Alfa-tocopherol and beta-carotene in roughages and milk in organic dairy herds Lisbeth Mogensen a, ⁎, Troels Kristensen a , Karen Søegaard a , Søren K. Jensen b , Jakob Sehested b a Department of Agroecology, Research Centre Foulum, Aarhus University, PO Box 50, DK-8830 Tjele, Denmark b Department of Animal Science, Research Centre Foulum, Aarhus University, PO Box 50, DK-8830 Tjele, Denmark article info abstract Article history: Received 2 May 2011 Received in revised form 20 December 2011 Accepted 21 December 2011 The aim of the present on-farm study was to analyse vitamin content in roughage at harvest and during storage and to analyze milk vitamin content when feeding the roughage to dairy cows. Roughages produced at five organic dairy farms were monitored at harvest and several times during winter as stored silage. As an average of several sampling times, roughage α- tocopherol and β-carotene contents (mg per kg DM) during the period when the roughage was fed were, respectively, 30 and 21 in grass–clover silage, 13 and 8 in maize wholecrop si- lage and 28 and 9 in cereal wholecrop silage. Daily intake of α-tocopherol was 876 mg per cow–431 mg from roughages, 89 mg from concentrates and 356 mg from a vitamin supple- ment. Milk yield was 25.9 kg energy-corrected milk (ECM) per cow per day with α- tocopherol and β-carotene contents (μg/ml) of 0.82 and 0.17. The study additionally showed the following tendency, but due to few observations no final conclusions could be drawn: • For grass–clover silage there were generally no losses of vitamins during the ensiling process and during storage, but there were huge variations between farms. • For wholecrop silage there was a loss of vitamins during the ensiling process, whereas there were no further losses during the feeding period. • The output of vitamins in milk was within farm positively correlated to supply of vitamins from roughage. © 2012 Elsevier B.V. All rights reserved. Keywords: α-Tocopherol β-Carotene Dairy cows Organic milk production Roughage Vitamin 1. Introduction Organic milk production is based on organic principles and objectives including naturalness and the recycling of nutrients. According to current regulations, the feed used in organic milk production must be 100% organically grown (EC, 1999). How- ever, the integrity of the organic production could be further enhanced if the frequent use of vitamin supplementation (Møller and Laursen, 2007) with artificial fat-soluble vitamins could be substituted by vitamins from natural sources. The use of vitamin supplements reflects the uncertainty regarding the actual content of vitamins in the feed at harvest and after storage during the winter-feeding period. The fat-soluble vitamins, A and E, are essential nutrients and both milk quality and performance of dairy cows depend on a supply of the vitamins or their precursors from feed or a vitamin supplement (Jensen and Nielsen, 1996; Weiss et al., 1990). There are eight different forms of vitamin E (α-to- copherols), which are equally present in synthetic products, whereas only RRR-α-tocopherol is naturally present in the feed plants. The naturally occurring RRR-α-tocopherol has the highest vitamin E activity of the eight forms and is thus the physiologically most important (Bondi, 1987), meaning that animal requirements can be fulfilled from a lower amount of the natural form (e.g. from home-grown rough- ages) as compared to a synthetic source of α-tocopherols. Vi- tamin A is synthesised in the cow from carotene precursors of plant origin, but animal requirements can also be fulfilled from vitamin supplements containing synthetic vitamin A Livestock Science 145 (2012) 44–54 ⁎ Corresponding author. Tel.: + 45 8715 8025; fax: + 45 8715 4798. E-mail address: Lisbeth.Mogensen@agrsci.dk (L. Mogensen). 1871-1413/$ – see front matter © 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.livsci.2011.12.021 Contents lists available at SciVerse ScienceDirect Livestock Science journal homepage: www.elsevier.com/locate/livsci