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

The milks of cows with known genetic variants of proteins were quantified b y 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 hapIo types B-A-B-A and B-A-B-B for alpha(s1)-, alpha(s2),-, beta-, and kappa-cas ein(CN), 137 daughters were selected. They were assigned into two groups ac cording 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 correlat ion 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 A A, AB and BE. The citrate content in the second interval between 170 and 21 5 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.