Genetic parameters for major milk proteins in Dutch Holstein-Friesians

Abstract

The objective of this study was to estimate genetic parameters for major milk proteins. One morning milk sample was collected from 1,940 first-parity Holstein-Friesian cows in February or March 2005. Each sample was analyzed with capillary zone electrophoresis to determine the relative concentrations of the 6 major milk proteins. The results show that there is considerable genetic variation in milk protein composition. The intraherd heritabilities for the relative protein concentrations were high and ranged from 0.25 for beta-casein to 0.80 for beta-lactoglobulin. The intraherd heritability for the summed whey fractions (0.71) was higher than that for the summed casein fractions (0.41). Further, there was relatively more variation in the summed whey fraction (coefficient of variation was 11% and standard deviation was 1.23) compared with the summed casein fraction (coefficient of variation was 2% and standard deviation was 1.72). For the caseins and alpha-lactalbumin, the proportion of phenotypic variation explained by herd was approximately 14%. For beta-lactoglobulin, the proportion of phenotypic variation explained by herd was considerably lower (5%). Eighty percent of the genetic correlations among the relative contributions of the major milk proteins were between -0.38 and +0.45. The genetic correlations suggest that it is possible to change the relative proportion of caseins in milk. Strong negative genetic correlations were found for beta-lactoglobulin with the summed casein fractions (-0.76), and for beta-lactoglobulin with casein index (-0.98). This study suggests that there are opportunities to change the milk protein composition in the cow's milk using selective breeding.

Seasonal and Milking-to-Milking Variations in Cow Milk Fat, Protein and Somatic Cell Counts

“…It has been found in the present study that the content of protein is rather constant throughout the seasons. This agrees with other studies that have shown that protein composition is influence by feeding practices only to a small extend ( Schopen et al, 2009;Heck et al, 2009;Coulon et al, 1998;Ozrenk and Selcuk Inci, 2008).…”

Selection for milk fat and milk protein composition

“…Heritability estimates for the six major milk proteins range from 0.25 to 0.80 (Schopen et al, 2009;Bonfatti et al, 2011). Heritability estimates from both studies differ for certain milk proteins, especially for b-casein and b-lactoglobulin, which might be because of differences in the methods used to quantify the milk proteins (capillary zone electrophoresis v. HPLC).…”

“…Recent studies demonstrate that milk protein composition is strongly affected by genetic factors (Schopen et al, 2009;Bonfatti et al, 2011). Heritability estimates for the six major milk proteins range from 0.25 to 0.80 (Schopen et al, 2009;Bonfatti et al, 2011).…”

Comparison of fat and protein fractions of milk constituents in Montbeliarde and Polish Holstein-Friesian cows from one farm in Poland

“…The main technological value of milk was characterised by casein ratio, according to application of the standards of the Center of Chemical Patterns in Italy and Foss, and also, by the casein number and casein index (Schopen et al 2009). …”