Effect of toasting field beans and of grass-clover: Maize silage ratio on milk production, milk composition and sensory quality of milk Lisbeth Mogensen a, ⁎, Jannie Steensig Vestergaard b , Xavier Fretté c , Peter Lund d , Martin Riis Weisbjerg d , Troels Kristensen a a Department of Agroecology and Environment, Faculty of Agricultural Sciences, Aarhus University, PO Box 50, DK-8830 Tjele, Denmark b Department of Food Science, Faculty of Life Sciences, University of Copenhagen, Rolighedsvej 30, DK-1958 Frederiksberg C, Denmark c Department of Food Science, Faculty of Agricultural Sciences, University of Aarhus, PO Box 50, DK-8830 Tjele, Denmark d Department of Animal Health Welfare and Nutrition, Faculty of Agricultural Sciences, Aarhus University, PO Box 50, DK-8830 Tjele, Denmark article info abstract Article history: Received 30 April 2009 Received in revised form 29 October 2009 Accepted 30 November 2009 The effect of toasting field beans and of grass-clover: maize silage ratio on milk production, milk composition and the sensory quality of the milk was investigated in a 2 ⁎ 2 factorial experiment. Toasting of field beans resulted in lower milk contents of both fat (44.2 versus 46.1 g/kg, P = 0.02) and protein (33.5 versus 34.2 g/kg, P =0.008), whereas milk production, urea and somatic cell contents were unaffected compared with the untreated field beans. Increasing the proportion of maize silage (from 9 to 21% of DM) in the ration decreased the content of urea in milk (P = 0.002), whereas milk production and milk content of fat and protein were unaffected. Milk from cows fed the high proportion of maize silage had a lower (P =0.04) long-chain fatty acid content (≥C18). Furthermore, milk from cows fed the high proportion of maize silage had a lower (13–26%) content of luteine (P = 0.03), 13-cis-β-carotene (P =0.04) and β-carotene (P =0.05). Toasting of field beans compared with untreated field beans did not affect the milk content of carotenoids and had only small effects on fatty acid composition. Regarding the sensory quality, the four treatments resulted in milk being characterized by a distinctly fatty mouthfeel and creamy flavour and a pronounced sugar-sweet taste and creamy odour. The higher proportions of maize in the feed resulted, in general, in milk characterized by a significantly more intense maize odour (P b 0.05). The effect of field bean toasting in combination with a high proportion of maize in the feed resulted in milk characterized by a significant and distinctly sour feed odour (P b 0.05). In conclusion, toasting field beans did not improve milk production, and toasted field beans in combination with a high proportion of maize in the feed resulted in milk with negative sensory characteristics. Increasing the proportion of maize silage at the expense of grass-clover silage did not affect milk production, but decreased the milk content of long-chain fatty acids, as well as the content of carotenes. © 2009 Elsevier B.V. All rights reserved. Keywords: Dairy cows Milk fat composition Organic Toasting Sensory characteristics 1. Introduction In Northern Europe, grass-clover is the main feed compo- nent for organic dairy cows, often combined with a large amount of barley and other cereals (Mogensen, 2004). This feed composition, however, with high proportions of cereals (N 4.6 kg) and fresh grass-clover (N 9.3 kg DM) has been found to be correlated with a high incidence of liver abscesses (Jørgensen et al., 2005). Liver abscesses are probably caused by a decreased rumen pH, which is a characteristic of the metabolism of barley and other feeds that have a high level of rumen-degradable starch (Arieli et al., 1995; Tothi et al., 2003). Heat treatment has been found to decrease rumen starch degradability of barley, wheat (Arieli et al., 1995) and field Livestock Science 128 (2010) 123–132 ⁎ Corresponding author. Tel.: + 45 8999 1223; fax: + 45 8999 1200. E-mail address: Lisbeth.Mogensen@agrsci.dk (L. Mogensen). 1871-1413/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.livsci.2009.11.011 Contents lists available at ScienceDirect Livestock Science journal homepage: www.elsevier.com/locate/livsci