title: Fatty acid profile differs between organic and conventionally produced cow milk independent of season or milking time.
abstract: Differing amounts of fresh forage and concentrates fed, and level of input contributes to the differences reported in fatty acid (FA) composition of organic and conventionally produced cow milk. In many previous studies designed to investigate this phenomenon, comparisons were made between grazed organic cows and housed conventional cows. In the present study, we have investigated differences between organic and conventional milk produced using year-round pasture grazing, as practiced in New Zealand. The FA composition was determined in milk sampled at morning and evening milking in both spring and autumn. Samples were taken from 45 cows from the Massey University organic herd and compared with 50 cows from the corresponding conventional herd grazed and managed similarly at the same location. Forty-three out of 51 analyzed FA were influenced by season, whereas 28 were different between production systems. In addition, one-half were also different due to time of milking. Levels of linoleic acid and α-linolenic acid were higher in organic milk, whereas conjugated linoleic acid (CLA) and vaccenic acid were higher in conventional milk. The first 3 FA (linoleic acid, α-linolenic acid, and CLA) were more abundant in milk harvested during autumn, and the CLA concentration was also significantly influenced by time of milking. Our results confirm reports that the FA profile is affected by season and time of milking, and we also showed an effect due to the production system, when both sets of cows were kept continuously on pasture, even after taking milking time and seasonal effect into account.
authors.affiliation: AgResearch Grasslands Research Centre, Tennent Drive, Palmerston North 4442, New Zealand. Electronic address: Heike.Schwendel@AgResearch.co.nz.
authors.forename: B H
authors.initials: BH
authors.lastname: Schwendel
authors.affiliation: Massey University, Tennent Drive, Palmerston North 4474, New Zealand.
authors.forename: P C H
authors.initials: PC
authors.lastname: Morel
authors.affiliation: Massey University, Tennent Drive, Palmerston North 4474, New Zealand.
authors.forename: T J
authors.initials: TJ
authors.lastname: Wester
authors.affiliation: AgResearch Grasslands Research Centre, Tennent Drive, Palmerston North 4442, New Zealand.
authors.forename: M H
authors.initials: MH
authors.lastname: Tavendale
authors.affiliation: Fonterra Research Centre Palmerston North, Dairy Farm Road, Palmerston North 4474, New Zealand.
authors.forename: C
authors.initials: C
authors.lastname: Deadman
authors.affiliation: Fonterra Research Centre Palmerston North, Dairy Farm Road, Palmerston North 4474, New Zealand.
authors.forename: B
authors.initials: B
authors.lastname: Fong
authors.affiliation: Massey University, Tennent Drive, Palmerston North 4474, New Zealand.
authors.forename: N M
authors.initials: NM
authors.lastname: Shadbolt
authors.affiliation: Massey University, Tennent Drive, Palmerston North 4474, New Zealand.
authors.forename: A
authors.initials: A
authors.lastname: Thatcher
authors.affiliation: AgResearch Grasslands Research Centre, Tennent Drive, Palmerston North 4442, New Zealand.
authors.forename: D E
authors.initials: DE
authors.lastname: Otter
mesh_terms: D000818:Animals; D002417:Cattle; D004032:Diet / Q000662:veterinary; D005260:Female; D058870:Food, Organic; D007774:Lactation; D019787:Linoleic Acid / Q000032:analysis*; D044243:Linoleic Acids, Conjugated / Q000032:analysis*; D008892:Milk / Q000737:chemistry*; D009520:New Zealand; D009829:Oleic Acids / Q000032:analysis*; D012621:Seasons; D017962:alpha-Linolenic Acid / Q000032:analysis*
chemical_list: D044243:Linoleic Acids, Conjugated; D009829:Oleic Acids; D017962:alpha-Linolenic Acid; D019787:Linoleic Acid; C050413:11-octadecenoic acid
keywords: fatty acid; milk; milking time; organic