Genomic Testing Accelerates

September 29, 2010 08:12 PM

Genomic testing of dairy cattle, with its first proofs offered in January 2009, is gaining even more momentum as high density SNP chips become available. Whereas the first tests look at 3,000 SNPs, the newest, high density chips will look at 800,000.

The higher density chips offer more accuracy.  For example, the parent average PTA for milk is about 42% reliable. Using the 3K chip increase accuracy to 60% and using the 800K chip bumps it to 72%.

The irony, notes Curt Van Tassell, USDA’s genomics guru, is that daughter data and progeny testing is still as critical today as it was prior to the genomic revolution. “Data is more critical than ever,” he says. Without daughter data, there is no way to verify whether the gene markers are accurate in the testing regime.

The other major concern with genomic selection is that it will increase inbreeding. But just the opposite might be true, if the technology is used correctly. Genomics can be used to identify sires with both high merit and be further away from breed average in terms of inbreeding. However, to know for sure, progeny tests of that particular bull’s daughters must be done to verify what the DNA tests are indicating, he says. 

The other hope is that genomics can be used to identify economically important, but lowly heritable traits much faster than conventional testing. For example, feed efficiency is critically important to both cost of production and carbon footprint. By intensively measuring feed efficiency in a 1,000 animals in a number of herds, for example, genomics should allow geneticists to identify the critical gene markers. That information can then be used to select high feed efficient sires. Again, field data is critical to verify the information.

Van Tassell spoke at one of the Education Seminars here at World Dairy Expo Wednesday. For more on genomic testing, visit the Holstein Association USA site.

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