A / Q000378:metabolism*; D014815:Vitamins / Q000378:metabolism*
chemical_list: D044243:Linoleic Acids, Conjugated; D014815:Vitamins; D014801:Vitamin A; D024505:Tocopherols
keywords: conjugated linoleic acid; lactating ewe; milk fat-soluble vitamin