Overview of Dairy Cattle Breeding

The overall objectives of dairy cattle breeding research are to generate new knowledge and to provide this information to breeders in Iowa and the nation. We are attempting to accomplish this by developing new knowledge that will be of value in the future and also have information that can be provided to the breeding industry to answer present-day problems. Because more than 70% of the dairy cattle in the United States are bred artificially, our work will have more impact if it can eventually be applied through the artificial insemination (AI) industry and breed associations. A great deal of research and groundwork needs to be done before research can be applied on an industry-wide basis

Milk Protein Genotypes Explain Variation of Milk Protein Composition

The data demonstrate that cows with the genotypes κ- casein BB and β-lactoglobulin BB produce milk with a protein composition that is favorable for increased cheese yield. For proportions of αS1-casein, κ-casein, and β-lactoglobulin in total milk protein, κ-casein and β-lactoglobulin genotypes explained more than 50 and 25% of the heritability and repeatability estimates, respectively, and more than 14% of the phenotypic variance. Diet had only a minimal effect on milk protein composition. In conclusion, increasing cheese yield through modification of milk protein composition can be achieved most rapidly by selection for cows with κ-casein BB and β-lactoglobulin BB genotypes