title: Association of genetic variants of casein and milk serum proteins with milk, fat, and protein production by dairy cattle.
abstract: Polyacrylamide gel electrophoresis methods were used to phenotype caseins for 2045 cows and milk serum proteins for 3870 cows distributed in 63 Quebec dairy herds. Frequencies were: alpha s1-casein A .003, alpha s1-casein B .970, alpha s1-casein C .027; beta-casein A1 .561, beta-casein A2 .421, beta-casein A3 .011, beta-casein B .007; kappa-casein A .744, kappa-casein B .256; beta-lactoglobulin A .387, beta-lactoglobulin B .613; alpha-lactalbumin B 1.00. Overall unadjusted means for 305-day production in first lactation were: 5530 +/- 26.6 kg, 197 +/- 1.0 kg, 172 +/- 1.0 kg, 3.58 +/- .009, 3.12 +/- .009 for milk yield, fat yield, protein yield, fat percentage, and protein percentage for 1687 cows for casein systems. Similar data for 2906 cows phenotyped for milk serum proteins were: 5412 +/- 20.6 kg, 193 +/- .8 kg, 170 +/- .7 kg, 3.57 +/- .007, and 3.13 +/- 007. Least squares analysis of variance showed that herd location, month of calving, age of cow at first calving, and protein variants had significant effects on production traits. alpha s1-Casein B and beta-casein A phenotypes were associated with higher milk, fat, and protein yields than other variants in the two casein systems. Milk from kappa-casein BB and beta-lactoglobulin AA phenotypes contained .13 and .05% more protein than the AA and BB phenotypes with the AB phenotype intermediate.
mesh_terms: D000818:Animals; D002364:Caseins / Q000235:genetics*; D002417:Cattle / Q000235:genetics* / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D014644:Genetic Variation; D007774:Lactation; D008055:Lipids / Q000096:biosynthesis; D008892:Milk / Q000378:metabolism; D008894:Milk Proteins / Q000096:biosynthesis / Q000235:genetics*; D010641:Phenotype
chemical_list: D002364:Caseins; D008055:Lipids; D008894:Milk Proteins