Journal of Dairy Research

Research Article

Investigation of the vitamins A and E and β-carotene content in milk from UK organic and conventional dairy farms

Kathryn A Ellisa1 c1, Ana Monteiroa2, Giles T Innocenta1, Dai Grove-Whitea3, Peter Crippsa3, W Graham McLeana4, C Vyvyan Howarda5 and Monika Mihma2

a1 Division of Animal Production and Public Health, University of Glasgow Veterinary School, Bearsden Road, Bearsden, Glasgow, G61 1QH, UK

a2 Division of Cell Sciences, Institute of Comparative Medicine, University of Glasgow Veterinary School, Bearsden Road, Bearsden, Glasgow, G61 1QH, UK

a3 Division of Livestock Health and Welfare, University of Liverpool Faculty of Veterinary Medicine, Leahurst, Neston, CH64 7TE, UK

a4 Department of Pharmacology & Therapeutics School of Biomedical Sciences, Sherrington Buildings, Ashton Street, Liverpool, Merseyside, L69 3GE, UK

a5 Centre for Molecular Biosciences, University of Ulster, Cromore Road, Coleraine, Co. Londonderry, BT52 1SA, UK

Abstract

During a 12-month longitudinal study, bulk-tank milk was collected from organic (n=17) and conventional (n=19) dairy farms in the UK. Milk samples were analysed for vitamin A (retinol), vitamin E (α-tocopherol) and β-carotene content. The farming system type, herd production level and nutritional factors affecting the milk fat vitamin content were investigated by use of mixed model analyses. Conventionally produced milk fat had a higher mean content of vitamin A than organically produced milk fat, although there were no significant differences in the vitamin E or β-carotene contents between the two types of milk fat. Apart from farming system, other key factors that affected milk fat vitamin content were season, herd yield and concentrate feeding level. Milk vitamin content increased in the summer months and in association with increased concentrate feeding, whilst higher-yielding herds had a lower milk vitamin E and β-carotene content. Thus, conventional dairy farms in the UK produced milk with a higher vitamin A content, possibly owing to increased vitamin A supplementation in concentrate feeds. However, knowledge of the effects of season, access to fresh grazing or specific silage types and herd production level may also be used by all producers and processors to enhance the vitamin content in milk.

(Received January 18 2007)

(Accepted July 11 2007)

(Online publication October 09 2007)

Correspondence:

c1 For correspondence; e-mail: k.ellis@vet.gla.ac.uk