title: Environmental and genetic factors influence the vitamin D content of cows' milk.
abstract: Vitamin D is obtained by cattle from the diet and from skin production via UVB exposure from sunlight. The vitamin D status of the cow impacts the vitamin D content of the milk produced, much like human breast milk, with seasonal variation in the vitamin D content of milk well documented. Factors such as changes in husbandry practices therefore have the potential to impact the vitamin D content of milk. For example, a shift to year-round housing from traditional practices of cattle being out to graze during the summer months and housed during the winter only, minimises exposure to the sun and has been shown to negatively influence the vitamin D content of the milk produced. Other practices such as changing dietary sources of vitamin D may also influence the vitamin D content of milk, and evidence exists to suggest genetic factors such as breed can cause variation in the concentrations of vitamin D in the milk produced. The present review aims to provide an overview of the current understanding of how genetic and environmental factors influence the vitamin D content of the milk produced by dairy cattle. A number of environmental and genetic factors have previously been identified as having influence on the nutritional content of the milk produced. The present review highlights a need for further research to fully elucidate how farmers could manipulate the factors identified to their advantage with respect to increasing the vitamin D content of milk and standardising it across the year.
authors.affiliation: Northern Ireland Centre for Food and Health,University of Ulster,Coleraine BT52 1SA,UK.
authors.forename: R R
authors.initials: RR
authors.lastname: Weir
authors.affiliation: Northern Ireland Centre for Food and Health,University of Ulster,Coleraine BT52 1SA,UK.
authors.forename: J J
authors.initials: JJ
authors.lastname: Strain
authors.affiliation: Dairy Council for Northern Ireland,Shaftesbury House, Edgewater Office Park, Belfast BT3 9JQ,UK.
authors.forename: M
authors.initials: M
authors.lastname: Johnston
authors.affiliation: Dairy Council for Northern Ireland,Shaftesbury House, Edgewater Office Park, Belfast BT3 9JQ,UK.
authors.forename: C
authors.initials: C
authors.lastname: Lowis
authors.affiliation: Agri-Food and Biosciences Institute,Belfast BT9 5PX,UK.
authors.forename: A M
authors.initials: AM
authors.lastname: Fearon
authors.affiliation: Agri-Food and Biosciences Institute,Belfast BT9 5PX,UK.
authors.forename: S
authors.initials: S
authors.lastname: Stewart
authors.affiliation: Northern Ireland Centre for Food and Health,University of Ulster,Coleraine BT52 1SA,UK.
authors.forename: L K
authors.initials: LK
authors.lastname: Pourshahidi
mesh_terms: D000375:Aging; D000822:Animal Husbandry / Q000379:methods; D000818:Animals; D001947:Breeding; D002417:Cattle / Q000235:genetics* / Q000378:metabolism*; D004032:Diet / Q000662:veterinary*; D004777:Environment; D005260:Female; D007774:Lactation; D008892:Milk / Q000737:chemistry*; D009752:Nutritional Status; D012621:Seasons; D012867:Skin / Q000378:metabolism; D013472:Sunlight; D014807:Vitamin D / Q000008:administration & dosage / Q000032:analysis* / Q000096:biosynthesis
chemical_list: D014807:Vitamin D
keywords:  25(OH)D3
                  25-hydroxyvitamin D3
                 ; Cows' milk; Environmental factors; Genetic factors; Vitamin D