Correlation between κ-casein variants and citrate content in milk quantified by capillary electrophoresis

The milks of cows with known genetic variants of proteins were quantified by capillary electrophoresis (CE) for citrate content. From seven test-bulls of the breed Swiss Brown x Brown Swiss (SB x BS) with the two casein hapIotypes B-A-B-A and B-A-B-B for alpha(s1)-, alpha(s2),-, beta-, and kappa-casein(CN), 137 daughters were selected. They were assigned into two groups according to the casein haplotype inherited from the father. During the first lactation, from each cow, two milk samples, i.e. between 30-80 and 170-215 days were analysed for citrate content. From the data obtained no correlation between the casein haplotype and the citrate content in milk was found. The same applies when the cows were grouped according to Ic-CN genotypes AA, AB and BE. The citrate content in the second interval between 170 and 215 days was for all cows significantly lower than in the first interval (30-80 days) of the lactation. (C) 2000 Published by Elsevier Science Ltd. All rights reserved.