Comparison of milk protein composition in a Swedish and a Danish dairy herd using reversed phase HPLC

Abstract

The milk composition in a Swedish herd, consisting of Swedish Red and White cows (SRB) and Swedish Holstein cows (SLB), and in a Danish herd, consisting of Danish Holstein-Friesian cows (SDM), was evaluated. Concentrations of the major milk proteins (κ-casein, α_S1-casein, β-casein, β-lactoglobulin A, β-lactoglobulin B and α-lactalbumin) of 134 individual milk samples were determined by reversed phase (RP) HPLC. Other parameters determined included milk fat, urea, lactose, calcium, lactoferrin, somatic cell count and protein degradation (determined as level of free amino-terminals). Analysis of variance was used to compare concentrations of analysed milk variables between SRB and SLB or between SLB and SDM. Concentration of total protein, total casein, β-casein and κ-casein were significantly higher in SRB milk compared with SLB milk. Concentration of α-lactalbumin and calcium were significantly higher in SDM milk than in SLB milk. The concentration of urea was higher in SLB than in SDM milk and is suggested to reflect differences in feeding regimes between the investigated Swedish and Danish herd.

Keywords:

• Calcium
• casein
• dairy cows
• free amino terminals
• urea
• whey protein

The authors wish to thank Hanne Damgaard Poulsen, Department of Animal Health, Welfare and Nutrition, Danish Institute of Agricultural Sciences, for performing the calcium analyses; Stina Greis Handberg and Helle Louise Christensen, Department of Food Quality, Danish Institute of Agricultural Sciences for excellent technical assistance and Gun Aldén, Swedish Dairy Association for determination of lactoferrin. Lennart Björck, Department of Food Science, Swedish University of Agricultural Sciences is acknowledged for supervision during the preparation of this manuscript and Anne Lundén, Department of Animal Breeding and Genetics for discussions regarding the statistical analyses. At the same department, PhD student Jessica Näslund is acknowledged for genotyping the genetic variants of β- and κ-CN and Gudrun Franzén and Lena Hagenvall for the milk sample collection. Financial support from the Swedish Farmers’ Foundation for Agricultural Research, Danish Dairy Research Foundation and the Innovation Law are gratefully acknowledged.