title: Potentials to differentiate milk composition by different feeding strategies.
abstract: To investigate the effect of the dietary intake of the cow on milk composition, bulk-tank milk was collected on 5 occasions from conventional (n = 15) and organic (n = 10) farms in Denmark and on 4 occasions from low-input nonorganic farms in the United Kingdom, along with management and production parameters. Production of milk based on feeding a high intake of cereals, pasture, and grass silage resulted in milk with a high concentration of alpha-linolenic acid (9.4 +/- 0.2 mg/kg of fatty acids), polyunsaturated fatty acids (3.66 +/- 0.07 mg/kg of fatty acids), and natural stereoisomer of alpha-tocopherol (RRR-alpha-tocopherol, 18.6 +/- 0.5 mg/kg of milk fat). A milk production system using a high proportion of maize silage, by-products, and commercial concentrate mix was associated with milk with high concentrations of linoleic acid (LA; 19.7 +/- 0.4 g/kg of fatty acids), monounsaturated fatty acids (27.5 +/- 0.3 mg/kg of fatty acids), and a high ratio between LA and alpha-linolenic acid (4.7 +/- 0.2). Comparing these 2 production systems with a very extensive nonorganic milk production system relying on pasture as almost the sole feed (95 +/- 4% dry matter intake), it was found that the concentrations of conjugated LA (cis-9,trans-11; 17.5 +/- 0.7 g/kg of fatty acids), trans-11-vaccenic acid (37 +/- 2 g/kg of fatty acids), and monounsaturated fatty acids (30.4 +/- 0.6 g/kg of fatty acids) were higher in the extensively produced milk together with the concentration of antioxidants; total alpha-tocopherol (32.0 +/- 0.8 mg/kg of milk fat), RRR-alpha-tocopherol (30.2 +/- 0.8 mg/kg of milk fat), and beta-carotene (9.3 +/- 0.5 mg/kg of milk fat) compared with the organic and conventional milk. Moreover, the concentration of LA (9.2 +/- 0.7 g/kg of fatty acids) in milk from the extensive milk production system was found to approach the recommended unity ratio between n-6 and n-3, although extensive milk production also resulted in a lower daily milk yield.
authors.affiliation: Department of Food Science, Faculty of Agricultural Sciences, University of Aarhus, Blichers Allé 20, PO Box 50, DK-8830 Tjele, Denmark.
authors.forename: T
authors.initials: T
authors.lastname: Slots
authors.forename: G
authors.initials: G
authors.lastname: Butler
authors.forename: C
authors.initials: C
authors.lastname: Leifert
authors.forename: T
authors.initials: T
authors.lastname: Kristensen
authors.forename: L H
authors.initials: LH
authors.lastname: Skibsted
authors.forename: J H
authors.initials: JH
authors.lastname: Nielsen
mesh_terms: D000818:Animals; D002417:Cattle / Q000378:metabolism / Q000502:physiology*; D003612:Dairying / Q000379:methods*; D004032:Diet / Q000662:veterinary*; D005223:Fats / Q000032:analysis; D015525:Fatty Acids, Omega-3 / Q000032:analysis; D043371:Fatty Acids, Omega-6 / Q000032:analysis; D005248:Feeding Methods / Q000662:veterinary*; D005260:Female; D058870:Food, Organic / Q000032:analysis*; D007774:Lactation; D008892:Milk / Q000737:chemistry* / Q000378:metabolism; D025341:Principal Component Analysis; D012044:Regression Analysis
chemical_list: D005223:Fats; D015525:Fatty Acids, Omega-3; D043371:Fatty Acids, Omega-6