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What Are We Breeding For, and Who Decides?


The future of dairy genetic programs are examined in an invited review published March 10, 2021, in the Journal of Dairy Science®.

John Cole, along with João Dürr and Ezequiel Nicolazzi of CDCB, authored the review, “The future of selection decisions and breeding programs: What are we breeding for, and who decides?.” It appears in advance of the Journal of Dairy Science, volume 104, issue 5 (May 2021), published by FASS Inc. and Elsevier.
 
According to a news release by JDS, the authors provide an insightful review of how U.S. dairy industry breeding selection objectives are established, and they detail opportunities and obstacles related to new technologies for documenting animal performance.
 
Genetic selection has been an extremely efficacious tool for the long-term enhancement of livestock populations, and the implementation of genomic selection has doubled the rate of gain in dairy cattle. Data captured through the national dairy herd improvement program are used to calculate genomic evaluations for comparing and ranking animals for selection. Over time, most of the focus on the selection indices used to rank bulls and cows on their genetic merit has changed from yield traits to fertility, health and fitness traits.
 
Today, most U.S. breeding stock are selected and marketed using the net merit dollars (NM$) selection index, which progressed from two traits in 1926 (milk and fat yield) to a mix of 36 individual traits following the most recent update three years ago. Updates to the index depend upon the estimation of a variety of values, and it can be challenging to reach an agreement among stakeholders on what should be included in the index at each review and how those traits should be weighted. Phenotypes for some of the new traits are difficult or costly to measure or depend upon changes to on-farm practices that have not been widely implemented. There is also a need to collect more comprehensive data about the environment in which animals perform, including information about feeding, housing, milking systems, and infectious and parasitic load.
 
“The rate of change is rapid, and farmers need objective sources of information more than ever before,” said first author John B. Cole, PhD, affiliated with USDA AGIL* at the time the review was accepted for publication. “The best way for the industry to meet the needs of the dairy producers, who drive the whole system, is to treat genetic evaluations as a shared good for the benefit of all.”
 
The number of traits evaluated continues to increase and is mind-boggling to many, which indicates that new approaches to classify and express traits may be necessary.
 
*United States Department of Agriculture, Animal Genomics and Improvement Laboratory


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