Ohio State DNA Marbling Test Update

Ohio State University research scientists Daral Jackwood and Francis Fluharty explained the basis of their DNA test for marbling potential during the BIF Emerging Technology Committee session Thursday afternoon in Omaha, Neb. The work, sponsored by Certified Angus Beef LLC (CAB), is based on association rather than linked studies, Jackwood said. That was necessary to avoid rejecting possibly significant markers in the initial search across a population of crossbred cattle, he added.
	“We started with 13 DNA sequences from areas we knew were important in marbling and tenderness, and chose RAPD [random amplified polymorphic DNA] and association analysis so that we could scan the entire bovine genome for these complex traits,” Jackwood said. 
	Only one significant marker has been discovered so far, he said, detailing the significance of the “613” marker for marbling potential, with its 0-, 1-, or 2-allele presence in bovine blood samples and shown by single or double-bright fluorescence in LightCycler analysis. In the initial test population of Angus and Simmental-Angus cross steers, there was little difference in marbling potential between individuals with 0 and 1 allele for 613, but some 89% with 2 alleles graded mid-Choice or higher. 
	Research partner Fluharty said in a followup study of Angus steers grading 93% Choice or better, the DNA marker test was still significant in that 96% of the steers grading Prime had 2 alleles of the 613 marker. He said inheritance studies found animals transmit 0, 1 or 2 copies of the 613 marker following simple Mendelian genetics, with expected outcomes noted on 578 animals 97% of the time. 
	Fluharty said the test could be useful for seedstock producers in taking a year or more off of the time required for generational selection decisions. It could be useful for feeders in targeting management and marketing.
	The scientists declined to estimate when the test would be commercially available, saying only that discussions were ongoing. They also said the significance of the test should not be overemphasized. “This will be a marketing focus tool, a piece of information, but no silver bullet,” Fluharty said. “Management will always be critical in whether an animal realizes its marbling potential.”
— by Steve Suther