Dairy Cattle Breed Statistics and Crossbreeding

The Council on Dairy Cattle Breeding (CDCB) provides statistics on various traditional dairy breeds in the United States that are enrolled in Dairy Herd Improvement (DHI) testing programs. Crossbreeding is gaining popularity due to its potential to produce cattle with high milk yield, excellent fertility, and health. Geneticists recommend a three-breed rotational system to optimize hybrid vigor, using combinations like:

• Holstein – Montbeliarde – Viking Red
• Holstein – Brown Swiss – Jersey
• Holstein – Jersey – Swedish Red
• Jersey – Swedish Red – Normande

For those interested in specific breeds, websites for traditional US dairy breeds such as Ayrshire, Brown Swiss, Guernsey, Holstein, Jersey, Milking Shorthorn, and Red and White, along with a composite dairy cattle registry, are provided.

Predicted Transmitting Abilities (PTA) and Genetic Evaluations

Genetic evaluations in the United States are conducted three times a year. PTAs are calculated relative to a genetic base that updates every five years. These evaluations are provided by the CDCB for yield and fitness traits and by the Holstein Association USA Inc. for conformation traits. An example of a bull, JENNY-LOU MRSHL TOYSTORY-ET, is used to illustrate PTA, and technical details for calculating various traits are available from the CDCB. The Holstein Foundation also offers resources like a dairy judging workbook for those interested in learning more about conformation traits.

Economic Selection Indexes and Genetic Progress

This video focuses on the process of developing economic selection indexes, which are breed-specific for Holstein, Jersey, and Brown Swiss, and calculated in their home countries for other breeds like Norwegian Red and Montbeliarde. The rate of genetic response (ΔG/year) in elite breeding populations that provide bulls for artificial insemination is determined by a formula that includes selection intensity, genetic standard deviation, and generation interval. Bulls with many daughters have highly accurate genetic evaluations, but this can increase the generation interval. Shortening the generation interval and using semen from top bulls can help minimize the lag in genetic merit between elite and commercial herds.

Genomic Testing and New Traits in Dairy Cattle Breeding

Genomic selection technologies allow for more accurate genetic evaluations of young bulls, thereby shortening the generation interval. Companies like Neogen and Zoetis provide genotyping services in the United States, with the data processed by the CDCB to generate genomic PTAs. New traits are now being evaluated thanks to genomics, including health and wellness traits. For example, Zoetis’s Dairy Wellness traits predict an animal’s risk for diseases such as mastitis, lameness, and various transition cow disorders like metritis and ketosis. An example of genomic selection for respiratory disease resistance in calves is provided through research available on PubMed.

Conclusion

The previous posts provide a comprehensive overview of dairy cattle genetics, covering breed statistics, the advantages of crossbreeding, the calculation of PTAs and selection indexes, the importance of reducing generation intervals, and the role of genomic selection in evaluating new traits. The use of advanced technologies like genomic selection, artificial insemination, and breed-specific genetic strategies is key to driving genetic progress in the dairy industry.